Comparing liquid homogeneous and multilayer phantoms for human body implantable antennas

We compare the performance of a ultrawideband implantable antenna when immersed in a liquid homogeneous phantom and in a multilayer phantom. The goal is to assess how good the simple liquid phantom is to represent the real body over a broad bandwidth. We evaluate not only the frequency-domain parameters – input reflection (s11) and transmission coefficients (s21) – but also the performance of the antenna in the time domain – pulse fidelity and window containing 90% of the pulse energy. The results show a good resemblance between both phantom results, suggesting that liquid homogeneous phantoms may be enough to test the performance of this type of antennas and potentially simplify the measurement setup.info:eu-repo/semantics/acceptedVersio

Dynamic critical exponents of the Ising model with multispin interactions

We revisit the short-time dynamics of 2D Ising model with three spin interactions in one direction and estimate the critical exponents $z,$ $\theta,$ $\beta$ and $\nu$. Taking properly into account the symmetry of the Hamiltonian we obtain results completely different from those obtained by Wang et al.. For the dynamic exponent $z$ our result coincides with that of the 4-state Potts model in two dimensions. In addition, results for the static exponents $\nu$ and $\beta$ agree with previous estimates obtained from finite size scaling combined with conformal invariance. Finally, for the new dynamic exponent $\theta$ we find a negative and close to zero value, a result also expected for the 4-state Potts model according to Okano et al.Comment: 12 pages, 9 figures, corrected Abstract mistypes, corrected equation on page 4 (Parameter Q

Webcam-based distance and surface estimation system for microwave imaging

One of the critical steps in Medical Microwave Imaging (MMWI) algorithms is the calculation of the distances between the antenna and the synthetical focal point, due to the different propagation velocities in the tissues and background medium. In fact, it has a major influence on the image accuracy. As a result, it is very important to have a priori information about the shape of the body part under examination. Here we propose a low cost optical system based on a single commercial webcam. We validate the new system by showing an application to breast imaging, where we reconstruct the scatterers inside the breast using the real and estimated shapes. The results show very good resemblance, thus proving the new system supplies a reliable estimation of the breast shape.info:eu-repo/semantics/publishedVersio

Systematic analysis of microwave breast imaging detection of different-sized malignant and benign tumors

Microwave Imaging (MWI) has been explored as an alternative to conventional breast tumor screening methods. It is acknowledged that benign and malignant tumors can be distinguishable by their architectural features: benign tumors are often round with well-defined margin, while malignant tumors have an ill-defined margin and are micro-lobulated or spiculated. We present a MWI-based systematic analysis of malignant and benign breast tumors of different sizes, to evaluate if its characteristics allow differentiating the images. To this end, we performed measurements on a dry MW setup, using a slot-based antenna in the 2–5 GHz frequency range to scan an anthropomorphic breast phantom. We placed inside eight malignant and benign tumors with 3, 4,… 10 mm average radius, one at a time. This study shows that both types of tumors can be detected, but not distinguishable only via MWI. Smaller tumors become harder to detect, the 3 mm tumor being unreliably caught.info:eu-repo/semantics/acceptedVersio

Antenna phase center and angular dispersion estimation using planar acquisition setup applied to microwave breast imaging

We propose a “near-field phase center” estimation technique based on planar acquisition setup. It requires a single antenna and an electrically small object to serve as target. The technique allows to estimate the phase center spatial coordinates, as well as its angular dispersion. This data is useful in microwave imaging applications where the antenna operate in near-field regime, such as medical applications (e.g. breast and head imaging). We demonstrate that for a commonly used Vivaldi antenna operating in the 2-5 GHz band, the angular dispersion of the pseudo phase center can be as high as 50 mm. Moreover, we show that incorporating this data in the signal processing algorithms improves the imaging results, by applying it to microwave breast imaging. We believe this type of antennacharacterization techniques will leverage the use of more informative imaging algorithms (e.g. truncated singular value decomposition), since they increase the accuracy of the distance calculations, thus improving the signal to noise ratio.info:eu-repo/semantics/acceptedVersio

