90 research outputs found
Multiferroic and magnetoelectric properties of Pb0.99[Zr0.45Ti0.47(Ni1/3Sb2/3)0.08]O3–CoFe2O4 multilayer composites fabricated by tape casting
A 2-2 type multiferroic composite device encompassing three CoFe2O4 (CFO) layers confined between four Pb0.99[Zr0.45Ti0.47(Ni1/3Sb2/3)0.08]O3 (PZT) layers was fabricated by tape casting. X-ray diffraction data showed good chemical compatibility between the two phases, whereas Scanning Electron Microscopy imaging also revealed an intimate contact between CFO and PZT layers. Under an applied electric field of 65 kV/cm, this multilayer device shows a saturated polarisation of 7.5 C/cm2 and a strain of 0.12%, whereas under a magnetic field of 10 kOe it exhibits a typical ferromagnetic response and a magnetic moment of 33 emu/g. These devices can be electrically poled, after which they exhibit magnetoelectric coupling
Light-driven motion of charged domain walls in isolated ferroelectrics
©2022 American Physical SocietyLight-induced ferroelectric domain wall motion turns out to be a promising phenomenon to de- velop new photo-controlled devices. However, the physical origin of this ligh-matter coupling when material is irradiated with visible light remains unclear. Here, a phenomenological model predicting the motion of charged domain walls (CDWs) is developed. The photo-induced electronic reconstruc- tion mechanism is proposed as the primary absorption mechanism, leading to a linear dependence for the polarization perturbation with the light intensity. Domain walls motion is then driven by the energetic difference between domains in a CDW array, such that the macroscopic polarization can be easily tuned.Postprint (author's final draft
Light-induced strain and its correlation with the optical absorption at charged domain walls in polycrystalline ferroelectrics
Photostrictive materials have a growing interest because of their great potential as light-driven actuators, among other optomechanical applications. In this context, the optical control of macroscopic strain in ferroelectrics has recently attracted remarkable attention as an effective alternative to the conventional electric control of strain. Here, a clear correlation between optical absorption and light-induced strain in polycrystalline BaTiO3 is shown. Specifically, the grain size and the sample thickness dependence of optical absorption when the material is irradiated with energy photons lower than the band gap evidence that light absorption at charged domain walls is the core of the observed photo-response in ferroelectrics. The photoinduced electronic reconstruction phenomenon is proposed as the primary physical mechanism for light absorption at charged domain walls. Results open a new pathway to designing ferroelectric-based devices with new functionalities like thickness gradient-based photo-controlled nanoactuators
Dynamics of normal to diffuse and relaxor phase transition in lead metaniobate-based ferroelectric ceramics
Tetragonal tungsten bronze-structured materials based on lead metaniobate (PbNb2O6) were studied in terms of thermal dynamics of dielectric properties, showing ferroelectric-to-paraelectric phase transition of diffuse and relaxor type in some specific cases. These features are normally ascribed to defects-induced structural disorder and compositional fluctuations associated with an arbitrary lattice site occupation between dopant and host ions. Nevertheless, for these lead metaniobate-based materials, the drastic change in the phase transition from normal to diffuse and relaxor is shown to take place when dopants are able to significantly shift the transition toward low temperatures, where these compounds are known to exhibit incommensurate superstructures that naturally present diffuse and relaxor dielectric characteristics.FAPESPCNP
Light-induced strain and its correlation with the optical absorption at charged domain walls in polycrystalline ferroelectrics
