Fractal analysis along stretch zone for an aluminum alloy

The topography of fracture surface along stretch zone front for Al7050 is analyzed about its fractal behavior and compared against local distributions of microstructural parameters and stretch zone height, considered here as a toughness parameter. Major influence on microscale was presented by precipitation density. Larger grains should be significant on topographic behavior at macroscale, besides the local toughness measured along stretch zone. The large scattering of fractal measurements along specimen width should limit the validity of models relating fractal values and fracture toughness. It is proposed that models based on mixed fractals must also consider some dispersion parameter instead of mean fractal measurements due to the overall complexity of fracture relief formation. It is suggested that sampling for fractal measurement must be restricted to plane strain region along fracture surface, due to smaller scattering in this region. (C) 2004 Elsevier B.V. All rights reserved.

Evaluation on fatigue strength of AISI 4340 steel aluminum coated by electroplating and IVD processes

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

Comparative analysis of root surface smear layer removal by different etching modalities or erbium:yttrium-aluminum-garnet laser irradiation. A scanning electron microscopy study

The purpose of this study was to evaluate the effect of erbium:yttrium-aluminum-garnet (Er:YAG) laser (2.94 mu m) irradiation on the removal of root surface smear layer of extracted human teeth and to compare its efficacy with that of citric acid, ethylenediamine tetra-acetic acid (EDTA), or a gel containing a mixture of tetracycline hydrochloride (HCl) and citric acid, using scanning electron microscopy (SEM). Thirty human dentin specimens were randomly divided into six groups: G1 (control group), irrigated with 10 ml of physiologic saline solution; G2, conditioned with 24% citric acid gel; G3, conditioned with 24% EDTA gel; G4, conditioned with a 50% citric acid and tetracycline gel; G5, irradiated with Er:YAG laser (47 mJ/10 Hz/5.8 J/cm(2)/pulse); G6, irradiated with Er:YAG laser (83 mJ/10 Hz/10.3 J/cm(2)/pulse). Electron micrographs were obtained and analyzed according to a rating system. Statistical analysis was conducted with Kruskal-Wallis and Mann-Whitney tests (P < 0.05). G1 was statistically different from all the other groups; no statistically significant differences were observed between the Er:YAG laser groups and those undergoing the other treatment modalities. When the two Er:YAG laser groups were compared, the fluency of G6 was statistically more effective in smear layer removal than the one used in G5 (Mann-Whitney test, P < 0.01). Root surfaces irradiated by Er:YAG laser had more irregular contours than those treated by chemical agents. It can be concluded that all treatment modalities were effective in smear layer removal. The results of our study suggest that the Er:YAG laser can be safely used to condition diseased root surfaces effectively. Furthermore, the effect of Er:YAG laser irradiation on root surfaces should be evaluated in vivo so that its potential to enhance the healing of periodontal tissues can be assessed.

Prostaglandin production by human gingival fibroblasts inhibited by triclosan in the presence of cetylpyridinium chloride

Background: the effect of triclosan plus the cationic detergent cetylpyridinium chloride (CPC) was evaluated for prostaglandin inhibition in human gingival fibroblasts. Since triclosan has previously been shown to inhibit proinflammatory cytokine induced prostaglandin E-2 (PGE(2)) production, we wanted to determine if triclosan, in the presence of CPC, could enhance these effects.Methods: Initial studies determined that both triclosan and CPC were cytotoxic to human gingival fibroblasts in concentrations exceeding 1.0 mu g/ml for either agent longer than 24 hours in a tissue culture. Therefore, subsequent studies measuring prostaglandin biosynthesis and cyclooxygenase (COX)-1 and COX-2 mRNA expression were performed in concentrations and times that did not significantly affect cell viability.Results: PGE2 biosynthesis was dose dependently inhibited by both triclosan and triclosan and CPC when challenged by tumor necrosis factor (TNF)-alpha or interleukin (IL)-1 beta. At pharmacologically relevant concentrations, triclosan and CPC inhibited ILAP-induced PGE(2) production to a greater extent than triclosan alone (P = 0.02). Moreover, enhanced COX-2 mRNA repression was observed with triclosan and CPC in comparison to triclosan alone in IL-1 beta and TNF-alpha stimulated cells. No effect on COX-I gene expression was observed. Further analysis of cell signaling mechanisms of triclosan and CPC indicates that nuclear factor-kappa B (NF-kappa B) and not p38 mitogen-activated protein kinase (MAPK) signaling may be impaired in the presence of triclosan and CPC.Conclusion: This study indicates that triclosan and CPC are more effective at inhibiting PGE(2) at the level of COX-2 gene regulation, and this combination may offer a potentially better anti -inflammatory agent in the treatment of inflammatory lesions in the oral cavity.

