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[SciELO Preprints] - Guidelines on the Diagnosis and Treatment of Hypertrophic Cardiomyopathy – 2024
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Fernandes, Fabio Simões, Marcus V. Correia, Edileide de Barros Marcondes-Braga, Fabiana G. Coelho-Filho, Otavio Rizzi Mesquita, Cláudio Tinoco Mathias-Junior, Wilson Rochitte, Carlos Eduardo Ramires, Felix José Alvarez Alves, Silvia Marinho Martins Montera, Marcelo Westerlund Lopes, Renato Delascio Oliveira-Junior, Mucio Tavares Scolari, Fernando L. Avila, Walkiria Samuel Canesin, Manoel Fernandes Bacal, Fernando Bocchi, Edimar Alcides Moura, Lídia Ana Zytynski Saad, Eduardo Benchimol Scanavacca, Mauricio I. Valdigem, Bruno Pereira Cano , Manuel Nicolas Abizaid , Alexandre Ribeiro, Henrique Barbosa Lemos-Neto, Pedro Alves Ribeiro, Gustavo Calado de Aguiar Jatene, Fabio Biscegli Dias, Ricardo Ribeiro Beck-da-Silva, Luis Rohde, Luis Eduardo P. Bittencourt, Marcelo Imbroinise Pereira, Alexandre Krieger, José Eduardo Villacorta, Humberto Martins, Wolney de Andrade Figueiredo-Neto, José Albuquerque de Cardoso , Juliano Novaes Pastore, Carlos Alberto Jatene, Ieda Biscegli Tanaka, Ana Cristina Sayuri Hotta, Viviane Tiemi Romano, Minna Moreira Dias Albuquerque, Denilson Campos de Mourilhe-Rocha, Ricardo Hajjar, Ludhmila Abrahão Brito, Fabio Sandoli de Caramelli , Bruno Calderaro, Daniela Farsky, Pedro Silvio Colafranceschi , Alexandre Siciliano Pinto, Ibraim Masciarelli Vieira , Marcelo Luiz Campos Danzmann, Luiz Claudio Barberato , Silvio Henrique Mady, Charles Martinelli-Filho, Martino Torbey , Ana Flavia Malheiros Schwartzmann, Pedro Vellosa Macedo, Ariane Vieira Scarlatelli Ferreira , Silvia Moreira Ayub Schmidt, Andre Melo , Marcelo Dantas Tavares de Lima-Filho, Moysés Oliveira Sposito, Andrei C. Brito, Flavio de Souza Biolo, Andreia Madrini-Junior, Vagner Rizk, Stéphanie Itala Mesquita, Evandro Tinoco

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Fecha de publicación: 2024-04-08

Resumen: Pt Es En

A cardiomiopatia hipertrófica (CMH) é uma forma de doença do músculo cardíaco de causa genética, caracterizada pela hipertrofia das paredes ventriculares. O diagnóstico requer detecção por métodos de imagem (Ecocardiograma ou Ressonância Magnética Cardíaca) de qualquer segmento da parede do ventrículo esquerdo com espessura > 15 mm, sem outra causa provável. A análise genética permite identificar mutações de genes codificantes de diferentes estruturas do sarcômero responsáveis pelo desenvolvimento da CMH em cerca de 60% dos casos, permitindo o rastreio de familiares e aconselhamento genético, como parte importante do manejo dos pacientes e familiares. Vários conceitos sobre a CMH foram recentemente revistos, incluindo sua prevalência de 1 em 250 indivíduos, não sendo, portanto, uma doença rara, mas subdiagnosticada. A vasta maioria dos pacientes é assintomática. Naqueles sintomáticos, a obstrução do trato de saída do ventrículo esquerdo (OTSVE) é o principal distúrbio responsável pelos sintomas, devendo-se investigar a sua presença em todos os casos. Naqueles em que o ecocardiograma em repouso ou com Manobra de Valsalva não detecta gradiente intraventricular significativo (> 30 mmHg), devem ser submetidos à ecocardiografia com esforço físico para detecção da OTSVE.   Pacientes com sintomas limitantes e grave OTSVE, refratários ao uso de betabloqueadores e verapamil, devem receber terapias de redução septal ou uso de novas drogas inibidoras da miosina cardíaca. Por fim, os pacientes adequadamente identificados com risco aumentado de morta súbita podem receber medida profilática com implante de cardiodesfibrilador implantável (CDI).

