1,720,989 research outputs found
Enhancement of Cell Migration Rate Toward a Superparamagnetic Scaffold Using LF Magnetic Fields
No full textRecently developed superparamagnetic scaffolds for bone tissue engineering are still a complex object to deal with. Thanks to the possibility of controlling them remotely and directing therapeutic action in a non-invasive way, this work deals with the necessity of a clear definition and quantification of the field gradient, the forces and velocity it could exert on magnetic nanocarriers in a static magnetic field, and the heat and power generated when a time-varying field is applied, better defining the frequency response of magnetic nanoparticles entrapped in a solid matrix
A Multiphysic Model for the Hyperthermia Treatment of Residual Osteosarcoma Cells in Upper Limbs Using Magnetic Scaffolds
No full textTo avoid high recurrence rate, the hyperthermia treatment (HT) of bone tumors after surgical intervention was investigated. Innovative magnetic biomaterials can be used as thermoseeds to perform local thermal therapy. This work copes with the multiphysic modeling of the HT of residual Osteosarcoma (OS) cells using the so-called magnetic scaffolds. The goal is to develop a model that can serve as a tool to plan an accurate, safe, and high-quality treatment. Therefore, the electromagneto-thermal problem of radio-frequency heating is solved to determine the spatial and temporal evolution of the temperature field in a simplified 2-D geometry of proximal humerus. Different assumptions about the nonuniformity of the external magnetic field are verified. The possibility of nonideal distribution of magnetic nanoparticles in the biomaterial is accounted for the first time. The pattern of the magnetic field and of the induced electric field is studied. Moreover, the spatio-temporal evolution of temperature is investigated in the different cases. With these improvements to the state-of-the-art model of the HT of bone tumors, it was possible to identify the field parameter which allows to deliver the therapeutic thermal dose to OS cells
Optimized Design and Multiphysics Analysis of a Ka-band Stacked Antenna for CubeSat Applications
Full text linkNowadays, the use of CubeSats for telecommunications and interplanetary missions is ever-increasing, thanks to their appealing low-cost character, as well as the space environment, which poses challenging multiphysics constraints on the antenna design. In this framework, the use of Ka-band for communication is explored. We present the design of a stacked patch antenna working across the down- and uplink Ka-bands. Materials and geometry of the radiator have been selected by accounting for the trade-off between electromagnetic, thermal and mechanical requirements. The design of the antenna is performed with a particle swarm optimization algorithm developed to control the bandwidth and matching. A bandwidth of [email protected] GHz has been obtained, with a gain around 8 dB. Furthermore, a multiphysics thermal analysis is performed to verify the operational stability of the optimized array, mounted on a 1 U satellite, in a case-study mission. The temperature patterns in the array are evaluated during the orbital period, and the influence of the operative temperature on the antenna responses and gain was considered. We found that the thermal loads can affect the antenna matching. However, thanks to the optimized design, the proposed stacked antenna can operate from −100 ∘ C to 100 ∘ C, with an almost constant gain. Finally, following a damage-tolerant approach, the level of mechanical deformation, which could be induced on the communication system, was studied. The stress analysis reveals that the stacked geometry can be used in a space mission. From the investigation of the strain and displacement field, we found a negligible impact on the antenna performance
A robust multi-band Sierpinski gasket monopole for microwave breast cancer imaging
Full text linkThanks to the intrinsic self-similarity, fractal antennas are characterized by multiple resonances, a feature that could be exploited in microwave imaging (MWI) for breast cancer to gather more information about the nature and position of the tumor. A Sierpinski gasket monopole antenna is presented in this paper, showing three operating bandwidths as well as high robustness to the presence of a numerical mammary phantom
Numerical Comparison of Magnetic Biomaterials for Hyperthermia Applications: The Osteosarcoma Case
No full textThe aim of this work is to evaluate the therapeutic performances of novel magnetic biomaterials developed for hyperthermia treatment of bone tumors in a numerical multiphysics scenario. A brief report of the state of the art of innovative and functional magnetic implants is provided. Then, the non-linear model for the heat dissipation during the hyperthermia treatment is explained and discussed. Finally, the performances of different magnetic biomaterials in treating Osteosarcoma tumor are presented and critically compared
A multiphysics model for bone repair using magnetic scaffolds for targeted drug delivery
No full textMagnetic bone substitutes are multifunctional nanocomposite biomaterials designed to serve as an in situ attraction platform for magnetic carriers of growth factors. The morphological and functional properties of these biomaterials were characterized so far, but very little is known on the treatment dynamics, and the latter cannot be designed from an engineering point of view. For the first time, this work deals with the mathematical modeling of the use of magnetic scaffolds and functionalized nanoparticles to evaluate the enhancement of osteogenesis and bone repair. The non-linear magnetization of the scaffolds is considered to simulate the attraction and transport of magnetic nanoparticles. Different biomaterials and drug carriers from the literature are analyzed. The drug release via RF-heating is modeled considering the multiphysics nature of the phenomena. The physiological process of bone healing is reproduced using nine non-linear equations. The influence of the delivered growth factor on osteogenesis is assessed and quantified in silico, while compared to numerical simulations of intravenous injection of growth factor and to its release from the biomaterial.The exploitation of magnetic carriers of biomolecules with magnetic scaffolds allows to produce a more homogeneous and uniform distribution of mature bone, overcoming the limitation of traditional drug delivery technique
A microwave imaging technique based on artificial neural networks for neck tumors detection
No full textA microwave imaging approach for the detection of neck tumors is proposed in this paper. Specifically, a preliminary artificial neural network (ANN) is adopted for the reconstruction of the properties of a cross section of the neck starting from scattered electric fields. To this end, realistic neck phantoms are developed to test the feasibility of the proposed method. Several test cases are performed to evaluate the performance of the ANN to discriminate different sizes of the tumor and different positions inside the neck. The preliminary results indicate quite good detection capabilities
Microwave medical imaging of the human neck using a neural-networks-based inversion procedure: A phantom study
No full textA preliminary experimental validation of a machine-learning technique for microwave imaging of the neck is reported in this paper. Specifically, a fully-connected neural network is used to retrieve the dielectric properties of a simplified neck phantom. The architecture of the network, e.g., number of layers and neurons in each layer, is optimized through a numerical analysis on simulated data. The initial results confirm that it is possible to train the network with simulated data only and to test it with real data, obtaining good reconstruction results
An inline microwave sensor for carasau bread moisture estimation
No full textWater content estimation is of capital importance during the production process of the Carasau bread. A suitable microwave sensor could help monitor the moisture level in a non-invasive and reliable way. A simple narrowband patch antenna is proven to be more performing than dual band or wideband antennas. Magnitude and phase of the scattering parameters could help discriminate also between water content and other geometrical parameter variations
Microwave-based tomography of the human neck by means of a neural-network technique
No full textIn this contribution, a microwave-based
tomographic approach by means of a neural network technique is applied to the human neck. The aim is to retrieve
the dielectric and geometric properties of a cross section of
the neck to detect the possible presence of tumors. A fullyconnected neural network and a numerical model to create
a neck phantom dataset are developed. A preliminary result shows the possibility to locate and identify a simulated
tumor
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