scholarly journals Nanotubular Oxide Layer Formed on Helix Surfaces of Dental Screw Implants

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 115 ◽  
Author(s):  
Magdalena Jażdżewska ◽  
Michał Bartmański
Keyword(s):  
Oxide Layer ◽  
Cross Sections ◽  
Surface Coverage ◽  
Artificial Saliva ◽  
Corrosion Current ◽  
Optical Microscope ◽  
Significant Difference ◽  
Helix Surfaces ◽  
Future Work ◽  
Oxidation Parameters

Surface modification is used to extend the life of implants. To increase the corrosion resistance and improve the biocompatibility of metal implant materials, oxidation of the Ti-13Nb-13Zr titanium alloy was used. The samples used for the research had the shape of a helix with a metric thread, with their geometry imitating a dental implant. The oxide layer was produced by a standard electrochemical method in an environment of 1M H3PO4 + 0.3% HF for 20 min, at a constant voltage of 30 V. The oxidized samples were analyzed with a scanning electron microscope. Nanotubular oxide layers with internal diameters of 30–80 nm were found. An analysis of the surface topography was performed using an optical microscope, and the Sa parameter was determined for the top of the helix and for the bottom, where a significant difference in value was observed. The presence of the modification layer, visible at the bottom of the helix, was confirmed by analyzing the sample cross-sections using computed tomography. Corrosion tests performed in the artificial saliva solution demonstrated higher corrosion current and less noble corrosion potential due to incomplete surface coverage and pitting. Necessary improved oxidation parameters will be applied in future work.

Role of Aluminium on the Microstructure and Corrosion Behaviour of Magnesium Prepared by Powder Metallurgy Method

2020 ◽  
Vol 17 (3) ◽  
pp. 8206-8213
Author(s):  
J. Alias
Keyword(s):  
Corrosion Resistance ◽  
Powder Metallurgy ◽  
Corrosion Behaviour ◽  
Corrosion Current ◽  
Optical Microscope ◽  
High Reactivity ◽  
Aluminium Content ◽  
Powder Metallurgy Method ◽  
X Ray Diffraction ◽  
Promising Development

Much research on magnesium (Mg) emphasises creating good corrosion resistance of magnesium, due to its high reactivity in most environments. In this study, powder metallurgy (PM) technique is used to produce Mg samples with a variation of aluminium (Al) composition. The effect of aluminium composition on the microstructure development, including the phase analysis was characterised by optical microscope (OM), scanning electron microscopy (SEM) and x-ray diffraction (XRD). The mechanical property of Mg sample was performed through Vickers microhardness. The results showed that the addition of aluminium in the synthesised Mg sample formed distribution of Al-rich phases of Mg17Al12, with 50 wt.% of aluminium content in the Mg sample exhibited larger fraction and distribution of Al-rich phases as compared to the 20 wt.% and 10 wt.% of aluminium content. The microhardness values were also increased at 20 wt.% and 50 wt.% of aluminium content, comparable to the standard microhardness value of the annealed Mg. A similar trend in corrosion resistance of the Mg immersed in 3.5 wt.% NaCl solution was observed. The corrosion behaviour was evaluated based on potentiodynamic polarisation behaviour. The corrosion current density, icorr, is observed to decrease with the increase of Al composition in the Mg sample, corresponding to the increase in corrosion resistance due to the formation of aluminium oxide layer on the Al-rich surface that acted as the corrosion barrier. Overall, the inclusion of aluminium in this study demonstrates the promising development of high corrosion resistant Mg alloys.

