Bond strength of AH Plus and Epiphany sealers on root dentine irradiated with 980 nm diode laser

Aim To evaluate the bond strength of AH Plus and Epiphany sealers to human root canal dentine irradiated with a 980 nm diode laser at different power and frequency parameters, using the push-out test. Methodology Sixty canine roots were sectioned below the cementoenamel junction to provide 4-mm-thick dentine discs that had their root canals prepared with a tapered bur and irrigated with sodium hypochlorite, ethylenediaminetetraacetic acid and distilled water. The specimens were assigned to five groups (n = 12): one control (no laser) and four experimental groups that were submitted to 980 nm diode laser irradiation at different power (1.5 and 3.0 W) and frequency (continuous wave and 100 Hz) parameters. Half of specimens in each group had their canals filled with AH Plus sealer and half with Epiphany. The push-out test was performed and data (MPa) were analysed statistically by ANOVA and Tukey`s test (P < 0.05). The specimens were split longitudinally and examined under SEM to assess the failure modes after sealer displacement. Results The specimens irradiated with the diode laser and filled with AH Plus had significantly higher bond strength values (8.69 +/- 2.44) than those irradiated and filled with Epiphany (3.28 +/- 1.58) and the nonirradiated controls (3.86 +/- 0.60). The specimens filled with Epiphany did not differ significantly to each other or to the control (1.75 +/- 0.69). There was a predominance of adhesive failures at Epiphany-dentine interface (77%) and mixed failures at AH Plus-dentine interface (67%). Conclusions The 980 nm diode laser irradiation of root canal dentine increased the bond strength of AH Plus sealer, but did not affect the adhesion of Epiphany sealer.

Effect of 980-nanometer diode laser on root canal permeability after dentin treatment with different chemical solutions

This study evaluated the effect of 980-nm diode laser at different parameters on root canal dentin permeability associated with different irrigants. Seventy-five canines were sectioned at 15 mm from the apex, prepared mechanically up to #40 .02 instrument, and irrigated with 2 mL distilled water. Final irrigation (10 mL) was used as follows: (1) distilled water; (2) 1% NaOCl; (3) 17% ethylenediaminetetraacetic acid + a cationic surfactant cetyltrimethylammonium bromide (EDTAC). Laser was applied at 1.5 or 3.0 W as either continuous wave or pulsed wave (100 Hz). The teeth were then processed histochemically, the percentage of copper ion penetration into the dentin of the canal walls was counted, and the data were analyzed statistically with the Tukey-Kramer test (alpha < .01). When laser was associated with water, an increase in permeability was found, whereas permeability decreased when associated with EDTAC. Dentin permeability after laser irradiation was directly dependent on the solution used for final irrigation.

Effect of Chelating Solutions on the Microhardness of Root Canal Lumen Dentin

Introduction: The greatest reduction in microhardness of the most superficial layer of dentin of the root canal lumen is desired. The use of chelating agents during biomechanical preparation of root canals removes smear layer, increasing the access of the irrigant into the dentin tubules to allow adequate disinfection, and also reduces dentin microhardness, facilitating the action of endodontic instruments. This study evaluated the effect of different chelating solutions on the microhardness of the most superficial dentin layer from the root canal lumen. Methods: Thirty-five recently extracted single-rooted maxillary central incisors were instrumented, and the roots were longitudinally sectioned in a mesiodistal direction to expose the entire canal extension. The specimens were distributed in seven groups according to the final irrigation: 15% EDTA, 10% citric acid, 5% malic acid, 5% acetic acid, apple vinegar, 10% sodium citrate, and control (no irrigation). A standardized volume of 50 mu L of each chelating solution was used for 5 minutes. Dentin microhardness was measured with a Knoop indenter under a 10-g load and a 15-second dwell time. Data were analyzed statistically by one-way analysis of variance and Tukey-Kramer multiple-comparison test at 5% significance level. Results: EDTA and citric acid had the greatest overall effect, causing a sharp decrease in dentin microhardness without a significant difference (p > .05) from each other. However, both chelators differed significantly from the other solutions (p < .001). Sodium citrate and deionized water were similar to each other (p > .05) and did not affect dentin microhardness. Apple vinegar, acetic acid, and malic acid were similar to each other (p > .05) and presented intermediate results. Conclusion: Except for sodium citrate, all tested chelating solutions reduced microhardness of the most superficial root canal dentin layer. EDTA and citric acid were the most efficient. (J Endod 2011;37:358-362)

