Non-volatile electric control of spin-charge conversion in a SrTiO3 Rashba system.

After 50 years of development, the technology of today's electronics is approaching its physical limits, with feature sizes smaller than 10 nanometres. It is also becoming clear that the ever-increasing power consumption of information and communication systems1 needs to be contained. These two factors require the introduction of non-traditional materials and state variables. As recently highlighted2, the remanence associated with collective switching in ferroic systems is an appealing way to reduce power consumption. A promising approach is spintronics, which relies on ferromagnets to provide non-volatility and to generate and detect spin currents3. However, magnetization reversal by spin transfer torques4 is a power-consuming process. This is driving research on multiferroics to achieve low-power electric-field control of magnetization5, but practical materials are scarce and magnetoelectric switching remains difficult to control. Here we demonstrate an alternative strategy to achieve low-power spin detection, in a non-magnetic system. We harness the electric-field-induced ferroelectric-like state of strontium titanate (SrTiO3)6-9 to manipulate the spin-orbit properties10 of a two-dimensional electron gas11, and efficiently convert spin currents into positive or negative charge currents, depending on the polarization direction. This non-volatile effect opens the way to the electric-field control of spin currents and to ultralow-power spintronics, in which non-volatility would be provided by ferroelectricity rather than by ferromagnetism.

Electric-field-induced multiferroic topological solitons.

Topologically protected spin whirls in ferromagnets are foreseen as the cart-horse of solitonic information technologies. Nevertheless, the future of skyrmionics may rely on antiferromagnets due to their immunity to dipolar fields, straight motion along the driving force and ultrafast dynamics. While complex topological objects were recently discovered in intrinsic antiferromagnets, mastering their nucleation, stabilization and manipulation with energy-efficient means remains an outstanding challenge. Designing topological polar states in magnetoelectric antiferromagnetic multiferroics would allow one to electrically write, detect and erase topological antiferromagnetic entities. Here we stabilize ferroelectric centre states using a radial electric field in multiferroic BiFeO3 thin films. We show that such polar textures contain flux closures of antiferromagnetic spin cycloids, with distinct antiferromagnetic entities at their cores depending on the electric field polarity. By tuning the epitaxial strain, quadrants of canted antiferromagnetic domains can also be electrically designed. These results open the path to reconfigurable topological states in multiferroic antiferromagnets.

Onset of Multiferroicity in Prototypical Single-Spin Cycloid BiFeO3 Thin Films.

In the room-temperature magnetoelectric multiferroic BiFeO3, the noncollinear antiferromagnetic state is coupled to the ferroelectric order, opening applications for low-power electric-field-controlled magnetic devices. While several strategies have been explored to simplify the ferroelectric landscape, here we directly stabilize a single-domain ferroelectric and spin cycloid state in epitaxial BiFeO3 (111) thin films grown on orthorhombic DyScO3 (011). Comparing them with films grown on SrTiO3 (111), we identify anisotropic in-plane strain as a powerful handle for tailoring the single antiferromagnetic state. In this single-domain multiferroic state, we establish the thickness limit of the coexisting electric and magnetic orders and directly visualize the suppression of the spin cycloid induced by the magnetoelectric interaction below the ultrathin limit of 1.4 nm. This as-grown single-domain multiferroic configuration in BiFeO3 thin films opens an avenue both for fundamental investigations and for electrically controlled noncollinear antiferromagnetic spintronics.

Visualizing Giant Ferroelectric Gating Effects in Large-Scale WSe2/BiFeO3 Heterostructures.

Multilayers based on quantum materials (complex oxides, topological insulators, transition-metal dichalcogenides, etc.) have enabled the design of devices that could revolutionize microelectronics and optoelectronics. However, heterostructures incorporating quantum materials from different families remain scarce, while they would immensely broaden the range of possible applications. Here we demonstrate the large-scale integration of compounds from two highly multifunctional families: perovskite oxides and transition-metal dichalcogenides (TMDs). We couple BiFeO3, a room-temperature multiferroic oxide, and WSe2, a semiconducting two-dimensional material with potential for photovoltaics and photonics. WSe2 is grown by molecular beam epitaxy and transferred on a centimeter-scale onto BiFeO3 films. Using angle-resolved photoemission spectroscopy, we visualize the electronic structure of 1 to 3 monolayers of WSe2 and evidence a giant energy shift as large as 0.75 eV induced by the ferroelectric polarization direction in the underlying BiFeO3. Such a strong shift opens new perspectives in the efficient manipulation of TMD properties by proximity effects.