INITIAL STEP OF SPECIALIZED CORPORA BUILDING: CLEANING PROCEDURES

2020 ◽  
Author(s):  
Vera Yakubson ◽  
Victor Zakharov
Keyword(s):  
Text Processing ◽  
Research Question ◽  
Initial Step ◽  
Main Research ◽  
Academic Texts ◽  
Linguistic Annotation ◽  
Significant Difference ◽  
Cleaning Procedures ◽  
Unique Source ◽  
Future Work

This paper deals with the specialized corpora building, specifically academic language corpus in the biotechnology field. Being a part of larger research devoted to creation and usage of specialized parallel corpus, this piece aims to analyze the initial step of corpus building. Our main research question was what procedures we need to implement to the texts before using them to develop the corpus. Analysis of previous research showed the significant quantity of papers devoted to corpora creation, including academic specialized corpora. Different sides of the process were analyzed in these researches, including the types of texts used, the principles of crawling, the recommended length of texts etc. As to the text processing for the needs of corpora creation, only the linguistic annotation issues were examined earlier. At the same time, the preliminary cleaning of texts before their usage in corpora may have significant influence on the corpus quality and its utility for the linguistic research. In this paper, we considered three small corpora derived from the same set of academic texts in the biotechnology field: “raw” corpus without any preliminary cleaning and two corpora with different level of cleaning. Using different Sketch Engine tools, we analyzed these corpora from the position of their future users, predominantly as sources for academic wordlists and specialized multi-word units. The conducted research showed very little difference between two cleaned corpora, meaning that only basic cleaning procedures such as removal of reference lists are can be useful in corpora design. At the same time, we found a significant difference between raw and cleaned corpora and argue that this difference can affect the quality of wordlists and multi-word terms extraction, therefore these cleaning procedures are meaningful. The main limitation of the study is that all texts were taken from the unique source, so the conclusions could be affected by this specific journal’s peculiarities. Therefore, the future work should be the verification of results on different text collections

Antibiotic Distribution in a Bone Cement Spacer Model

2007 ◽  
Vol 17 (4) ◽  
pp. 218-223 ◽  
Author(s):  
K. Shiramizu ◽  
V. Lovric ◽  
A.M.D. Leung ◽  
W.R. Walsh
Keyword(s):  
Liquid Phase ◽  
Bone Cement ◽  
Cross Sections ◽  
High Dose ◽  
Cement Spacer ◽  
Traditional Technique ◽  
Low Viscosity ◽  
Significant Difference ◽  
Group A ◽  
Medium Viscosity

Purpose To mix high dose antibiotic powder to the bone cement more easily, Hanssen et al reported mixing the antibiotics with the cement during its liquid phase but made no comments about the relevance of cement viscosity and antibiotic distribution. The purpose of this study was to investigate the effect of the cement mixing technique and cement viscosity on the antibiotics distribution in a cement spacer model. Methods Thirty cylindrical models from three groups were examined. Group A was made by mixing the antibiotics with medium viscosity cement prior to adding the liquid monomer (traditional technique). Group B was made by mixing the antibiotics with medium viscosity cement during its liquid phase (Hanssen's technique). Group C was made by traditional technique with low viscosity cement. In all groups 2 g of tetracycline was used. Three 0.1 mm thick cross sections from each spacer model were examined under the fluorescent microscope. The fluorescent spots of tetracycline were calculated automatically in pixels. To evaluate the distribution of the antibiotics in the spacer model, we selected the cross section with the highest number of pixels and the one with the lowest number of pixels from each of the three cross sections and calculated the difference between them. The distribution disequilibrium was compared between group A and B, A and C. Results No significant difference was observed in either comparison. Conclusion The Hanssen's mixing technique can be used when using high dose antibiotics, and either medium or low viscosity cement could be used in terms of antibiotic distribution.

scholarly journals Evaluation of color stability of different temporary restorative materials

2015 ◽  
Vol 44 (5) ◽  
pp. 262-267 ◽  
Author(s):  
José Vitor Quinelli Mazaro ◽  
Luiz Miguel Minani ◽  
Adriana Cristina Zavanelli ◽  
Caroline Cantieri de Mello ◽  
Cleidiel Aparecido Araújo Lemos
Keyword(s):  
Storage Time ◽  
Color Change ◽  
Artificial Saliva ◽  
Color Stability ◽  
Time Interval ◽  
Acrylic Resins ◽  
Significant Difference ◽  
Restorative Materials ◽  
Before And After ◽  
Level Of Significance

