Studies Regarding the Architectural Design of Various Composites and Nanofibres Used in Dental Medicine

2018 ◽  
Vol 69 (2) ◽  
pp. 328-331
Author(s):  
Irina Gradinaru ◽  
Leonard Ignat ◽  
Cristina Gena Dascalu ◽  
Laurentiu Valentin Soroaga ◽  
Magda Ecaterina Antohe
Keyword(s):  
Composite Structures ◽  
Architectural Design ◽  
Dental Restoration ◽  
Fibrillar Structure ◽  
Fiber Post ◽  
Fiber Glass ◽  
Full Agreement ◽  
Sem Images ◽  
Structural Modifications ◽  
New Formulation

The aim of this study was represented by the definition and testing of a new formulation strategy and the functionality of composite materials, while ensuring the optimization of the relevant properties for the dental restoration processes through the use of precise techniques of characterization, the modification and functionality of the components in view of obtaining results that are characterized by an optimum biomechanical and bioactive relation, in full agreement with the particularities of the dental structure that requires restoration. In view of obtaining new resistant composite structures we made a number of 10 samples including extracted teeth with various losses of dental substance and the structural modifications included 3 types of composites, whose structure was improved by the introduction of inorganic fillings based on hydroxyapatite and silver nanoparticles. All these structures were reinforced with two types of fibers, Reforpost fiber glass kit (Angelus) and Fiber post Schulzer Pre-silanized; With regard to the use of composite structures improved by HA addition, we notice a slight lacunary structure on the SEM images due to the properties of HA, an aspect present at much smaller dimensions in the silver � HA mix. The size of the grains associated with their continuous uniformity and adherence for the fibrillar structure stands out at the samples with hydroxyapatite, the first place as uniformity and adherence going to the composite of the nanofiller technology category.

Fabrication of All-Cellulose Composite from Cotton Fabric via NaOH/Urea Solvent Using Vacuum Bagging-Assisted Process

2021 ◽  
Vol 889 ◽  
pp. 9-14
Author(s):  
Pawarit Chumpon ◽  
Phattharasaya Rattanawongkun ◽  
Nattaya Tawichai ◽  
Uraiwan Intatha ◽  
Nattakan Soykeabkaew
Keyword(s):  
Tensile Strength ◽  
Cotton Fabric ◽  
Composite Structures ◽  
Interfacial Adhesion ◽  
Urea Solution ◽  
Dissolution Time ◽  
Sem Images ◽  
Cellulose Composites ◽  
Wide Range ◽  
Cellulose Composite

All-cellulose composites (ACCs) become growingly attractive materials in wide range applications due to its green profile, biocompatibility, and enable recycling. In this work, the ACCs was fabricated from cotton fabric (CF) by partial dissolution via aqueous NaOH/urea solution. The alternative ACC fabrication technique using vacuum bagging in the dissolution step was introduced in this study. SEM images confirmed that a vacuum aid during CF-ACC fabrication effectively improved the consolidation of resulting composites, showing better bonding and structure integrity. The CF-ACC prepared with vacuum bagging-assisted process showed almost two-fold enhancement in tensile strength as compared to another one prepared without vacuum bagging. The effect of dissolution time (15-45 min) on structure and properties of CF-ACCs was also investigated. The CF-ACC prepared with vacuum bagging at dissolution time of 15 min showed the highest tensile strength of 35.25 ± 1.39 MPa and elongation of 21.17 ± 1.46 %. The longer dissolution time, the larger portion of the crystalline fibers dissolved and converted into the amorphous matrix phase of CF-ACCs (confirmed by XRD). With longer dissolution times, the tensile strength of the prepared composites was decreased. However, it was found that with increasing dissolution time and using vacuum bagging in the fabrication of CF-ACCs could enhance their Young’s modulus values, indicating a greater interfacial adhesion gained in these composite structures.

scholarly journals Maturation of the Meniscal Collagen Structure Revealed by Polarization-Resolved and Directional Second Harmonic Generation Microscopy

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Maxime Pinsard ◽  
Sheila Laverty ◽  
Hélène Richard ◽  
Julia Dubuc ◽  
Marie-Claire Schanne-Klein ◽  
...  
Keyword(s):  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
Second Harmonic ◽  
Large Field ◽  
Fibrillar Structure ◽  
Collagen Structure ◽  
Future Studies ◽  
Structural Modifications ◽  
Second Harmonic Generation Microscopy

AbstractWe report Polarization-resolved Second Harmonic Generation (P-SHG) and directional SHG (forward and backward, F/B) measurements of equine foetal and adult collagen in meniscus, over large field-of-views using sample-scanning. Large differences of collagen structure and fibril orientation with maturation are revealed, validating the potential for this novel methodology to track such changes in meniscal structure. The foetal menisci had a non-organized and more random collagen fibrillar structure when compared with adult using P-SHG. For the latter, clusters of homogeneous fibril orientation (inter-fibrillar areas) were revealed, separated by thick fibers. F/B SHG showed numerous different features in adults notably, in thick fibers compared to interfibrillar areas, unlike foetal menisci that showed similar patterns for both directions. This work confirms previous studies and improves the understanding of meniscal collagen structure and its maturation, and makes F/B and P-SHG good candidates for future studies aiming at revealing structural modifications to meniscus due to pathologies.