Imaging Topological Defects in a Noncollinear Antiferromagnet.

We report on the formation of topological defects emerging from the cycloidal antiferromagnetic order at the surface of bulk BiFeO_{3} crystals. Combining reciprocal and real-space magnetic imaging techniques, we first observe, in a single ferroelectric domain, the coexistence of antiferromagnetic domains in which the antiferromagnetic cycloid propagates along different wave vectors. We then show that the direction of these wave vectors is not strictly locked to the preferred crystallographic axes as continuous rotations bridge different wave vectors. At the junctions between the magnetic domains, we observe topological line defects identical to those found in a broad variety of lamellar physical systems with rotational symmetries. Our work establishes the presence of these magnetic objects at room temperature in the multiferroic antiferromagnet BiFeO_{3}, offering new possibilities for their use in spintronics.

Superhydrophobic µ-pillars via simple and scalable SLA 3D-printing: the stair-case effect and their wetting models.

In nature, superhydrophobic surfaces (SHSs) exhibit microstructures with several roughness scales. Scalable fabrication and build-up along the X-Y plane represent the promise of 3D printing technology. Herein we report 3D printed microstructures with a dual roughness scale that achieves SHS using a readily available Formlabs stereolithography (SLA) printer. Pillar-like structure (PLS) arrangements with a wide range of geometrical shapes were 3D printed at three resolutions and two printing orientations. We discovered that a tilted printing direction enables a stair-case pattern on the µ-PLS surfaces, conferring them a µ-roughness that reduces the solid-liquid contact area. The programmed resolution governs the number of polymerized layers that give rise to the stepped pattern on the µ-PLS surfaces. However, this is reduced as the printing resolution increases. Also, all samples' experimental contact angles were consistent with theoretical predictions from Cassie-Baxter, Wenzel, and Nagayama wettability models. The underlying mechanisms and governing parameters were also discussed. It is believed that this work will enable scalable and high throughput roughness design in augmenting future 3D printing object applications.

Depth profiling charge accumulation from a ferroelectric into a doped Mott insulator.

The electric field control of functional properties is a crucial goal in oxide-based electronics. Nonvolatile switching between different resistivity or magnetic states in an oxide channel can be achieved through charge accumulation or depletion from an adjacent ferroelectric. However, the way in which charge distributes near the interface between the ferroelectric and the oxide remains poorly known, which limits our understanding of such switching effects. Here, we use a first-of-a-kind combination of scanning transmission electron microscopy with electron energy loss spectroscopy, near-total-reflection hard X-ray photoemission spectroscopy, and ab initio theory to address this issue. We achieve a direct, quantitative, atomic-scale characterization of the polarization-induced charge density changes at the interface between the ferroelectric BiFeO3 and the doped Mott insulator Ca(1-x)Ce(x)MnO3, thus providing insight on how interface-engineering can enhance these switching effects.

Incidence and characteristics of chronic postsurgical pain at 6 months after total mastectomy under pectoserratus and interpectoral plane block combined with general anesthesia: a prospective cohort study.

INTRODUCTION: Chronic postsurgical pain (CPSP) occurs in 20%-30% of patients who undergo total mastectomy (TM) performed under general anesthesia alone and significantly affects the quality of life. Pectoserratus and interpectoral plane block have been reportedly combined with general anesthesia to control immediate postoperative pain after TM. Our prospective cohort study aimed to evaluate the incidence of CPSP after TM when pectoserratus and interpectoral plane block were combined with general anesthesia. METHODS: We recruited adult women scheduled to undergo TM for breast cancer. Patients planned for TM with flap surgery, those who underwent breast surgery in the past 5 years, or those presenting with residual chronic pain after prior breast surgery were excluded. After general anesthesia induction, an anesthesiologist performed pectoserratus and interpectoral plane block with a ropivacaine (3.75 mg/mL) and clonidine (3.75 µg/mL) in 40 mL of 0.9% sodium chloride. The primary endpoint was the occurrence of CPSP-defined as pain with a Numeric Rating Scale Score of ≥3, either at the breast surgical site and/or at axilla, without other identifiable causes-evaluated during a pain medicine consultation at 6 months post TM. RESULTS: Overall, 43/164 study participants had CPSP (26.2%; 95% CI: 19.7 to 33.6); of these, 23 had neuropathic type of pain (53.5%), 19 had nociceptive (44.2%), and 1 had mixed (2.3%) type of pain. CONCLUSION: Although postoperative analgesia has significantly improved in the last decade, there is still need for improvement to reduce CPSP after oncologic breast surgery. TRIAL REGISTRATION NUMBER: NCT03023007.