La miocardiopatía hipertrófica (MCH) es una forma de enfermedad cardíaca de origen genético, caracterizada por el engrosamiento de las paredes ventriculares. El diagnóstico requiere la detección mediante métodos de imagen (Ecocardiograma o Resonancia Magnética Cardíaca) que muestren algún segmento de la pared ventricular izquierda con un grosor > 15 mm, sin otra causa probable. El análisis genético permite identificar mutaciones en genes que codifican diferentes estructuras del sarcómero responsables del desarrollo de la MCH en aproximadamente el 60% de los casos, lo que permite el tamizaje de familiares y el asesoramiento genético, como parte importante del manejo de pacientes y familiares. Varios conceptos sobre la MCH han sido revisados recientemente, incluida su prevalencia de 1 entre 250 individuos, por lo tanto, no es una enfermedad rara, sino subdiagnosticada. La gran mayoría de los pacientes son asintomáticos. En los casos sintomáticos, la obstrucción del tracto de salida ventricular izquierdo (TSVI) es el trastorno principal responsable de los síntomas, y su presencia debe investigarse en todos los casos. En aquellos en los que el ecocardiograma en reposo o la maniobra de Valsalva no detecta un gradiente intraventricular significativo (> 30 mmHg), deben someterse a ecocardiografía de esfuerzo para detectar la obstrucción del TSVI. Los pacientes con síntomas limitantes y obstrucción grave del TSVI, refractarios al uso de betabloqueantes y verapamilo, deben recibir terapias de reducción septal o usar nuevos medicamentos inhibidores de la miosina cardíaca. Finalmente, los pacientes adecuadamente identificados con un riesgo aumentado de muerte súbita pueden recibir medidas profilácticas con el implante de un cardioversor-desfibrilador implantable (CDI).

Hypertrophic cardiomyopathy (HCM) is a form of genetically caused heart muscle disease, characterized by the thickening of the ventricular walls. Diagnosis requires detection through imaging methods (Echocardiogram or Cardiac Magnetic Resonance) showing any segment of the left ventricular wall with a thickness > 15 mm, without any other probable cause. Genetic analysis allows the identification of mutations in genes encoding different structures of the sarcomere responsible for the development of HCM in about 60% of cases, enabling screening of family members and genetic counseling, as an important part of patient and family management. Several concepts about HCM have recently been reviewed, including its prevalence of 1 in 250 individuals, hence not a rare but rather underdiagnosed disease. The vast majority of patients are asymptomatic. In symptomatic cases, obstruction of the left ventricular outflow tract (LVOT) is the primary disorder responsible for symptoms, and its presence should be investigated in all cases. In those where resting echocardiogram or Valsalva maneuver does not detect significant intraventricular gradient (> 30 mmHg), they should undergo stress echocardiography to detect LVOT obstruction. Patients with limiting symptoms and severe LVOT obstruction, refractory to beta-blockers and verapamil, should receive septal reduction therapies or use new drugs inhibiting cardiac myosin. Finally, appropriately identified patients at increased risk of sudden death may receive prophylactic measure with implantable cardioverter-defibrillator (ICD) implantation.

https://doi.org/10.1590/SciELOPreprints.8394

Efeitos de Longo Prazo do Implante Valvar Pulmonar e Evolução da Prótese em Pacientes com Tetralogia de Fallot Corrigida
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Caneo, Luiz Fernando

; Turquetto, Aida Luiza Ribeiro

; Boschiero, Matheus Negri

; Amato, Luciana Patrick

; Ishikawa, Walther Yoshiharu

; Hodas, Fabiana Padilha

; Ligeiro, Melissa Ganeko

; Agostinho, Daniela Regina

; Miana, Leonardo Augusto

; Tanamati, Carla

; Gonçalves, Rilvani Cavalcante

; Penha, Juliano Gomes

; Massoti, Maria Raquel Brigoni

; Jatene, Marcelo Biscegli

; Jatene, Fabio Biscegli

Arquivos Brasileiros de Cardiologia

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2024, Volumen 121 Nº 7 elocation e20230585

