Quantitative micro-computed tomography analysis and rheological investigation of Nitrile rubber/Rockwool composites

2021 ◽  
pp. 002199832110338
Author(s):  
Elisson BD da Rocha ◽  
Ana Maria F de Sousa ◽  
Ana Lúcia N da Silva ◽  
Cristina RG Furtado ◽  
Marcos V Colaço ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Elastic Modulus ◽  
Aspect Ratio ◽  
Volume Fraction ◽  
Nitrile Rubber ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Rubber Composites ◽  
Ratio Data ◽  
Ct Analysis

This study reports the reinforcement degree investigation of two types of rockwool fibers (F1 and F2), in nitrile rubber composites. The micro-computed tomography (micro-CT) 3D images showed that both fibers were well-dispersed in the NBR matrix, without a preferential orientation. The micro-CT analysis also allowed quantifying volume fraction, inter-fiber distance, and aspect ratio. Those morphometric parameters were used for supporting the composites rheological behavior assessment. Changes in the elastic modulus and phase angle followed the same trend of the inter-fiber distance values, regardless the type of fiber. Both volume fraction and aspect ratio data from the micro-CT analysis were used to predict theoretical values of elastic modulus using the Guth-Gold and modified Guth-Gold equations, and the results obtained were compared to the rheological experimental data. This analysis was helpful to better understand the rockwool fibers reinforcement degree differences in the production of the nitrile rubber composites.

scholarly journals Retreatment of mesial roots of mandibular molars filled with resin- based and bioceramic sealers

2021 ◽  
Vol 20 ◽  
pp. e210432
Author(s):  
Marina de Almeida Salim ◽  
Fabiola Ormiga ◽  
Ricardo Tadeu Lopes ◽  
Heloisa Gusman
Keyword(s):  
Computed Tomography ◽  
Root Canal ◽  
T Test ◽  
Filling Material ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Mandibular Molars ◽  
Ct Analysis ◽  
Ah Plus ◽  
Endodontic Retreatment

Aim: The aim of this study was to evaluate, by micro-computed tomography (micro-CT) analysis, the remaining filling material during endodontic retreatment performed with Protaper retreatment without solvent. Methods: Forty mandibular molars were divided into two groups (n = 20) according to the sealer used in the obturation: the bioceramic TotalFill BC (TF) or the resin-based AH Plus (AHP). The specimens were scanned before instrumentation, after obturation and after filling removal. Only the mesial roots were analysed. The filling volumes and the remaining filling material were calculated in the entire root canal and in the cervical, middle and apical thirds. Results: The volume of obturation and the volume of remaining filling material in the entire root canal and in the cervical, middle and apical thirds of the canal between the groups were not statistically different (independent t-test, p > 0.05). In the AHP group, there was a higher percentage of remaining filling material in the middle third than in the cervical third (p < 0.05). Conclusion: The filling material could not be entirely removed from any specimen.

scholarly journals Comparison of Obturation Quality after MTA Orthograde Filling with Various Obturation Techniques

2021 ◽  
Vol 10 (8) ◽  
pp. 1719
Author(s):  
Hae Jin An ◽  
Hyunjung Yoon ◽  
Hoi In Jung ◽  
Dong-Hoon Shin ◽  
Minju Song
Keyword(s):  
Computed Tomography ◽  
Mineral Trioxide Aggregate ◽  
Total Porosity ◽  
Filling Material ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Maxillary Molars ◽  
Percentage Volume ◽  
Ct Analysis ◽  
Total P

This study aimed to quantify and compare the obturation quality after mineral trioxide aggregate (MTA) orthograde fillings with three different obturation techniques. Thirty-three extracted human maxillary molars were collected. Distobuccal and palatal canals were prepared to an apical size of #40/06 with a Profile Ni-Ti system. All 66 canals were divided into two groups according to the material (EZ-seal or OrthoMTA) and then obturated using three different techniques: manual compaction using S-kondenser (group H), compactor activation (group C), or reverse rotary motion of Ni-Ti file (group R). The obturated roots were scanned using micro-computed tomography (micro-CT). The percentage of voids located in the apical 5 mm was measured separately, that is, closed, open, and total porosity. There was no relation between the filling material and obturation technique (p > 0.05). The percentage volume of open and total porosity was higher in EZ-seal than in OrthoMTA (open: p = 0.002, total: p = 0.001). Group H showed higher open and total porosity than groups C and R. Micro-CT analysis showed that the void volume after orthograde MTA fillings significantly decreased when the additional activation was accompanied by hand condensation. Obturation with a Ni-Ti file using reverse motion could be recommended as an MTA orthograde filling technique.

scholarly journals Micro computed tomography based finite element models for elastic and strength properties of 3D printed glass scaffolds