Voltage-based magnetization switching and reading in magnetoelectric spin-orbit nanodevices.

As CMOS technologies face challenges in dimensional and voltage scaling, the demand for novel logic devices has never been greater, with spin-based devices offering scaling potential, at the cost of significantly high switching energies. Alternatively, magnetoelectric materials are predicted to enable low-power magnetization control, a solution with limited device-level results. Here, we demonstrate voltage-based magnetization switching and reading in nanodevices at room temperature, enabled by exchange coupling between multiferroic BiFeO3 and ferromagnetic CoFe, for writing, and spin-to-charge current conversion between CoFe and Pt, for reading. We show that, upon the electrical switching of the BiFeO3, the magnetization of the CoFe can be reversed, giving rise to different voltage outputs. Through additional microscopy techniques, magnetization reversal is linked with the polarization state and antiferromagnetic cycloid propagation direction in the BiFeO3. This study constitutes the building block for magnetoelectric spin-orbit logic, opening a new avenue for low-power beyond-CMOS technologies.

A ferroelectric memristor.

Memristors are continuously tunable resistors that emulate biological synapses. Conceptualized in the 1970s, they traditionally operate by voltage-induced displacements of matter, although the details of the mechanism remain under debate. Purely electronic memristors based on well-established physical phenomena with albeit modest resistance changes have also emerged. Here we demonstrate that voltage-controlled domain configurations in ferroelectric tunnel barriers yield memristive behaviour with resistance variations exceeding two orders of magnitude and a 10 ns operation speed. Using models of ferroelectric-domain nucleation and growth, we explain the quasi-continuous resistance variations and derive a simple analytical expression for the memristive effect. Our results suggest new opportunities for ferroelectrics as the hardware basis of future neuromorphic computational architectures.

Atomic and electronic structure of the BaTiO3/Fe interface in multiferroic tunnel junctions.

Artificial multiferroic tunnel junctions combining a ferroelectric tunnel barrier of BaTiO(3) with magnetic electrodes display a tunnel magnetoresistance whose intensity can be controlled by the ferroelectric polarization of the barrier. This effect, called tunnel electromagnetoresistance (TEMR), and the corollary magnetoelectric coupling mechanisms at the BaTiO(3)/Fe interface were recently reported through macroscopic techniques. Here, we use advanced spectromicroscopy techniques by means of aberration-corrected scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy (EELS) to probe locally the nanoscale structural and electronic modifications at the ferroelectric/ferromagnetic interface. Atomically resolved real-space spectroscopic techniques reveal the presence of a single FeO layer between BaTiO(3) and Fe. Based on this accurate description of the studied interface, we propose an atomistic model of the ferroelectric/ferromagnetic interface further validated by comparing experimental and simulated STEM images with atomic resolution. Density functional theory calculations allow us to interpret the electronic and magnetic properties of these interfaces and to understand better their key role in the physics of multiferroics nanostructures.

BiFeO3 Nanoparticles: The "Holy-Grail" of Piezo-Photocatalysts?

