28 research outputs found
A feasibility study of a rotary planar electrode array for electrical impedance mammography using a digital breast phantom
A feasibility study of an electrical impedance mammography (EIM) system
with a rotary planar electrode array, named RPEIM, is presented. The RPEIM
system is an evolution of the Sussex MK4 system, which is a prototype
instrument for breast cancer detection. Comparing it with the other planar
electrode EIM systems, the rotation feature enables a dramatic increase in
the number of independent measurements. To assist impedance evaluation
exploiting electrode array rotation, a synchronous mesh method is proposed.
Using the synchronous mesh method, the RPEIM system is shown to
have superior performance in image accuracy, spatial resolution and noise
tolerance over the MK4 system. To validate the study, we report simulations
based on a close-to-realistic 3D digital breast phantom, which comprises of:
skin, nipple, ducts, acinus, fat and tumor. A digital breast phantom of a real
patient is constructed, whose tumor was detected using the MK4 system. The
reconstructed conductivity image of the breast phantom indicates that the
breast phantom is a close replica of the patientâs real breast as assessed by the
MK4 system in a clinical trial. A comparison between the RPEIM system and
the MK4 system is made based on this phantom to assess the advantages of
the RPEIM system
Biocomposite films based on Îș-carrageenan/locust bean gum blends and clays : physical and antimicrobial properties
The aims of this work were to evaluate the physical and antimicrobial properties of biodegradable films composed of mixtures of Îș-carrageenan (Îș-car) and locust bean gum (LBG) when organically modified clay Cloisite 30B (C30B) was dispersed in the biopolymer matrix. Film-forming solutions were prepared by adding C30B (ranging from 0 to 16 wt.%) into the Îș-car/LBG solution (40/60 wt.%) with 0.3 % (w/v) of glycerol. Barrier properties (water vapour permeability, P vapour; CO2 and O2 permeabilities), mechanical properties (tensile strength, TS, and elongation-at-break, EB) and thermal stability of the resulting films were determined and related with the incorporation of C30B. Also, X-ray diffraction (XRD) was done in order to investigate the effect of C30B in film structure. Antimicrobial effects of these films against Listeria monocytogenes, Escherichia coli and Salmonella enterica were also evaluated. The increase of clay concentration causes a decrease of P vapour (from 5.34âĂâ10â11 to 3.19âĂâ10â11 g (m sâPa)â1) and an increase of the CO2 permeability (from 2.26âĂâ10â14 to 2.91âĂâ10â14 g (m sâPa)â1) and did not changed significantly the O2 permeability for films with 0 and 16 wt.% C30B, respectively. Films with 16 wt.% clay exhibited the highest values of TS (33.82 MPa) and EB (29.82 %). XRD patterns of the films indicated that a degree of exfoliation is attained depending on clay concentration. Îș-car/LBGâC30B films exhibited an inhibitory effect only against L. monocytogenes. Îș-car/LBGâC30B composite films are a promising alternative to synthetic films in order to improve the shelf life and safety of food products.J. T. Martins, A. I. Bourbon, A. C. Pinheiro and M. A. Cerqueira gratefully acknowledge the Fundacao para a Ciencia e Tecnologia (FCT, Portugal) for their fellowships (SFRH/BD/32566/2006, SFRH/BD/73178/2010, SFRH/BD/48120/2008 and SFRH/BPD/72753/2010, respectively), and B. W. S. Souza acknowledges the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES, Brazil)