ESTUDO DE MATERIAIS MAGNÉTICOS MACIOS SINTERIZADOS PARA APLICAÇÃO EM SERVOMOTORES

Resumo Este trabalho teve por objetivo o estudo de ligas sinterizadas a partir de Fe puro, FeP, FeSi e FeNi obtidas a partir do processo da Metalurgia do Pó e sua aplicação em núcleos de rotor e estator de servomotores, operando com corrente elétrica de armadura de alta freqüência, reduzindo assim, nestas frequências, as correntes parasitas, as quais causam perda de potência nestas máquinas. O estudo compreendeu obtenção de curvas de histerese destas diversas ligas, ensaios para avaliação de perdas elétricas e simulação em software de elementos finitos para obtenção de fluxo de entreferro e conjugado eletromagnético (torque). Os estudos teóricos e simulações foram realizados em um servomotor de topologia convencional e os testes foram realizados comparativamente a servomotores com núcleos obtidos a partir de chapas de aço laminadas. Nas simulações realizadas estaticamente, o torque instantâneo e o fluxo magnético no núcleo de Fe1%P resultaram valores próximos em relação às tradicionais chapas de aço laminadas. O núcleo de Fe1%P apresentou torque instantâneo de 1,59 N.m e fluxo magnético de 1,70 T e o núcleo de chapas de aço laminadas, respectivamente, 1,65 N.m e 1,66 T.Palavras-chave: Metalurgia do Pó. Servomotores. Simulação por elementos finitos. ABSTRACT This work aimed to study sintered alloys from pure Fe, FeP, FeSi and FeNi obtained by Powder Metallurgy process, and its application in rotor and stator cores of servomotors, operating with armature electric current in high frequency, thus reducing, in these frequencies, eddy currents, which cause loss of power in these machines. The study comprised obtaining hysteresis curves from these different alloys, tests to evaluate electrical losses and simulation in finite element software to obtain airflow and electromagnetic conjugate (torque). Theoretical studies and simulations were performed on a conventional topology of servomotor, and the tests were carried out comparatively to servomotors with cores obtained from rolled steel sheets. In the simulations performed statically, the instantaneous torque and the magnetic flux in the Fe1%P core resulted close values in relation to the traditional laminated steel sheets. The Fe1%P core had an instantaneous torque of 1.59 N.m and a magnetic flux of 1.70 T and the core of rolled steel sheets, respectively, 1.65 N.m and 1.66 T.Keywords: Powder Metallurgy. Servomotors. Finite Element Simulation

Concentration polarization around polyelectrolyte-coated electrodes. Model and observations

Financial support of this investigation by FEDER/Junta de Andalucía-Consejería de Transformación Económica, Industria, Conocimiento y Universidades, Spain (Grant No. P20_00233) and Consejería de Conocimiento, Investigación y Universidad, Junta de Andalucía, Spain (Grant No. A-FQM492-UGR20) is gratefully acknowledged. Thanks are also due for the grant TED2021-131855BI00/AEI/10.13039/501100011033/Unión Europea Next Generation EU/PRTR.An investigation on the phenomenon of concentration polarization (CP) in conducting porous particles is presented in this work, considering both bare and polyelectrolyte-coated particles. The conducting nature of the porous structure brings about the induction of a surface (and hence volume) charge distribution by the applied external field. The polymer charge (with its counterions from solution) is superimposed on this field-induced component. From the solution of Poisson’s equation, the concentration and potential profiles are evaluated, and from them, the concentration polarization can be calculated. The results are presented as concentration perturbation as a function of time after application of the field, both for bare and coated particles. Experiments are also performed aimed at measuring the CP using a solution of fluorescent dye (rhodamine B). From the increase or decrease of fluorescence, the concentration perturbations are observed around the particle. Importantly, depletion of concentration is observed on both sides of the particle when this is bare. In contrast, if the particles are coated, the classical pattern of a pole of increased concentration and an opposite one of decreased concentration is found. Dielectric dispersion experiments in suspensions of bare and brush-coated particles confirm this fact.FEDER/Junta de Andalucía P20_00233, A-FQM492-UGR20TED2021-131855BI00/AEI/10.13039/501100011033/Unión Europea Next Generation EU/PRT

Sublobar minimally invasive surgery vs. stereotactic ablative radiotherapy for early stage non-small cell lung cancer

Although lobectomy has been traditionally considered the standard treatment for early stage non-small cell lung cancer (NSCLC), lung-sparing resections usually called “sublobar resections” have exponentially increased in their use in the age of minimally-invasive surgery. Sublobar resection, especially anatomical segmentectomy, has shown comparable oncological outcomes in tumors less than 2 cm in diameter without nodal involvement and distant metastasis. On the other hand, more advanced radiation techniques such as stereotactic ablative radiotherapy, have shown excellent local control rates in stage I NSCLC, with low rates of post-treatment complications, so not only is its role growing in inoperable patients, but also in standard-risk stage I patients. There is a need for multicenter randomized trials addressing specifically this issue. This review aims to collect comparative data about the outcomes of both treatment strategies in early stage NSCLC

