Implementation of a low cost prototype for electrical impedance tomography based on the integrated circuit for body composition measurement AFE4300

Electrical impedance tomography (EIT) is a technique of image reconstruction of the electrical conductivity distribution in a tissue or region under observation. An electrical system for EIT comprises complex hardware and software modules, which are designed for a specific application which requires that the system to be able to detect conductivity variations within the study object. The Front-End for body composition measurement, AFE4300 from Texas Instruments allows a minimal implementation of an electrical impedance tomography system. It is the main device in the development of the EIT system presented in this paper, this device injects the current signal and measures the tensions generated on the study region boundary by 8 electrodes, the image reconstruction software was developed on the National Instruments platform Labview. The system includes a microcontroller PIC16F886 to configure the 8 channels for the definition of the patterns of injection and measurement of signals, also defines the current signal frequency and the bluetooth communication with the computer for the image reconstruction. The developed system was validated by a planar resistive phantom (CardiffEIT phantom), obtaining a stable voltage measurement every 50 ms per pair of electrodes, and a signal to noise ratio (SNR) maximum of 71.8 dB, for a current signal of 50 kHz. Additionally, tests were carried out in a saline tank with a concentration of 4 g/L, the developed system can simultaneously estimate the presence of conductive and non-conductive disturbances into the tank. CopyrightPeer ReviewedPostprint (published version

Luminescent Optical Fiber Oxygen Sensor following Layer-by-layer Method

AbstractA sensor based on luminescence has been prepared depositing the luminescent complex platinum tetrakis pentrafluorophenyporphine (PtTFPP) onto a plastic-clad silica (PCS) optical fiber. The sensing film is constructed in terms of Layer-by-Layer method. A LED centered at 400nm was used to interrogate the sensor in a reflection configuration, registering a luminescent signal from the sensing material located at 648nm. The transduction principle is based on the quenching suffered by PtTFPP as the oxygen (O2) concentration increases. The sensor was characterized for O2 concentrations from 0% to 75%, showing a linear Stern–Volmer relationship (R2 = 0.9962)

Anderson Photon-Phonon Colocalization in Certain Random Superlattices

International audienceFundamental observations in physics ranging from gravitational wave detection to laser cooling of a nanomechanical oscillator into its quantum ground state rely on the interaction between the optical and the mechanical degrees of freedom. A key parameter to engineer this interaction is the spatial overlap between the two fields, optimized in carefully designed resonators on a case-by-case basis. Disorder is an alternative strategy to confine light and sound at the nanoscale. However, it lacks an a priori mechanism guaranteeing a high degree of colocalization due to the inherently complex nature of the underlying interference processes. Here, we propose a way to address this challenge by using GaAs=AlAs vertical distributed Bragg reflectors with embedded geometrical disorder. Because of a remarkable coincidence in the physical parameters governing light and motion propagation in these two materials, the equations for both longitudinal acoustic waves and normal-incidence light become practically equivalent for excitations of the same wavelength. This guarantees spatial overlap between the electromagnetic and displacement fields of specific photon-phonon pairs, leading to strong light-matter interaction. In particular, a statistical enhancement in the vacuum optomechanical coupling rate, g o , is found, making this system a promising candidate to explore Anderson localization of high frequency (∼20 GHz) phonons enabled by cavity optomechanics. The colocalization effect shown here unlocks the access to unexplored localization phenomena and the engineering of light-matter interactions mediated by Anderson-localized states

Comparative theoretical analysis between parallel and perpendicular geometries for 2d particle patterning in photovoltaic ferroelectric substrates

This paper describes the dielectrophoretic potential created by the evanescent electric field acting on a particle near a photovoltaic crystal surface depending on the crystal cut. This electric field is obtained from the steady state solution of the Kukhtarev equations for the photovoltaic effect, where the diffusion term has been disregarded. First, the space charge field generated by a small, square, light spot where d ≪ l (being d a side of the square and l the crystal thickness) is studied. The surface charge density generated in both geometries is calculated and compared as their relation determines the different properties of the dielectrophoretic potential for both cuts. The shape of the dielectrophoretic potential is obtained and compared for several distances to the sample. Afterwards other light patterns are studied by the superposition of square spots, and the resulting trapping profiles are analysed. Finally the surface charge densities and trapping profiles for different d/l relations are studiedThis work was supported by the Spanish Ministerio de Economia y Competitividad under grants MAT2011-28379- C03 and MAT2014-57704-C

THz Generation via Optical Rectification in Nanomaterials: Universal Modeling Approach and Effective chi(2)chi^{(2)} Description

Optical rectification (OR) at the nanoscale has attracted an increasing interest in the prospect of providing efficient ultracompact terahertz (THz) sources. Here, a universal modeling approach capable of addressing both isotropic and anisotropic all-dielectric nonlinear nanomaterials on an ultra-broad spectral range, covering the highly dispersive phonon-polariton window, and different orientations of the crystallographic axes with respect to the geometry of the structure is reported. This analysis is exemplified by considering two study cases, that is, nanopillars of AlGaAs and of LiNbO3. A close comparison between the two cases is established in terms of THz generation efficiency from 4 to 14 THz. Phonon-polariton contributions to the OR process are disentangled from the electronic one, and a model order reduction based on the reciprocity theorem is applied and validated on both the considered configurations. These results, combined with the inspection of the THz near-field features, pave the way to the design and optimization of nonlinear metasurfaces for THz generation and detection at the nanoscale

Data-driven model for the assessment of mycobacterium tuberculosis transmission in evolving demographic structures