scholarly journals Predicción de la Resistencia de las Conexiones Tipo Canal en Estructuras Compuestas de Acero y Hormigón

2018 ◽  
Vol 3 (1) ◽  
pp. 259
Author(s):  
Rafael Larrúa Quevedo ◽  
Ramiro Vargas Vergara ◽  
Jennifer Espino Louzado
Keyword(s):  
Artificial Intelligence ◽  
Composite Structures ◽  
Statistical Techniques ◽  
International Literature ◽  
Structural Elements ◽  
Statistical Measures ◽  
Region Data ◽  
Resistance Prediction ◽  
New Formulation ◽  
Keywords Composite

This article deals with channel connections in steel and concrete composite structures, with the main objective of obtaining a new formulation to determine the resistance of this widely used type of connection in the American region. Data from channel connections tests are collected from reliable experimental and numerical sources, and a valid database is created to make predictions by means of different combinations of artificial intelligence techniques, to obtain the most effective cases. Finally, a new formulation is proposed to calculate the resistance of channel connections in solid slab, applying statistical techniques to a database that incorporates experimental, numerical and artificial intelligence results, demonstrating its superiority with respect to the existing formulations in the international literature, by means of statistical measures appropriately applied to the studied case. The proposed methodology is novel and effective, and it can be expanded to other types of structural elements.  Keywords: composite structures, connections, resistance, prediction. 

scholarly journals Restorative strategies for weakened roots: Systematic review and Meta-analysis of in vitro studies

2019 ◽  
Vol 22 (1) ◽  
pp. Process
Author(s):  
Gislene Corrêa ◽  
Lucas Pradebon Brondani ◽  
Rafael Sarkis-Onofre ◽  
César Dalmolin Bergoli
Keyword(s):  
Fracture Resistance ◽  
Meta Analysis ◽  
Dental Restoration ◽  
Fiber Post ◽  
Study Results ◽  
Significant Difference ◽  
Post And Core ◽  
The Difference ◽  
Meta Analyses

Objective: This study evaluated fracture resistance values and failure mode of weakened roots restored with cast post and core, fiber post and anatomical posts. Materials and methods: In vitrostudies, published in English, Portuguese and Spanish, that evaluated weakened roots restored with at least two of mentioned strategies were searched for in three databases MEDLINE, PubMed and Scopus until June 2017; there was no restriction regarding the publication year. Fracture resistance values were obtained, and the following comparisons: cast post and core vs. fiber post and vs. anatomical post and fiber post vs. anatomical post were performed. Meta-analyses were conducted using the random effects model to calculate the combined effect of the difference between the averages. Six articles were included in the study. Results: There was no significant difference between the fracture resistance values, but more catastrophic failures were observed on cast post and core, and the included studies presented a low risk of bias for the most domains. Conclusion: It was concluded that weakened roots restored with the searched strategies seem to have similar fracture strength, but fiber and anatomic post decreases the possibility of catastrophic failure.KeywordsReview; Root; Dental restoration.

scholarly journals Physicochemical and Biological Performance of Aloe Vera-Incorporated Native Collagen Films

Pharmaceutics ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 1173 ◽  
Author(s):  
Mireia Andonegi ◽  
Ainhoa Irastorza ◽  
Ander Izeta ◽  
Koro de la Caba ◽  
Pedro Guerrero
Keyword(s):  
Biomedical Applications ◽  
Aloe Vera ◽  
Xrd Analysis ◽  
Biological Properties ◽  
Fibrillar Structure ◽  
Scanning Calorimetry ◽  
Sem Images ◽  
Biological Assays ◽  
Native Collagen ◽  
Biological Performance

Collagen was obtained from porcine skin by mechanical pretreatments with the aim of preserving the triple helix structure of native collagen, which was indirectly corroborated by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) results. Moreover, aloe vera (AV), with inherent biological properties, was incorporated into collagen film formulations, and films were prepared by compression and characterized to assess their suitability for biomedical applications. SEM images showed that the fibrillar structure of collagen changed to a rougher structure with the addition of AV, in accordance with the decrease in the lateral packaging of collagen chains observed by XRD analysis. These results suggested interactions between collagen and AV, as observed by FTIR. Considering that AV content higher than 20 wt % did not promote further interactions, this formulation was employed for biological assays and the suitability of AV/collagen films developed for biomedical applications was confirmed.

scholarly journals Wave sensitivity analysis for periodic and arbitrarily complex composite structures

