1,720,988 research outputs found
Residual stress analysis on tensile MMC specimens after loading/unloading tests in several conditions
No full textResidualstresseshavebeeninvestigatedinsamplesmadeofAA6061+22%Al2O3inordertocorrelate microstructural characteristics with mechanical performances. In particular, the possible occurrence of a brittle fracture induced by an excessive load transfer from the matrix to the reinforcement was investigated. To this end, macrostresses and microstresses were analysed.
A neutron diffraction test on 12 specimens submitted to several loading/unloading conditions at different temperatures was performed. These measurements aimed to establish the optimal temperature for the initial extruded billet in pre-heating stage, before forging the final wheel hub
Neutron and synchrotron radiation non-destructive methods for the characterisation of materials for different applications.
Full text linkNeutron and synchrotron radiation techniques are very powerful non-destructive methods for the characterisation of a wide variety of materials. In particular, neutron and synchrotron radiation diffraction is nowadays widely used for the evaluation of residual stresses induced by thermal and mechanical treatments in materials and components for industrial applications. By small angle neutron scattering (SANS), microstructural features induced by thermomechanical treatments, such as precipitation and cavitation, can be investigated from a quantitative point of view (determination of size distributions, volume fraction). A review is presented of the techniques mentioned above, and some applications to materials for technological applications will be presented
Synchrotron radiation microtomography for the ex-vivo and in-vivo evaluation of nanoparticle-labeled stem cell homing in muscular tissue.
No full textOsteoinductive properties study of collagenated Dual-Blocks by synchrotron radiation phase-contrast microtomography
No full textThe restoration of large bony maxillofacial defects represents one of the tissue engineering main challenges. It has been recently explored using cells and tissues developed in vitro that should ideally be immunologically, functionally, structurally and mechanically identical to the native tissue. In the present study, the early stages of in vitro bone formation in a xenofree culture system of human Periodontal Ligament Stem Cells and collagenated porcine Dual-Blocks were investigated by Synchrotron Radiation X-ray phase contrast micro-computed tomography (SR micro-CT)
Quantitative Kinetics Evaluation of Blocks Versus Granules of Biphasic Calcium Phosphate Scaffolds (HA/β-TCP 30/70) by Synchrotron Radiation X-ray Microtomography: A Human Study
No full textIntroduction: Successful bone regeneration using both granules and blocks of biphasic calcium phosphate materials has been reported in the recent literature, in some clinical applications for maxillary sinus elevation, but the long-term kinetics of bone regeneration has still not been fully investigated.
Materials and Methods: Twenty-four bilateral sinus augmentation procedures were performed and grafted with hydroxyapatite/[beta]-tricalcium phosphate 30/70, 12 with granules and 12 with blocks. The samples were retrieved at different time points and were evaluated for bone regeneration, graft resorption, neovascularization, and morphometric parameters by computed microtomography and histology.
Results: A large amount of newly formed bone was detected in the retrieved specimens, together with a good rate of biomaterial resorption and the formation of a homogeneous and rich net of new vessels. The morphometric values were comparable at 5/6 months from grafting but, 9 months after grafting, revealed that the block-based specimens mimicked slightly better than granule-based samples the healthy native bone of the maxillary site.
Conclusion: The scaffold morphology was confirmed to influence the long-term kinetics of bone regeneration
Chapter 8: Synchroton Radiation and Nanotechnology for Stem Cell Researchers
No full textStem cell-based tissue engineering therapies involve the administration of ex vivo manipulated stem cell populations for the purpose of repairing and regenerating damaged or diseased tissue. Currently available methods for monitoring transplanted cells are limited. Monitoring stem cell therapy outcomes requires the development of nondestructive strategies capable to identify the location, magnitude, and duration of cellular survival and fate. The recent development of imaging techniques offers great potential for addressing these critical issues by noninvasively
tracking the fate of the transplanted cells. We offer a focused presentation of some examples of the use of imaging techniques connected to the nanotechnological world in research areas related to stem cells. In particular, investigations concerning
human stem cell treatment of Duchenne muscular dystrophy in animal models, bioscaffolds for cell proliferation to form muscular fi bers, and bone tissue engineering are discussed
Defect analysis on optical waveguide arrays by synchrotron radiation microtomography
Full text linkIn recent years, great attention has been devoted to the study
and realization of polymeric optical waveguides embedded in printed
circuit boards due to the increasing need of transferring large amounts
of data at high speed within computer and telecommunication devices.
Nonuniform microstructural defects that can be induced during the manufacturing
process can dramatically influence the waveguide performance.
The synchrotron radiation computed microtomography technique was
used to obtain 3-D microstructural information, specifically to observe
small defects, such as porosities, in a nondestructive way. Porosity level
and pore size range were evaluated
The Stem Cells meet the Physics Big Machines
No full textStem cell based regenerative therapies involve the administration of selected stem cell populations with the purpose of repairing and regenerating damaged or diseased tissue. Currently available methods of monitoring transplanted cells are quite limited because they have to offer non-destructive strategies capable to identify the location, magnitude, and duration of cellular survival and their fate both at early and late stages. The recent development of imaging techniques offers great potential to address these critical issues by non-invasively tracking the fate of the transplanted cells. This article offers a focused presentation of some examples of the use of imaging techniques connected to the nanotechnological world in research areas related to stem cells. In particular, investigations concerning stem cell treatment of Duchenne muscular dystrophy, Infarcted Heart and bone tissue engineering in animal models are discussed
On Long Term Effects of Low Power Laser Therapy on Bone Repair: A Demonstrative Study by Synchrotron Radiation-based Phase-Contrast Microtomography
No full textLaser effects on fracture healing are still controversial and
require further quantitative 3D measures of newly formed bone
microstructural parameters. We performed a demonstrative
investigation, by synchrotron radiation-based phase-contrast
microtomography (SR-phc-microCT), on bone regeneration process
in rats submitted to femoral osteotomy and treated with low power
laser therapy (LPLT).
Six Wistar rats were subjected to transverse osteotomy of the
right and left femurs and randomly divided into four experimental
groups: not grafted with biomaterials and not laser-treated (Group
I, n = 3), not grafted with biomaterials but laser-treated (Group II,
n = 3), grafted with biomaterials and not laser-treated (Group III, n
= 3), grafted with biomaterials and laser-treated (Group IV, n = 3).
LPLT was performed at dose of 16 J/cm2 per exposure, immediately
after osteotomy, every 48 hours for the first week and every 72
hours for the next two weeks. Animals were sacrificed after 24
days. Bone regeneration and mineralization degree, with or without
biomaterial’s grafts, were evaluated by SR-phc-microCT.
We observed that, for regenerated bone struts in the dimensional
ranges thicker than 200 mm and in absence of any biomaterial graft,
the bone volume percentage in the LPLT-treated samples was
almost two-fold greater vs. the controls. This effect is magnified in
presence of Bioss grafts when the bone volume percentage in the
LPLT-treated samples was found to be almost three-fold greater vs.
not treated samples.
Despite the reduced sample size, we demonstrated that
SR-phc-microCT technique can play a fundamental role in the
advanced characterization of laser-treated sites. In fact it allows,
in a nondestructive way, a quantitative, statistically significant and
high-resolution 3D analysis of newly formed bone microstructural
parameters, keeping the sacrificed animals to the minimumin
accordance with recent ethical standards
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