Photocatalytic Magnetic Microgyroscopes with Activity-Tunable Precessional Dynamics.

Magnetic nano/microrotors are passive elements spinning around an axis due to an external rotating field while remaining confined to a plane. They have been used to date in different applications related to fluid mixing, drug delivery, or biomedicine. Here we realize an active version of a magnetic microgyroscope which is simultaneously driven by a photoactivated catalytic reaction and a rotating magnetic field.

Curvature induces and enhances transport of spinning colloids through narrow channels.

The effect of curvature and how it induces and enhances the transport of colloidal particles driven through narrow channels represent an unexplored research avenue. Here we combine experiments and simulations to investigate the dynamics of magnetically driven colloidal particles confined through a narrow, circular channel. We use an external precessing magnetic field to induce a net torque and spin the particles at a defined angular velocity.

Molecular dynamics simulations of microscopic structural transition and macroscopic mechanical properties of magnetic gels.

Magnetic gels with embedded micro-/nano-sized magnetic particles in cross-linked polymer networks can be actuated by external magnetic fields, with changes in their internal microscopic structures and macroscopic mechanical properties. We investigate the responses of such magnetic gels to an external magnetic field, by means of coarse-grained molecular dynamics simulations. We find that the dynamics of magnetic particles are determined by the interplay of magnetic dipole-dipole interactions, polymer elasticity, and thermal fluctuations.

Clustering induces switching between phoretic and osmotic propulsion in active colloidal rafts.

Active particles driven by chemical reactions are the subject of intense research to date due to their rich physics, being intrinsically far from equilibrium, and their multiple technological applications. Recent attention in this field is now shifting towards exploring the fascinating dynamics of active and passive mixtures. Here we realize active colloidal rafts, composed of a single catalytic particle encircled by several shells of passive microspheres, and assembled via light-activated chemophoresis.

Overcrowding induces fast colloidal solitons in a slowly rotating potential landscape.

Collective particle transport across periodic energy landscapes is ubiquitously present in many condensed matter systems spanning from vortices in high-temperature superconductors, frictional atomic sliding, driven skyrmions to biological and active matter. Here we report the emergence of fast solitons propagating against a rotating optical landscape. These experimentally observed solitons are stable cluster waves that originate from a coordinated particle exchange process which occurs when the number of trapped microparticles exceeds the number of potential wells.

Large Scale Zigzag Pattern Emerging from Circulating Active Shakers.

We report the emergence of large zigzag bands in a population of reversibly actuated magnetic rotors that behave as active shakers, namely squirmers that shake the fluid around them without moving. The shakers collectively organize into dynamic structures displaying self-similar growth and generate topological defects in the form of cusps that connect vortices of rolling particles with alternating chirality. By combining experimental analysis with particle-based simulation, we show that the special flow field created by the shakers is the only ingredient needed to reproduce the observed spatiotemporal pattern.

Postmortem Ultrastructural Analysis of the Retina from COVID-19 Deceased Patients.

Purpose: COVID-19 (coronavirus disease 2019) is an infectious disease caused by SARS-CoV-2, first reported in 2019 in Wuhan, China. Among the common complications is a pro-inflammatory and hypercoagulative response that compromises the vasculature among various organs.

Methods: In this report, we present the postmortem retinal findings of five patients observed by means of optical microscopy and transmission and scanning electron microscopy techniques.

Unveiling the Rolling to Kayak Transition in Propelling Nanorods with Cargo Trapping and Pumping.

Magnetic nanorods driven by rotating fields in water can be rapidly steered along any direction while generating strong and localized hydrodynamic flow fields. Here we show that, when raising the frequency of the rotating field, these nanopropellers undergo a dynamic transition from a rolling to a kayak-like motion due to the increase in viscous drag and acquire a finite inclination angle with respect to the plane perpendicular to the bottom surface. We explain these experimental observations with a theoretical model which considers the nanorod as a pair of ferromagnetic particles hydrodynamically interacting with a close stationary surface.

Hydrodynamic interactions hinder transport of flow-driven colloidal particles.