Chemical sterilization in in vitro propagation of Arundina bambusifolia Lindl. and Epidendrum ibaguense Kunth

There is a great demand for simpler and less costly laboratory techniques and for more accessible procedures for orchid breeders who do not have the necessary theoretical basis to use the traditional seed and clone production methods of orchids in vitro. The aim of this study was to assess the use of sodium hypochlorite (NaClO) as a decontaminant in the process of inoculating adult orchid explants of Arundina bambusifolia and Epidendrum ibaguenses. Solutions of NaClO (1.200, 2.400, 3.600, 4.800 and 6.000 mg L-1 - equivalent to 50, 100, 150, 200 and 250 mL L-1 of commercial bleach - CB) were sprayed on the explants (1.0 mL) and the culture medium (GB5), in the presence or absence of activated charcoal (2 g L-1). The explants used were nodal segments of field-grown adult plants. The procedures for inoculating the explants were conducted outside the laminar flow chamber (LFC), except for the control treatment (autoclaved medium and explant inoculation inside the LFC). The best results for fresh weight yield, height and number of shoots were obtained using NaClO in solution at 1.200 mg L-1 (equivalent to 50 mL L-1 commercial bleach) with activated charcoal in the culture medium. Fresh weight figures were 1.10 g/jar for Arundina bambusifolia and 0.16 g/jar for Epidendrum ibaguenses. Spraying the NaClO solutions controls the contamination of the culture medium already inoculated with the explants.

Eliminação do Cr(VI) na fase de neutralização de um efluente industrial proveniente de processos de galvanoplastia

A presente tese teve por base a identificação e resolução de um problema existente no tratamento de efluentes provenientes dos processos de tratamento de superfícies por galvanoplastia, na OGMA – Indústria Aeronáutica de Portugal S.A.. Observou-se a ocorrência, esporádica, de crómio hexavalente, (Cr (VI)), em valor superior ao valor limite de emissão (VLE). Os resultados foram monitorizados e os dados recolhidos no decorrer da actividade de tratamento de efluentes, durante o período de, aproximadamente, 5 anos (2006 a 2011). A recolha de resultados decorreu no âmbito da actividade profissional da mestranda, que, para além da responsabilidade técnica dos processos de galvanoplastia na empresa, é também responsável pelo suporte técnico ao processo de tratamento de efluentes resultantes da actividade de tratamento de superficies por processos de galvanoplastia. A empresa OGMA – Indústria Aeronáutica de Portugal S.A., é uma empresa de actividade aeronáutica dedicada à Fabricação e Manutenção de aeronaves, nomeadamente a prestação de serviços de Manutenção, Revisão e Modernização de, Aeronaves, Motores e Componentes, bem como Fabricação e Montagem de Aeroestruturas. Integrada na OGMA, S.A. encontra-se a área de tratamentos electroquímicos, onde são realizados processos de tratamento de materiais metálicos por electrodeposição, deposição química e conversão química. Desta actividade resulta uma quantidade considerável de efluentes líquidos que necessitam de tratamento adequado previamente à sua descarga em cursos de água. Devido ao tipo de contaminantes que estes efluentes possuem, o tratamento dos mesmos é realizado em várias etapas, passando pela oxidação de cianetos, a redução de cromatos e a neutralização. Posteriormente segue-se uma sedimentação e a remoção de lamas. De modo a garantir um controlo dos parâmetros de descarga dos efluentes tratados, de acordo com a legislação ambiental em vigor, o efluente obtido é analisado periodicamente em laboratório acreditado. Na perspectiva de solucionar o problema em questão, procedeu-se à realização de ensaios experimentais utilizando os efluentes provenientes dos tanques de reacção da redução de cromatos e da oxidação de cianetos da linha com cádmio, com especial incidência na variação dos intervalos de pH recomendados para cada uma das fases do tratamento de efluentes, e observação do comportamento das misturas em termos de presença de Cr (VI), quando sujeitos a variações de pH. Após análise dos dados disponíveis e realização de todos os ensaios, conclui-se que, o processo de oxidação de cianeto da linha com cádmio e o processo de redução de cromatos na mesma linha estão a funcionar adequadamente. Concluiu-se que o reaparecimento de Cr (VI) ocorre devido à existência de hipoclorito de sódio, em excesso, no tanque de oxidação de cianeto que, quando passa para o tanque de neutralização e entra em contacto com o efluente proveniente do tanque de redução de cromatos, oxida parte do crómio trivalente, (Cr (III)), existente, a Cr (VI). Para impedir a ocorrência deste fenómeno separou-se todo o efluente contendo crómio que passou a ser tratado na linha de tratamento de efluentes isenta de cádmio, não entrando assim em contacto com o efluente que contém hipoclorito não reagido, evitando a oxidação do Cr (III) a Cr (VI).