Recently, piezoelectric-based catalysis has been demonstrated to be an efficient means and promising alternative to sunlight-driven photocatalysis, where mechanical vibrations trigger redox reactions. Here, 60 nm-size BiFeO3 nanoparticles are shown to be very effective for piezo-degrading Rhodamine B (RhB) model dye with record degradation rate reaching 13 810 L mol-1  min-1 , and even 41 750 L mol-1  min-1 (i.e., 100% RhB degradation within 5 min) when piezocatalysis is synergistically combined with sunlight photocatalysis. These BiFeO3 piezocatalytic nanoparticles are also demonstrated to be versatile toward several dyes and pharmaceutical pollutants, with over 80% piezo-decomposition within 120 min. The maintained high piezoelectric coefficient combined with low dielectric constant, high-elastic modulus, and the nanosized shape make these BiFeO3  nanoparticles extremely efficient piezocatalysts. To avoid subsequent secondary pollution and enable their reusability, the BiFeO3 nanoparticles are further embedded in a polymer P(VDF-TrFE) matrix. The as-designed flexible, chemically stable, and recyclable nanocomposites still keep remarkable piezocatalytic and piezo-photocatalytic performances (i.e., 92% and 100% RhB degradation, respectively, within 20 min). This work opens a new research avenue for BiFeO3 that is the model multiferroic and offers a new platform for water cleaning, as well as other applications such as water splitting, CO2 reduction, or surface purification.

Temporal and spatial tracking of ultrafast light-induced strain and polarization modulation in a ferroelectric thin film.

Ultrashort light pulses induce rapid deformations of crystalline lattices. In ferroelectrics, lattice deformations couple directly to the polarization, which opens the perspective to modulate the electric polarization on an ultrafast time scale. Here, we report on the temporal and spatial tracking of strain and polar modulation in a single-domain BiFeO3 thin film by ultrashort light pulses. To map the light-induced deformation of the BiFeO3 unit cell, we perform time-resolved optical reflectivity and time-resolved x-ray diffraction. We show that an optical femtosecond laser pulse generates not only longitudinal but also shear strains. The longitudinal strain peaks at a large amplitude of 0.6%. The access of both the longitudinal and shear strains enables to quantitatively reconstruct the ultrafast deformation of the unit cell and to infer the corresponding reorientation of the ferroelectric polarization direction in space and time. Our findings open new perspectives for ultrafast manipulation of strain-coupled ferroic orders.

[Withholding or withdrawing life-sustaining treatments in acute oncology situations: History and regulatory aspects in France]. / La « Limitation et/ou arrêt des thérapeutiques ¼ (LAT) en oncologie face à une situation aigüe : historique et aspects réglementaires en France.

The management of oncology patients, especially hospitalized patients, can lead to almost daily discussions regarding therapeutic limitations. Here, we review the history and propose a summary of the texts framing the notion of "withholding and withdrawing life-sustaining treatment" in oncology practice in France. This decision is regulated by the Claeys-Léonetti Law of February 2, 2016 recommending a collegial discussion and its documentation in the medical record. The decision to withhold or withdraw life-sustaining treatments is the subject of discussion between the patient, his physicians and his family and may take place at any time during his management. The work of intensive-care physicians provides many useful recommendations for acute oncology situations, however articles specific for oncology practice are scarce; this is a topic that oncologists must take up.

Extensive Comparative Genomic Analysis of Enterococcus faecalis and Enterococcus faecium Reveals a Direct Association between the Absence of CRISPR-Cas Systems, the Presence of Anti-Endonuclease (ardA) and the Acquisition of Vancomycin Resistance in E. faecium.

Here, we performed a comparative genomic analysis of all available genomes of E. faecalis (n = 1591) and E. faecium (n = 1981) and investigated the association between the presence or absence of CRISPR-Cas systems, endonuclease/anti-endonuclease systems and the acquisition of antimicrobial resistance, especially vancomycin resistance genes. Most of the analysed Enterococci were isolated from humans and less than 14% of them were from foods and animals. We analysed and detected CRISPR-Cas systems in 75.36% of E. faecalis genomes and only 4.89% of E. faecium genomes with a significant difference (p-value < 10-5). We found a negative correlation between the number of CRISPR-Cas systems and genome size (r = -0.397, p-value < 10-5) and a positive correlation between the genome %GC content and the number of CRISPR-Cas systems (r = 0.215, p-value < 10-5). Our findings showed that the presence of the anti-endonuclease ardA gene may explain the decrease in the number of CRISPR-Cas systems in E. faecium, known to deactivate the endonucleases' protective activities and enable the E. faecium genome to be versatile in acquiring mobile genetic elements, including carriers of antimicrobial resistance genes, especially vanB. Most importantly, we observed that there was a direct association between the absence of CRISPR-Cas, the presence of the anti-CRISPR ardA gene and the acquisition of vancomycin resistance genes.