Resumen: En Pt | Texto: En Pt | PDF: En | PDF: Pt

Abstract Background Pulmonary valve regurgitation is a significant long-term complication in patients with tetralogy of Fallot (TOF). Objective This study aims to investigate the effects of pulmonary valve implantation (PVI) on the anatomy and function of the right ventricle (RV) and the long-term evolution of the implanted prosthesis in the pulmonary position. Methods A single-center retrospective cohort analysis was performed in 56 consecutive patients with TOF who underwent PVI. The study included patients of both sexes, aged ≥ 12 years, and involved assessing clinical and surgical data, pre- and post-operative cardiovascular magnetic resonance imaging, and echocardiogram data more than 1 year after PVI. Results After PVI, there was a significant decrease in RV end-systolic volume indexed by body surface area (BSA), from 89 mL/BSA to 69 mL/BSA (p < 0.001) and indexed RV end-diastolic volume, from 157 mL/BSA to 116 mL/BSA (p < 0.001). Moreover, there was an increase in corrected RV ejection fraction [ RVEFC = net pulmonary flow (pulmonary forward flow − regurgitant flow) / R V end-diastolic volume] from 23% to 35% (p < 0.001) and left ventricular ejection fraction from 58% to 60% (p = 0.008). However, a progressive increase in the peak pulmonary valve gradient was observed over time, with 25% of patients experiencing a gradient exceeding 60 mmHg. Smaller prostheses (sizes 19 to 23) were associated with a 4.3-fold higher risk of a gradient > 60 mmHg compared to larger prostheses (sizes 25 to 27; p = 0.029; confidence interval: 1.18 to 17.8). Conclusion As expected, PVI demonstrated improvements in RV volumes and function. Long-term follow-up and surveillance are crucial for assessing the durability of the prosthesis and detecting potential complications. Proper sizing of prostheses is essential for improved prosthesis longevity. longterm long term TOF. . (TOF) (PVI (RV position singlecenter single center 5 sexes years pre postoperative post operative imaging endsystolic end systolic BSA, BSA , (BSA) 8 mLBSA mL 6 0.001 0001 0 001 enddiastolic diastolic 15 11 0.001. Moreover 23 35 58 0.008. 0008 0.008 008 0.008) However time sizes 4.3fold 43fold fold 4.3 4 3 2 27 0.029 0029 029 interval 118 18 1.1 17.8. 178 17.8 17 17.8) expected Longterm Long followup follow up complications longevity (TOF (BSA 0.00 000 00 3fold 43 4. 0.02 002 02 1. 17. 0.0 0.

Resumo Fundamento A regurgitação valvar pulmonar é uma importante complicação de longo prazo em pacientes com tetralogia de Fallot (TF). Objetivo O presente estudo tem como objetivo investigar os efeitos do implante valvar pulmonar (IVP) na anatomia e função do ventrículo direito (VD) e na evolução em longo prazo da prótese implantada em posição pulmonar. Métodos Uma análise de coorte retrospectiva e unicêntrica foi realizada em 56 pacientes consecutivos com TF submetidos a IVP. O estudo incluiu pacientes de ambos os gêneros, com idade ≥ 12 anos e compreendeu avaliação de dados clínicos e cirúrgicos, ressonância magnética cardiovascular pré e pós-operatória e dados ecocardiográficos obtidos mais de 1 ano após IVP. Resultados Após o IVP, houve uma diminuição significativa do volume sistólico final do VD indexado pela área de superfície corpórea (ASC), de 89 mL/ASC para 69 mL/ASC (p < 0,001) e do volume diastólico final indexado do VD, de 157 mL/ASC para 116 mL/ASC (p < 0,001). Além disso, houve aumento da fração de ejeção corrigida do VD [ FEVDc = fluxo pulmonar ajustado (fluxo pulmonar anterógrado − fluxo regurgitante) / volume diastólico final do VD ] de 23% para 35% (p < 0,001) e da fração de ejeção do ventrículo esquerdo de 58% para 60% (p = 0,008). No entanto, foi observado um aumento progressivo no gradiente de pico da válvula pulmonar ao longo do tempo, com 25% dos pacientes apresentando um gradiente superior a 60 mmHg. Próteses menores (tamanhos 19 a 23) foram associadas a um risco 4,3 vezes maior de gradiente > 60 mmHg em comparação com próteses maiores (tamanhos 25 a 27; p = 0,029; intervalo de confiança: 1,18 a 17,8). Conclusão Conforme esperado, o IVP demonstrou melhorias nos volumes e na função do VD. O acompanhamento e a vigilância a longo prazo são cruciais para avaliar a durabilidade da prótese e detectar potenciais complicações. O dimensionamento adequado das próteses é essencial para melhorar a longevidade da prótese. TF. . (TF) (IVP (VD 5 gêneros cirúrgicos pósoperatória pós operatória ASC, ASC , (ASC) 8 mLASC mL 6 0,001 0001 0 001 15 11 0,001. disso regurgitante 23 35 58 0,008. 0008 0,008 008 0,008) entanto tempo tamanhos 43 4 3 4, 2 27 0,029 0029 029 confiança 118 18 1,1 17,8. 178 17,8 17 17,8) esperado complicações (TF (ASC 0,00 000 00 0,02 002 02 1, 17, 0,0 0,

https://doi.org/10.36660/abc.20230585

The electronic structure and physicochemical characteristics of chlorohydroquinone compounds using density functional theory and Hartree-Fock techniques
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Mohammed, Bast Ahmed

