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Rabelo, Katharina Alves,Cavalcanti, Yuri Wanderley,de Oliveira Pinto, Martina Gerlane,Melo, Saulo Leonardo Sousa,Campos, Paulo Sergio Flores,de Andrade Freitas Oliveira, Luciana Soares,de Melo, Daniel Korean Academy of Oral and Maxillofacial Radiology 2017 Imaging Science in Dentistry Vol.47 No.3
Purpose: To quantify artifacts from different root filling materials in cone-beam computed tomography (CBCT) images acquired using different exposure parameters. Materials and Methods: Fifteen single-rooted teeth were scanned using 8 different exposure protocols with 3 different filling materials and once without filling material as a control group. Artifact quantification was performed by a trained observer who made measurements in the central axial slice of all acquired images in a fixed region of interest using ImageJ. Hyperdense artifacts, hypodense artifacts, and the remaining tooth area were identified, and the percentages of hyperdense and hypodense artifacts, remaining tooth area, and tooth area affected by the artifacts were calculated. Artifacts were analyzed qualitatively by 2 observers using the following scores: absence (0), moderate presence (1), and high presence (2) for hypodense halos, hypodense lines, and hyperdense lines. Two-way ANOVA and the post-hoc Tukey test were used for quantitative and qualitative artifact analysis. The Dunnet test was also used for qualitative analysis. The significance level was set at P<.05. Results: There were no significant interactions among the exposure parameters in the quantitative or qualitative analysis. Significant differences were observed among the studied filling materials in all quantitative analyses. In the qualitative analyses, all materials differed from the control group in terms of hypodense and hyperdense lines (P<.05). Fiberglass posts did not differ statistically from the control group in terms of hypodense halos(P>.05). Conclusion: Different exposure parameters did not affect the objective or subjective observations of artifacts in CBCT images; however, the filling materials used in endodontic restorations did affect both types of assessments.
Greison Rabelo de Oliveira,Leandro Pozzer,Lucas Cavalieri-Pereira,Paulo Hemerson de Moraes,Sergio Olate,Jose Ricardo de Albergaría Barbosa 대한치주과학회 2012 Journal of Periodontal & Implant Science Vol.42 No.6
Purpose: Several parameters have been described for determining the success or failure of dental implants. The surface properties of transgingival implant components have had a great impact on the long-term success of dental implants. The purpose of this study was to compare the tendency of two periodontal pathogens to adhere to and colonize zirconia abutments and titanium alloys both in hard surfaces and soft tissues. Methods: Twelve patients participated in this study. Three months after implant placement, the abutments were connected. Five weeks following the abutment connections, the abutments were removed, probing depth measurements were recorded,and gingival biopsies were performed. The abutments and gingival biopsies taken from the buccal gingiva were analyzed using real-time polymerase chain reaction to compare the DNA copy numbers of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and total bacteria. The surface free energy of the abutments was calculated using the sessile water drop method before replacement. Data analyses used the Mann Whitney U-test, and P-values below 0.05 find statistical significance. Results: The present study showed no statistically significant differences between the DNA copy numbers of A. actinomycetemcomitans,P. gingivalis, and total bacteria for both the titanium and zirconia abutments and the biopsies taken from their buccal gingiva. The differences between the free surface energy of the abutments had no influence on the microbiological findings. Conclusions: Zirconia surfaces have comparable properties to titanium alloy surfaces and may be suitable and safe materials for the long-term success of dental implants.
Lucas Rabelo Crunivnel,Gregorio Sandro Vieira,Juliano Geraldo Ribeiro Neto 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.6
Due to the wide variety of cross-sections and their good mass/strength ratio, cold-formed steel (CFS) components are gaining prominence among steel structures, although this material is more susceptible to local, distortional, and global buckling. The design procedure based on the direct strength method (DSM) presented in some codes as the Brazilian, the American Iron and Steel Institute, and the Australia/New Zealand (AS/NZ), have been well accepted for estimating simply and safely the moment capacity of beams subject to distortional buckling. However, more recent studies show that DSM design can lead to unsafe moment capacity for beams with a high slenderness factor of distortional buckling. This study analyzes the results from 64 models developed using the fi nite element analyses (FEA) with the Abaqus software to determine the distortional moment capacity of CFS rack type beams. The selection of the specimens in which the distortional buckling mode is predominant (modal participation analysis) was performed through a linear stability analysis using the GBTul software. The nonlinear elastoplastic fi nite element model was created, including initial imperfections, and a parametric study was developed to investigate the infl uence of the slenderness factor of distortional buckling on CFS rack beams' moment capacity. The FEA results were compared with DSM results to verify the accuracy of this method to predict distortional moment capacity. It is shown that, for CFS rack beams subject to uniform bending and distortional buckling with slenderness factor of distortional buckling higher than 1.0, the DSM overestimates the moment capacity.
Influence of Electrolytic and Crevice Corrosion on Mechanical Resistance of Porcelain Insulators
Matheus Rabelo,Simpy Sanyal,Taeyong Kim,Ju-Am Son,In-Hyuk Choi,Junsin Yi 한국신재생에너지학회 2021 한국신재생에너지학회 학술대회논문집 Vol.2021 No.7
Porcelain insulators are widely used in transmission lines; however, their durability and considerable overall maintenance cost have become problems over the years. In this work, porcelain insulators were collected from various locations in South Korea and classified according to their length of service. Mechanical and electrical load tests were performed, and the failure load and damaged region were recorded for each specimen. The fast degradation of the pin in porcelain insulators exceeding 50 years in operation was notable because there was no pin breakage among the samples in service for less than 50 years. Moreover, the failure of 73.68% of all porcelain insulators in service for 54 years occurred in the pin. The average failure load of these samples was 14% lower than that of samples in use for 45 years. To confirm the pin’s deterioration mechanism over time, a mechanical analysis of the reduction in the pin cross-section was performed using the finite element analysis method. Accordingly, a novel degradation mechanism is proposed in this study. Previous studies that focused on the critical areas of the porcelain insulator found that the exposed pin side was easily damaged by the external load. The current findings revealing an unfamiliar porcelain deterioration mechanism may aid in the formulation of a better design to mitigate the problems described above.