In the case of tuberculosis (TB), the capabilities of epidemic models to produce quantitatively robust forecasts are limited by multiple hindrances. Among these, understanding the complex relationship between disease epidemiology and populations’ age structure has been highlighted as one of the most relevant. TB dynamics depends on age in multiple ways, some of which are traditionally simplified in the literature. That is the case of the heterogeneities in contact intensity among different age strata that are common to all airborne diseases, but still typically neglected in the TB case. Furthermore, while demographic structures of many countries are rapidly aging, demographic dynamics are pervasively ignored when modeling TB spreading. In this work, we present a TB transmission model that incorporates country-specific demographic prospects and empirical contact data around a data-driven description of TB dynamics. Using our model, we find that the inclusion of demographic dynamics is followed by an increase in the burden levels predicted for the next decades in the areas of the world that are most hit by the disease today. Similarly, we show that considering realistic patterns of contacts among individuals in different age strata reshapes the transmission patterns reproduced by the models, a result with potential implications for the design of age-focused epidemiological interventions

Follow-up of a new titanium-coated polyetheretherketone cage for the cervical spine

Poly-ether-ether-ketone (PEEK) cages have lower modulus of elasticity when compared with Titanium (TTN) cages. This suggests that PEEK-cages could show a lower rate of subsidence after anterior cervical discectomy-fusion (ACDF) and might lead to a lower loss of correction. We investigated the one to five year-results of standalone PEEK-TTN-porous coated cages in a patient cohort from 2014 to 2017. The patients underwent single-level ACDF for disc herniation and degenerative discopathy. Clinical and radiological outcome were assessed in 50 eligible patients after a mean of 27 months. Results: Solid arthrodesis was found in 84%. Neck disability index (NDI), and visual analogue scale (VAS) of neck and arm show comparable results to the literature. Conclusions: Clinical and radiological outcomes of ACDF with PEEK-body-cages with a porous coated surface show good bony integration. The modulus of elasticity, design, shape, size, cage surface architecture, as well as bone density, endplate preparation, radical microdiscectomy and distraction during surgery should be considered as important factors influencing the clinical results. One main advantage, over titanium cages, is the absence of MRI artifacts, allowing an excellent postoperative follow-up. inferior clinical outcome compared with bone grafts due to a higher elasticity modulus, which could result in cage subsidence.8 Nevertheless, due to structural properties, TTN implants are likely to provide a good osseo-integration9 and several clinical studies demonstrate successful results after implantation of TTN-cages.10-13 PEEKcages have a modulus of elasticity closely resembling that of cortical bone, which might lead to advantages in load sharing and stress distribution. This might reduce the subsidence rate with an improved segmental correction in the long term and a potentially higher fusion rate.14-16 A direct comparison of cervical TTNand PEEKcages in a clinical setting is very rarely found in the literature, 16, 17 and even less studies consequently compare the radiological results.16, 17 The latter studies showed the PEEK-implants being superior in maintaining cervical interspace height and achieving radiographic fusion, 16, 17 even suggesting to cease the application of TTN-cages in cervical spine surgery.16 A solution in-between are newer cages that combine the benefit of both materials: PEEK-body cages plasma-sprayed with a porous titanium surface which is tightly bonded to the PEEK surface.18, 19 On TTN alloy substrates, osteoblasts exhibit a more differentiated phenotype and increased bone morphogenetic protein production than on poly-ether-ether-ketone.20 A group of Japanese surgeons found that TTN-coated PEEK cages exhibit radiographic signs of bone on-growth, as represented by vertebral cancellous condensation around the cage, compared with that around the uncoated PEEK cage.21 Therefore, a TTN-coated PEEK cage may have the potential to promote solid fusion and to improve clinical outcomes in cervical interbody fusion surgery. This keeps the ideal elasticity modulus close to a bonelike elasticity modulus and offers a highly biocompatible surface that is well tolerated by bone and allows its ongrowth to the porous surface. The aim of the present study is to assess clinical and radiological results of CeSpace XP®, a titanium-coated PEEK cage

Fluorescent Orthopalladated Complexes of 4-Aryliden-5(4H)-oxazolones from the Kaede Protein: Synthesis and Characterization

The goal of the work reported here was to amplify the fluorescent properties of 4-aryliden-5(4H)-oxazolones by suppression of the hula-twist non-radiative deactivation pathway. This aim was achieved by simultaneous bonding of a Pd center to the N atom of the heterocycle and the ortho carbon of the arylidene ring. Two different 4-((Z)-arylidene)-2-((E)-styryl)-5(4H)-oxazolones, the structures of which are closely related to the chromophore of the Kaede protein and substituted at the 2- and 4-positions of the arylidene ring (1a OMe; 1b F), were used as starting materials. Oxazolones 1a and 1b were reacted with Pd(OAc)2 to give the corresponding dinuclear orthometalated palladium derivates 2a and 2b by regioselective C-H activation of the ortho-position of the arylidene ring. Reaction of 2a (2b) with LiCl promoted the metathesis of the bridging carboxylate by chloride ligands to afford dinuclear 3a (3b). Mononuclear complexes containing the orthopalladated oxazolone and a variety of ancillary ligands (acetylacetonate (4a, 4b), hydroxyquinolinate (5a), aminoquinoline (6a), bipyridine (7a), phenanthroline (8a)) were prepared from 3a or 3b through metathesis of anionic ligands or substitution of neutral weakly bonded ligands. All species were fully characterized and the X-ray determination of the molecular structure of 7a was carried out. This structure has strongly distorted ligands due to intramolecular interactions. Fluorescence measurements showed an increase in the quantum yield (QY) by up to one order of magnitude on comparing the free oxazolone (QY < 1%) with the palladated oxazolone (QY = 12% for 6a). This fact shows that the coordination of the oxazolone to the palladium efficiently suppresses the hula-twist deactivation pathway