; Kareem, Rebaz Obaid

; Hamad, Othman Abdulrahman

; Kebiroglu, Hanifi

South African Journal of Chemistry

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2024, Volumen 78 Paginas 85 - 94

Resumen: En | Texto: En | PDF: En

In the present research, the computer program Gaussian 5.0.9W was used to perform all calculations and physicochemical characteristics of 2-chlorobenzene-1,4-diol, 2,5-dichlorobenzene-1,4-diol, and 2,3,5,6-tetrachlorobenzene-1,4-diol molecules. The novelty of the work lies in the application of quantum computing analysis, specifically employing density functional theory (DFT) and Hartree-Fock (HF) techniques with a variety of basis sets (3-21G, 6-31G and 6-311G) to study the structure and characteristics of title compounds. In the current investigation, the influence of an increasing concentration of Cl compound on the electronegativity, dipole moment, and ionization potential was investigated. The following quantum chemical properties were derived: Eh omo-Elumo energy band gap (BG), energy ground state, ultraviolet (UV) spectroscopy, molecule electrostatic potential (MEP) on surfaces, density of states (DOS), reduced density gradient (RDG), nuclear magnetic resonance (NMR) including ground state energy E (B3LYP), thermodynamic parameters including thermal energy (E), entropy (S), molar heat capacity (Cv). Using a 6-31G basis set for DFT, the maximum amount of BG energy that can be transferred between HOMO and LUMO in a 2-chlorobenzene-1,4-diol molecule is 5.46 eV. Finally, based on our findings, the HF technique has a larger energy gap than the DFT approach. According to this, chlorohydroquinone compounds are less stable when using the DFT method, which suggests a higher degree of chemical reactivity.

https://doi.org/10.17159/0379-4350/2024/v78a12

Phase stability, mechanical, electronic, magnetic and thermodynamic properties of the Pd2PrX(X=Cl, F) compounds: An Ab-initio study
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Benatmane, S.

; Affane, M.

; Bouali, Y.

; Bouadjemi, B.

; Cherid, S.

; Benstaali, W.

Revista mexicana de física

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Feb 2023, Volumen 69 Nº 1

Resumen: En | Texto: En | PDF: En

Abstract Many of the known examples of half-metallic ferromagnets HMF are oxides, sulfides, or Heusler alloys have attracted some interest for their potential use in spintronics. In order to achieve such understanding we have performed an ab-initio calculations with spin polarization using plane-wave pseudo potential technique based on the density-functional theory (DFT), the exchange-correlation potential was treated with the generalized gradient approximation (PBE-GGA), whereas for the treatment of on-site electron-electron correlations the PBE-GGA+U approximation (where U is the Hubbard Coulomb energy term) are applied for the calculation of the structural, electronic, elastic and magnetic properties of Pd2PrX (X=Cl, F). The results showed that for Pd2PrCl and Pd2PrF, Hg2CuTi-type structure is energetically more stable than Cu2MnAl-type structure at the equilibrium volume. Electronically, Pd2PrCl and Pd2PrF exhibit half-metallicity with small band gaps of 0.06 and 0.25 eV respectively with GGA-PBE+U in the spin-down channels whereas spin-up channels are conducting. The calculated total magnetic moment of 2.00 μB per formula unit is very close to integer value and agree well with the Slater-Pauling rules ( M t o t = 34 - Z t o t), where the magnetic moment is basically carried by Pr atoms. However, the elastic properties show that Pd2PrX (X=Cl, F) compounds are ductile and anisotropic according to the analysis of B/G and Cauchy’s pressure. The Thermodynamic properties were also analyzed using the quasi-harmonic Debye model. Both the compounds are found structurally stable.

https://doi.org/10.31349/revmexfis.69.011003

Classification of 1p/19q Status in Low-Grade Gliomas: Experiments with Radiomic Features and Ensemble-Based Machine Learning Methods 1p19q pq 1p 19q p q LowGrade Low Grade Gliomas EnsembleBased Ensemble Based
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Medeiros, Tony Alexandre

; Saraiva Junior, Raimundo Guimarães

; Cassia, Guilherme de Souza e

; Nascimento, Francisco Assis de Oliveira

; Carvalho, João Luiz Azevedo de

Brazilian Archives of Biology and Technology

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2023, Volumen 66 elocation e23230002