Photostrictive materials have a growing interest because of their great potential as light-driven actuators, among other optomechanical applications. In this context, the optical control of macroscopic strain in ferroelectrics has recently attracted remarkable attention as an effective alternative to the conventional electric control of strain. Here, a clear correlation between optical absorption and light-induced strain in polycrystalline BaTiO3 is shown. Specifically, the grain size and the sample thickness dependence of optical absorption when the material is irradiated with energy photons lower than the band gap evidence that light absorption at charged domain walls is the core of the observed photo-response in ferroelectrics. The photoinduced electronic reconstruction phenomenon is proposed as the primary physical mechanism for light absorption at charged domain walls. Results open a new pathway to designing ferroelectric-based devices with new functionalities like thickness gradient-based photo-controlled nanoactuators.Postprint (published version
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A 112 Gb/s Radiation-Hardened Mid-Board Optical Transceiver in 130-nm SiGe BiCMOS for Intra-Satellite Links
We report the design of a 112 Gb/s radiation-hardened (RH) optical transceiver applicable to intra-satellite optical interconnects. The transceiver chipset comprises a vertical-cavity surface-emitting laser (VCSEL) driver and transimpedance amplifier (TIA) integrated circuits (ICs) with four channels per die, which are adapted for a flip-chip assembly into a mid-board optics (MBO) optical transceiver module. The ICs are designed in the IHP 130 nm SiGe BiCMOS process (SG13RH) leveraging proven robustness in radiation environments and high-speed performance featuring bipolar transistors (HBTs) with fT/fMAX values of up to 250/340 GHz. Besides hardening by technology, radiation-hardened-by-design (RHBD) components are used, including enclosed layout transistors (ELTs) and digital logic cells. We report design features of the ICs and the module, and provide performance data from post-layout simulations. We present radiation evaluation data on analog devices and digital cells, which indicate that the transceiver ICs will reliably operate at typical total ionizing dose (TID) levels and single event latch-up thresholds found in geostationary satellites
Autoantibodies neutralizing type I IFNs are present in ~4% of uninfected individuals over 70 years old and account for ~20% of COVID-19 deaths
Publisher Copyright: © 2021 The Authors, some rights reserved.Circulating autoantibodies (auto-Abs) neutralizing high concentrations (10 ng/ml; in plasma diluted 1:10) of IFN-alpha and/or IFN-omega are found in about 10% of patients with critical COVID-19 (coronavirus disease 2019) pneumonia but not in individuals with asymptomatic infections. We detect auto-Abs neutralizing 100-fold lower, more physiological, concentrations of IFN-alpha and/or IFN-omega (100 pg/ml; in 1:10 dilutions of plasma) in 13.6% of 3595 patients with critical COVID-19, including 21% of 374 patients >80 years, and 6.5% of 522 patients with severe COVID-19. These antibodies are also detected in 18% of the 1124 deceased patients (aged 20 days to 99 years; mean: 70 years). Moreover, another 1.3% of patients with critical COVID-19 and 0.9% of the deceased patients have auto-Abs neutralizing high concentrations of IFN-beta. We also show, in a sample of 34,159 uninfected individuals from the general population, that auto-Abs neutralizing high concentrations of IFN-alpha and/or IFN-omega are present in 0.18% of individuals between 18 and 69 years, 1.1% between 70 and 79 years, and 3.4% >80 years. Moreover, the proportion of individuals carrying auto-Abs neutralizing lower concentrations is greater in a subsample of 10,778 uninfected individuals: 1% of individuals 80 years. By contrast, auto-Abs neutralizing IFN-beta do not become more frequent with age. Auto-Abs neutralizing type I IFNs predate SARS-CoV-2 infection and sharply increase in prevalence after the age of 70 years. They account for about 20% of both critical COVID-19 cases in the over 80s and total fatal COVID-19 cases.Peer reviewe
The risk of COVID-19 death is much greater and age dependent with type I IFN autoantibodies
