The diverse applications of terahertz (THz) radiation and its importance to fundamental science makes finding ways to generate, manipulate and detect THz radiation one of the key areas of modern ...applied physics. One approach is to utilize carbon nanomaterials, in particular, single-wall carbon nanotubes and graphene. Their novel optical and electronic properties offer much promise to the field of THz science and technology. This article describes the past, current, and future of THz science and technology of carbon nanotubes and graphene. We will review fundamental studies such as THz dynamic conductivity, THz nonlinearities and ultrafast carrier dynamics as well as THz applications such as THz sources, detectors, modulators, antennas and polarizers.
Ultrafast laser techniques have revealed extraordinary spin dynamics in magnetic materials that equilibrium descriptions of magnetism cannot explain. Particularly important for future applications is ...understanding non-equilibrium spin dynamics following laser excitation on the nanoscale, yet the limited spatial resolution of optical laser techniques has impeded such nanoscale studies. Here we present ultrafast diffraction experiments with an X-ray laser that probes the nanoscale spin dynamics following optical laser excitation in the ferrimagnetic alloy GdFeCo, which exhibits macroscopic all-optical switching. Our study reveals that GdFeCo displays nanoscale chemical and magnetic inhomogeneities that affect the spin dynamics. In particular, we observe Gd spin reversal in Gd-rich nanoregions within the first picosecond driven by the non-local transfer of angular momentum from larger adjacent Fe-rich nanoregions. These results suggest that a magnetic material's microstructure can be engineered to control transient laser-excited spins, potentially allowing faster (~ 1 ps) spin reversal than in present technologies.
We show that if the solutions to the (2+1)-dimensional massless Dirac equation for a given one-dimensional (1D) potential are known, then they can be used to obtain the eigenvalues and eigenfunctions ...for the same potential, orientated at an arbitrary angle, in a 2D Dirac material possessing tilted, anisotropic Dirac cones. This simple set of transformations enables all the exact and quasi-exact solutions associated with 1D quantum wells in graphene to be applied to the confinement problem in tilted Dirac materials such as 8-Pmmn borophene. We also show that smooth electron waveguides in tilted Dirac materials can be used to manipulate the degree of valley polarization of quasiparticles travelling along a particular direction of the channel. We examine the particular case of the hyperbolic secant potential to model realistic top-gated structures for valleytronic applications.
Essentials
Patients with hemophilia A and inhibitors receiving emicizumab experience breakthrough bleeding.
Safety concerns may exist when combining emicizumab with bypassing agents.
Combined ...bypassing agent and bispecific antibody increased thrombin generation up to 17‐fold.
Thrombotic effects should be considered when combining emicizumab with plasma bypassing agent.
Summary
Background
Investigational non‐factor products such as emicizumab offer a treatment option for patients with hemophilia and inhibitors. However, their mechanism of action raises questions regarding safety when they are combined with treatments for breakthrough bleeding.
Objectives
To evaluate in vitro thrombin generation (TG) and clot formation for combinations of activated prothrombin complex concentrate (aPCC), recombinant activated factor VII (rFVIIa), and a sequence‐identical analog of emicizumab (SIA).
Methods
Therapeutic concentrations of SIA (20–600 nm) alone or with aPCC (0.05–1 U mL−1), isolated aPCC components or rFVIIa (0.88–5.25 μg mL−1) were tested for TG and compared with reference ranges for healthy donor plasma. Coagulation of FVIII‐inhibited blood was determined with a widely established method, i.e. rotational thromboelastometry (ROTEM), and confirmed with the Total Thrombus‐formation Analysis System.
Results and conclusions
SIA (600 nm) or aPCC (0.5 U mL−1) alone resulted in peak thrombin levels of 21.4 nm and 38.6 nm, respectively, both of which are lower than normal (83.7 ± 29.8 nm). SIA plus aPCC (0.5 U mL−1) increased the peak thrombin level 17‐fold over SIA alone, exceeding the reference plasma value by 4.2‐fold. This hypercoagulable effect occurred with 600 nmSIA combined with as little as 0.25 U mL−1 aPCC, confirmed by ROTEM. FIX was the main driver for enhanced TG. SIA plus rFVIIa (1.75 μg mL−1) induced a 1.8‐fold increase in the peak thrombin level in platelet‐rich plasma, but it did not reach the normal range. These in vitro experiments demonstrate excessive TG after administration of a combination of aPCC and SIA at clinically relevant doses. Careful judgement may be required when breakthrough bleeding is treated in patients receiving emicizumab.
Oxidation of the cathode carbon catalyst support in polymer electrolyte fuel cells (PEMFC) has been examined. For this purpose platinum supported electrodes and pure carbon electrodes were fabricated ...and tested in membrane-electrode-assemblies (MEAs) in air and nitrogen atmosphere. The in situ experiments account for the fuel cell environment characterized by the presence of a solid electrolyte and water in the gas and liquid phases. Cell potential transients occurring during automotive fuel cell operation were simulated by dynamic measurements. Corrosion rates were calculated from CO
2 and CO concentrations in the cathode exhaust measured by non-dispersive infrared spectroscopy (NDIR). Results from these potentiodynamic measurements indicate that different potential regimes relevant for carbon oxidation can be distinguished. Carbon corrosion rates were found to be higher under dynamic operation and to strongly depend on electrode history. These characteristics make it difficult to predict corrosion rates accurately in an automotive drive cycle.
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