1,721,047 research outputs found
Procedimento per la realizzazione di un prodotto per la modellazione e simulazione del comportamento fisico ed ingegneristico di un oggetto, di un sistema, o di campi fisici
No full textProcedimento per la realizzazione di un prodotto per la modellazione e simulazione di problemi scientifici ed ingegneristici basato sul Metodo delle Celle e sviluppato su piattaforma ID
Long-term culture of bone explants in simulated microgravity conditions can reproduce skeletal abnormalities observed after spaceflight: a structural analysis
No full textLong-term culture of bone explants in simulated microgravity conditions can reproduce skeletal abnormalities observed after spaceflight: a structural analysi
3D Structural Analysis of Ground-Wall Insulation of ac Rotating Machines Using X-Ray Tomography
No full textThe X-ray computed tomography has been applied here to inspect the internal features of two types of ground-wall insulation systems of ac rotating machines. Samples extracted from complete coils were scanned and their internal structure was analyzed by means of virtual slicing and 3D rendering procedures. Specialized software tools have been used to discover the morphological features of both the distributed voids and the high-density anomalies. It is was found that the resin penetration as well as the density and the geometries of the distributed micro-voids depend from the tape characteristics
BIOREACTOR-BASED 3D CULTURE OF BONE EXPLANTS AND MICRO-STRUCTURAL NUMERICAL ANALYSIS OF BONE VOLUMES: NEW TOOLS FOR THE STUDY OF BONE LOSS PATHOPHYSIOLOGY AND TARGETED THERAPIES
No full textMineral loss and increased bone fragility are common to different systemic and multi-factorial pathophysiological conditions, which involve hormonal, nutritional and mechanical determinants. Gravitational unloading during spaceflight leads to severe (1-2% bone mass loss/month), site-specific (cancellous weight-bearing bones) and time-/age-related skeletal alterations.
In the present study we investigated the long-term effect of gravitational unloading (microgravity) on the structural and mechanical features of whole cancellous bone explants (rat tibial proximal epiphyses) kept in vitro for up to 4 weeks in the Rotating Cell Culture System (RCCS) bioreactor. Simulated microgravity (vector-averaged gravity) was obtained by setting RCCS operational conditions according to the specific experimental needs. Quantification of micro-structural changes in trabecular bone structure was performed by the Cell method (Patent: PTC-WO03/082118, Trieste University) applied to the static analysis of microstructures obtained from the 3D reconstruction of computed micro-tomography scans performed at the Elettra Synchrotron facility.
The results obtained, consistent with the skeletal alterations observed in vivo after spaceflight, confirmed the value of our culture model. By allowing reproducible and controlled changes in specific biochemical and biomechanical factors, our RCCS bioreactor-based culture system demonstrated to provide the technological means to investigate, in vitro, fundamental mechanisms of bone cells function in a complex 3D microenvironment. Furthermore, the possibility to combine conventional histomorphologic, biochemical and molecular analyses with a numerical simulation able to quantify bone structural changes, open new perspectives for a better understanding of the mechanisms leading to bone loss in humans, and may help in the identification of more efficacious preventive/interventional strategies
Structural dissymmetry in the iliac cancellous network supports postural/gait-related problems in the KNM-WT 15000 early adolescent from Nariokotome.
No full textAnalisi dell’anisotropia microstrutturale in materiali compositi rinforzati con fibre corte
Full text linkLa microtomografia con luce di sincrotrone si è rivelata una tecnica particolarmente efficace per l’analisi della struttura risultante dalla distribuzione degli orientamenti assunti dalle fibre di rinforzo di compositi rinforzati con fibre di vetro. La ricostruzione dell'immagine tridimensionale ha consentito la visualizzazionedella distribuzione spaziale delle fibre all'interno della matrice polimerica anche nel caso di fibre di piccole dimensioni (diametro medio di 10 micrometri). E' stato quindi possibile misurare le differenze nell'orientamento delle fibre nei differenti strati di un campione utilizzando metodi basati sulla valutazione del Mean Intercept Length (MIL) e del fabric tensor. La tecnica descritta è stata applicata a un campione di poliammide 6 rinforzato con il 30% di fibre corte di vetro ricavato da lastra
Analisi microstrutturale con tomografia a luce di sincrotrone
No full textLa micro-tomografia con luce di sincrotrone è una
tecnica particolarmente efficace per l’analisi della
struttura risultante dalla distribuzione degli
orientamenti assunti dalle fibre di rinforzo di
compositi rinforzati con fibre di vetro.
La ricostruzione dell’immagine tridimensionale
consente la visualizzazione della distribuzione
spaziale delle fibre all’interno della matrice
polimerica anche nel caso di fibre di piccole
dimensioni (diametro medio di 10 micrometri).
È possibile misurare le differenze nell’orientamento
delle fibre nei differenti strati di un campione
utilizzando metodi basati sulla valutazione del Mean
Intercept Length (MIL) e del fabric tensor. La tecnica
descritta è stata applicata a un campione di
poliammide 6 rinforzato con il 30% di fibre corte di
vetro ricavato da una lastra iniettata di testa e da un
provino di geometria più complessa
Quantitative structural evaluation of bone tissue explants kept in different experimental conditions
No full textAs new biomaterials are developed, the need grows for new technological tools in basic research, and for innovative analytical methods able to predict the clinical relevance of novel composites. In this work we investigated the mechanical properties of the structures obtained from healthy bone explants, with those of bone samples kept in long-term culture by the traditional 2D method on plastic dishes, or by the microgravity-based 3D conditions generated by the dynamic RCCSTM bioreactor. A quantitative evaluation of the structural differences among the samples was possible by means of numerical simulations based on 3D synchrotron radiation micro-CT reconstructions of the trabecular bone structure, and a Cell Method model. Significant differences were found between the three sets of samples. While the mechanical properties of samples maintained in 2D culture do not show a definite trend, those of the bone fragments kept in the RCCSTM bioreactor specifically decreased, as occur after in vivo exposure to microgravity conditions. These findings indicate that a promising research tool for predicting the clinical relevance of novel, bioengineered, implantable bone tissue analogues can be obtained by combining tissue engineering methods with advanced numerical models, able to quantify the biomaterials performance, possibly by reducing also the need for animal experimentation
Polycapillary Parallel Collimators for X-ray Imaging: Experimental Characterization of the Energy and Angular Response Function
No full text- …
