Noncontact rotation, levitation, and acceleration of flowing liquid metal wires.

This paper reports the noncontact manipulation of free-falling cylindrical streams of liquid metals into unique shapes, such as levitated loops and squares. Such cylindrical streams form in aqueous media by electrochemically lowering the interfacial tension. The electrochemical reactions require an electrical current that flows through the streams, making them susceptible to the Lorentz force. Consequently, varying the position and shape of a magnetic field relative to the stream controls these forces. Moreover, the movement of the metal stream relative to the magnetic field induces significant forces arising from Lenz's law that cause the manipulated streams to levitate in unique shapes. The ability to control streams of liquid metals in a noncontact manner will enable strategies for shaping electronically conductive fluids for advanced manufacturing and dynamic electronic structures.

Liquid Metal-Enabled Tunable Synthesis of Nanoporous Polycrystalline Copper for Selective CO2-to-Formate Electrochemical Conversion.

Copper-based catalysts exhibit high activity in electrochemical CO2 conversion to value-added chemicals. However, achieving precise control over catalysts design to generate narrowly distributed products remains challenging. Herein, a gallium (Ga) liquid metal-based approach is employed to synthesize hierarchical nanoporous copper (HNP Cu) catalysts with tailored ligament/pore and crystallite sizes. The nanoporosity and polycrystallinity are generated by dealloying intermetallic CuGa2 formed after immersing pristine Cu foil in liquid Ga in a basic or acidic solution. The liquid metal-based approach allows for the transformation of monocrystalline Cu to the polycrystalline HNP Cu with enhanced CO2 reduction reaction (CO2RR) performance. The dealloyed HNP Cu catalyst with suitable crystallite size (22.8 nm) and nanoporous structure (ligament/pore size of 45 nm) exhibits a high Faradaic efficiency of 91% toward formate production under an applied potential as low as -0.3 VRHE. The superior CO2RR performance can be ascribed to the enlarged electrochemical catalytic surface area, the generation of preferred Cu facets, and the rich grain boundaries by polycrystallinity. This work demonstrates the potential of liquid metal-based synthesis for improving catalysts performance based on structural design, without increasing compositional complexity.

Neural Tracing Protein-Functionalized Nanoparticles Capable of Fast Retrograde Axonal Transport in Live Neurons.

Neural tracing proteins like horseradish peroxidase-conjugated wheat germ agglutinin (WGA-HRP) can target the central nervous system (CNS) through anatomic retrograde transport without crossing the blood-brain barrier (BBB). Conjugating WGA-HRP to nanoparticles may enable the creation of BBB-bypassing nanomedicine. Microfluidics and two-photon confocal microscopy is applied to screen nanocarriers for transport efficacy and gain mechanistic insights into their interactions with neurons. Protein modification of gold nanoparticles alters their cellular uptake at the axonal terminal and activates fast retrograde transport. Trajectory analysis of individual endosomes carrying the nanoparticles reveals a run-and-pause pattern along the axon with endosomes carrying WGA-HRP-conjugated gold nanoparticles exhibiting longer run duration and faster instantaneous velocity than those carrying nonconjugated nanoparticles. The results offer a mechanistic explanation of the different axonal transport dynamics as well as a cell-based functional assay of neuron-targeted nanoparticles with the goal of developing BBB-bypassing nanomedicine for the treatment of nervous system disorders.

Liquid Metal Doping Induced Asymmetry in Two-Dimensional Metal Oxides.

The emergence of ferroelectricity in two-dimensional (2D) metal oxides is a topic of significant technological interest; however, many 2D metal oxides lack intrinsic ferroelectric properties. Therefore, introducing asymmetry provides access to a broader range of 2D materials within the ferroelectric family. Here, the generation of asymmetry in 2D SnO by doping the material with Hf0.5Zr0.5O2 (HZO) is demonstrated. A liquid metal process as a doping strategy for the preparation of 2D HZO-doped SnO with robust ferroelectric characteristics is implemented. This technology takes advantage of the selective interface enrichment of molten Sn with HZO crystallites. Molecular dynamics simulations indicate a strong tendency of Hf and Zr atoms to migrate toward the surface of liquid metal and embed themselves within the growing oxide layer in the form of HZO. Thus, the liquid metal-based harvesting/doping technique is a feasible approach devised for producing novel 2D metal oxides with induced ferroelectric properties, represents a significant development for the prospects of random-access memories.

Modeling COVID-19 spread using multi-agent simulation with small-world network approach.

