Influence Of Backing And Matching Layers In Ultrasound Transducers Performance

In this work we have investigated the influence of the backing layer composition and the matching layer thickness in the performance of ultrasound transducers constructed with piezoelectric ceramic discs. We have constructed transducers with backing layers of different compositions, using mixtures of epoxy with alumina powder and/or Tungsten powder and with λ/4 or 3λ/4 thickness epoxy matching layers. The evaluation tests were performed in pulse-echo mode, with a flat target, and in transmission/reception mode, with a calibrated PVDF hydrophone. The acoustical field emitted by each transducer was mapped in order to measure the on-axis and transverse field profiles, the aperture size and the beam spreading. The bandwidths of the transducers were determined in pulse-echo mode. Comparing the evaluation tests results of two transducers constructed with the same backing layer, the one constructed with λ/4 thickness epoxy matching layer showed better performance. The results showed that the transducers constructed with epoxy, alumina and Tungsten powders backing layers have larger bandwidth. The larger depth of field was measured for transducers constructed with epoxy and Tungsten powder backing layers. These transducers and those constructed with epoxy, Tungsten and alumina powders backing layers showed the larger field intensities in the measured transverse profiles.50358696(1999) Standard Guide for Evaluating Characteristics of Ultrasonic Search Units, , ASTM E-1065 1999Desilets, C.S., Fraser, J.D., Kino, G.S., The design of efficient broad-band piezoelectric transducers (1978) IEEE Transactions on Sonics and Ultrasonics, SU-25 (3), pp. 115-125(1996) Ultrasonics Real Time Pulse-echo Systems: Test Procedures to Determine Performance Specification, , IEC-1390(1989) IEEE Guide for Medical Ultrasound Field Parameter Measurements, , IEEE American National Standard Std 790(1978) IEEE Standard on Piezoelectricity, , IEEE American National Standard Std 176Inoue, T., Ohta, M., Takahashi, S., Design of ultrasonic transducers with multiple acoustic matching layers for medical applications (1987) IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 34 (1)Lockwood, G.R., Turnbull, D.H., Foster, F.S., Fabrication of high frequency spherically shaped ceramic transducers (1994) IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 41 (2)Mitra, R., Saksena, T.K., Study on the vibrational characteristics of ultrasonic transducers using tapered piezoelectric ceramic elements (1995) Journal of the Acoustical Society of America, 58 (2)Sayers, C.M., Tait, C.E., Ultrasonic properties of transducer backing (1984) Ultrasonics, 22 (2

Evaluation of clinical, epidemiological and electrophysiological variables for early diagnosis of amyotrophic lateral sclerosis

Motor neuron disease (MND) is a systemic disease with a broad clinical spectrum. It is characterized by primary involvement of the lower or upper motor neuron (UMN), or both, simultaneously, represented by the most common form, amyotrophic lateral sclerosis (ALS). ALS is rapidly progressive and fatal disease that evolve to death due to respiratory failure, on average, in three to five years since the onset of symptoms. This fact attends to the early and correct diagnosis of the disease. Objective: To evaluate clinical, epidemiological and electrophysiological variables for the early diagnosis of ALS. Methods: This is an observational, descriptive and retrospective study, conducted from the collect of the database, in which the variables were submitted to statistical analysis: Mann-Whitney test and Fisher's exact test. Results: When correlating clinical, epidemiological and electrophysiological findings of patients with ALS and other forms of MND, the variables: age of onset of symptoms (P=0,02) hyperreflexia (P=0,001), presence of bulbar symptoms/signs (P0,001), pathological reflexes (P=0.001), and presence of fasciculation in electromyography (P=0,001) presented statistical significance for the diagnosis of ALS. Conclusion: Despite the small sample size, the findings reinforce the importance of well- done neurological examination, to search for signs of involvement of the UMN, in the first evaluation of patients with suspected MND. And that more research is needed to better understand the different phenotypes of the disease in order to obtain an increasingly early diagnosis to offer improvements in the quality of life of thesepatients

Interrelationships between Circular Economy and Industry 4.0: A Research Agenda for Sustainable Supply Chains