The flow-driven transport of interacting micron-sized particles occurs in many soft matter systems spanning from the translocation of proteins to moving emulsions in microfluidic devices. Here we combine experiments and theory to investigate the collective transport properties of colloidal particles along a rotating ring of optical traps. In the corotating reference frame, the particles are driven by a vortex flow of the surrounding fluid.

Friction Induces Anisotropic Propulsion in Sliding Magnetic Microtriangles.

In viscous fluids, motile microentities such as bacteria or artificial swimmers often display different transport modes than macroscopic ones. A current challenge in the field aims at using friction asymmetry to steer the motion of microscopic particles. Here we show that lithographically shaped magnetic microtriangles undergo a series of complex transport modes when driven by a precessing magnetic field, including a surfing-like drift close to the bottom plane.

Elastically-mediated collective organisation of magnetic microparticles.

Gels are soft elastic materials made of a three-dimensional cross-linked polymer network and featuring both elastic and dissipative responses under external mechanical stimuli. Here we investigate how such gels mediate the organization of embedded magnetic microparticles when driven by an external field. By constructing a continuum theory, we demonstrate that the collective dynamics of the embedded particles result from the delicate balance between magnetic dipole-dipole interactions, thermal fluctuations and elasticity of the polymer network, verified by our experiments.

Breaking action-reaction with active apolar colloids: emergent transport and velocity inversion.

Artificial active particles are autonomous agents able to convert energy from the environment into net propulsion, breaking detailed balance and the action-reaction law, clear signatures of their out-of-equilibrium nature. Here we investigate the emergence of directed motion in clusters composed of passive and catalytically active apolar colloids. We use a light-induced chemophoretic flow to rapidly assemble hybrid self-propelling clusters composed of hematite particles and passive silica spheres.

Hydrodynamic synchronization and clustering in ratcheting colloidal matter.

Ratchet transport systems are widespread in physics and biology; however, the effect of the dispersing medium in the collective dynamics of these out-of-equilibrium systems has been often overlooked. We show that, in a traveling wave magnetic ratchet, long-range hydrodynamic interactions (HIs) produce a series of remarkable phenomena on the transport and assembly of interacting Brownian particles. We demonstrate that HIs induce the resynchronization with the traveling wave that emerges as a "speed-up" effect, characterized by a net raise of the translational speed, which doubles that of single particles.

Nitazoxanide in Patients Hospitalized With COVID-19 Pneumonia: A Multicentre, Randomized, Double-Blind, Placebo-Controlled Trial.

Background: Nitazoxanide exerts antiviral activity and and anti-inflammatory effects, but its impact on patients hospitalized with COVID-19 pneumonia is uncertain.

Methods: A multicentre, randomized, double-blind, placebo-controlled trial was conducted in 19 hospitals in Brazil. Hospitalized adult patients requiring supplemental oxygen, with COVID-19 symptoms and a chest computed tomography scan suggestive of viral pneumonia or positive RT-PCR test for COVID-19 were enrolled.

Rivaroxaban versus no anticoagulation for post-discharge thromboprophylaxis after hospitalisation for COVID-19 (MICHELLE): an open-label, multicentre, randomised, controlled trial.

Background: Patients hospitalised with COVID-19 are at risk for thrombotic events after discharge; the role of extended thromboprophylaxis in this population is unknown.

Methods: In this open-label, multicentre, randomised trial conducted at 14 centres in Brazil, patients hospitalised with COVID-19 at increased risk for venous thromboembolism (International Medical Prevention Registry on Venous Thromboembolism [IMPROVE] venous thromboembolism [VTE] score of ≥4 or 2-3 with a D-dimer >500 ng/mL) were randomly assigned (1:1) to receive, at hospital discharge, rivaroxaban 10 mg/day or no anticoagulation for 35 days. The primary efficacy outcome in an intention-to-treat analysis was a composite of symptomatic or fatal venous thromboembolism, asymptomatic venous thromboembolism on bilateral lower-limb venous ultrasound and CT pulmonary angiogram, symptomatic arterial thromboembolism, and cardiovascular death at day 35.

Hydrodynamic Interactions Can Induce Jamming in Flow-Driven Systems.