AbstractIntroductionTemporary restorative materials are widely used, however, little is know about their color stability.Objectiveto evaluate the color stability of the following temporary restorative materials: acrylic and bis-acrylic resins after immersion in pigmenting solutions for different periods of storage.Material and methodFour materials were tested (Dêncor/Clássico, Protemp 4/3M ESPE; Structur 2 SC/Voco; Luxatemp AM Plus/DMG) and 30 test specimens (15 mm in diameter and 2 mm thick) per material were fabricated. They were divided according to the storage medium (artificial saliva, saliva + cola type soda, and saliva + coffee) and storage time intervals (2, 5, 7 and 15 days). Color measurements were made before and after immersions, with use of a spectrophotometer, by means of the CIE L*a*b* system. The data were analyzed by the analysis of variance and the Tukey Test, at a level of significance of 5%.ResultAcrylic resin presented greater color stability in comparison with bis-acrylic resins (p<0.001). When bis-acrylic resins were compared no significant difference was observed between the resins Structur and Luxatemp (p=0.767). As regards solutions tested, coffee showed the highest color change values (p<0.001), and the longer the storage time interval, the greater was the color change in all the temporary restorative materials analyzed (p<0.001).ConclusionAcrylic resin presented greater color stability in comparison with bis-acrylic resins (p<0.001). Coffee caused the greatest color change, and immersion time was determinant in color stability of the temporary materials analyzed.

Experimental Identification of Material Properties of Piezoelectric Patch Transducer

2013 ◽  
Vol 486 ◽  
pp. 205-210
Author(s):  
Zuzana Lašová ◽  
Robert Zemcik
Keyword(s):  
Health Monitoring ◽  
Material Properties ◽  
Element Model ◽  
Experimental Methods ◽  
Optical Microscope ◽  
Piezoelectric Patch ◽  
Experimental Identification ◽  
Substrate Structure ◽  
Significant Difference ◽  
Voltage Signal

This work is focused on identification of material properties of piezoelectric patch transducers used e.g. for structural health monitoring before attaching to the substrate structure. Two experimental methods were concerned. At first two piezoelectric patches were supplied with a pair of collocated strain gauge rosettes. Both transducers were actuated with the same periodical signal. Significant difference in the results for two transducers was found, however it was claimed to be within tolerance by the producer. As an alternative method a measurement in an optical microscope was chosen. The patch was clamped at one side and actuated by a voltage signal. The displacement of the free end was captured by the microscope and processed in a graphical editor. Finally, a finite element model of the transducer was created and its material data were obtained by calibration with experimental data.

scholarly journals Development of Evaluation Method for Damage of Oxidation CoNiCrAlY Coating

2019 ◽  
Vol 804 ◽  
pp. 47-51
Author(s):  
Mo Chen ◽  
Kodai Yoshikawa ◽  
Zhen Qiang Song ◽  
Shijie Zhu
Keyword(s):  
Cross Sections ◽  
Gas Turbines ◽  
Evaluation Method ◽  
Thermal Spraying ◽  
Optical Microscope ◽  
Thermally Grown Oxide ◽  
Interfacial Damage ◽  
Barrier Coating ◽  
Plasma Sprayed ◽  
Conicraly Coating