2021 ◽  
Author(s):  
Erica Farina ◽  
Dario Gastaldi ◽  
Francesco Baino ◽  
Enrica Vernè ◽  
Jonathan Massera ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Mechanical Properties ◽  
Finite Element ◽  
Elastic Modulus ◽  
Strength Properties ◽  
Design Parameters ◽  
Finite Element Models ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
3D Printed

Abstract In this study, the mechanical properties of glass scaffolds manufactured by robocasting are investigated through micro computed tomography ($$\mu -CT$$ μ - C T ) based finite element modeling. The scaffolds are obtained by printing fibers along two perpendicular directions on parallel layers with a $$90^\circ $$ 90 ∘ tilting between two adjacent layers. A parametric study is first presented with the purpose to assess the effect of the major design parameters on the elastic and strength properties of the scaffold; the mechanical properties of the 3D printed scaffolds are eventually estimated by using the $$\mu -CT$$ μ - C T data with the aim of assessing the effect of defects on the final geometry which are intrinsic in the manufacturing process. The macroscopic elastic modulus and strength of the scaffold are determined by simulating a uniaxial compressive test along the direction which is perpendicular to the layers of the printed fibers. An iterative approach has been used in order to determine the scaffold strength. A partial validation of the computational model has been obtained through comparison of the computed results with experimental values presented in [10] on a ceramic scaffold having the same geometry. All the results have been presented as non-dimensional values. The finite element analyses have shown which of the selected design parameters have the major effect on the stiffness and strength, being the porosity and fiber shifting between adjacent layers the most important ones. The analyses carried out on the basis of the $$\mu -CT$$ μ - C T data have shown elastic modulus and strength which are consistent with that found on ideal geometry at similar macroscopic porosity. Graphic Abstract In this work, elastic and strength properties of glass-ceramic Bone Tissue Engineering scaffolds manufactured by robocasting are investigated through micro-CT based finite element models. An incremental simulation using a multi-grid finite element solver has been implemented to perform a parametric study on the effect of the major geometrical parameters of the scaffold design as well as the effect. Eventually, the effect of the geometrical imperfections deriving from the 3D printing process has been investigated by means of micro-CT image-based models. The porosity and the shifting between adjacent layers play the dominant role in determing elasticity and strength of the scaffolds. The elastic and strength properties of 3D-printed real scaffold were assessed to be consistent those obtained from the idealized geometric models, at least for the subdomain used in this study.

scholarly journals Micro-Computed Tomography Analysis of Subchondral Bone Regeneration Using Osteochondral Scaffolds in an Ovine Condyle Model

2021 ◽  
Vol 11 (3) ◽  
pp. 891
Author(s):  
Taylor Flaherty ◽  
Maryam Tamaddon ◽  
Chaozong Liu
Keyword(s):  
Computed Tomography ◽  
Bone Regeneration ◽  
Subchondral Bone ◽  
Volume Ratio ◽  
Bone Volume ◽  
Osteochondral Defects ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Trabecular Thickness ◽  
Osteochondral Scaffold

Osteochondral scaffold technology has emerged as a promising therapy for repairing osteochondral defects. Recent research suggests that seeding osteochondral scaffolds with bone marrow concentrate (BMC) may enhance tissue regeneration. To examine this hypothesis, this study examined subchondral bone regeneration in scaffolds with and without BMC. Ovine stifle condyle models were used for the in vivo study. Two scaffold systems (8 mm diameter and 10 mm thick) with and without BMC were implanted into the femoral condyle, and the tissues were retrieved after six months. The retrieved femoral condyles (with scaffold in) were examined using micro-computed tomography scans (micro-CT), and the micro-CT data were further analysed by ImageJ with respect to trabecular thickness, bone volume to total volume ratio (BV/TV) ratio, and degree of anisotropy of bone. Statistical analysis compared bone regeneration between scaffold groups and sub-set regions. These results were mostly insignificant (p < 0.05), with the exception of bone volume to total volume ratio when comparing scaffold composition and sub-set region. Additional trends in the data were observed. These results suggest that the scaffold composition and addition of BMC did not significantly affect bone regeneration in osteochondral defects after six months. However, this research provides data which may guide the development of future treatments.

scholarly journals Using micro-computed tomography to reveal the anatomy of adult Diaphorina citri Kuwayama (Insecta: Hemiptera, Liviidae) and how it pierces and feeds within a citrus leaf

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Javier Alba-Tercedor ◽  
Wayne B. Hunter ◽  
Ignacio Alba-Alejandre
Keyword(s):  
Computed Tomography ◽  
Significant Advance ◽  
Micro Ct ◽  
Diaphorina Citri ◽  
Ct Reconstruction ◽  
Internal Anatomy ◽  
Micro Computed Tomography ◽  
Citrus Leaf ◽  
Teaching Aids ◽  
Adult Feeding