Resumen: En | Texto: En | PDF: En

Abstract Gliomas comprise the vast majority of all malignant brain tumors. Low-grade glioma patients with combined whole-arm losses of 1p and 19q chromosomes were shown to have significantly better overall survival rates compared to non-deleted patients. This work evaluates several approaches for assessment of 1p/19q status from T2-weighted magnetic resonance images, using radiomics and machine learning. Experiments were performed using images from a public database (102 codeleted, 57 non-deleted). We experimented with sets of 68 and 100 radiomic features, and with several classifiers, including support vector machine, k-nearest neighbors, stochastic gradient descent, logistic regression, decision tree, Gaussian naive Bayes, and linear discriminant analysis. We also experimented with several ensemble-based methods, including four boosting-based classifiers, random forest, extra-trees, and bagging. The performance of these methods was compared using various metrics. Our best results were achieved using a bagging ensemble estimator based on the decision tree classifier, using only texture-based radiomics features. Compared to other works that used the same database, this approach provided higher sensitivity. It also achieved higher sensitivity than that provided by neurosurgeons and neuroradiologists analyzing the same images. We also show that including radiomic features associated with first order statistics and shape does not improve the performance of the classifiers, and in many cases worsens it. The molecular assessment of brain tumors through biopsies is an invasive procedure, and is subject to sampling errors. Therefore, the techniques presented in this work have strong potential for aiding in better clinical, surgical, and therapeutic decision-making. Lowgrade Low grade wholearm whole arm p q nondeleted non deleted 1p19q pq T2weighted Tweighted T2 weighted T learning 102 (10 codeleted 5 nondeleted. . non-deleted) 6 10 classifiers knearest k nearest neighbors descent regression Bayes analysis ensemblebased boostingbased boosting forest extratrees, extratrees extra trees, trees extra-trees metrics classifier texturebased texture it procedure errors Therefore clinical surgical decisionmaking. decisionmaking making. making decision-making (1 1 (

https://doi.org/10.1590/1678-4324-2023230002

Preliminary design of a compact superconducting solenoid, for material science applications
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Chavez, D.

; Huamani, Y.

; Napsuciale, M.

; Hernandez Chahin, K.

; Juarez-Hernandez, M.

; Cordova-Fraga, T.

; Gomez-Solis, C.

Journal of applied research and technology

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2023, Volumen 21 Nº 5 Paginas 787 - 795

Resumen: En | Texto: En | PDF: En

Abstract Innovation on new materials is strongly associated with different techniques and technological developments used on the growth and characterization of samples. Recent studies suggest that one could increase the preferable orientation of the crystals, while they are being formed on the substance, by applying a strong magnetic field. Uncertainty on the magnetic field magnitude, time of exposure, and temperature requirements, impose a challenge from the technological perspective. An upper boundary of 10 T provides a wide enough range for researching the material’s growth. In this work, we present a preliminary design of a 7 Tesla superconducting solenoid. The solenoid uses NbTi cable-in-conduit technology for the windings. The proposed geometry incorporates an experimentation chamber, thermally isolated from the cryogenic solenoid windings, for magnetic stimulation of samples. The sample could be exposed to a temperature gradient ranging from ambient temperature to 200 C, as required by some substrates. We applied an optimization process to reduce the required superconductor and expand the magnetics field uniform from 3 cm wide x 3.5 cm high to a region 3 cm wide and 10 cm tall, large enough to stack their samples vertically. A magnetic force study assisted in determining the election materials for the support structures.

https://doi.org/10.22201/icat.24486736e.2023.21.5.1557

Computational study of structural stability, elastic, electronic, magnetic and thermodynamic properties of the Rh2-based full-Heusler compounds: Rh2MnZ (Z = Sn, Pb, Tl) by FP-LAPW method
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Benichou, B.

; Bouchenafa, H.

; Nabi, Z.

; Bouabdallah, B.

Revista mexicana de física

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Dic 2022, Volumen 68 Nº 6

Resumen: En | Texto: En | PDF: En

Abstract The structural, elastic, electronic and thermodynamic properties as well as the magnetism of the ternary full-Heusler alloys Rh2MnZ (X = Sn, Pb and Tl) have been investigated by using the full-potential linearized augmented plane wave (FP-LAPW) method based on density functional theory (DFT) within the generalized gradient approximation (GGA). The AlCu2Mn-type structure is energetically more favorable than the CuHg2Ti-type structure for all the compounds studied here and found to be are ferromagnetic. The electronic structures calculations are found to exhibit a metallic character for all the herein studied compounds Rh2MnZ (X = Sn, Pb and Tl) alloys. The magnetic properties reveal that the Mn atom is responsible for large magnetic moment. Moreover, the mechanical behavior shows that all studied compounds are mechanically stable, ductile and anisotopic in nature. The elastic and thermodynamic properties for Rh2MnTl compound have not yet been established. The obtained results for various properties of the series of Rh2MnZ (X = Sn, Pb and Tl) are compared with those found experimentally and theoretically.

