scholarly journals A chemical activity evaluation of two dental calcium silicate-based materials

2015 ◽  
Vol 28 (2) ◽  
pp. 89-91
Author(s):  
Renata Chalas ◽  
Ewelina Mielko ◽  
Joanna Zubrzycka-Wrobel ◽  
Jakub Nowak
Keyword(s):  
Raman Spectroscopy ◽  
Elemental Composition ◽  
Chemical Reaction ◽  
Calcium Silicate ◽  
Interfacial Layer ◽  
Chemical Activity ◽  
Activity Evaluation ◽  
Methods Of Analysis ◽  
Bioactive Potential

Abstract Calcium silicate-based materials are interesting products widely used in dentistry. The study was designed to compare the chemical reaction between analyzed two preparates and dentin during cavity lining. In our work, dentinal discs were prepared from human extracted teeth filled with Biodentine and MTA+. The samples were then analyzed by way of SEM, EDS and Raman spectroscopy. The obtained results revealed differences in elemental composition between both materials. Biodentine showed higher activity in contact with dentine. Moreover, the interfacial layer in the tooth filled by Biodentine was wider than that in the tooth filled with MTA+. The applied methods of analysis confirmed that both materials have a bioactive potential which is a promising ability.

scholarly journals Effects of Different Ion Irradiation on the Contact Resistance of Pd/Graphene Contacts

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3928 ◽  
Author(s):  
Kashif Shahzad ◽  
Kunpeng Jia ◽  
Chao Zhao ◽  
Dahai Wang ◽  
Muhammad Usman ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Contact Resistance ◽  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Chemical Reaction ◽  
Ion Irradiation ◽  
Metal Deposition ◽  
Pristine Graphene ◽  
Bombardment Energy ◽  
Induced Defects

The effect of ion-induced defects on graphene was studied to investigate the contact resistance of 40 nm palladium (Pd) contacting on graphene. The defect development was considered and analyzed by irradiating boron (B), carbon (C), nitrogen (N2), and argon (Ar) ions on as-transferred graphene before metallization. The bombardment energy was set at 1.5 keV and ion dose at 1 × 1014 ions/cm2. The defect yields under different ion irradiation conditions were examined by Raman spectroscopy. Although, dissolution process occurs spontaneously upon metal deposition, chemical reaction between metal and graphene is more pronounced at higher temperatures. The rapid thermal annealing (RTA) treatment was performed to improve the Pd/graphene contact after annealing at 450 °C, 500 °C, 550 °C, and 600 °C. The lowest contact resistance of 95.2 Ω-µm was achieved at 550 °C RTA with Ar ion irradiation. We have proved that ion irradiation significantly enhance the Pd/graphene contact instead of pd/pristine graphene contact. Therefore, in view of the contention of results ion induced defects before metallization plus the RTA served an excellent purpose to reduce the contact resistance.

Biocompatibility and Bioactive Potential of New Calcium Silicate–based Endodontic Sealers: Bio-C Sealer and Sealer Plus BC

2020 ◽  
Vol 46 (10) ◽  
pp. 1470-1477
Author(s):  
Evelin Carine Alves Silva ◽  
Mario Tanomaru-Filho ◽  
Guilherme Ferreira da Silva ◽  
Mateus Machado Delfino ◽  
Paulo Sérgio Cerri ◽  
...  
Keyword(s):  
Calcium Silicate ◽  
Bioactive Potential ◽  
Endodontic Sealers

Silicate Bond Characteristics in Calcium–Silicate–Hydrates Determined by High Pressure Raman Spectroscopy

2020 ◽  
Vol 124 (33) ◽  
pp. 18335-18345
Author(s):  
David W. Gardner ◽  
Jiaqi Li ◽  
Ali Morshedifard ◽  
Saeed Masoumi ◽  
Mohammad Javad Abdolhosseini Qomi ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
High Pressure ◽  
Calcium Silicate ◽  
Calcium Silicate Hydrates ◽  
Bond Characteristics

scholarly journals ON SUBJECT TO FORECAST CAUSAL FACTORS FOR SPONTANEOUS FIRES IN COAL MINES

2020 ◽  
Author(s):  
Vadym Tarasov ◽  
Keyword(s):  
Organic Matter ◽  
Elemental Composition ◽  
Analytical Data ◽  
Chemical Activity ◽  
Spontaneous Ignition ◽  
Mining Operations ◽  
Carbonization Process ◽  
Coal Beds ◽  
Operation Conditions ◽  
Main Components