Katharina Alves Rabelo,Yuri Wanderley Cavalcanti,Martina Gerlane de Oliveira Pinto,Saulo Leonardo Sousa Melo,Paulo Sérgio Flores Campos,Luciana Soares de Andrade Freitas Oliveira,Daniela Pita de Melo 대한영상치의학회 2017 Imaging Science in Dentistry Vol.47 No.3
Purpose: To quantify artifacts from different root filling materials in cone-beam computed tomography (CBCT) images acquired using different exposure parameters. Materials and Methods: Fifteen single-rooted teeth were scanned using 8 different exposure protocols with 3 different filling materials and once without filling material as a control group. Artifact quantification was performed by a trained observer who made measurements in the central axial slice of all acquired images in a fixed region of interest using ImageJ. Hyperdense artifacts, hypodense artifacts, and the remaining tooth area were identified, and the percentages of hyperdense and hypodense artifacts, remaining tooth area, and tooth area affected by the artifacts were calculated. Artifacts were analyzed qualitatively by 2 observers using the following scores: absence (0), moderate presence (1), and high presence (2) for hypodense halos, hypodense lines, and hyperdense lines. Two-way ANOVA and the post-hoc Tukey test were used for quantitative and qualitative artifact analysis. The Dunnet test was also used for qualitative analysis. The significance level was set at P<.05. Results: There were no significant interactions among the exposure parameters in the quantitative or qualitative analysis. Significant differences were observed among the studied filling materials in all quantitative analyses. In the qualitative analyses, all materials differed from the control group in terms of hypodense and hyperdense lines (P<.05). Fiberglass posts did not differ statistically from the control group in terms of hypodense halos (P>.05). Conclusion: Different exposure parameters did not affect the objective or subjective observations of artifacts in CBCT images; however, the filling materials used in endodontic restorations did affect both types of assessments.
Baccharis trimera (carqueja) promotes gastroprotection on ethanol-induced acute gastric ulcer
Ana Carolina Silveira Rabelo,Fernanda Caetano Camini,Melissa Maia Bittencourt,Kíssyla Lacerda,Wanderson Geraldo de Lima,Daniela Caldeira Costa 경희대학교 융합한의과학연구소 2020 Oriental Pharmacy and Experimental Medicine Vol.20 No.4
One of the factors that can promote gastric ulcer is the acute and/or chronic consumption of ethanol. One of the most used therapeutic measures is the use of proton pump inhibitor, like omeprazole. However, these drugs have several side effects, making it necessary to search for new alternatives. To investigate the gastroprotective effect of Baccharis trimera (carqueja) we used an ethanol-induced acute gastric ulcer model. For this, gastric ulcer was induced in rats using absolute ethanol for 2 consecutive days. After analysis of the stomach, an increase in oxidative stress was observed, as well as the reduction of the antioxidant defense. In addition, we observed in histology that there was an increase in inflammatory cells, necrosis, hemorrhage and hyperemia. Treatment with B. trimera was able to decrease oxidative damage as well as improve antioxidant defense. There was also a decrease in inflammation, collagen area and hemorrhage. All the beneficial effects promoted by carqueja were similar to those found by the positive controls used in our study (vitamin C and omeprazole). Analyzing our data, we can conclude that B. trimera presents a gastroprotective effect and should be further studied for its application in gastric ulcer therapy.
De Oliveira, Greison Rabelo,Pozzer, Leandro,Cavalieri-Pereira, Lucas,De Moraes, Paulo Hemerson,Olate, Sergio,De Albergaria Barbosa, Jose Ricardo Korean Academy of Periodontology 2012 Journal of Periodontal & Implant Science Vol.42 No.6
Purpose: Several parameters have been described for determining the success or failure of dental implants. The surface properties of transgingival implant components have had a great impact on the long-term success of dental implants. The purpose of this study was to compare the tendency of two periodontal pathogens to adhere to and colonize zirconia abutments and titanium alloys both in hard surfaces and soft tissues. Methods: Twelve patients participated in this study. Three months after implant placement, the abutments were connected. Five weeks following the abutment connections, the abutments were removed, probing depth measurements were recorded, and gingival biopsies were performed. The abutments and gingival biopsies taken from the buccal gingiva were analyzed using real-time polymerase chain reaction to compare the DNA copy numbers of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and total bacteria. The surface free energy of the abutments was calculated using the sessile water drop method before replacement. Data analyses used the Mann Whitney U-test, and P-values below 0.05 find statistical significance. Results: The present study showed no statistically significant differences between the DNA copy numbers of A. actinomycetemcomitans, P. gingivalis, and total bacteria for both the titanium and zirconia abutments and the biopsies taken from their buccal gingiva. The differences between the free surface energy of the abutments had no influence on the microbiological findings. Conclusions: Zirconia surfaces have comparable properties to titanium alloy surfaces and may be suitable and safe materials for the long-term success of dental implants.