SignificanceThere is growing evidence that preexisting autoantibodies neutralizing type I interferons (IFNs) are strong determinants of life-threatening COVID-19 pneumonia. It is important to estimate their quantitative impact on COVID-19 mortality upon SARS-CoV-2 infection, by age and sex, as both the prevalence of these autoantibodies and the risk of COVID-19 death increase with age and are higher in men. Using an unvaccinated sample of 1,261 deceased patients and 34,159 individuals from the general population, we found that autoantibodies against type I IFNs strongly increased the SARS-CoV-2 infection fatality rate at all ages, in both men and women. Autoantibodies against type I IFNs are strong and common predictors of life-threatening COVID-19. Testing for these autoantibodies should be considered in the general population
The risk of COVID-19 death is much greater and age dependent with type I IFN autoantibodies
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection fatality rate (IFR) doubles with every 5 y of age from childhood onward. Circulating autoantibodies neutralizing IFN-α, IFN-ω, and/or IFN-β are found in ∼20% of deceased patients across age groups, and in ∼1% of individuals aged 4% of those >70 y old in the general population. With a sample of 1,261 unvaccinated deceased patients and 34,159 individuals of the general population sampled before the pandemic, we estimated both IFR and relative risk of death (RRD) across age groups for individuals carrying autoantibodies neutralizing type I IFNs, relative to noncarriers. The RRD associated with any combination of autoantibodies was higher in subjects under 70 y old. For autoantibodies neutralizing IFN-α2 or IFN-ω, the RRDs were 17.0 (95% CI: 11.7 to 24.7) and 5.8 (4.5 to 7.4) for individuals <70 y and ≥70 y old, respectively, whereas, for autoantibodies neutralizing both molecules, the RRDs were 188.3 (44.8 to 774.4) and 7.2 (5.0 to 10.3), respectively. In contrast, IFRs increased with age, ranging from 0.17% (0.12 to 0.31) for individuals <40 y old to 26.7% (20.3 to 35.2) for those ≥80 y old for autoantibodies neutralizing IFN-α2 or IFN-ω, and from 0.84% (0.31 to 8.28) to 40.5% (27.82 to 61.20) for autoantibodies neutralizing both. Autoantibodies against type I IFNs increase IFRs, and are associated with high RRDs, especially when neutralizing both IFN-α2 and IFN-ω. Remarkably, IFRs increase with age, whereas RRDs decrease with age. Autoimmunity to type I IFNs is a strong and common predictor of COVID-19 death.The Laboratory of Human Genetics of Infectious Diseases is supported by the Howard Hughes Medical Institute; The Rockefeller University; the St. Giles Foundation; the NIH (Grants R01AI088364 and R01AI163029); the National Center for Advancing Translational Sciences; NIH Clinical and Translational Science Awards program (Grant UL1 TR001866); a Fast Grant from Emergent Ventures; Mercatus Center at George Mason University; the Yale Center for Mendelian Genomics and the Genome Sequencing Program Coordinating Center funded by the National Human Genome Research Institute (Grants UM1HG006504 and U24HG008956); the Yale High Performance Computing Center (Grant S10OD018521); the Fisher Center for Alzheimer’s Research Foundation; the Meyer Foundation; the JPB Foundation; the French National Research Agency (ANR) under the “Investments for the Future” program (Grant ANR-10-IAHU-01); the Integrative Biology of Emerging Infectious Diseases Laboratory of Excellence (Grant ANR-10-LABX-62-IBEID); the French Foundation for Medical Research (FRM) (Grant EQU201903007798); the French Agency for Research on AIDS and Viral hepatitis (ANRS) Nord-Sud (Grant ANRS-COV05); the ANR GENVIR (Grant ANR-20-CE93-003), AABIFNCOV (Grant ANR-20-CO11-0001), CNSVIRGEN (Grant ANR-19-CE15-0009-01), and GenMIS-C (Grant ANR-21-COVR-0039) projects; the Square Foundation; Grandir–Fonds de solidarité pour l’Enfance; the Fondation du Souffle; the SCOR Corporate Foundation for Science; The French Ministry of Higher Education, Research, and Innovation (Grant MESRI-COVID-19); Institut National de la Santé et de la Recherche Médicale (INSERM), REACTing-INSERM; and the University Paris Cité. P. Bastard was supported by the FRM (Award EA20170638020). P. Bastard., J.R., and T.L.V. were supported by the MD-PhD program of the Imagine Institute (with the support of Fondation