87,349 research outputs found
Monitoring the degradation of bone elastic properties induced by microgravity: a proposal.
No full textBackground
Important alterations occurring in living organisms during space flight concern the trabecular compartment of load-bearing bones, and result in significant bone mineral loss and decay of mechanical properties [1, 2].
Composition, mineral content, and the complex micro-scale trabecular microarchitecture contribute together to the macro-scale functional strength of bone as a whole [3]. Bone alterations, including those due to reduced gravitational load conditions, are mainly assessed by measuring bone density, even though, alone, it cannot comprehensively assess skeletal integrity [4]. Micro-tomographic techniques [5], not suitable for monitoring, allow for a pre- and post-mission examination of the trabecular bone component, which undergoes the fastest and most important alterations, placing astronauts at serious risk of fracture upon re-entry [5]. Mesoscale studies in modeled microgravity conditions combined with numerical simulations, show that degradation of apparent mechanical properties must be considered to achieve an accurate description of bone performance [6, 7].
To quantify the pathological alterations in the bone micro-architecture in a clinical setting, a patented, CE marked, software medical device, the Bone Elastic Structure Test, BES TEST, has been developed. Results are uncorrelated to BMD and independent of load [8, 9]. BES TEST has a diagnostic accuracy of 78% as a 3-year fracture risk estimator [10] and can be used to complete the densitometry picture and as monitoring tool for bone follow-up in in rheumatology [9], oncology [11], nephrology [12] and rare bone diseases [13].
Its prospective application for bone alteration monitoring during spaceflights is discussed.
Method
BES TEST simulates the application of forces on an X-ray functional biopsy of the patient’s hand [14-19]. Results are combined in an index, BSI, and its T-score and Z-score (Fig.1). Characteristics: X-ray dose < 0.0005 μSV; CV intra-operator=0.06; 95%CI±8 BSI; CV inter-operator =0.11; 95% CI=±10.8 BSI [20, 21], in line with the diagnostic gold standard.
Requirements for investigation of BES TEST space application:
- Acquisition: x-ray scanner, small detector. Several possible arrangements are possible, tests in simulated space flight will clarify the best configuration.
- Calibration: the acquisition set-up will likely differ from the clinical one.
- Analysis: radiograms upload to automatic service.
Results
BES TEST monitors trabecular bone, which changes more rapidly than cortical bone and BMD in response to physio-pathological alterations, like those occurring during spaceflight.
Conclusion
BESTEST is fast, easy to perform, cost-effective and can be significantly repeated within just weeks, showing potential for monitoring the changes in bone functionality during long-duration space missions.
Acknowledgements
Area Science Park financially supported the development of this work at various stages.
References
1. Vico, L. et al. Bone. 1998.
2. Lang, T. et al. J Bone and Mineral Research. 2004.
3. Kleerekoper, M. et al. Calcif Tissue Int. 1985.
4. J.D. Sibonga et al. Aerosp.Med.Hum. perform. 2015.
5. J.D. Sibonga et al. J. Clin. Densitom. 2020.
6. Cosmi F. et al. J. Mech. Behav. Biomed. Mater. 2009
7. Francesca Cosmi et al. J. Mech. Behav. Biomed. Mater. 2015
8. Cosmi F et al. Mater Today: Proc. 2018.
9. Saviola G. et al. Minerva Medica. 2019.
10. Francesca Cosmi et al. 2023.
11. S. Saracchini et al. 2019.
12. M. Ferraro et al. NDT. 2021.
13. Cosmi F and Maximova N. Mater. Today. 2019
14. Wilczek M. L et al. Eur Radiol. 2013.
15. Albanese CV et al. R. Radiol Med. 2011.
16. Alenfeld FE et al. Osteoporosis Int. 1998.
17. Mele R. Osteoporos Int. 1997.
18. Tonti E. Computer Modeling in Engineering and Science. 2001.
19. Cosmi F. Molecular and Cellular Biology. 2015.
20. Cosmi F. et al. Proc IMechE Part C. 2022.
21. Cosmi F. et al. Proc IMechE Part C. 2023
A new numerical test for quantifying microgravity-induced bone alterations in cosmonauts
No full textOne of the most important alterations that occur in man and experimental animals during spaceflight affects the skeletal system (trabecular compartment of load-bearing bones), and results from an important bone loss and mechanical properties decay. The macro-scale mechanical properties of cancellous bone derive from its mass (composition and mineral content) and from its complex micro-scale structure (trabecular micro-architecture arrangement), and it is widely accepted that both these factors contribute to determine the mechanical strength of the whole bone [1]. In space research, bone quality changes due to unloading, are usually assessed by measuring bone density. More rarely, 3D micro-imaging, complemented by morphological indexes, has been used [2,3]. A software that, by means of numerical simulations, evaluates the load bearing capabilities of trabecular bone from planar radiographic images, has recently been developed at the University of Trieste [4]. The technique, already proved to be able to classify the quality of bone for the evaluation of fracture risk in osteoporotic patients [5,6], is here proposed for a more effective monitoring of bone quality changes in long duration spaceflight.
References
1. Kleerekoper, M. et al., “The role of three dimensional trabecular microstructure in the pathogenesis of vertebral compression fractures”, Calcif Tissue Int, Vol. 37, pp. S594-S597, 1985.
2. Vico, L. et al., “Effects of gravitational changes on the bone system in vitro and in vivo”, Bone, Vol. 22, pp. 95-100, 1998.
