Evaluation of Hydroxyapatite Film by Powder Jet Deposition after Artificial Aging

2012 ◽  
Vol 529-530 ◽  
pp. 229-232
Author(s):  
Ryo Akatsuka ◽  
Ken Matsumura ◽  
Miyoko Noji ◽  
Chihiro Nishikawa ◽  
Kei Sato ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Cycling ◽  
Vickers Hardness ◽  
Bonding Strength ◽  
Artificial Aging ◽  
Three Dimensional ◽  
Human Tooth ◽  
Significant Difference ◽  
Before And After ◽  
New Type

This study aimed to create a thick hydroxyapatite (HAp) film on the surface of a human tooth by using a newly developed powder jet deposition (PJD) device for dental handpieces, and sought to examine the microstructural and mechanical properties of the resulting HAp film. The film was evaluated on three-dimensional view, surface roughness, Vickers hardness, and bonding strength before and after artificial aging through thermal cycling (555°C) for 500 cycles (30 sec for each cycle, 20 sec of dwell time).The HAp particles in the deposited film were densely packed, and the HAp films three-dimensional microstructure and its rough surface were maintained after thermal cycling. There was no significant difference in either the HAp films Vickers hardness or the bonding strength between the film and the enamel substrate before and after thermal cycling. The HAp films created in this study demonstrated excellent microstructural and mechanical properties even after the application of thermal stress. We demonstrated the possibility of using a new type of powder jet deposition (PJD) method we developed to form a new type of interface between the tooth and biomaterials. Consequently, we propose the use of this method in new dental treatments.

scholarly journals Cytotoxicity of three-dimensional paper-based models from a three-dimensional paper-based printer

NEMESIS ◽  
2018 ◽  
Vol 3 (1) ◽  
pp. 15 ◽  
Author(s):  
Marcin Kozakiewicz ◽  
Piotr Szymor ◽  
Raphael Olszewski
Keyword(s):  
Operating Room ◽  
Dermal Fibroblast ◽  
Statistical Significance ◽  
Three Dimensional ◽  
Dermal Fibroblasts ◽  
Tissue Adhesive ◽  
Biological Behaviour ◽  
Sterilization Method ◽  
Significant Difference ◽  
Before And After

Objective: Our study aimed to determine the possibility of using models created with a low-cost, paper based 3D printer in an operating room. Therefore influence of different methods of sterilization on models was tested and cytotoxicity of generated models was determined. Material and methods: 30 cuboids divided into three groups were used for verification of shape stability after sterilization. Each group was sterilized either with: Ethylene oxide in temperature 55˚C, Hydrogen peroxide gas plasma in temperature 60˚C or Gamma irradiation at 21˚C, 25kGy. Each cuboid was measured using calliper three times before and three times after sterilization. Results were analysed statistically in Statgraphics Plus. Statistical significance was determined as p< 0.05. Sixty cylinders divided into six groups were used for cytotoxicity tests. Three of those groups were covered before sterilization with 2-octyl-cyanoacrylate. Each group was sterilized with one of the previously described methods. Cytotoxicity was tested by Nanostructural and Molecular Biophysics Laboratory in Technopark Lodz using normal adult human dermal fibroblasts. Survival of cells was tested using spectrophotometry with XTT and was defined as ratio of absorbency of tested probe to absorbency of control probe. Calcein/Ethidium dyeing test was performed according to LIVE/DEAD Viability/Cytotoxicity Kit protocol. Observation was done under Olympus GX71 fluorescence microscope. Results: There was no statistically significant difference for established statistical significance p=0.05 in cuboids dimensions before and after sterilization regardless of sterilization method. In XTT analysis all samples showed higher cytotoxicity against normal, human, adult dermal fibroblast culture when compared to positive control. ANOVA statistical analysis confirmed that 2-octyl cyanoacrylate coating of paper model improved biological behaviour of the material. It decreased cytotoxicity of the model independently of sterilization method. In calcein/ethidium dyeing test due to the high fluorescence of the background caused by cylinders of analysed substance it was impossible to perform the exact analysis of the number of marked cells. Conclusions: Acquired results allow to conclude that Mcor Technology Matrix 300 3D paper-based models can be used in operating room only if covered with cyanoacrylate tissue adhesive. Nemesis relevance: We found no statistically significant difference in cuboids dimensions before and after sterilization regardless of sterilization method. Three-dimensional paper-based models present with high cytotoxicity without coating.