Hydrodynamic interactions between fluid-dispersed particles are ubiquitous in soft matter and biological systems and they give rise to intriguing collective phenomena. While it was reported that these interactions can facilitate force-driven particle motion over energetic barriers, here we show the opposite effect in a flow-driven system, i.e.

Corrigendum to "Nitazoxanide superiority to placebo to treat moderate COVID-19 - A Pilot prove of concept randomized double-blind clinical trial." [EClinicalMedicine 37 (2021) 100981].

[This corrects the article DOI: 10.1016/j.eclinm.

Collective hydrodynamic transport of magnetic microrollers.

We investigate the collective transport properties of microscopic magnetic rollers that propel close to a surface due to a circularly polarized, rotating magnetic field. The applied field exerts a torque to the particles, which induces a net rolling motion close to a surface. The collective dynamics of the particles result from the balance between magnetic dipolar interactions and hydrodynamic ones.

Thermally active nanoparticle clusters enslaved by engineered domain wall traps.

The stable assembly of fluctuating nanoparticle clusters on a surface represents a technological challenge of widespread interest for both fundamental and applied research. Here we demonstrate a technique to stably confine in two dimensions clusters of interacting nanoparticles via size-tunable, virtual magnetic traps. We use cylindrical Bloch walls arranged to form a triangular lattice of ferromagnetic domains within an epitaxially grown ferrite garnet film.

Medically Ill hospitalized Patients for COVID-19 THrombosis Extended ProphyLaxis with rivaroxaban ThErapy: Rationale and Design of the MICHELLE Trial.

Background: The devastating Coronavirus disease (COVID-19) pandemic is associated with a high prothrombotic state. It is unclear if the coagulation abnormalities occur because of the direct effect of SARS-CoV-2 or indirectly by the cytokine storm and endothelial damage or by a combination of mechanisms. There is a clear indication of in-hospital pharmacological thromboprophylaxis for every patient with COVID-19 after bleed risk assessment.

Presumed SARS-CoV-2 Viral Particles in the Human Retina of Patients With COVID-19.

Importance: The presence of the SARS-CoV-2 virus in the retina of deceased patients with COVID-19 has been suggested through real-time reverse polymerase chain reaction and immunological methods to detect its main proteins. The eye has shown abnormalities associated with COVID-19 infection, and retinal changes were presumed to be associated with secondary microvascular and immunological changes.

Objective: To demonstrate the presence of presumed SARS-CoV-2 viral particles and its relevant proteins in the eyes of patients with COVID-19.

Nitazoxanide superiority to placebo to treat moderate COVID-19 - A Pilot prove of concept randomized double-blind clinical trial.

Background: The absence of specific antivirals to treat COVID-19 leads to the repositioning of candidates' drugs. Nitazoxanide (NTZ) has a broad antiviral effect.

Methods: This was a randomized, double-blind pilot clinical trial comparing NTZ 600 mg BID versus Placebo for seven days among 50 individuals (25 each arm) with SARS-COV-2 RT-PCR+ (PCR) that were hospitalized with mild respiratory insufficiency from May 20, 2020, to September 21, 2020 (ClinicalTrials.

Topological Boundary Constraints in Artificial Colloidal Ice.

The effect of boundaries and how these can be used to influence the bulk behavior in geometrically frustrated systems are both long-standing puzzles, often relegated to a secondary role. Here, we use numerical simulations and "proof of concept" experiments to demonstrate that boundaries can be engineered to control the bulk behavior in a colloidal artificial ice. We show that an antiferromagnetic frontier forces the system to rapidly reach the ground state (GS), as opposed to the commonly implemented open or periodic boundary conditions.

COVID-19 Retinal Findings in Patients Admitted to Intensive Care Units and Wards.

The main purpose of this study was to investigate ocular clinical findings in patients with confirmed COVID-19 infection, of various levels of disease severity, who required mechanical ventilation and admission to intensive care units or specialized wards. Longitudinal, observational study conducted from March 2020 to June 2020. Color fundus and red-free photography were performed in both eyes following pupillary dilation.