The bond coat plays an important role in the failure of the thermal barrier coating (TBC) system used for gas turbines [1,2]. In this research, the CoNiCrAlY coated Ni-base superalloy specimens were used for developing evaluation method for interfacial damage in the coat. Samples were exposed at 1000°C and 1100°C for up to 1000 hours. The morphology and residual stress in the thermally grown oxide (TGO) layer on the CoNiCrAlY coating were characterized by microscopic observation and luminescence spectroscope, respectively. The microstructure and damage o\n both the coating surfaces and the cross sections were observed by optical microscope and scanning electron microscope. According to the results, the low pressure plasma sprayed CoNiCrAlY coating (LPPS) showed the thinnest TGO layer and lowest residual stress.Residual stress decreased with an increase in exposure time, depending on the morphology of TGO layer. The effects of thermal spraying methods on the oxidation of yttrium in TGO layer and BC layer and its influence on interfacial damage were discussed.

scholarly journals Evaluation of the apical seal after intraradicular retainer removal with ultrasound or carbide bur

2007 ◽  
Vol 21 (3) ◽  
pp. 253-258 ◽  
Author(s):  
Tomie Nakakuki Campos ◽  
Cleber Henrique Inoue ◽  
Elcio Yamamoto ◽  
Ângela Toshie Araki ◽  
Lena Katekawa Adachi ◽  
...  
Keyword(s):  
Optical Microscope ◽  
Dental Alloys ◽  
Experimental Conditions ◽  
Alloy Type ◽  
Cyanoacrylate Adhesive ◽  
Significant Difference ◽  
Post And Core ◽  
To Receive ◽  
Apical Leakage ◽  
Cervical Area

There are situations in which intraradicular retainers have to be removed and replaced. The objective of this research was to evaluate the apical seal after the removal of a custom cast post and core with a carbide bur or with an ultrasound apparatus. Twenty five roots of extracted human incisors were used. They were endodontically treated and prepared to receive the posts. The posts and cores were cast with 2 types of dental alloys, CuAlZn and PdAg, and were cemented with zinc phosphate cement. After 24 hours, they were removed using the two above mentioned techniques. Then, the roots had their external surface made impermeable by two layers of cyanoacrylate adhesive, leaving only the cervical area for dye penetration. The teeth were immersed in rhodamine for 24 hours. They were then cut and observed under an optical microscope and analyzed with appropriate software (Imagelab). The results were submitted to ANOVA, and they evidenced that, regarding the alloy factor, PdAg posts presented a larger mean infiltration value (2.23 ± 0.48 mm) as compared to the posts made of CuAlZn (1.39 ± 0.48 mm) (p = 0.025). Regarding the technique factor, there was no significant difference (p = 0.9) between the removal of the intraradicular retainer using ultrasound (1.99 ± 0.62 mm) or using a rotating cutting instrument (1.62 ± 0.62 mm). Under these experimental conditions, it was possible to conclude that the degree of apical leakage was directly related to the alloy type, and it was present in both techniques used.

scholarly journals Corrosion investigations of Al-Si casting alloys in 0.6 M NaCl solution

2021 ◽  
Vol 41 (3) ◽  
Author(s):  
Sunčana Smokvina Hanza ◽  
Ladislav Vrsalović ◽  
Lovro Štic ◽  
Lovro Liverić
Keyword(s):  
Potentiodynamic Polarization ◽  
Electrochemical Behavior ◽  
Die Casting ◽  
Electrochemical Corrosion ◽  
Microstructural Characterization ◽  
Casting Process ◽  
Corrosion Current ◽  
Optical Microscope ◽  
Open Circuit ◽  
Polarization Measurements

This paper presents results of the corrosion investigations of specimens made from finished parts for the automotive industry, produced by high-pressure die casting and gravity die casting process of six Al-Si alloys (40000 series). Open circuit potential and potentiodynamic polarization measurements have been performed using a potentiostat with three-electrode set-up in 0.6 M NaCl naturally aerated solution. Microstructural characterization before and after electrochemical investigations has been carried out with optical microscope to establish the connection between microstructure and corrosion parameters of investigated alloys and to analyze and record surface changes of each sample due to electrochemical corrosion. All alloys show good corrosion resistance, which manifests with low values of corrosion rates, calculated from the corrosion current densities obtained from potentiodynamic polarization measurements. Differences in electrochemical behavior appear due to the distinctions in their chemical composition and microstructure. The type of casting process does not affect electrochemical behavior of Al-Si alloys.