Effects of Sintering Process on the Properties of Ti3SiC2/Cu Composite

2012 ◽  
Vol 512-515 ◽  
pp. 377-381 ◽  
Author(s):  
Jin Rong Lu ◽  
Yang Zhou ◽  
Yong Zheng ◽  
Shi Bo Li ◽  
Zhen Ying Huang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Vickers Hardness ◽  
Hot Pressing ◽  
Sintering Temperature ◽  
Sintering Process ◽  
Vacuum Sintering ◽  
New Type ◽  
Sintering Conditions ◽  
The Relationship ◽  
Better Than

In this paper, a new type of Ti3SiC2/Cu composites with the volume fractions of 30% Ti3SiC2 particle was prepared by hot pressing and vacuum sintering respectively. The effects of sintering temperature and holding time on the density, resistance and Vickers hardness of Cu-30vol%Ti3SiC2 composite were investigated. The results show that the mechanical properties of the composites prepared by hot pressing are better than that prepared by vacuum sintering. The relative densities of Cu-30vol% Ti3SiC2 composites are rather high in suitable sintering conditions. It achieved 100% for the composites prepared by hot pressing at 930°C for 2h, and 98.4% for the composites prepared by vacuum sintering at 1250°C for 1h. At the same time, the maximum Vickers hardness reached 1735MPa at 900°C by hot pressing. The resistance and Vickers hardness of the composites decreased with an increase in sintering temperature, whereas the density increased. Scanning electron microscope (SEM) and energy-dispersive spectroscopy (EDS) were used to observe the microstructure of the composites. The relationship between microstructure and mechanical properties was discussed.

scholarly journals The visceral pericardium: macromolecular structure and contribution to passive mechanical properties of the left ventricle

2007 ◽  
Vol 293 (6) ◽  
pp. H3379-H3387 ◽  
Author(s):  
Paul D. Jöbsis ◽  
Hiroshi Ashikaga ◽  
Han Wen ◽  
Emily C. Rothstein ◽  
Keith A. Horvath ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Ex Vivo ◽  
Second Harmonic ◽  
Three Dimensional ◽  
Left Ventricular ◽  
Opening Angle ◽  
Passive Stiffness ◽  
Photon Excitation ◽  
Before And After

Much attention has been focused on the passive mechanical properties of the myocardium, which determines left ventricular (LV) diastolic mechanics, but the significance of the visceral pericardium (VP) has not been extensively studied. A unique en face three-dimensional volumetric view of the porcine VP was obtained using two-photon excitation fluorescence to detect elastin and backscattered second harmonic generation to detect collagen, in addition to standard light microscopy with histological staining. Below a layer of mesothelial cells, collagen and elastin fibers, extending several millimeters, form several distinct layers. The configuration of the collagen and elastin layers as well as the location of the VP at the epicardium providing a geometric advantage led to the hypothesis that VP mechanical properties play a role in the residual stress and passive stiffness of the heart. The removal of the VP by blunt dissection from porcine LV slices changed the opening angle from 53.3 ± 10.3 to 27.3 ± 5.7° (means ± SD, P < 0.05, n = 4). In four porcine hearts where the VP was surgically disrupted, a significant decrease in opening angle was found (35.5 ± 4.0°) as well as a rightward shift in the ex vivo pressure-volume relationship before and after disruption and a decrease in LV passive stiffness at lower LV volumes ( P < 0.05). These data demonstrate the significant and previously unreported role that the VP plays in the residual stress and passive stiffness of the heart. Alterations in this layer may occur in various disease states that effect diastolic function.

scholarly journals Microstructure and Mechanical Properties of Composite Resins Subjected to Accelerated Artificial Aging

2013 ◽  
Vol 24 (6) ◽  
pp. 599-604 ◽  
Author(s):  
Andrea Candido dos Reis ◽  
Denise Tornavoi de Castro ◽  
Marco Antonio Schiavon ◽  
Leandro Jardel da Silva ◽  
Jose Augusto Marcondes Agnelli
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Artificial Aging ◽  
Thermal Analyses ◽  
Surface Hardness ◽  
Composite Resins ◽  
Scanning Calorimetry ◽  
Good Thermal Stability ◽  
Microstructure And Mechanical Properties ◽  
Before And After