BACKGROUND: The rapid global spread of COVID-19 has seriously impacted people's daily lives and the social economy while also posing a threat to their lives. The analysis of infectious disease transmission is of significant importance for the rational allocation of epidemic prevention and control resources, the management of public health emergencies, and the improvement of future public health systems. METHODS: We propose a spatiotemporal COVID-19 transmission model with a neighborhood as an agent unit and an urban spatial network with long and short edge connections. The spreading model includes a network of defined agent attributes, transformation rules, and social relations and a small world network representing agents' social relations. Parameters for each stage are fitted by the Runge-Kutta method combined with the SEIR model. Using the NetLogo development platform, accurate dynamic simulations of the spatial and temporal evolution of the early epidemic were achieved. RESULTS: Experimental results demonstrate that the fitted curves from the four stages agree with actual data, with only a 12.27% difference between the average number of infected agents and the actual number of infected agents after simulating 1 hundred times. Additionally, the model simulates and compares different "city closure" scenarios. The results showed that implementing a 'lockdown' 10 days earlier would lead to the peak number of infections occurring 7 days earlier than in the normal scenario, with a reduction of 40.35% in the total number of infections. DISCUSSION: Our methodology emphasizes the crucial role of timely epidemic interventions in curbing the spread of infectious diseases, notably in the predictive assessment and evaluation of lockdown strategies. Furthermore, this approach adeptly forecasts the influence of varying intervention timings on peak infection rates and total case numbers, accurately reflecting real-world virus transmission patterns. This highlights the importance of proactive measures in diminishing epidemic impacts. It furnishes a robust framework, empowering policymakers to refine epidemic response strategies based on a synthesis of predictive modeling and empirical data.

Mechanistic Observation of Interactions between Macrophages and Inorganic Particles with Different Densities.

Many different types of inorganic materials are processed into nano/microparticles for medical utilization. The impact of selected key characteristics of these particles, including size, shape, and surface chemistries, on biological systems, is frequently studied in clinical contexts. However, one of the most important basic characteristics of these particles, their density, is yet to be investigated. When the particles are designed for drug delivery, highly mobile macrophages are the major participants in cellular levels that process them in vivo. As such, it is essential to understand the impact of particles' densities on the mobility of macrophages. Here, inorganic particles with different densities are applied, and their interactions with macrophages studied. A set of these particles are incubated with the macrophages and the outcomes are explored by optical microscopy. This microscopic view provides the understanding of the mechanistic interactions between particles of different densities and macrophages to conclude that the particles' density can affect the migratory behaviors of macrophages: the higher the density of particles engulfed inside the macrophages, the less mobile the macrophages become. This work is a strong reminder that the density of particles cannot be neglected when they are designed to be utilized in biological applications.

Autocorrelation analysis-based OCT velocimetry for axial blood flow velocity imaging of the cerebral capillary network.

The accurate measurement of blood flow velocity in the capillary network is challenging due to the small size of the vessels and the slow flow of red blood cells (RBCs) within the vessel. Here, we introduce an autocorrelation analysis-based optical coherence tomography (OCT) method that takes less acquisition time to measure the axial blood flow velocity in the capillary network. The axial blood flow velocity was obtained from the phase change in the decorrelation period of the first-order field autocorrelation function (g1) of the OCT field data, which was acquired with M-mode acquisition (repeated A-scans). The rotation center of g1 in the complex plane was first re-centralized to the origin, then the phase change due to the movement of RBCs was extracted in the g1 decorrelation period which is usually 0.2-0.5 ms. In phantom experiments, the results suggest that the proposed method could accurately measure the axial speed with a wide range of 0.5-15 mm/s. We further tested the method on living animals. Compared with the phase-resolved Doppler optical coherence tomography (pr-DOCT), the proposed method can obtain robust axial velocity measurements with more than five times shorter acquisition time.

Optical coherence tomography-based design for a real-time motion corrected scanning microscope.

While two-photon fluorescence microscopy is a powerful platform for the study of functional dynamics in living cells and tissues, the bulk motion inherent to these applications causes distortions. We have designed a motion tracking module based on spectral domain optical coherence tomography which compliments a laser scanning two-photon microscope with real-time corrective feedback. The module can be added to fluorescent imaging microscopes using a single dichroic and without additional contrast agents. We demonstrate that the system can track lateral displacements as large as 10 µm at 5 Hz with latency under 14 ms and propose a scheme to extend the system to 3D correction with the addition of a remote focusing module. We also propose several ways to improve the module's performance by reducing the feedback latency. We anticipate that this design can be adapted to other imaging modalities, enabling the study of samples subject to motion artifacts at higher resolution.

Multideuteration of Nitroaromatics by Silver-Catalyzed Hydrogen-Isotope Exchange.

Silver-catalyzed deuteration of nitroaromatics has been achieved using D2O as the deuterium source. Distinct from the well-established directing group-guided hydrogen-isotope exchange, this protocol showed an interesting deuteration pattern, where considerable deuterium accumulation was observed around the aromatic rings. Controlling experiments suggested that the deuteration was initiated by a silver-promoted C-H activation. Therefore, a tentative two-stage deuteration mechanism involving aryl-silver species was proposed to explain the deuteration on meta- and para-positions.

Enhancement of Plasmon-Induced Photoelectrocatalytic Water Oxidation over Au/TiO2 with Lithium Intercalation.