Uniportal VATS Left Posterobasal Anatomical Segmentectomy (S9+10)

<p>Anatomical sublobar resections, both segmental and subsegmental, are becoming more and more common. They are used to treat benign lesions and pulmonary metastasis, but they are especially used because they have shown comparable oncologic outcomes in early stage adenocarcinomas with lepidic growth [1,2] and better postoperative profiles by preserving more lung parenchyma when compared to lobar resections. The high frequency of anatomical variations make these procedures more challenging than lobar resections [3], but there are some specific anatomical segmentectomies that present more difficulties, which should be addressed.<br></p><p>This video shows a posterobasal (S9+10) left lower lobe segmentectomy for a lepidic adenocarcinoma of 1.7 cm without nodal involvement. Arterial segmental division can be easily achieved when the pulmonary artery is divided by identifying the central branch of the artery (between the upper segment artery A6 and the anterior segment artery A8). Division of the vein requires careful identification of segmental veins for the upper segment, anterior segment, and posterobasal segments. There is a high frequency of variation in the intersegmental veins, so special attention should be focused to clearly determine which of the veins drains S9+10 in order to preserve venous drainage for the remaining segments and avoid segmental infarction [4].</p><p>What the authors find most difficult in this procedure is division of the bronchus and the intersegmental fissures. The segmental bronchus for S9+10 lies just below the arterial stump for the segments, but dissection and division is difficult due to its central location within the lobe. After dissection of the S9+10 bronchus, the authors prefer to first divide the anterior intersegmental fissure (between S8 and S9+10) with endostaplers. After that, they divide the superior intersegmental fissure between the upper segment (S6) and the anterior segment (S8). For this, they place the anvil of the stapler above the pulmonary artery and the segmental bronchus, and pull the parenchyma between those segments (S6 and S8 initially, S6 and S9+10 in the posterior portion) towards the stapler. After this maneuver, segmental bronchial division with a stapler can be easily performed. Finally, it is only necessary to divide the intersegmental fissures, being careful with the segmental veins for the remaining segments in order to preserve them.</p><p>This procedure can be safely performed through uniportal VATS approach.</p> <p><strong>References</strong></p><ol><li>Altorki NK, Kamel MK, Narula N, et al. Anatomical segmentectomy and wedge resections are associated with comparable outcomes for patients with small cT1N0 non-small cell lung cancer. <em><a href="https://doi.org/10.1016/j.jtho.2016.06.031">J Thorac Oncol. 2016;11(11):1984-1992</a></em>.</li><li>Dziedzic R, Zurek W, Marjanski T, et al. Stage I non-small-cell lung cancer: long-term results of lobectomy versus sublobar resection from the Polish National Lung Cancer Registry. <em><a href="https://doi.org/10.1093/ejcts/ezx092">Eur J Cardiothorac Surg. 2017;52(2):363-369</a></em>.</li><li>Nagashima T, Shimizu K, Ohtaki Y, et al. An analysis of variations in the bronchovascular pattern of the right upper lobe using three-dimensional CT angiography and bronchography. <em><a href="https://doi.org/10.1007/s11748-015-0531-1">Gen Thorac Cardiovasc Surg. 2015;63(6):354-360</a></em>.</li><li>Gossot D, Lutz JA, Grigoroiu M, Brian E, Seguin-Givelet A. Unplanned procedures during thoracoscopic segmentectomies. <em><a href="https://doi.org/10.1016/j.athoracsur.2017.05.081">Ann Thorac Surg. 2017;104(5):1710-1717</a></em>.</li></ol

The (truly) first fossil freshwater molluscs from Antarctica

New collection work in Mount Flora, Hope Bay, Antarctic Peninsula, has confirmed the presence of bivalve moulds in the Jurassic Mount Flora Formation. In contrast to a twenty-first century article claiming to report the first discovery of fossil freshwater molluscs in Antarctica, evidence of these molluscs was first reported for Antarctica more than 110 years ago by J. Gunnar Andersson. The bivalve was formally described and named some 50 years later, by Camacho, as Antediplodon esperanzaensis. The species was subsequently transferred to the genus Diplodon for unknown reasons. Here, we illustrate specimens from the same locality for the first time with photographs, considering them Unionida incertae saedis, in view of the absence of diagnostic characters. In fact, two morphotypes are present, one elongated, very similar to the nominal species A. esperanzaensis, and another one subelliptical in shape.Fil: Martínez, Sergio. Universidad de la República; UruguayFil: Scasso, Roberto Adrian. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; ArgentinaFil: Elgorriaga, Andres. Museo Paleontológico Egidio Feruglio; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Capelli, Ignacio Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; ArgentinaFil: del Valle, Rodolfo. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Puerta, Pablo. Museo Paleontológico Egidio Feruglio; ArgentinaFil: Lirio, Juan Manuel. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Rodriguez Amenabar, Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentin