978 resultados para pulp drying


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

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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This study aimed to evaluate the sensitiveness of the information obtained for the residual lignin from Eucalyptus grandis kraft pulps analyzed through the nitrobenzene oxidation, copper oxide (CuO) reduction and acidolysis techniques. The chips were cooked, resulting pulps of kappa number 14,5 and 16,9, respectively. Both lignins' pulps were evaluated through three methods (nitrobenzene oxidation, copper oxide oxidation and acidolysis). Then, they were subjected to an oxygen delignification stage. The 16,9 kappa number pulp resulted in higher levels of non-condensed lignin structures by the acidolysis method, higher syringyl/vanillin ratios (S/V) by the nitrobenzene and copper oxide methods and better performance in the oxygen delignification stage. The different methods allowed to differ the residual lignin pulps with kappa number 14,5 and 16,9, and the nitrobenzene oxidation method showed the highest sensitiveness in this study results.

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According to the Convention on International Trade in Endangered Species, 36 wild feline species are threatened by extinction or severely endangered, and to save them is the target of several conservation programs. This study aimed to assess the viability of the freeze-drying technique for domestic cat sperm cells, with the ultimate goal of transferring this technology to the wild feline species. The domestic cat is an excellent experimental model for wild felids. It is in this scenario that the freeze-drying process (low-temperature vacuum dehydration) of sperm cells shows its value in preserving male cats' germplasm. Results from membrane and DNA integrity analysis are promising and validates the use of frozen-dried sperm samples in intracytoplasmic sperm injections (ICSIs). Further studies are still necessary to evaluate the ICSI embryo production using domestic cat frozen-dried sperm and the possibility of using such technology with wild felines.

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

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Turmeric (Curcuma longa L.), which has been used for long time as a spice, food preservative and coloring agent, is a rich source of beneficial phenolic compounds identified as curcuminoids. These phenolic compounds are known for their antioxidant, anti-inflammatory and antimutagenic properties, among others. On the other hand, they are very susceptible to oxidation, requiring protection against oxygen, light and heat. This protection can be achieved by microencapsulation. In this work, the characteristics and the stability of turmeric oleoresin encapsulated by freeze-drying using mixtures of maltodextrin and gelatin as wall materials were studied. Encapsulated turmeric oleoresin was stored at –20, 25 and 60 °C, in the absence of light, and analyzed over a period of 35 days for curcumin and total phenolic contents and color. Results showed that the samples produced with 26% maltodextrin/0.6% gelatin and 22% maltodextrin/3% gelatin presented good encapsulation efficiencies and solubility. In general, the method of encapsulation employed originated products with satisfactory thermal stability, although the encapsulated materials with a higher proportion of maltodextrin in relation to gelatin had better stabilities, especially at –20 and 25 °C temperatures.

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

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

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To assess the cytotoxicity of 35% hydrogen peroxide (HP) bleaching gel applied for 15 min to sound or restored teeth with two-step self-etching adhesive systems and composite resin. Materials and Methods: Sound and restored enamel/dentin disks were stored in water for 24 h or 6 months + thermocycling. The disks were adapted to artificial pulp chambers and placed in compartments containing culture medium. Immediately after bleaching, the culture medium in contact with dentin was applied for 1 h to previously cultured odontoblast-like MDPC-23 cells. Thereafter, cell viability (MTT assay) and morphology (SEM) were assessed. Data were analyzed by two-way ANOVA and Tukey's test (a = 5%). Results: In comparison to the negative control group (no treatment), no significant cell viability reduction occurred in those groups in which sound teeth were bleached. However, a significant decrease in cell viability was observed in the adhesive-restored bleached groups compared to negative control. No significant difference among bleached groups was observed with respect to the presence of restoration and storage time. Conclusion: The application of 35% HP bleaching gel to sound teeth for 15 min does not cause toxic effects in pulp cells. When this bleaching protocol was performed in adhesive-restored teeth, a significant toxic effect occurred.

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To evaluate the short-term response of human pulps to ethanol-wet bonding technique. Methods Deep class V cavities were prepared on 17 sound premolars and divided into three groups. After acid-etching, the cavities from groups 1 (G1) and 2 (G2) were filled with 100% ethanol or distilled water, respectively, for 60 s before the application of Single Bond 2. In group 3 (G3, control), the cavity floor was lined with calcium hydroxide before etching and bonding. All cavities were restored with resin composite. Two teeth were used as intact control. The teeth were extracted 48 h after the clinical procedures. From each tooth serial sections were obtained and stained with haematoxylin and eosin (H/E) and Masson's trichrome. Bacteria microleakage was assessed using Brown & Brenn. All sections were blindly evaluated for five histological features. Results Mean remaining dentine thickness was 463 ± 65 μm (G1); 425 ± 184 μm (G2); and 348 ± 194 μm (G3). Similar pulp reactions followed ethanol- or water-wet bonding techniques. Slight inflammatory responses and disruption of the odontoblast layer related to the cavity floor were seen in all groups. Stained bacteria were not detected in any cavities. Normal pulp tissue was observed in G3 except for one case. Conclusions After 48 h, ethanol-wet bonding does not increase pulpal damage compared to water-wet bonding technique. Clinical significance Ethanol-wet bonding may increase resin-dentine bond durability. This study reported the in vivo response of human pulp tissue when 100% ethanol was applied previously to an etch-and-rinse simplified adhesive system.

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To evaluate the effect of the oxidative stress on human dental pulp cells (HDPCs) promoted by toxic concentrations of hydrogen peroxide (H2O2) on its odontoblastic differentiation capability through time. Methods HDPCs were exposed to two different concentrations of H2O2 (0.1 and 0.3 μg/ml) for 30 min. Thereafter, cell viability (MTT assay) and oxidative stress generation (H2DCFDA fluorescence assay) were immediately evaluated. Data were compared with those for alkaline phosphatase (ALP) activity (thymolphthalein assay) and mineralized nodule deposition (alizarin red) by HDPCs cultured for 7 days in osteogenic medium. Results A significant reduction in cell viability and oxidative stress generation occurred in the H2O2-treated cells when compared with negative controls (no treatment), in a concentration-dependent fashion. Seven days after H2O2 treatment, the cells showed significant reduction in ALP activity compared with negative control and no mineralized nodule deposition. Conclusion Both concentrations of H2O2 were toxic to the cells, causing intense cellular oxidative stress, which interfered with the odontogenic differentiation capability of the HDPCs. Clinical significance The intense oxidative stress on HDPCs mediated by H2O2 at toxic concentrations promotes intense reduction on odontoblastic differentiation capability in a 7-day evaluation period, which may alter the initial pulp healing capability in the in vivo situation.