2017 ◽  
Vol 34 (5) ◽  
pp. 1572-1597 ◽  
Author(s):  
Dimitrios Chronopoulos ◽  
Manuel Collet ◽  
Mohamed Ichchou
Keyword(s):  
Composite Structures ◽  
Dynamic Performance ◽  
Fe Modelling ◽  
Structural Dynamic ◽  
Content Type ◽  
Structural Modifications ◽  
Discrete Approach ◽  
Stiffness Matrices ◽  
Periodic Composite ◽  
The Waves

Purpose This paper aims to present the development of a numerical continuum-discrete approach for computing the sensitivity of the waves propagating in periodic composite structures. The work can be directly used for evaluating the sensitivity of the structural dynamic performance with respect to geometric and layering structural modifications. Design/methodology/approach A structure of arbitrary layering and geometric complexity is modelled using solid finite element (FE). A generic expression for computing the variation of the mass and the stiffness matrices of the structure with respect to the material and geometric characteristics is hereby given. The sensitivity of the structural wave properties can thus be numerically determined by computing the variability of the corresponding eigenvalues for the resulting eigenproblem. The exhibited approach is validated against the finite difference method as well as analytical results. Findings An intense wavenumber dependence is observed for the sensitivity results of a sandwich structure. This exhibits the importance and potential of the presented tool with regard to the optimization of layered structures for specific applications. The model can also be used for computing the effect of the inclusion of smart layers such as auxetics and piezoelectrics. Originality/value The paper presents the first continuum-discrete approach specifically developed for accurately and efficiently computing the sensitivity of the wave propagation data for periodic composite structures irrespective of their size. The considered structure can be of arbitrary layering and material characteristics as FE modelling is used.

scholarly journals Solid-state Synthesis of Composite Structures of Various Cu(I)-based Oxides with g-C3 N4 for Harvesting Solar Energy

2018 ◽  
Vol 2 (1) ◽  
Keyword(s):  
Solid State ◽  
Solar Energy ◽  
Composite Structures ◽  
Solar Spectrum ◽  
Moderate Activity ◽  
Solar Simulator ◽  
Sem Images ◽  
One Step ◽  
The Stability ◽  
Xrd Patterns

Development of novel materials for an efficient harvesting of solar energy towards applications in environment and energy sectors is an important area of research. A metal-free polymeric material, g-C3 N4 is modified with three Cu(I)- based oxides namely Cu2 O, CuVO3 , and Cu3 VO4 to extend the absorption of the solar spectrum. The composite structures are synthesized by a facile one-step solid-state reaction under inter atmosphere and atmospheric pressure. The amounts of loadings of Cu(I)-based oxides onto g-C3 N4 is varied from 2 wt.% to 10 wt.%. Powder XRD patterns showed that the graphitic structure of carbon nitride is maintained upon the construction of hybrid structures with Cu(I) oxides. SEM images show the textural transformation of the bulk structure of g-C3 N4 into nanosheets upon thermal retreatment. FT-IR spectra further confirmed the stability of g-C3 N4 observed in the XRD patterns. In comparison with the pristine g-C3 N4 , the DR-UV-Vis spectra of the modified solid powders demonstrated a clear red shift in the absorption towards higher wavelength and their better prospects in harvesting solar energy. Tauc plots derived from the DR-UV-Vis spectra showed a narrowing of the direct-allowed band gap upon modifications with Cu(I)-based oxides. The composites showed moderate activity in photocatalytic degradation of rhodamine B under irradiation from a solar simulator

Structural modifications of intercellular junctions.

1978 ◽  
Vol 36 (2) ◽  
pp. 330-331
Author(s):  
J. Metz ◽  
M. Merlo ◽  
W. G. Forssmann
Keyword(s):  
Gap Junctions ◽  
Intercellular Junctions ◽  
Cell Isolation ◽  
Extrahepatic Cholestasis ◽  
Structural Modifications ◽  
Pancreatic Duct Ligation ◽  
Pancreatic Cells ◽  
Duct Ligation ◽  
Thin Sectioning ◽  
And Function

Structure and function of intercellular junctions were studied under the electronmicroscope using conventional thin sectioning and freeze-etch replicas. Alterations of tight and gap junctions were analyzed 1. of exocrine pancreatic cells under cell isolation conditions and pancreatic duct ligation and 2. of hepatocytes during extrahepatic cholestasis.During the different steps of cell isolation of exocrine pancreatic cells, gradual changes of tight and gap junctions were observed. Tight junctions, which formed belt-like structures around the apex of control acinar cells in situ, subsequently diminished, became interrupted and were concentrated into macular areas (Fig. 1). Aggregations of membrane associated particles, which looked similar to gap junctions, were intermixed within tight junctional areas (Fig. 1). These structures continously disappeared in the last stages of the isolation procedure. The intercellular junctions were finally separated without destroying the integrity of the cell membrane, which was confirmed with porcion yellow, lanthanum chloride and horse radish peroxidase.

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