AbstractThe Asian citrus psyllid (ACP), Diaphorina citri, is a harmful pest of citrus trees that transmits Candidatus Liberibacter spp. which causes Huanglongbing (HLB) (citrus greening disease); this is considered to be the most serious bacterial disease of citrus plants. Here we detail an anatomical study of the external and internal anatomy (excluding the reproductive system) using micro-computed tomography (micro-CT). This is the first complete 3D micro-CT reconstruction of the anatomy of a psylloid insect and includes a 3D reconstruction of an adult feeding on a citrus leaf that can be used on mobile devices. Detailed rendered images and videos support first descriptions of coxal and scapus antennal glands and sexual differences in the internal anatomy (hindgut rectum, mesothoracic ganglion and brain). This represents a significant advance in our knowledge of ACP anatomy, and of psyllids in general. Together the images, videos and 3D model constitute a unique anatomical atlas and are useful tools for future research and as teaching aids.

scholarly journals A Micro-Computed Tomography Comparison of the Porosity in Additively Fabricated CuCr1 Alloy Parts Using Virgin and Surface-Modified Powders

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1995
Author(s):  
Mirko Sinico ◽  
Suraj Dinkar Jadhav ◽  
Ann Witvrouw ◽  
Kim Vanmeensel ◽  
Wim Dewulf
Keyword(s):  
High Energy ◽  
High Energy Density ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Powder Bed ◽  
Metallurgical Defects ◽  
Ct Analysis ◽  
Ct Data ◽  
Surface Modified ◽  
Fusion Pores

Recently, the use of novel CuCr1 surface-modified powder for reliable laser powder-bed fusion (LPBF) manufacturing has been proposed, enabling a broader LPBF processing window and longer powder storage life. Nevertheless, virgin CuCr1 powder is also LPBF processable, on the condition that a high-energy density is employed. In this work, we compare two dense specimens produced from virgin and surface-modified CuCr1 powder. Furthermore, a third sample fabricated from surface-modified powder is characterized to understand an abnormal porosity content initially detected through Archimedes testing. Utilizing high-resolution micro-CT scans, the nature of the defects present in the different samples is revealed. Pores are analyzed in terms of size, morphology and spatial distribution. The micro-CT data reveal that the virgin CuCr1 dense specimen displays keyhole pores plus pit cavities spanning multiple layer thicknesses. On the other hand, the sample fabricated with the surface-modified CuCr1 powder mainly contains small and spherical equi-distributed metallurgical defects. Finally, the CT analysis of the third specimen reveals the presence of a W contamination, favoring lack-of-fusion pores between subsequent LPBF layers. The LPBF melting mode (keyhole or conductive), the properties of the material, and the potential presence of contaminants are connected to the different porosity types and discussed.

scholarly journals Analysis of Porous Structure in Autoclaved Materials Modified by Glass Sand

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 408
Author(s):  
Anna Stepien
Keyword(s):  
Computed Tomography ◽  
Building Materials ◽  
Micro Ct ◽  
Structure Building ◽  
Acoustic Insulation ◽  
Ct Analysis ◽  
Glass Sand ◽  
Aerated Concrete ◽  
Wall Construction ◽  
Dominant Phase

This paper describes the use of glass sand in the production of autoclaved bricks. Traditional autoclaved materials consist of SiO2, CaO, and H2O. The purpose of the tests is to analyze the possibility of using glass sand in autoclaved materials and to determine their properties and durability. Depending on the structure, building materials can have porosities ranging from 0% (glass, metals) to over 90% (thermal insulation materials such as aerated concrete). Porosity of materials is directly related to the strength of materials and their density, and further to the thermal and acoustic insulation properties of products used especially for external wall construction, i.e., bricks, concrete, and aerated concrete. This type of silicate brick is formed at a temperature of 203 °C, therefore the dominant phase forming the microstructure is tobermorite, in contrast to the C-S-H phase, which dominates in concretes and which is characterized by a larger specific surface. The nature of pores, their number, appearance and arrangement in the material can be studied using computer techniques (SEM, XRD, computed tomography, porosimetry). Computed tomography (micro-CT analysis) showed that the number of voids in the material modified by glass sand is about 20% in relation to the weight of the product. The density of the product with glass sand was determined to be 2.2 kg/dm3.

MicroCT protocols for scanning of embryos and juvenile Hexaplex trunculus v1

2021 ◽  
Author(s):  
Eva Chatzinikolaou ◽  
Kleoniki Keklikoglou
Keyword(s):  
Computed Tomography ◽  
High Resolution ◽  
3D Imaging ◽  
Imaging Technique ◽  
Ct Scanning ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Gastropod Species ◽  
Biological Studies ◽  
Hexaplex Trunculus

Micro-computed tomography (micro-CT) is a high-resolution 3D-imaging technique which is now increasingly applied in biological studies focusing on taxonomy and functional morphology. The creation of virtual representations of specimens can increase availability of otherwise underexploited and inaccessible samples. This protocol aims to standardise micro-CT scanning procedures for embryos and juveniles of the marine gastropod species Hexaplex trunculus.

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