Citotoxicidade do ácido peracético: avaliação metabólica, estrutural e de morte em fibroblastos L929

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

Biocompatibilidade de resinas acrílicas para base e reembasamento de próteses após períodos de imersão em soluções desinfetantes: análise do metabolismo celular

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

In vitro action of some disinfectants on Paracoccidioides brasiliensis yeast forms

The fungicidal action of sodium hypochlorite (0.3, 1, 2.5, 5 and 10%); formaldehyde (2, 5, and 10%); and ethyl alcohol (70%) on yeast forms of Paracoccidioides brasiliensis Pb 18 and a newly-isolated Goiana strain was described. Contact between the fungus and the disinfectants was maintained for 1, 2, 24, 48 and 72 hours at room temperature. Viability was evaluated by the fluorescein diacetate-ethidium bromide treatment, culture in solid and liquid media (36ºC and 26ºC); yeast to mycelial germination at room temperature; and radiometric study of metabolic activity. All concentrations of disinfectants were found to be effective in inactivating Pb 18 and Goiana strains, except for the 1-hour contact with 2% formaldehyde, in which fluorescein diacetate-ethidium bromide treatment was found to reveal 40 and 27% of viable cells, respectively. The yeast to mycelial germination method was considered to reveal faster and similar results as compared to culture in solid and liquid media.

Antibacterial properties of multifunctional coatings Ag-ZrCN for biomedical devices: a novel approach

PhD in Sciences Specialty in Physics

Reproducing the organic matter model of anthropogenic dark earth of Amazonia and testing the ecotoxicity of functionalized charcoal compounds

The objective of this work was to obtain organic compounds similar to the ones found in the organic matter of anthropogenic dark earth of Amazonia (ADE) using a chemical functionalization procedure on activated charcoal, as well as to determine their ecotoxicity. Based on the study of the organic matter from ADE, an organic model was proposed and an attempt to reproduce it was described. Activated charcoal was oxidized with the use of sodium hypochlorite at different concentrations. Nuclear magnetic resonance was performed to verify if the spectra of the obtained products were similar to the ones of humic acids from ADE. The similarity between spectra indicated that the obtained products were polycondensed aromatic structures with carboxyl groups: a soil amendment that can contribute to soil fertility and to its sustainable use. An ecotoxicological test with Daphnia similis was performed on the more soluble fraction (fulvic acids) of the produced soil amendment. Aryl chloride was formed during the synthesis of the organic compounds from activated charcoal functionalization and partially removed through a purification process. However, it is probable that some aryl chloride remained in the final product, since the ecotoxicological test indicated that the chemical functionalized soil amendment is moderately toxic.