https://doi.org/10.31349/revmexfis.68.060502

The BigFLUX Magnetic Matrix Technology
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Ribeiro, José Pancrácio

; Ribeiro, Cláudio Henrique Teixeira

; Vieira, Eric Guimarães

REM - International Engineering Journal

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Sep 2022, Volumen 75 Nº 3 Paginas 275 - 278

Resumen: En | Texto: En | PDF: En

Abstract The Magnetic separation of ultra-fine ore particles has always posed a challenge to the JONES/WHIMS process. Despite many advances in this technology, no effective improvement has been made to its core component: The Magnetic Matrix. The current approach to separate ultra-fine particles teaches that the gap of the matrix and its teeth size must be smaller than usual in order to accommodate the small size of the particles. However, practice proved this approach to be far from ideal. The closing of the gap between grooved plates, whose teeth are smaller, drastically reduces the flow area, reduces the feed capacity, and makes the matrices prone to clogging. In addition, smaller teeth reduce the magnetic field and its gradient, leading to poor results with ultra-fine ore particles. This research proves that bigger teeth are better suited for high intensity magnetic separation of ultra-fines because they avoid matrix clogging thanks to the larger slurry flow area. Additionally, bigger teeth amplify the magnetic field “Bmax” and increases the magnetic gradient “Grad (∆B /∆X)”. The positive results of this new “BigFLUX Matrix” technology, are being displayed in several mining operations worldwide, increasing metallurgical recovery and producing high quality concentrates and low iron content sand from iron ore tailings.

https://doi.org/10.1590/0370-44672022750035

Development of innovation routes for iron ore using high intensity magnetic separators
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Menezes, Késsius Bortolan

; Gonçalves, Ana Vitória de Moura

; Rodrigues, Otávia Martins Silva

; Reis, Érica Linhares

REM - International Engineering Journal

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Abr 2022, Volumen 75 Nº 2 Paginas 167 - 175

Resumen: En | Texto: En | PDF: En

Abstract The mineral processing of low-grade iron ores commonly generates large volumes of slime, which are disposed as tailings. Modern mining requires strives to eliminate the use of tailings dams in a maximum effort to increase metallurgical recovery, the security and reduction of the operational cost. This research aims for the recovery of iron contained in the slime, which consists of a material with 38% Fe and <40 µm, originating from the desliming cyclones. Pilot tests were performed on the Wet High-Intensity Magnetic Separator (WHIMS) and on the Vertical Ring Pulsating High Gradient Magnetic Separator (VPHGMS) considering different configurations in terms of operating parameters and routes. The best results were obtained for VPHGMS with an iron content in the concentrate of 67.06% and mass and metallurgical recovery of 32.42% and 56.86%, respectively. In the best condition tested, around 540 thousand tons of concentrate can be incorporated into production and has great environmental relevance.

https://doi.org/10.1590/0370-44672021750076

10.

Radially Periodic Metasurface Lenses for Magnetic Field Collimation in Resonant Wireless Power Transfer Applications
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Soares, I. V.

; Resende, U. C.

Journal of Microwaves, Optoelectronics and Electromagnetic Applications

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Mar 2022, Volumen 21 Nº 1 Paginas 48 - 60

Resumen: En | Texto: En | PDF: En

Abstract In this paper, a new procedure and topology of magnetic metasurface lens are proposed for improving the performance of Resonant Wireless Power Transfer systems. Firstly, three subwave-length unit cells are optimized in order to get negative magnetic permeability in the same frequency, each one with a different refractive index, and they are experimentally characterized. Then, the Transformation Optics technique is applied in order to find the unit cell arrangements which lead to the magnetic field focusing in a given direction. For this purpose, two coordinate transformations are proposed, and the effective electric permittivity and permeability that generate these profiles are calculated. It is shown from simulations and measurements that the refractive index gradient produced by the radial disposition of the unit cells can lead to a magnetic field manipulation similar to the optical converging and diverging lenses. Both metamaterials lenses are built, and the calculation of the magnetic flux density as a function of the measured induced voltage in a probe coil verifies their effects on the magnetic field. Finally, their performance in a resonant wireless power transfer system is tested, and improvements in terms of efficiency and range are presented. The proposed design method and the lenses that were developed demonstrate that metasurface lenses can improve efficiency without reducing the range, once these lenses are positioned close to the transmitter coil. Besides that, this method can reduce the losses due to misalignment between coils once the field can be collimated in a specific direction.

https://doi.org/10.1590/2179-10742022v21i1253604

11.