The aim of this study was to investigate the influence of accelerated artificial aging (AAA) on the microstructure and mechanical properties of the Filtek Z250, Filtek Supreme, 4 Seasons, Herculite, P60, Tetric Ceram, Charisma and Filtek Z100. composite resins. The composites were characterized by Fourier-transform Infrared spectroscopy (FTIR) and thermal analyses (Differential Scanning Calorimetry - DSC and Thermogravimetry - TG). The microstructure of the materials was examined by scanning electron microscopy. Surface hardness and compressive strength data of the resins were recorded and the mean values were analyzed statistically by ANOVA and Tukey's test (α=0.05). The results showed significant differences among the commercial brands for surface hardness (F=86.74, p<0.0001) and compressive strength (F=40.31, p<0.0001), but AAA did not affect the properties (surface hardness: F=0.39, p=0.53; compressive strength: F=2.82, p=0.09) of any of the composite resins. FTIR, DSC and TG analyses showed that resin polymerization was complete, and there were no differences between the spectra and thermal curve profiles of the materials obtained before and after AAA. TG confirmed the absence of volatile compounds and evidenced good thermal stability up to 200 °C, and similar amounts of residues were found in all resins evaluated before and after AAA. The AAA treatment did not significantly affect resin surface. Therefore, regardless of the resin brand, AAA did not influence the microstructure or the mechanical properties.

scholarly journals A Facile Way to Prolong Service Life of Double Base Propellant

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2236 ◽  
Author(s):  
Shixiong Sun ◽  
Song Ma ◽  
Benbo Zhao ◽  
Guangpu Zhang ◽  
Yunjun Luo
Keyword(s):  
Mechanical Properties ◽  
Service Life ◽  
Storage Time ◽  
Artificial Aging ◽  
Mechanical Performance ◽  
Diffusion Characteristics ◽  
Actual Service ◽  
Before And After ◽  
Double Base ◽  
And Diffusion

The safe storage time for double base propellant (DBP or DB propellant) with stabilizers could usually be calculated to be greater than 40 years. However, the actual service life is far below that, which is largely caused by the decline of propellant mechanical performance. In this work polytetrafluoroethylene (PTFE) was introduced into the double base propellant formula as an additive. The tensile properties of this propellant before and after artificial aging were determined. The evaporation and diffusion characteristics of nitroglycerin (NG) in propellant were evaluated by thermogravimetry analysis (TGA). The results showed that mechanical properties of propellant were improved due to PTFE, especially for elongation at −40 °C, which was greatly increased by 115%. Moreover, the results of TGA showed that NG migration was reduced due to PTFE, which delayed the decline of propellant mechanical performance during aging. The reduction in elongation at −40 °C caused by aging was decreased by 68.5% for PTFE modified DBP. Enhanced mechanical properties and reduced NG migration could potentially prolong propellant service life.

scholarly journals Impact of nonsurgical spinal decompression on paraspinal muscle morphology and mechanical properties in young adults with low back pain

2020 ◽  
Vol 48 (7) ◽  
pp. 030006052091923
Author(s):  
Wai Leung Ambrose Lo ◽  
Di Lei ◽  
Yan Leng ◽  
Huanjie Huang ◽  
Biru Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Young Adults ◽  
Low Back Pain ◽  
Back Pain ◽  
Subcutaneous Tissue ◽  
Paraspinal Muscle ◽  
Low Back ◽  
Spinal Decompression ◽  
Significant Difference ◽  
Before And After

