Biomedical subjects

V Crupi

Publications and source records attributed to V Crupi.

6 recordsLinked to original sources

PubMed2005

Elastic neutron scattering study of water dynamics in ion-exchanged type-A zeolites.

With the aim to investigate, by means of elastic neutron scattering, the effects produced by the cation substitution on the dynamics of water in zeolites, we measured, using a neutron backscattering spectrometer, the temperature dependence of mean-square atomic displacements [u2] derived from window integrated quasielastic spectra of fully and partially hydrated Na-A and Mg50-A zeolites. The results, collected in the 20-273 K temperature range, reveal that, at low temperature, the [u2] shows a harmonic trend independent of hydration and cation substitution, and, at higher temperatures, the onset of a non-Gaussian dynamics of the elastic intensity. This latter takes place at T approximately 200 K and approximately 150 K for fully and partially hydrated samples, respectively. This behavior has been interpreted in terms of reorientational jumps of H atoms described by two-site processes within an asymmetric double-minimum potential. In spite of its simplicity, the model seems to reproduce the rearrangement of the hydrogen bond network of zeolitic water. The fit results indicate a reduced proton mobility by diminishing the water content and by the induced Na+-->Mg2+ ion exchange, in agreement with previous incoherent quasielastic neutron scattering results at higher temperatures.

Journal Article↗

PubMed2005

Radiograph-based femur morphing method.

Many applications in orthopaedic surgery require the creation of personalised design models that can serve as the basis for navigation in computer aided surgery systems or be used to create a personalised model to perform structural analysis during pre-operative planning or post-operative follow-up. The paper introduces a method for developing a three-dimensional (3D) patient-specific model of a femur bone from an antero-posterior radiograph. A generic femur was employed and was altered on the basis of bone boundaries visible on radiographs. Morphological errors were evaluated against 3D models obtained from computed tomography (CT) scans. When only the antero-posterior radiograph was used, the average radius estimation error was 4.8 mm, the average percentage area estimation error was 14%, and the average percentage estimation error for inertial moments was 15%. If both the medial-lateral and the anterior-posterior radiographs were used, these errors were 2.0 mm, 5% and 7%, respectively. The procedure described can be profitably employed whenever CT scans are not available, such as during a retrospective analysis, or when CT scans cannot be justified because of X-ray exposure and cost considerations.

Femur↗

PubMed2004

Numerical analysis of bone adaptation around an oral implant due to overload stress.

A finite element (FE) numerical model of an oral implant was implemented with the theory of bone adaptation to predict the response over time of the bone tissue to the implant and to explain a phenomenon regarding the clinical situation: the bone loss due to an overload stress. An adaptation routine, based on Beaupré theory, was developed to interface with the FE packages. The value of the mechanical stimulus, corresponding to the overload stress, was evaluated by applying the Taylor crack propagation theory. The predictions obtained by the numerical analyses demonstrated that the overload resorption is blocked only with spongy bone of 'good quality'.

Adaptation, Physiological↗

PubMed2003

A FT-IR absorption analysis of vibrational properties of water encaged in NaA zeolites: evidence of a "structure maker" role of zeolitic surface.

We performed, in the O-H stretching region, Fourier-transform Infrared (FT-IR) Absorption measurements for investigating the vibrational dynamics on water confined in NaA zeolite, vs. temperature and for different hydration percentages. The spectral substructure of the O-H stretching band is explained postulating the existence of three major components centred at approximately 3290 cm(-1) (omega(1)), approximately 3470 cm(-1) (omega(2)), approximately 3590 cm(-1) (omega(3)), with different dynamical properties traced over the full T-range investigated.

Journal Article↗

PubMed2002

FT-IR spectroscopy: a powerful tool in pharmacology.

In the present work we report a Fourier Transform Infrared (FT-IR) analysis performed on rat encephalon samples in the CH-OH vibrational stretching region (2400-3800) cm(-1), in order to reveal the presence of a very diffuse commercial benzodiazepine: VALIUM. The comparison between the spectral features of normal brain and the ones of samples with administrated substance has unambiguously showed that the CH stretching region seems not to suffer from any change for the pharmacological treatment, instead the OH band is strongly modified probably due to the presence of a new spectral contribution characteristic of diazepam molecule.

Animals↗

PubMed1999

Kinematic and dynamic analysis of running under conditions of variable gravity.

A new training system was designed and realised by the engineer G. Scuderi: a centrifugal track for runners. The principal advantage of this track is to increase the forces on athlete during the run with an effect very similar to that of an "artificial gravity", so the athlete can develop more muscle power. A multibody numerical model of a runner was developed to analyse the behaviour of the athlete on the centrifugal track. The multibody model was calibrated by experimental analysis; in fact, the joint angles were measured by a digital image processing system and introduced as input in the numerical simulation. The numerical results obtained are the values of many kinematic and dynamic variables, in particular the ground reaction force and the moments in the hip, knee, and ankle joints. A comparison between the normal running and that on the centrifugal track was carried out, demonstrating the validity of training on the latter. The results of the numerical simulation confirm that the power developed during running on the track, and the corresponding work performed by the joints, is considerably greater than that found during normal running.

Ankle Joint↗