The purpose of this article is to propose a novel classification of the interrelationships between I4.0 technologies and CE principles that highlights the most conclusive findings and extant gaps in the relevant research. A Systematic Literature Review has been developed to locate, select and evaluate relevant contributions made to CE interrelationships with I4.0 technologies. Studies have been analysed and classified according to the specific I4.0 technology and CE principle addressed (10Rs). The articles have been clustered into three main groups: (i) useful application of materials; (ii) extending the lifespan of products and their parts, and (iii) smarter product use and manufacture. A mind map of the investigated articles has been used to establish the interrelationships between individual technologies and each CE principle at the supply chain level. Based on this classification, a focus group interview (FGI) was held with experts to dig deeper into the interrelationships between I4.0 technologies and CE principles. The FGI results have identified how each as yet unexplored I4.0 technology could be linked to each CE principle. A Fuzzy Delphi (FD) study was also applied to identify the most relevant I4.0 technologies for improving CE principles and closing gaps in the literature regarding the 10R CE principles. In addition, guidelines have been established to assist with practical applications and generate a research agenda on the interrelationships between I4.0 technologies and CE principles at the supply chain level. Implications for theory include the extension of view from the research gaps between I4.0 technologies and the 10Rs identified in the literature; also, an FGI and FD were performed based on the detected research gaps to identify future lines of research for academics and offer useful guidance to directors and managers on I4.0 technology interrelationships for improving at least one of the 10R CE principles. The contribution to practice aims to enable managers to easily identify which technology from the I4.0 domain should be used to advance any given CE principle. Lastly, we provide useful guidance on the application of as yet-unused technologies to improve CE principles

Mills’ syndrome: case report

The syndrome of progressive, ascending or descending hemiplegia, with no significant sensory impairment was first describes by Mills in 1900, which several cases were reported later. However after diagnostic tests and image improvements, the number of reports has shortened. A possible explanation for this shortage is the identification of other diseases that could mimic the clinical picture. Currently, the syndrome has an uncertain nosological status, since it was described based on clinical examination only. We can find this clinical presentation (Mills syndrome) in cases of amyotrophic lateral sclerosis (ALS), predominant upper motor neuron amyotrophic lateral sclerosis (UMN-ALS) and primary lateral sclerosis (PLS), besides its symptomatic (secondary) forms. We describe a case (initial presentation and one year follow-up) of progressive ascending hemiplegia with clinical isolated upper neuron signs and normal sensory examination, discussing its nosological status, electromyographic findings, differential diagnosis and prognosis

Citizen science for policy formulation and implementation

Citizen science, the active participation of the public in scientific research projects, is a rapidly expanding field in open science and open innovation. It provides an integrated model of public knowledge production and engagement with science. As a growing worldwide phenomenon, it is invigorated by evolving new technologies that connect people easily and effectively with the scientific community. Catalysed by citizens’ wishes to be actively involved in scientific processes, as a result of recent societal trends, it also offers contributions to the rise in tertiary education. In addition, citizen science provides a valuable tool for citizens to play a more active role in sustainable development. This book identifies and explains the role of citizen science within innovation in science and society, and as a vibrant and productive science-policy interface. The scope of this volume is global, geared towards identifying solutions and lessons to be applied across science, practice and policy. The chapters consider the role of citizen science in the context of the wider agenda of open science and open innovation, and discuss progress towards responsible research and innovation, two of the most critical aspects of science today

Battery-like behavior of Ni-ceria based systems: synthesis, surface defects and electrochemical assessment

NiO, CeO2 and respective composites are extensively used in energy storage devices due to mostly their high electrochemical activity. However, the assessment of battery-like behavior of Ni-ceria based systems comprising (Ni or Gd)-doped ceria combined with NiO seems to be neglected in the literature. In this work, NiO and ceria-based solid solutions composite powders were obtained by a co-precipitation synthesis method. The structure and particle size of the calcined powders were investigated by X-ray diffractometry (XRD) and field emission scanning electron microscopy (FESEM), respectively. Oxidative states of composites were inspected by X-ray photoelectron spectroscopy (XPS). The electrochemical performance of powders was evaluated by cyclic voltammetry, galvanostatic charge-discharge and impedance spectroscopy. Refinement of the XRD patterns showed that powders have nanosized crystallites and mean size of particles within 20 – 70 nm were revealed by FESEM. The improved specific capacity of the NiO-CeO2 electrode material (about 2.5 times higher than that of NiO-CGO at 5 mV s−1) is due to an increase in Faradic reactions taken place on its surface with a higher fraction of defects (namely Ni3+, Ce3+ and oxygen vacancies), as determined by XPS. The superior electrochemical performance of the NiO-CeO2 electrode is also confirmed by electrochemical impedance spectroscopy.publishe

Stationary solutions for the parity-even sector of the CPT-even and Lorentz-covariance-violating term of the standard model extension

In this work, we focus on some properties of the parity-even sector of the CPT-even electrodynamics of the standard model extension. We analyze how the six non-birefringent terms belonging to this sector modify the static and stationary classical solutions of the usual Maxwell theory. We observe that the parity-even terms do not couple the electric and magnetic sectors (at least in the stationary regime). The Green's method is used to obtain solutions for the field strengths E and B at first order in the Lorentz- covariance-violating parameters. Explicit solutions are attained for point-like and spatially extended sources, for which a dipolar expansion is achieved. Finally, it is presented an Earth-based experiment that can lead (in principle) to an upper bound on the anisotropic coefficients as stringent as $(\widetilde{\kappa}_{e-}) ^{ij}<2.9\times10^{-20}.$Comment: 8 pages, revtex style, revised published version, to appear in EPJC (2009