Objective The mechanism underlying the benefit of nonsurgical spinal decompression (NSSD) on low back pain is unclear. This study was performed to investigate the immediate impact of NSSD on the mechanical properties and morphology of the paraspinal muscles. Methods Participants with low back pain were recruited. NSSD therapy was provided on one occasion. A myotonometer was placed perpendicularly on the skin surface over the paraspinal muscle at the level of L3/L4 to measure the mechanical muscle properties. The multifidus thickness was measured using B-mode ultrasound and defined as the distance between the transverse process and subcutaneous tissue fascia. The difference between before and after NSSD was analyzed by a paired t-test. Results Thirty participants (mean age, 20.9 ± 0.8 years; 9 male, 21 female) were recruited. No significant difference was observed in the muscle mechanical properties or morphology between before and after the intervention. Conclusions NSSD intervention did not induce immediate changes in the paraspinal muscle mechanical properties or multifidus thickness in young adults with low back pain. NSSD might produce benefits by stimulating mechanical receptors rather than inducing morphological changes or mechanical property alterations of the muscle fibers. These parameters may not be suitable outcome measures for NSSD intervention.

scholarly journals Effect of Fe Content on the Microstructure and Mechanical Properties of Ti-Al-Mo-V-Cr-Fe Alloys

2017 ◽  
Vol 62 (2) ◽  
pp. 1105-1108
Author(s):  
K.C. Bae ◽  
J.J. Oak ◽  
Y.H. Kim ◽  
Y.H. Park
Keyword(s):  
Mechanical Properties ◽  
Volume Fraction ◽  
Alloy System ◽  
Microstructure And Mechanical Properties ◽  
Nucleation Sites ◽  
Fe Content ◽  
Significant Difference ◽  
Before And After ◽  
The Matrix ◽  
Fe Alloys

AbstractTo investigate the effect of Fe content on the correlation between the microstructure and mechanical properties in near-b titanium alloys, the Ti-5Al-5Mo-5V-1Cr-xFe alloy system has been characterized in this study. As the Fe content increased, the number of nucleation sites and the volume fraction of theαphase decreased. We observed a significant difference in the shape and size of theαphase in the matrix before and after Fe addition. In addition, these morphological deformations were accompanied by a change in the shape of theαphase, which became increasingly discontinuous, and changed into globular-typeαphase in the matrix. These phenomena affected the microstructure and mechanical properties of Ti alloys. Specimen #2 exhibited a high ultimate tensile strength (1071 MPa), which decreased with further addition of Fe.

scholarly journals Analysis of the Mechanical Behavior and Effect of Cyclic Fatigue on the Implant-Abutment Interface

2020 ◽  
pp. 208-218
Author(s):  
Ramón Germán Sandoval ◽  
Marine Ortiz Magdaleno ◽  
Paula Sánchez Robles ◽  
Norma Zavala Alonso ◽  
Gabriel Fernando Romo Ramírez
Keyword(s):  
Mechanical Behavior ◽  
Compressive Stress ◽  
Three Dimensional ◽  
Cyclic Fatigue ◽  
Chromium Alloy ◽  
Fe Method ◽  
Manufacturing Technique ◽  
Significant Difference ◽  
Implant Abutment ◽  
Before And After

Purpose: The seal of the interface formed at the implant-abutment connection is essential for the long-term success of the implant-supported restoration. The aim of this study was to analyze the mechanical behavior and the effect of cyclic fatigue before and after in the marginal fit of implant-abutment according to the manufacturing technique of the abutment. Materials and methods: Machined titanium abutments (DENTIS), cast abutments with Nickel-Chromium alloy (VeraBond II), and manufacturing custom milled Zirconia abutments (Zirkonzahn) were evaluated. The implant-abutment assemblies were subjected to cyclic loads of 133 N at a frequency of 19.1 Hz for 200,000 cycles. The microgap was measured using Scanning Electronic Microscope and the distribution of compressive stress by the three-dimensional Finite Element (FE) method. Results: The microgap measurement values of the machined abutments were 1.62 μm and 1.92 μm, cast abutments were 14.14 μm, and 28.44 μm, and the milled abutments were 14.18 μm and 20.15 μm before and after cyclic fatigue, respectively. Only the cast abutments and the machined abutments showed a statistically significant difference before and after cyclic fatigue (p ≤ 0.05). The FE analysis showed that the critical areas of compressive stress were located at the implant-abutment connection, increasing in the cast abutments and decreasing in the milled and the machined abutments. Conclusion: Cyclic fatigue exerts an effect on the dimensions of the microgap at the implant-abutment interface before and after loading; this microgap depends of the type of abutment material and the manufacturing technique.

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