Additively manufactured high-performance polymeric materials and their potential use in the oil and gas industry.

The oil and gas industry has been tagged as among the largest revenue-generating sectors in the world. High-performance polymers (HPPs), on the other hand, are among the most useful industrial materials, while the utility of 3D printing technologies has evolved and transitioned from rapid prototyping of composite materials to manufacturing of functional parts. In this prospective, we highlight the potential uses and industrial applications of 3D-printed HPP materials in the oil and gas sector, including the challenges and opportunities present.

Kinome rewiring during acquired drug resistance in neuroendocrine neoplasms.

Although there is evidence of a significant rise of neuroendocrine neoplasms (NENs) incidence, current treatments are largely insufficient due to somewhat poor knowledge of these tumours. Despite showing differentiated features, NENs exhibit therapeutic resistance to most common treatments, similar to other cancers in many instances. Molecular mechanisms responsible for this resistance phenomenon are badly understood. We aimed at identifying signalling partners responsible of acquired resistance to treatments in order to develop novel therapeutic strategies. We engineered QGP-1 cells resistant to current leading treatments, the chemotherapeutic agent oxaliplatin and the mTor inhibitor everolimus. Cells were chronically exposed to the drugs and assessed for acquired resistance by viability assay. We used microarray-based kinomics to obtain highthroughput kinase activity profiles from drug sensitive vs resistant cells and identified 'hit' kinases hyperactivated in drug-resistant cells, including kinases from FGFR family, cyclin-dependant kinases and PKCs in oxaliplatin-resistant (R-Ox) QGP-1 cells. We then validated these 'hit' kinases and observed that ERK signalling is specifically enhanced in QGP-1 R-Ox cells. Finally, we assessed drug-resistant cells sensitivity to pharmacological inhibition of 'hit' kinases or their signalling partners. We found that FGFR inhibition markedly decreased ERK signalling and cell viability in QGP-1 R-Ox cells. These results suggest that the FGFR/ERK axis is hyperactivated in response to oxaliplatin-based chemotherapeutic strategy. Thus, this sensitive approach, based on the study of kinome activity, allows identifying potential candidates involved in drug resistance in NENs and may be used to broadly investigate markers of NENs therapeutic response.

An optimized stepwise algorithm combining rapid antigen and RT-qPCR for screening of COVID-19 patients.

BACKGROUND & AIM: We investigated the combination of rapid antigen detection (RAD) and RT-qPCR assays in a stepwise procedure to optimize the detection of COVID-19. METHODS: From August 2020 to November 2020, 43,399 patients were screened in our laboratory for COVID-19 diagnostic by RT-qPCR using nasopharyngeal swab. Overall, 4,691 of the 43,399 were found to be positive, and 200 were retrieved for RAD testing allowing comparison of diagnostic accuracy between RAD and RT-qPCR. Cycle threshold (Ct) and time from symptoms onset (TSO) were included as covariates. RESULTS: The overall sensitivity, specificity, PPV, NPV, LR-, and LR+ of RAD compared with RT-qPCR were 72% (95%CI 62%-81%), 99% (95% CI95%-100%), 99% (95%CI 93%-100%), and 78% (95%CI 70%-85%), 0.28 (95%CI 0.21-0.39), and 72 (95%CI 10-208) respectively. Sensitivity was higher for patients with Ct ≤ 25 regardless of TSO: TSO ≤ 4 days 92% (95%CI 75%-99%), TSO > 4 days 100% (95%CI 54%-100%), and asymptomatic 100% (95%CI 78-100%). Overall, combining RAD and RT-qPCR would allow reducing from only 4% the number of RT-qPCR needed. CONCLUSIONS: This study highlights the risk of misdiagnosing COVID-19 in 28% of patients if RAD is used alone. A stepwise analysis that combines RAD and RT-qPCR would be an efficient screening procedure for COVID-19 detection and may facilitate the control of the outbreak.