3. Lang, T. et al., “Cortical and trabecular bone mineral loss from the spine and hip in long duration spaceflight”, J Bone and Mineral Research, Vol. 19, pp. 1006-1012, 2004.
4. Patent: USA No. 10509512, deposited by University of Trieste, 2008.
5. Cosmi F., Dreossi D., “The Application of the Cell Method in a Clinical Assessment of Bone Fracture Risk”, Acta of Bioengineering & Biomechanics, Vol. 9, pp. 35-39, 2007.
6. Cosmi F., Mazzoleni G., “Un nuovo metodo strutturale per la valutazione del rischio di frattura nelle malattie degenerative”, 41° Convegno AIAS, Vicenza (I), Sept. 5-8, 2012
Bone structure and fragility fracture risk factors: a population analysis
Get PDFOsteoporosis (OP) is a silent disease, characterized by a decreasing bone strength, which leads to a progressive increase in fracture risk. Mechanical properties of bone depend on both its composition and its trabecular component micro-architectural arrangement. OP diagnosis is made on the basis of bone mineral density (BMD), possibly combined with algorithms based on the clinical risk factors, e.g. FRAX®, but about half of those at risk of OP still go undetected, since their OP risk is linked to alterations of the trabecular architecture. The BESTEST® is a test based on the simulated application of loads on a virtual biopsy of the patient. Briefly, the test uses planar X-rays projections to assess the mechanical properties of the patient’s trabecular bone tissue. In this work, we aim to identify the distributions of fragility fracture risk factors in a population of female volunteers
The effect of microstructure on the tensile and impact behaviour of short-glass fibre-reinforced polyamide 6.6 as assessed by micro-computed tomography
Get PDFInjection moulding of short-fibre-reinforced thermoplastics opens a new dimension in the field of mass production of complicated net-shaped parts with accurate dimensions and the new challenge is to produce parts with tailored properties. However, the layered structure frequently observed in these composites strongly affects their mechanical behaviour and constitutes the main difficulty in transferring the results of tests performed on standard specimens to actual components and parts. In addition, to use injection-moulded composite materials safely, their mechanical behaviour under different loading conditions must be well understood. In the present work, the effect of microstructure, in terms of fibre length and orientation, on the tensile and impact behaviour of injection-moulded short-glass fibre-reinforced polyamide 6.6 was investigated. Digital reconstruction of the three-dimensional structure of samples, differently oriented with respect to the melt flow path, was obtained by the high-spatial-resolution non-destructive technique of synchrotron radiation micro-computed tomography (micro-CT). Automatic evaluation of the fibre length distribution was developed by a global method based on the mean fibre length distribution, computed from the star length distribution (SLD). The results of uniaxial tensile tests and Izod impact experiments were successfully correlated with morphological analysis of fractured surfaces and the results of SLD. These studies revealed important changes in fibre orientation distribution when the sample orientation is changed with respect to melt flow direction, which also strongly influenced the composite mechanical response.Fil: Rosic, N.. Instituto Nacional de Tecnología Industrial; ArgentinaFil: Mollo, M.. Instituto Nacional de Tecnología Industrial; ArgentinaFil: Bernal, Celina Raquel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnología en Polímeros y Nanotecnología. Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnología en Polímeros y Nanotecnología; ArgentinaFil: Cosmi, F.. Università degli Studi di Trieste; Itali
La difficile equazione sull'identità castellana: recupero e conservazione tra luogo e società
No full textLo studio analizza la problematica edilizia legata al recupero dell’architettura fortificata. In particolare vengono esaminati i rapporti tra valore della permanenza storica e contesto. La possibilità di un futuro recupero della stessa viene valutata nella più generale prospettiva del dibattito culturale attuale
Sono ancora attuali i fondamenti della casa operaia?
No full textQuesta pubblicazione riporta i risultati di un lungo lavoro di ricerca relativo all’analisi tipologica e sociale del villaggio Crespi d’Adda. Tale lavoro si colloca in un più ampio quadro di ricerca interdisciplinare, tendente ad analizzare i fondamentali elementi caratterizzazione della casa operaia, anche in un quadro di confronto con gli attuali requisiti socio-funzionali che caratterizzano la residenza economico e popolare.
Il caso studio considerato, pur nella sua unicità architettonica, ha consentito di evidenziare alcune soglie di riferimento per quanto riguarda le prestazioni funzionali, che potranno costituire utili indicazioni per la formulazione di future linee guida di carattere progettuale
Analysis of the dependence of the tensile behaviour of a short fibre reinforced polyamide upon fibre volume fraction, length and orientation
No full textThe tensile properties of different grades of a short fibre reinforced polyamide, having various contents of glass fibres, were analysed. The fibre length distributions, obtained by optical microscope observations of the fibres extracted from the matrix, were statistically analysed and compared. The tensile behaviour of the different materials was modelled by applying micro-mechanical models, taking into account the fibre length distributions. The effect of the fibre content on the fibre orientation distribution is discussed on the basis of the analysis of the reconstructions of the internal fibre structure by micro tomography using synchrotron light. The relationship between the degree of anisotropy and the orientation factors used in the models is discussed
Orientamento delle fibre in polimeri rinforzati con fibre corte: analisi morfologica e microstrutturale di componenti intagliati
No full textPoliammide rinforzata con fibre corte di carbonio: analisi mediante tecniche microtomografiche in contrasto di fase
No full text
- …