First-principle calculations of Co2MSi (M=Cr, Mn, Fe) Heusler alloys
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Pathak, Ashish

; Sankarasubramanian, R.

Journal of applied research and technology

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2022, Volumen 20 Nº 3 Paginas 355 - 368

Resumen: En | Texto: En | PDF: En

Abstract The present work describes the electronic structure, magnetic and elastic properties of ordered Co2MSi (M = Cr, Mn, Fe) Heusler alloys in L21 structure calculated using density functional theory within generalized gradient approximation. The calculated band structures, density of states and magnetic moments have been discussed. The magnetic moment values obtained in present study follow the Slater-Pauling rule. A small band gap in the minority band structure at the Fermi level suggests half-metallicity. Hundred percentage spin polarization in this ordered structure implies that these materials possess ferromagnetism. All the three materials satisfy stability criteria in terms of elastic constants and are predicted to have ductile behavior based on the ratio of shear to bulk modulus.

https://doi.org/10.22201/icat.24486736e.2022.20.3.780

12.

Predictive study of ferromagnetism and antiferromagnetism coexistence in Ba1-xGdxRuO3 induced by Gd-doping
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Labdelli, A.

; Hamdad, N.

Revista mexicana de física

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Dic 2021, Volumen 67 Nº 6 elocation 061002

Resumen: En | Texto: En | PDF: En

Abstract Some ferromagnetic alloys which adopt the perovskite or double-perovskite structure exhibit some remarkable properties, such as electromagnetic effects, charge and orbital ordering, i.e., dielectric and magnetoresistance effects in the same time. These phenomena are related to both electrical conductivity and spin orbit orientation. In order to optimize and explore the structural, magnetic and electronic properties of Ba1-xGdxRuO3 alloy, we investigated here the first-principles calculations using the generalized gradient approximation (GGA+U+SO) as implemented in the Wien2K package. The concentration classification of Ba1-xGdxRuO3 alloy with (x = 0, 0.125, 0.25, 0.5, 0.875, 1) is given. In this work, we have identified features such transition phases, spin ordered and charge conduction that enable a priori of both crystal structure and magnetic behavior prediction. Our Ba1-xGdxRuO3 alloy is a half-metallic in the cubic phase and a Mott insulator for x = 0.875 and semiconductor for x = 1 in the orthorhombic phase. The Ba1-xGdxRuO3 alloy therefore undergoes a transition between a cubic phase and another orthorhombic at x = 0.5. It is clear that at this point our alloy (Ba0,5Gd0.5RuO3) is at the same time FM and AFM A-type, in another way, we can say that A-AFM and FM configurations coexist in our alloys. In the case of our GdxBa1-xRuO3 alloy, we can see that the total magnetic moment increases linearly with the concentrations “x” since it has passed from 15.99 μB for x = 0 to 39.95 μB for x = 0.5, this is valid in the cubic phase. That is related to a heavily magnetic moment of spin in the Ru atom which increases also linearly with increasing x, while the magnetic moment of Gd decreases slightly. In the orthorhombic phase, its value remains zero regardless of the concentration because we are in an antiferromagnetic (AF) configuration. The collaboration of the 3d-Ru and 2p-O states is suggested to play an important role for the ferromagnetism in the considered alloy. These orbitals were the most regular in the two bands respectively: the conduction band and the valence band in the two phases given here (cubic and orthorhombic). We also note the mixed collaboration of the states 3d-Ba. On the other hand, the contribution of 3d-Gd states was only effective in the band of conduction, at the time when that of the 4f-Gd states was noticed especially in the orthorhombic phase.

https://doi.org/10.31349/revmexfis.67.061002 27 descargas

13.

Propiedades estructurales, magnéticas e hiperfinas de la ferrita mgfe2o4: estudio mediante cálculos ab-initio
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Medina Chanduví, H. H.

; Gil Rebaza, A. V.

; Errico, L. A.

Anales (Asociación Física Argentina)

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Dic 2020, Volumen 31 Nº 4 Paginas 121 - 126

Resumen: En Es | Texto: En Es | PDF: En | PDF: Es

Abstract: We present here a first principles study of the structural, electronic, magnetic, and hyperfine properties of magnesium ferrite, MgFe2O4 (spinel structure). The study was carried out within the framework of Functional Density Theory (DFT) using the full potential linearized augmented plane waves method (FPLAPW) using both the Generalized Gradient (GGA) and the GGA+U approximations for the exchange and correlation potential. To discuss the magnetic ordering and the lowest energy structure of the system we consider different distributions of Mg and Fe ions in both cationic sites of the spinel structure, as well as different spin configurations. Our calculations predict that the equilibrium structure corresponds to an inverted antiferromagnetic configuration, in which the magnetic moments of the Fe atoms located at sites A are ferromagnetically ordered among themselves and antiferromagnetically with respect to the Fe located at the sublattice of sites B. Our GGA calculations underestimate the energy band-gap of the system, while GGA+U predict a band-gap of 2.3 eV, in excellent agreement with the reported values. The results for the hyperfine properties at the Fe sites (isomer shift, quadrupole splitting and hyperfine field) are in excellent agreement with the Mössbauer spectroscopy results reported in the literature, giving support to the equilibrium structure predicted by FP-LAPW.