scholarly journals PERBEDAAN LEBAR CELAH TEPI TUMPATAN SEMEN IONOMER KACA MODIFIKASI RESIN NANO DAN MODIFIKASI RESIN

2017 ◽  
Vol 4 (1) ◽  
pp. 7
Author(s):  
Yuliana Ratna Kumala ◽  
Dini Rachmawati ◽  
Amanda Andika Sari
Keyword(s):  
Artificial Saliva ◽  
Statistical Test ◽  
Nano Particles ◽  
Marginal Gap ◽  
Nano Technology ◽  
Tooth Structure ◽  
Significant Difference ◽  
Conventional Material ◽  
Gap Width ◽  
Ionomer Cement

Background: One over many ways to treat dental caries is by restoration.Glass ionomer cement (GIC) is the restorations material that bonds physically and chemically to tooth structure. GIC has been developed by combining the conventional material with monomer resin, known as resin  modified GIC (RMGIC). Presently, with the development of nano  technology, RMGIC restoration also available in the form of nano   particles, called nanofilled RMGIC (RMGICn). One disadvantage of GIC is the marginal gap which may affects the durability ofrestoration. Purpose: The purpose of this study to compare the marginal gap width of RMGIC and nanofilled RMGIC.Methods: This study used scanning electron microscope (SEM) to observing and measuring the marginal gap width in two kelompoks of 9 maxillary first premolar teeth. The first kelompok restored with RMGIC, the second kelompok restored with nanofilled RMGIC. Following immersion in artificial saliva and the teeth were thermocycled at a temperature of 5oC, 37oC, and 55oC (250 cycles) 1 minute each. Data analysis was done using independent t-test with 95% confidence interval (α = 0.05).Results: Statistical test showed a significant difference for marginal gap width in both kelompok (p = 0.000).Conclusion: There is marginal gap in RMGIC and RMGICn restoration. RMGIC restoration presented lower marginal gap width than RMGIC.

scholarly journals Generation I and Generation II Elastomeric Chains Characteristics Comparison in Artificial Saliva Immersion

2020 ◽  
Vol 24 (1) ◽  
Author(s):  
Marisa Icha Aisya Subroto ◽  
Anindita Permata Hardarini Putri ◽  
Leliana Sandra Devi Ade Putri ◽  
Lusi Hidayati
Keyword(s):  
Artificial Saliva ◽  
Orthodontic Force ◽  
Force Decay ◽  
Significant Difference ◽  
Chain Force ◽  
Cie Lab ◽  
Elastomeric Chains ◽  
Research Period ◽  
Color Reader

Objective: To determine the force decay and discoloration in Generation I and Generation II elastomeric chain on artificial saliva immersion. Material and methods: Generation I and Generation II elastomeric chains stretched on an acrylic board and immersed in artificial saliva for 1, 7, 14, 21, and 28 days according to the group of days. On each specified day, the force of each sample measured by an orthodontic force gauge and the magnitude of the force obtained is entered to the formula to find out the force decay in percentage, whereas discoloration of each sample analyzed by the color reader with CIE Lab analysis. Results: The force decay between Generation I and Generation II elastomeric chains showed a statistically significant difference in every group of days, in which Generation II is more effective in maintaining stretch force. Similar to force decay, the discoloration in Generation I elastomeric chains on the 14th day showed significant value and Generation II elastomeric chains were more stable in maintaining color compared to Generation I. Conclusions: over the entire research period time, Generation II elastomeric chains are more stable in maintaining stretch forces and color compared to Generation I elastomeric chains. KEYWORDS Discoloration; Elastomeric chain; Force decay; Generation I; Generation II.

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