We predict a very large spin-orbit torque (SOT) capability of magnetic chromium-based transition-metal dichalcogenide (TMD) monolayers in their Janus forms CrXTe, with X = S, Se. The structural inversion symmetry breaking, inherent to Janus structures is responsible for a large SOT response generated by giant Rashba splitting, equivalent to that obtained by applying a transverse electric field of ∼100 V nm in non-Janus CrTe, completely out of experimental reach. By performing transport simulations on carefully derived Wannier tight-binding models, Janus systems are found to exhibit an SOT performance comparable to the most efficient two-dimensional materials, while additionally allowing for field-free perpendicular magnetization switching, due to their reduced in-plane symmetry.
View Article and Find Full Text PDFWe report a theoretical description of novel spin-orbit torque components emerging in two-dimensional Dirac materials with broken inversion symmetry. In contrast to usual metallic interfaces where fieldlike and dampinglike torque components are competing, we find that an intrinsic dampinglike torque which derives from all Fermi-sea electrons can be simultaneously enhanced along with the fieldlike component. Additionally, hitherto overlooked torque components unique to Dirac materials emerge from the coupling between spin and pseudospin angular momenta, leading to spin-pseudospin entanglement.
View Article and Find Full Text PDFWe report an unconventional quantum spin Hall phase in the monolayer WTe_{2}, which exhibits hitherto unknown features in other topological materials. The low symmetry of the structure induces a canted spin texture in the yz plane, which dictates the spin polarization of topologically protected boundary states. Additionally, the spin Hall conductivity gets quantized (2e^{2}/h) with a spin quantization axis parallel to the canting direction.
View Article and Find Full Text PDFImproved fabrication techniques have enabled the possibility of ballistic transport and unprecedented spin manipulation in ultraclean graphene devices. Spin transport in graphene is typically probed in a nonlocal spin valve and is analyzed using spin diffusion theory, but this theory is not necessarily applicable when charge transport becomes ballistic or when the spin diffusion length is exceptionally long. Here, we study these regimes by performing quantum simulations of graphene nonlocal spin valves.
View Article and Find Full Text PDFSpin-orbit coupling stands as a powerful tool to interconvert charge and spin currents and to manipulate the magnetization of magnetic materials through spin-torque phenomena. However, despite the diversity of existing bulk materials and the recent advent of interfacial and low-dimensional effects, control of this interconversion at room temperature remains elusive. Here, we demonstrate strongly enhanced room-temperature spin-to-charge interconversion in graphene driven by the proximity of WS.
View Article and Find Full Text PDFGraphene is an excellent material for long-distance spin transport but allows little spin manipulation. Transition-metal dichalcogenides imprint their strong spin-orbit coupling into graphene via the proximity effect, and it has been predicted that efficient spin-to-charge conversion due to spin Hall and Rashba-Edelstein effects could be achieved. Here, by combining Hall probes with ferromagnetic electrodes, we unambiguously demonstrate experimentally the spin Hall effect in graphene induced by MoS proximity and for varying temperatures up to room temperature.
View Article and Find Full Text PDFObjectives: Primary: to assess the use of simulators in prostate digital rectal examination and bladder catheterization on mental workload and the level of confidence in medical students. Secondary: to analyze student satisfaction and skills acquired by students with simulators.
Methods: We conducted a prospective, randomized study on medical students.
Since its discovery, graphene has been a promising material for spintronics: its low spin-orbit coupling, negligible hyperfine interaction, and high electron mobility are obvious advantages for transporting spin information over long distances. However, such outstanding transport properties also limit the capability to engineer active spintronics, where strong spin-orbit coupling is crucial for creating and manipulating spin currents. To this end, transition metal dichalcogenides, which have larger spin-orbit coupling and good interface matching, appear to be highly complementary materials for enhancing the spin-dependent features of graphene while maintaining its superior charge transport properties.
View Article and Find Full Text PDFWe report on fundamental aspects of spin dynamics in heterostructures of graphene and transition metal dichalcogenides (TMDCs). By using realistic models derived from first principles we compute the spin lifetime anisotropy, defined as the ratio of lifetimes for spins pointing out of the graphene plane to those pointing in the plane. We find that the anisotropy can reach values of tens to hundreds, which is unprecedented for typical 2D systems with spin-orbit coupling and indicates a qualitatively new regime of spin relaxation.