Resumen: Presentamos un estudio de primeros principios de las propiedades estructurales, electrónicas, magnéticas e hiperfinas de la ferrita de magnesio, MgFe2O4 (estructura espinela). El estudio fue realizado en el marco de la Teoría de la Funcional Densidad (DFT) mediante el método Full-Potential Linearized Augmented Plane Waves (FPLAPW), empleando la aproximación del Gradiente Generalizado (GGA) y la aproximación GGA+U para el término de potencial e intercambio. Para discutir el ordenamiento magnético y la estructura de mínima energía del sistema se consideraron diferentes distribuciones de los iones Mg y Fe en los dos sitios catiónicos de la estructura espinela, así como distintas configuraciones de espín. Los cálculos muestran que la estructura de equilibrio corresponde a una configuración invertida y antiferromagnética, en la cual los momentos magnéticos de los átomos de Fe en los sitios A están ordenados ferromagnéticamente entre sí y antiferromagnéticamente con respecto a los Fe de la subred de sitios B. Los cálculos GGA subestiman el band-gap de energía del sistema, mientras que los cálculos GGA+U predicen un band-gap de 2.3 eV, en acuerdo con el valor reportado. Los resultados para las propiedades hiperfinas en los sitios Fe (corrimiento isomérico, desdoblamiento cuadrupolar y campo hiperfino) están en excelente acuerdo con los obtenidos mediante espectroscopia Mössbauer reportados en la literatura, lo que sustenta la estructura de equilibrio predicha por FPLAPW.

https://doi.org/10.31527/analesafa.2020.31.4.121 125 descargas

14.

Structural, elastic, electronic, and magnetic properties of quaternary alloys BBi0.75 Mn0.125 N0.125: A first-principles study
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Tab, S.

; Boudali, A.

; Berber, M.

; Driss Khodja, M.

; Lhaj ElHachemi, O.

; Moujri, H.

Revista mexicana de física

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Oct 2020, Volumen 66 Nº 5 Paginas 627 - 631

Resumen: En | Texto: En | PDF: En

Abstract In this study, we have employed the first-principle methods based on density functional theory to investigate the structural, elastic, electronic, and magnetic properties of BBi0.75Mn0.125N0.125. The exchange and correlation potential are described by the generalized gradient approximation of Perdew, Burke, and Ernzerhof (GGA-PBEsol) + SOC coupled with TB-mBJ approaches. The studied structure shows that the compound BBi0.75Mn0.125N0.125 is stable in the ferromagnetic phase, the elastic property indicates that the structure is brittle and mechanically stable. The half-metallic description is predicted with the energy spin bandgap in the spin-up channel. The structure attributed to half-metallic ferromagnetism could be suitable for spintronics devices. To our knowledge, this is the first time that a study has been done on this alloy, and we would like it to serve as a reference for the next studies.

https://doi.org/10.31349/revmexfis.66.627 11 descargas

15.

Spinelectronic investigation of the quaternary vanadium fluoride Rb2NaVF6: Ab-initio method
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Berber, M.

; Nour Bouzouira, B.

; Abid, H.

; Boudali, A.

; Moujri, H.

Revista mexicana de física

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Oct 2020, Volumen 66 Nº 5 Paginas 604 - 609

Resumen: En | Texto: En | PDF: En

Abstract In this study, we have investigated the structural, electronic, and magnetic properties of the Rb2NaVF6 compound. We have performed our calculations by the use of first-principle methods based on spin-polarized density functional theory, where the electronic exchangecorrelation potential is treated by the generalized gradient approximation GGA- PBEsol coupled with the improved TB-mBJ approach. The calculated structural parameters of Rb2NaVF6 are in good agreement with the available experimental data. Rb2NaVF6 exhibits a halfmetallic ferromagnetic feature with a spin polarization of 100% at the Fermi level and a direct large half-metallic gap of 3.582 eV. The total magnetic moments are 2 µB. This material is half-metallic ferromagnets, and it can be potential candidates for spintronics applications at a higher temperature.

https://doi.org/10.31349/revmexfis.66.604 10 descargas

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