Apparent stable-isotope heterogeneities in gangue carbonates of the Mississippi Valley-type Zn-Pb deposits of San-Vicente, Central Peru

The aim of the present communication is to emphasize that some variations of the measured delta(13)C and delta(18)O values are apparent, and due to analytical interferences caused by the presence of sulfur and organosulfur compounds in the analyzed carbonates. This is particularly relevant for isotopic studies on carbonate-hosted mineral deposits, where the nearly ubiquitous association of the host carbonates with organic matter and sulfides can certainly affect the metallogenetic interpretations. In this work two methods were used to overcome the disturbing effects of sulfides and organic matter: (1) sample pretreatment following the method proposed by Charef and Sheppard (1984), combining the oxidation of organic matter with sodium hypochlorite and trapping of the sulfur species with silver phosphate; and (2) laser-based microprobe extraction. Apparent isotopic variations in sparry dolomite from a single hand sample of zebra ore from the MVT Zn-Pb deposit, San Vicente, central Peru, are as large as 6 parts per thousand delta(13)C and 4 parts per thousand delta(18)O. These variations are reduced to several tenths of a per mil when the samples are pretreated. A careful examination of the effects of treatment with NaOCl and/or Ag3PO4 in relation to the concentration of sulfide inclusions indicates that the main disturbing effects for delta(13)C values are the presence of sulfur species and organic matter, whereas the delta(18)O values are mainly affected by the presence of sulfides. Fine- and medium-grained replacement carbonates from MVT and other sediment-hosted base metal deposits are potentially the most affected during isotope analysis, due to the common presence of organic matter and sulfides. Using in situ laser microprobe techniques, it is possible to determine isotopic variations at a sub-millimeter scale. Our results show that laser extraction analysis allows a more precise sampling of the carbonate minerals, and minimizes contamination of the sample with sulfides and to some extent with intergrown organic matter. However, there is an isotopic shift associated with the laser extraction technique, of the order of 0.5-1 parts per thousand for delta(13)C and delta(18)O values.

Paperitehdasintegraatin tuorevesien käsittely kloorikaasun korvaavalla menetelmällä

Työn tarkoitus on löytää paperitehdasintegraatin tuorevesien käsittelyyn kloorikaasun korvaava desinfiointimenetelmä Stora Enso Publication Papers Oy Ltd.:n Anjalan tehtailla. Tehtaalla on ympäristöluvassaan velvoite selvittää mahdollisuudet tuoreveden desinfiointiin käytettävän kaasumaisen kloorin korvaamiseen hypokloriitilla. Kloorikaasun käyttö tehtaalla on työturvallisuusriski, ja jäännösklooripitoisuuksien hallittavuus kloorikaasua käytettäessä on heikko. Työssä tutkittava vesijae on kemiallisesti puhdistettu vesi. Koeajossa käytettävät kemikaalit ovat 10 % natriumhypokloriitti (NaOCl) ja kantaja-aine eli bromikloori- di-metyyli-hydantoiini (BCDMH). Tuloksista voidaan päätellä, että NaOCl:lla ja NaOCl:lla yhdessä BCDMH:n kanssa saavutetaan veden käyttökohteessa korkeammat aktiivisen kloorin jäännöspitoisuudet kuin kloorikaasulla. NaOCl:n ja kaksikomponenttisysteemin käyttökustannukset ovat kuitenkin yli kuusinkertaiset kloorikaasuun verrattuna. NaOCl annosteltuna yhteen pisteeseen olisi vaivattomin menetelmä kloorikaasun korvaamiseen. NaOCl:n annostelulla kahteen pisteeseen voitaisiin saavuttaa korkeampia jäännöspitoisuuksia kuin yhden pisteen annostelulla, mutta menetelmä vaatii lisätutkimuksia. Kaksikomponenttisysteemillä saavutetaan korkeimmat aktiivisen kloorin jäännöspitoisuudet, mutta sen seurantamenetelmien luotettavuudesta tulee varmistua ennen menetelmän käyttöönottoa. Korroosion ehkäisyn ja työturvallisuuden kannalta sekä NaOCl että NaOCl yhdessä BCDMH:n kanssa ovat turvallisempia vaihtoehtoja kuin kaasukloori.