Microwave breast imaging using a dry setup

This article demonstrates for the first time, both numerically and experimentally, the feasibility of radar-based microwave imaging of anthropomorphic heterogeneously dense breasts in prone position, requiring no immersion liquid. The dry, contactless approach greatly simplifies the setup, favors patient comfort, and further avoids lengthy sanitation procedures after each exam. We use a radar-type technique with the antennas distributed in cylindrical configuration around the breast phantom. The reflectivity map is reconstructed using a wave-migration algorithm in the frequency domain. This article presents new developed strategies to cope with the challenges of a dry setup, namely increased skin artifact due to the concomitant absence of matching liquid and nonuniform breast shape. We propose an iterative and adaptive algorithm based on singular value decomposition that effectively removes the skin backscattering under the abovementioned conditions. It is compatible with automatic processing, and computationally fast. One of its inputs is the breast three-dimensional surface information, and its distance to the antennas, all obtained automatically from a proposed low-cost procedure based on a webcam. The imaging method is reasonably resilient to the presence of fibroglandular tissues, and to uncertainties of tissue permittivity. Another tackled challenge is the miniaturization of the antenna in air, which is achieved with an optimized balanced antipodal Vivaldi of the same size as counterparts used in dense immersion liquids. Finally, all the building blocks are combined to demonstrate experimentally the overall dry system performance, with very good detection of the tumor at three different positions in the breast, even in low-contrast scenarios.info:eu-repo/semantics/acceptedVersio

EcDBS1R4, an antimicrobial peptide effective against Escherichia coli with in vitro fusogenic ability

©2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open accessarticle distributed under the terms and conditions of the Creative Commons Attribution(CC BY) license (http://creativecommons.org/licenses/by/4.0/)Discovering antibiotic molecules able to hold the growing spread of antimicrobial resistance is one of the most urgent endeavors that public health must tackle. The case of Gram-negative bacterial pathogens is of special concern, as they are intrinsically resistant to many antibiotics, due to an outer membrane that constitutes an effective permeability barrier. Antimicrobial peptides (AMPs) have been pointed out as potential alternatives to conventional antibiotics, as their main mechanism of action is membrane disruption, arguably less prone to elicit resistance in pathogens. Here, we investigate the in vitro activity and selectivity of EcDBS1R4, a bioinspired AMP. To this purpose, we have used bacterial cells and model membrane systems mimicking both the inner and the outer membranes of Escherichia coli, and a variety of optical spectroscopic methodologies. EcDBS1R4 is effective against the Gram-negative E. coli, ineffective against the Gram-positive Staphylococcus aureus and noncytotoxic for human cells. EcDBS1R4 does not form stable pores in E. coli, as the peptide does not dissipate its membrane potential, suggesting an unusual mechanism of action. Interestingly, EcDBS1R4 promotes a hemi-fusion of vesicles mimicking the inner membrane of E. coli. This fusogenic ability of EcDBS1R4 requires the presence of phospholipids with a negative curvature and a negative charge. This finding suggests that EcDBS1R4 promotes a large lipid spatial reorganization able to reshape membrane curvature, with interesting biological implications herein discussed.This research was funded by Fundação para a Ciência e a Tecnologia—Ministério da Ciência, Tecnologia e Ensino Superior (FCT-MCTES, Portugal), Marie Skłodowska-Curie Research and Innovation Staff Exchange (MSCA-RISE, European Union) project INPACT (call H2020-MSCA-RISE-2014, grant agreement 644167), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, Brazil), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES, Brazil), Fundação de Amparo a Pesquisa do Distrito Federal (FAPDF, Brazil) and Fundação de Apoio ao Desenvolvimento do Ensino, Ciência e Tecnologia do Estado de Mato Grosso do Sul (FUNDECT, Brazil). M.M. and M.R.F. also acknowledge FCT-MCTES fellowships SPRH/BD/128290/2017 and SPRH/BD/100517/2014, respectively.info:eu-repo/semantics/publishedVersio