Bettencourt Schueller). Work at the Neurometabolic Disease lab received funding from Centre for Biomedical Research on Rare Diseases (CIBERER) (Grant ACCI20-767) and the European Union's Horizon 2020 research and innovation program under grant agreement 824110 (EASI Genomics). Work in the Laboratory of Virology and Infectious Disease was supported by the NIH (Grants P01AI138398-S1, 2U19AI111825, and R01AI091707-10S1), a George Mason University Fast Grant, and the G. Harold and Leila Y. Mathers Charitable Foundation. The Infanta Leonor University Hospital supported the research of the Department of Internal Medicine and Allergology. The French COVID Cohort study group was sponsored by INSERM and supported by the REACTing consortium and by a grant from the French Ministry of Health (Grant PHRC 20-0424). The Cov-Contact Cohort was supported by the REACTing consortium, the French Ministry of Health, and the European Commission (Grant RECOVER WP 6). This work was also partly supported by the Intramural Research Program of the National Institute of Allergy and Infectious Diseases and the National Institute of Dental and Craniofacial Research, NIH (Grants ZIA AI001270 to L.D.N. and 1ZIAAI001265 to H.C.S.). This program is supported by the Agence Nationale de la Recherche (Grant ANR-10-LABX-69-01). K.K.’s group was supported by the Estonian Research Council, through Grants PRG117 and PRG377. R.H. was supported by an Al Jalila Foundation Seed Grant (Grant AJF202019), Dubai, United Arab Emirates, and a COVID-19 research grant (Grant CoV19-0307) from the University of Sharjah, United Arab Emirates. S.G.T. is supported by Investigator and Program Grants awarded by the National Health and Medical Research Council of Australia and a University of New South Wales COVID Rapid Response Initiative Grant. L.I. reports funding from Regione Lombardia, Italy (project “Risposta immune in pazienti con COVID-19 e co-morbidità”). This research was partially supported by the Instituto de Salud Carlos III (Grant COV20/0968). J.R.H. reports funding from Biomedical Advanced Research and Development Authority (Grant HHSO10201600031C). S.O. reports funding from Research Program on Emerging and Re-emerging Infectious Diseases from Japan Agency for Medical Research and Development (Grant JP20fk0108531). G.G. was supported by the ANR Flash COVID-19 program and SARS-CoV-2 Program of the Faculty of Medicine from Sorbonne University iCOVID programs. The 3C Study was conducted under a partnership agreement between INSERM, Victor Segalen Bordeaux 2 University, and Sanofi-Aventis. The Fondation pour la Recherche Médicale funded the preparation and initiation of the study. The 3C Study was also supported by the Caisse Nationale d’Assurance Maladie des Travailleurs Salariés, Direction générale de la Santé, Mutuelle Générale de l’Education Nationale, Institut de la Longévité, Conseils Régionaux of Aquitaine and Bourgogne, Fondation de France, and Ministry of Research–INSERM Program “Cohortes et collections de données biologiques.” S. Debette was supported by the University of Bordeaux Initiative of Excellence. P.K.G. reports funding from the National Cancer Institute, NIH, under Contract 75N91019D00024, Task Order 75N91021F00001. J.W. is supported by a Research Foundation - Flanders (FWO) Fundamental Clinical Mandate (Grant 1833317N). Sample processing at IrsiCaixa was possible thanks to the crowdfunding initiative YoMeCorono. Work at Vall d’Hebron was also partly supported by research funding from Instituto de Salud Carlos III Grant PI17/00660 cofinanced by the European Regional Development Fund (ERDF/FEDER). C.R.-G. and colleagues from the Canarian Health System Sequencing Hub were supported by the Instituto de Salud Carlos III (Grants COV20_01333 and COV20_01334), the Spanish Ministry for Science and Innovation (RTC-2017-6471-1; AEI/FEDER, European Union), Fundación DISA (Grants OA18/017 and OA20/024), and Cabildo Insular de Tenerife (Grants CGIEU0000219140 and “Apuestas científicas del ITER para colaborar en la lucha contra la COVID-19”). T.H.M. was supported by grants from the Novo Nordisk Foundation (Grants NNF20OC0064890 and NNF21OC0067157). C.M.B. is supported by a Michael Smith Foundation for Health Research Health Professional-Investigator Award. P.Q.H. and L. Hammarström were funded by the European Union’s Horizon 2020 research and innovation program (Antibody Therapy Against Coronavirus consortium, Grant 101003650). Work at Y.