Regulations for assessment of workable bed hazardous characteristics during the mining operations include the coal metamorphic grade classification indices borrowed from the industrial classifications without any proper scientific justification. For true forecasting the workable bed hazardous characteristics during the mining operations, the method to detect the metamorphic grades by changing the content of main components and moisture in the organic matter has been developed. Purpose. Development of the forecasting technique logical sequence for workable bed liability to spontaneous ignition in different stages of coal metamorphic conversion and their chemical activity during the mining operations. Methods. They are based on assumption of spontaneous fires with three blocks of factors independent of each other. The factors of block one describe the chemical activity of coals. They are defined by their elemental composition and properties at the different stages of bed metamorphic conversion. The second group of impacting factors characterizes the mining and geological conditions of bedding. It includes the coal beds position relative to each other, their occurrence depth, thickness and degree of inclination, presence of geological breaches and adjacent strata properties. The factors of block three is independently connected with the mining operation conditions. The forecasting technique for workable bed liability to spontaneous ignition avoids any stable correlation relationships between the factor parameters of three blocks under consideration. It allows separate consideration of each block and avoid their random correlations with factors of other blocks. Results. The statistical processing result analysis of more than 1000 coal samples with carbon content of 80÷94% has allowed establishing the relationship between the organic matter components and total moisture, as well as their share of participation in carbonization process that reflects the Donets Basin coal metamorphic conversions. Compliance of the initial data with analytical data of different coal deposits has been established. For the first time, the technique has been developed; and organic matter separate components and total moisture participation shares in coal carbonization process indices creation, which is one of evaluation criteria for workable bed metamorphic conversion degree for different deposits, have been established. The revealed regularities of change ambiguity for organic matter elemental composition components and their different participation shares together with the moisture in carbonization process have allowed establishing the distinctive features of the coal metamorphic conversion different stages for true forecasting the workable bed hazardous characteristics during the mining operations. In the course of this approach, the real chemical activity of coals is established by their elemental composition in different stages of bed metamorphic conversions; certain places of long-term contacts between the mine air and coal are differentially forecasted in the mine field. It enables the enhanced automated monitoring of mine air condition and revealing of spontaneous combustion places in early stages of their creation. Scientific novelty. The pattern of change for classification indices of coal industrial classification has been revealed to establish the workable bed hazardous characteristics during the mining operations. Practical relevance. Opportunity to improve the regulatory framework for safe processing of workable beds by establishing the interrelation between fossil coal metamorphic conversions and their elemental composition.

scholarly journals Ytterbium Oxide as Radiopacifier of Calcium Silicate-Based Cements. Physicochemical and Biological Properties

2018 ◽  
Vol 29 (5) ◽  
pp. 452-458 ◽  
Author(s):  
Bernardo Cesar Costa ◽  
Juliane Maria Guerreiro-Tanomaru ◽  
Roberta Bosso-Martelo ◽  
Elisandra Márcia Rodrigues ◽  
Idomeo Bonetti-Filho ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Cell Viability ◽  
Calcium Silicate ◽  
Setting Time ◽  
Neutral Red ◽  
Biological Properties ◽  
Alizarin Red ◽  
Ytterbium Oxide ◽  
Physicochemical And Biological Properties ◽  
Bioactive Potential

Abstract This study evaluated physicochemical properties, cytotoxicity and bioactivity of MTA Angelus (MTA), calcium silicate-based cement (CSC) and CSC with 30% Ytterbium oxide (CSC/Yb2O3). Setting time was evaluated using Gilmore needles. Compressive strength was evaluated in a mechanical machine. Radiopacity was evaluated using radiographs of materials and an aluminum scale. Solubility was evaluated after immersion in water. Cell viability was evaluated by means of MTT assay and neutral red staining, and the mineralization activity by using alkaline phosphatase activity and Alizarin Red staining. The data were submitted to ANOVA, Tukey and Bonferroni tests (5% significance). The bioactive potential was evaluated by scanning electron microscopy. The materials presented similar setting time. MTA showed the lowest compressive strength. MTA and CSC/Yb2O3 presented similar radiopacity. CSC/Yb2O3 showed low solubility. Saos-2 cell viability tests showed no cytotoxic effect, except to 1:1 dilution in NR assay which had lower cell viability when compared to the control. ALP at 1 and 7 days was similar to the control. MTA and CSC had greater ALP activity at 3 days when compared to control. All the materials present higher mineralized nodules when compared with the control. SEM analysis showed structures suggesting the presence of calcium phosphate on the surface of materials demonstrating bioactivity. Ytterbium oxide proved to be a properly radiopacifying agent for calcium silicate-based cement since it did not affected the physicochemical and biological properties besides preserving the bioactive potential of this material.

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