Hapettavan BIMODES-mikrobientorjuntamenetelmän vaikutukset paperikoneella

The aim of this study was to examine the effects of oxidising BIMODES microbiological control program on three paper machine process. The chemicals used in BIMODES program are sodium hypochlorite (NaOCl) and bromo-chloro-di-methyl-hydantoin (BCDMH). The literary part of this study discusses the microbiological problems in paper making industry, describes functional mechanisms of oxidants and also introduces the BIMODES- program. In the experimental part the aim was to examine the effects of BIMODES in three different paper machines. The purpose was to find out the effects and changes in wet end chemistry, bacterial counts, in the other additives and also in the sheet defects and holes. The study also examines what are the most important measurements to control BIMODES dosing. In addition the optimal dosing level for each machine was tried to find out. It was found that there is a clear correlation between the total chlorine level and bacterial counts. Changes in the BIMODES dosing level can be measured by redox potential, but the correlation is very poor. BIMODES program doesn’t have straight influence to pH values, but if dosage level is too low the bacterial activity can affect degreasing in the pH value. In this study couldn’t find any consequential effects for the other additives by using BIMODES. In addition the optimal dosing levels were found and by following correct halogen levels it is possible to decrease bacterial levels for very low level.

Determinação espectrofotométrica por injeção em fluxo de paracetamol (acetaminofeno) em formulações farmacêuticas

A flow injection spectrophotometric procedure is proposed for the determination of paracetamol (acetaminophen) in pharmaceutical formulations. Powdered and liquid samples were previously dissolved/diluted in 0.05 mol L-1 hydrochloric acid solution and a volume of 250 µL was injected directly into a carrier stream of this same acid solution, flowing at 2.5 mL min-1. Paracetamol reacts with sodium hypochlorite forming N-acetyl-p-benzoquinoneimine which then reacts with sodium salicylate in sodium hydroxide solution yielding a blue indophenol dye which was measured at 640 nm in the pH range of 9.5-10.0. Paracetamol was determined in pharmaceutical products in the 1.0 to 100.0 mg L-1 (3.3x10-6 a 6.6x10-4 mol L-1) concentration range, with a detection limit of 0.5 mg L-1 (1.6x10-6 mol L-1). The recovery of this analyte in five samples ranged from 98.0 to 103.6 %. The analytical frequency was 80 determinations per hour and the RSDs were less than 1% for paracetamol concentrations of 25.0, 50.0 and 75.0 mg L-1 (n=10). A paired t-test showed that all results obtained for paracetamol in commercial formulations using the proposed flow injection procedure and a spectrophotometric batch procedure agree at the 95% confidence level.

Efeitos da beta-polinitração na eficiência catalítica de rutenioporfirinas em reações de oxidação de cicloexano

Rutheniumporphyrins, especially with several nitro groups in b-positions, were used in the cyclohexane oxidation in the presence of iodosylbenzene, hydrogen peroxide and sodium hypochlorite as oxygen donors, under mild conditions. The beta-polynitrated complexes were able to promote the catalytic cyclohexane oxidation. They show an exceptionally high catalytic efficiency and resistance to attack by strong oxidizing agents. The cyclohexane oxidation was monitored by gas chromatography and the results showed that the beta-polynitrated rutheniumporphyrins are better catalysts when compared to other complexes not beta-polynitrated. In all cases, the 2-phenylsubstituted complexes were more efficient than 4-phenylsubstituted complexes. The importance of the ortho effect to oxidation was shown.