Effects of aluminum-copper alloy filtration on photon spectra, air kerma rate and image contrast

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Baclofen into the lateral parabrachial nucleus induces hypertonic sodium chloride and sucrose intake in rats

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

EFFECT of METAL PRIMERS on BOND STRENGTH of RESIN CEMENTS TO BASE METALS

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

Determination of the maximum inhibitory dilution of cetylpyridinium chloride-based mouthwashes against Staphylococcus aureus: an in vitro study

The aim of this in vitro study was to determine the maximum inhibitory dilution (MID) of four cetylpyridinium chloride (CPC)based mouthwashes: CPC+Propolis, CPC+Malva, CPC+Eucaliptol+Jua+Roma+Propolis (Natural Honey (R)) and CPC (Cepacol (R)), against 28 Staphylococcus aureus field strains, using the agar dilution method. Decimal dilutions ranging from 1/10 to 1/655,360 were prepared and added to Mueller Hinton Agar. Strains were inoculated using Steers multipoint inoculator. The inocula were seeded onto the surface of the culture medium in Petri dishes containing different dilutions of the mouthwashes. The dishes were incubated at 37 degrees C for 24 h. For readings, the MID was considered as the maximum dilution of mouthwash still capable of inhibiting microbial growth. The obtained data showed that CPC+Propolis had antimicrobial activity against 27 strains at 1/320 dilution and against all 28 strains at 1/160 dilution, CPC+Malva inhibited the growth of all 28 strains at 1/320 dilution, CPC+Eucaliptol+Jua+Roma+Propolis inhibited the growth of 2 strains at 1/640 dilution and all 28 strains at 1/320 dilution, and Cepacol (R) showed antimicrobial activity against 3 strains at 1/320 dilution and against all 28 strains at 1/160 dilution. Data were submitted to Kruskal-Wallis test, showing that the MID of Cepacol (R) was lower than that determined for the other products (p<0.05). In conclusion, CPC-mouthwashes showed antimicrobial activity against S. aureus and the addition of other substances to CPC improved its antimicrobial effect.

The Influence of Calcium Chloride on the Setting Time, Solubility, Disintegration, and pH of Mineral Trioxide Aggregate and White Portland Cement with a Radiopacifier

This study evaluated the influence of addition of 10% calcium chloride (CaCl(2)) on the setting time, solubility, disintegration, and pH of white MTA (WMTA) and white Portland cement (WPC). A test of the setting time was performed following the #57 ADA specifications and a test of the final setting time according to the ASTM. For the solubility tests disintegration and pH, Teflon rings were filled with the cements and weighed after setting. After 24 h in a desiccator, they were once again weighed. Thereafter, they were immersed in MiliQ water for 24 and 72 h and 7, 14, and 28 days, with maintenance in the desiccator and weighing between periods. The pH of water in which the rings were immersed was measured immediately after contact with them and in the other periods. The addition of CaCl(2) provided a significant reduction (50%) in the initial setting time of cements. The final setting time of WMTA was reduced in 35.5% and the final setting time of WPC in 68.5%. The WMTA with CaCl(2) absorbed water and gained weight with time, except for in the 24-h period. The addition of CaCl(2) to the WPC reduced its solubility. The addition of CaCl(2) increased the pH of WMTA in the immediate period and at 24 and 72 h and for WPC in the immediate period and at 24 h. The addition of CaCl(2) to WMTA and WPC reduced the setting times and solubility of both and increased the pH of cements in the initial periods. (J Endod 2009;35:550-554)

Influence of different levels of aluminum on the development of citrus rootstock swingle citrumelo (Citrus paradisi mcf. x Poncirus trifoliata raf.) in nutrient solution

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Histochemical technique for the detection of chloride cells in fish

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

Morphological Changes in Poly(Caprolactone)/Poly(Vinyl Chloride) Blends Caused by Biodegradation

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

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.

Photodegradation of polycaprolactone/poly(vinyl chloride) blend

The photodegradation of a 1:1 w/w blend of polycaprolactone and poly(vinyl chloride) has been studied by following carbon dioxide emission during UV exposure. Similar measurements were performed for polycaprolactone and poly(vinyl chloride) homopolymers which were prepared and irradiated in the same way. It was found that the blend gave lower CO2 emission than either of the two homopolymers, indicating that the interaction of the two components in the blend provided a beneficial reduction of photodegradation. It is therefore deduced that the detailed morphological characteristics of the blend have a controlling influence over the photo-oxidation. (c) 2007 Elsevier Ltd. All rights reserved.

Biodegradation of a polylactic acid/polyvinyl chloride blend in soil

This study investigated the microbial action in soil on poly(L-lactic acid) (PLLA) and polyvinyl chloride (PVC) films and a PLLA/PVC 7 : 3 blend, using Fourier transform infrared spectroscopy (FTIR), contact angle and scanning electron microscopy (SEM). The films (50 mu m) were obtained from the evaporation of dichloromethane solutions and buried in soil columns, in controlled conditions, for 120 days. The results showed that the surface of the PLLA films and blend became 18 and 31% more hydrophilic, respectively. The morphology of the films also changed after 120 days of microbial treatment, particularly that of the PLLA phase in the blend, confirmed by structural and conformational changes in the FTIR CO region at 12001000 cm1 and an increase in the relative intensity of the band at 1773 cm1, which was attributed to C O group vibration due to a rotational isomer in the interlamellar region (semi-ordered region). Besides the biotreated PVC presented changes in the C-Cl band at 738 cm1, due to the presence of some PVC conformational isomer. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012