-L.L.’s laboratory in the University of Hong Kong (HKU) was supported by the Society for the Relief of Disabled Children. MBBS/PhD study of D.L. in HKU was supported by the Croucher Foundation. J.L.F. was supported in part by the Evaluation-Orientation de la Coopération Scientifique (ECOS) Nord - Coopération Scientifique France-Colombie (ECOS-Nord/Columbian Administrative department of Science, Technology and Innovation [COLCIENCIAS]/Colombian Ministry of National Education [MEN]/Colombian Institute of Educational Credit and Technical Studies Abroad [ICETEX, Grant 806-2018] and Colciencias Contract 713-2016 [Code 111574455633]). A. Klocperk was, in part, supported by Grants NU20-05-00282 and NV18-05-00162 issued by the Czech Health Research Council and Ministry of Health, Czech Republic. L.P. was funded by Program Project COVID-19 OSR-UniSR and Ministero della Salute (Grant COVID-2020-12371617). I.M. is a Senior Clinical Investigator at the Research Foundation–Flanders and is supported by the CSL Behring Chair of Primary Immunodeficiencies (PID); by the Katholieke Universiteit Leuven C1 Grant C16/18/007; by a Flanders Institute for Biotechnology-Grand Challenges - PID grant; by the FWO Grants G0C8517N, G0B5120N, and G0E8420N; and by the Jeffrey Modell Foundation. I.M. has received funding under the European Union’s Horizon 2020 research and innovation program (Grant Agreement 948959). E.A. received funding from the Hellenic Foundation for Research and Innovation (Grant INTERFLU 1574). M. Vidigal received funding from the São Paulo Research Foundation (Grant 2020/09702-1) and JBS SA (Grant 69004). The NH-COVAIR study group consortium was supported by a grant from the Meath Foundation.Peer reviewe
Obtenção, propriedades e fenomenologia de materiais ferroelétricos com estrutura tungstênio bronze
The processing of lead metaniobate (PN) ferroelectric ceramics was optimized, therefore, in
this work, the main details to obtain PN ceramics with density higher than 96 % of the ideal density
are presented and discussed.
Taking into account the potential of the lead metaniobate for different applications, mainly for
high temperatures, the phase transition characteristics of this material, in both undoped and doped
compositions, were detaily investigated.
It was verified that the addition of Ti4+ enhances the densification and increase the Curie
temperature. Nevertheless, the ferro-paraelectric phase transition is affected by an electric
conductive process, which appears in temperatures below and above the Curie temperature. The
double ionized oxygen vacancies are proposed to be the charge carriers responsible for this
conductive process. The undoped and Ti4+-doped PN ceramics show low values of the mechanical
quality factor and high piezoelectric anisotropy, which are desired characteristics for the fabrication
of broad band electro-mechanical transducers, mainly to operate in the thickness mode.
The addition of Ba2+ to the PN (PBN) considerably decreases the Curie temperature, but it
induces a phase transition, leading to the formation of a morphotropic phase boundary (MPB)
around the composition with 37 % of Ba2+, in which some properties are enhanced. In this way, the
characteristics of the ferro-paraelectric phase transition, for compositions around the MPB, were
investigated for Ba2+-doped PN ceramics, textured by hot forging. It was found that the MPB
extends towards a wide composition range, in which both tetragonal 4mm and orthorhombic m2m
tungsten bronze (TB) phases coexist. In addition, with the increasing temperature, two phase
transitions were observed for this composition range. First, the material portion with orthorhombic
(m2m) symmetry transforms into the tetragonal (4mm) phase and, second, the 4mm phase (that
represents the material in its totality) transforms into the paraelectric phase with the tetragonal
4/mmm TB symmetry. These results helped to complete the reported PBN phase diagram.