View Article and Find Full Text PDFWe report on a theoretical study of the spin Hall Effect (SHE) and weak antilocalization (WAL) in graphene/transition metal dichalcogenide (TMDC) heterostructures, computed through efficient real-space quantum transport methods, and using realistic tight-binding models parametrized from ab initio calculations. The graphene/WS system is found to maximize spin proximity effects compared to graphene on MoS, WSe, or MoSe with a crucial role played by disorder, given the disappearance of SHE signals in the presence of strong intervalley scattering. Notably, we found that stronger WAL effects are concomitant with weaker charge-to-spin conversion efficiency.
View Article and Find Full Text PDFUnlabelled: Objective describe the multi-professional team's perception of nurses' competences in liver transplantation programs.
Method: descriptive study with a qualitative approach. Data were collected through a questionnaire.
Objective: To verify the influence of sociodemographic factors on the quality of life of patients after liver transplant.
Method: Cross-sectional study with 150 patients who underwent liver transplant at a referral center. A sociodemographic instrument and the Liver Disease Quality of Life questionnaire were applied.
Space-occupying lesions of the liver may be cystic or solid. Ultrasonography is an extremely useful method for initial screening, and suffices for diagnosis of simple hepatic cysts. Complex cysts and solid masses require computed tomography or magnetic resonance imaging for confirmation.
View Article and Find Full Text PDFHepatocellular carcinoma is a malignancy of global importance and is associated with a high rate of mortality. Recent advances in the diagnosis and treatment of this disease make it imperative to update the recommendations on the management of the disease. In order to draw evidence-based recommendations concering the diagnosis and management of hepatocellular carcinoma, the Brazilian Society of Hepatology has sponsored a single-topic meeting in João Pessoa (PB).
View Article and Find Full Text PDFArq Gastroenterol
April 2016
Background: Treatment of hepatitis C virus infection in post-transplantation patients is a challenge due to poor tolerance and low success rates.
Objective: To determine the response rate to pegylated interferon and ribavirin in post-liver transplant patients with hepatitis C recurrence.
Methods: Between 18 May 2002 and 18 December 2011, 601 patients underwent liver transplantation at our service (Hospital Universitário Walter Cantídio, University of Ceará), 176 (29.
Introduction: The aim of this study is to evaluate the risk factors for acute kidney injury (AKI) and 30-day mortality after liver transplantation.
Material And Methods: This is a retrospective cohort of consecutive adults undergoing orthotopic liver transplantation (OLT) at a referral hospital in Brazil, from January 2013 to January 2014. Risk factors for AKI and death were investigated.
We describe an efficient numerical approach to calculate the longitudinal and transverse Kubo conductivities of large systems using Bastin's formulation. We expand the Green's functions in terms of Chebyshev polynomials and compute the conductivity tensor for any temperature and chemical potential in a single step. To illustrate the power and generality of the approach, we calculate the conductivity tensor for the quantum Hall effect in disordered graphene and analyze the effect of the disorder in a Chern insulator in Haldane's model on a honeycomb lattice.
View Article and Find Full Text PDFBackground: Combined liver-kidney transplant is a routine procedure in many transplant centers. The increase in its number coincided with the introduction in 2002 of the MELD (Model for End-stage Liver Disease) score for allocation of livers, prioritizing patients with renal dysfunction. Aim : To analyze the experience with combined liver-kidney transplantation in a liver transplant center in Brazil.
View Article and Find Full Text PDFContext: Liver transplantation has been accepted as a therapeutic option for patients with end-stage liver disease and acute liver failure. Currently, Brazil has a well-established public organ transplant program, performing 7,425 solid organs transplants in 2012 alone, among which 1,595 were liver transplants. Jehovah's Witnesses report 7,6 million members worldwide.
View Article and Find Full Text PDFContext: Liver transplantation is one of the last viable resources for patients with end-stage liver disease. Many strategies are been used to improve the number of available organs and overcome waiting list delay. However, hepatic steatosis is one of the mainly concerns when organs are consider to transplantation due to it is importance as a risk factor for primary dysfunction.
View Article and Find Full Text PDFBackground: Liver transplantation is the only effective treatment for chronic liver diseases and terminal survival rate has increased in recent decades. However, biliary complications have high incidence and remain as the "Achilles heel" for liver transplantation.
Aim: To evaluate retrospectively endoscopic treatment outcomes of biliary complications in post-liver transplantations.