Peptides with dual antimicrobial and anticancer activities

Copyright © 2017 Felício, Silva, Gonçalves, Santos and Franco. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC-BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.In recent years, the number of people suffering from cancer and multi-resistant infections has increased, such that both diseases are already seen as current and future major causes of death. Moreover, chronic infections are one of the main causes of cancer, due to the instability in the immune system that allows cancer cells to proliferate. Likewise, the physical debility associated with cancer or with anticancer therapy itself often paves the way for opportunistic infections. It is urgent to develop new therapeutic methods, with higher efficiency and lower side effects. Antimicrobial peptides (AMPs) are found in the innate immune system of a wide range of organisms. Identified as the most promising alternative to conventional molecules used nowadays against infections, some of them have been shown to have dual activity, both as antimicrobial and anticancer peptides (ACPs). Highly cationic and amphipathic, they have demonstrated efficacy against both conditions, with the number of nature-driven or synthetically designed peptides increasing year by year. With similar properties, AMPs that can also act as ACPs are viewed as future chemotherapeutic drugs, with the advantage of low propensity to resistance, which started this paradigm in the pharmaceutical market. These peptides have already been described as molecules presenting killing mechanisms at the membrane level, but also acting toward intracellular targets, which increases their success compartively to one-target specific drugs. This review will approach the desirable characteristics of small peptides that demonstrated dual activity against microbial infections and cancer, as well as the peptides engaged in clinical trials.This work was supported by Fundação para a Ciência e a Tecnologia – Ministério da Ciência, Tecnologia e Ensino Superior (FCT-MCTES, Portugal), by Brazilian funding agencies CNPq, CAPES, FADPDF, FINEP, and FUNDECT, and by Marie Skłodowska-Curie, Research, and Innovation Staff Exchange (MSCA-RISE, European Union) project INPACT (call H2020-MSCA-RISE-2014, grant agreement 644167). MF acknowledges FCT-MCTES fellowship SPRH/BD/100517/2014. OS holds a postdoctoral scholarship from the National Council of Technological and Scientific Development (CNPq) and Fundação de Apoio ao Desenvolvimento do Ensino, Ciência e Tecnologia do Estado de Mato Grosso do Sul (FUNDECT; 300583/2016-8).info:eu-repo/semantics/publishedVersio

Wrist-Worn RFID Antenna Printed on Additive Manufactured Flexible Substrate

We assess the feasibility of fabricating a flexible RFID wrist-worn antenna printed on a substrate manufactured using 3D-printing technology, as to enable full customization of the bracelet at low cost. Numerical results show adequate power transmission to the RFID chip. Also, the fabricated prototype shows enough flexibility to be bent around the wrist.info:eu-repo/semantics/acceptedVersio

Design of a Rotman lens operating in the full K/Ka band using ridge waveguide technology

Several services associated with satellite on the move and 5G applications are populating the K and Ka frequency bands. Beam forming networks are crucial components for achieving the necessary beam flexibility and agility of these systems. The Rotman lens is being widely investigate as a cost-effective solution for overcoming the main limitations of other types of beam forming networks, namely bandwidth, complexity, and size. One of the main design challenges is obtaining broadband transitions for the array and beam ports. In this work, we used a standard K/Ka double ridge (WRD180) for interfacing with the Rotman Lens. The main motivation for this choice is the wide bandwidth, compatible with the K/Ka satcom frequency bands, and the use of air/vacuum propagation medium in the parallel plate waveguide section to avoid dielectric losses associated with microstrip implementations. We present a design capable of fully exploiting the ridge waveguide bandwidth with wide beam scanning, outperforming previous works. The presented design consists of a 13×7 Rotman Lens with a scanning range of ±50 degrees operating between 16 and 40 GHz, validated through full-wave simulations.info:eu-repo/semantics/acceptedVersio