Moreover, it was found that the La3+ addition to the PBN, for the composition with 56 % of Pb2+,
induces the formation of the orthorhombic (m2m) phase.
All the (doped and undoped) PN ceramics showed two dielectric dispersion processes at low
temperatures, i.e. from 30 to 300 K, which seems to be an inherent feature of all materials with TB
structure and ((A1)x(A2)5-xNb10O30) structural formula. The two processes were associated to a
phase transition and the formation of incommensurate structures, respectively. The influence of
such incommensurate structures on the relaxor behavior and diffusivity of the ferro-paraelectric
phase transition was also analyzed.Universidade Federal de Sao CarlosO processo de obtenção de cerâmicas ferroelétricas de metaniobato de chumbo (PN) foi
otimizado, de forma que este trabalho oferece os detalhes necessários para a obtenção de
cerâmicas de PN com densidades superiores aos 96 % da densidade ideal.
Levando-se em consideração a potencialidade do metaniobato de chumbo para diferentes
tipos de aplicações, principalmente em altas temperaturas, foi realizada uma investigação
detalhada das características da transição de fase nesse material puro e dopado.
Verificou-se que a adição de Ti4+ favorece a densificação das cerâmicas e aumenta a
temperatura de Curie. Contudo, a transição de fase ferro-paraelétrica é afetada por um processo
de condutividade elétrica que se manifesta tanto em temperaturas inferiores quanto superiores à
temperatura de Curie. Por outro lado, determinou-se que o portador de carga responsável por tal
processo condutivo são as vacâncias de oxigênio duplamente ionizadas. As cerâmicas de PN,
puras e dopadas com Ti4+, apresentaram baixos valores do fator de qualidade mecânico e uma
alta anisotropia piezoelétrica. Tais características são desejáveis para a fabricação de
transdutores eletro-mecânicos de banda larga, principalmente para operar no modo de espessura.
A adição de Ba2+ ao PN (PBN) diminui consideravelmente a sua temperatura de Curie, mas
induz uma transição de fase, formando um contorno de fase morfotrópico (CFM), ao redor da
composição com 37 % de Ba2+, na qual algumas propriedades são maximizadas. Assim, utilizando
cerâmicas texturadas de PN dopadas com Ba2+, obtidas por forjamento a quente, foi possível
investigar as características da transição de fase ferro-paraelétrica para composições ao redor do
CFM. Verificou-se que a região do CFM se estende em uma ampla faixa de composições onde
coexistem as estruturas tungstênio bronze (TB) com simetria tetragonal 4mm e ortorrômbica m2m.
Observou-se também que, nessa região de composições, ocorrem duas transições de fase com o
aumento da temperatura. Inicialmente a fração de fase ortorrômbica se transforma em tetragonal
e, posteriormente, todo o material com simetria 4mm passa ao estado paraelétrico, onde adota a
estrutura TB com simetria tetragonal 4/mmm. Com esses resultados foi possível complementar o
diagrama de fases do PBN existente na literatura. A adição de La3+, na cerâmica de PBN com 56
% de chumbo, favoreceu a formação da estrutura TB com simetria ortorrômbica.
Em todas as cerâmicas de PN (puro e dopado), foram observados dois processos de
dispersão dielétrica em baixas temperaturas, entre 30 e 300 K, aparentemente são inerentes a
todos os materiais com estrutura TB e fórmula estrutural ((A1)x(A2)5-xNb10O30), e estão
relacionados com uma transição de fase e com a formação de superestruturas incomensuráveis
respectivamente. Foi analisada também a influência de tais superestruturas no comportamento
relaxor e na difusividade da transição de fase ferro-paraelétrica das cerâmicas estudadas
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