Plasmon-induced chemical reaction is an emerging field but its development faces huge challenges because of low quantum efficiency. Herein, we report that the solar energy conversion efficiency of Au/TiO2 in plasmon-induced water oxidation is greatly enhanced by intercalating Li+ into TiO2 . An incident photon-to-current efficiency as high as 2.0 %@520 nm is achieved by Au/Li0.2 TiO2 in photoelectrocatalytic water oxidation, realizing a 33-fold enhancement in photocurrent density compared with Au/TiO2 . The superior photoelectrocatalytic performance is mainly ascribed to the enhanced electric conductivity and higher catalytic activity of Li0.2 TiO2 . Furthermore, the ultrafast transient absorption spectroscopy suggests that lithium intercalation into TiO2 could change the dynamics of hot electron relaxation in Au nanoparticles. This work demonstrates that intercalation of alkaline ions into semiconductors can promote the charge separation efficiency of the plasmonic effect of Au/TiO2 .

Imaging localized fast optical signals of neural activation with optical coherence tomography in awake mice.

We report optical coherence tomography (OCT) imaging of localized fast optical signals (FOSs) arising from whisker stimulation in awake mice. The activated voxels were identified by fitting the OCT intensity signal time course with a response function over a time scale of a few hundred milliseconds after the whisker stimulation. The significantly activated voxels were shown to be localized to the expected brain region for whisker stimulation. The ability to detect functional stimulus-evoked, depth-resolved FOS with intrinsic contrast from the cortex provides a new tool for neural activity studies.

Bi-Sn Catalytic Foam Governed by Nanometallurgy of Liquid Metals.

Metallic foams, with intrinsic catalytic properties, are critical for heterogeneous catalysis reactions and reactor designs. Market ready catalytic foams are costly and made of multimaterial coatings with large sub-millimeter open cells providing insufficient active surface area. Here we use the principle of nanometallurgy within liquid metals to prepare nanostructured catalytic metal foams using a low-cost alloy of bismuth and tin with sub-micrometer open cells. The eutectic bismuth and tin liquid metal alloy was processed into nanoparticles and blown into a tin and bismuth nanophase separated heterostructure in aqueous media at room temperature and using an indium brazing agent. The CO2 electroconversion efficiency of the catalytic foam is presented with an impressive 82% conversion efficiency toward formates at high current density of -25 mA cm-2 (-1.2 V vs RHE). Nanometallurgical process applied to liquid metals will lead to exciting possibilities for expanding industrial and research accessibility of catalytic foams.

Liquid Metal Droplet and Graphene Co-Fillers for Electrically Conductive Flexible Composites.

Colloidal liquid metal alloys of gallium, with melting points below room temperature, are potential candidates for creating electrically conductive and flexible composites. However, inclusion of liquid metal micro- and nanodroplets into soft polymeric matrices requires a harsh auxiliary mechanical pressing to rupture the droplets to establish continuous pathways for high electrical conductivity. However, such a destructive strategy reduces the integrity of the composites. Here, this problem is solved by incorporating small loading of nonfunctionalized graphene flakes into the composites. The flakes introduce cavities that are filled with liquid metal after only relatively mild press-rolling (<0.1 MPa) to form electrically conductive continuous pathways within the polymeric matrix, while maintaining the integrity and flexibility of the composites. The composites are characterized to show that even very low graphene loadings (≈0.6 wt%) can achieve high electrical conductivity. The electrical conductance remains nearly constant, with changes less than 0.5%, even under a relatively high applied pressure of >30 kPa. The composites are used for forming flexible electrically-conductive tracks in electronic circuits with a self-healing property. The demonstrated application of co-fillers, together with liquid metal droplets, can be used for establishing electrically-conductive printable-composite tracks for future large-area flexible electronics.

Capillary red blood cell velocimetry by phase-resolved optical coherence tomography.

We present a phase-resolved optical coherence tomography (OCT) method to extend Doppler OCT for the accurate measurement of the red blood cell (RBC) velocity in cerebral capillaries. OCT data were acquired with an M-mode scanning strategy (repeated A-scans) to account for the single-file passage of RBCs in a capillary, which were then high-pass filtered to remove the stationary component of the signal to ensure an accurate measurement of phase shift of flowing RBCs. The angular frequency of the signal from flowing RBCs was then quantified from the dynamic component of the signal and used to calculate the axial speed of flowing RBCs in capillaries. We validated our measurement by RBC passage velocimetry using the signal magnitude of the same OCT time series data.

Effect of salt concentration on the quality and microbial community during pickled peppers fermentation.

This work aimed to investigate the effect of salt concentration on the quality and microbial community of pickled peppers during fermentation, and the cross-correlation between microorganisms and quality was also revealed. The results showed that 9 volatile flavor compounds were unique to the low salt concentration group (D group), which also contained higher content of FAA, lactic acid and acetic acid than high salt concentration group (G group). Meanwhile, the samples of D2 group have a better texture properties. Firmicutes, Proteobacteria, Ascomycota, Lactobacillus, Pectobacterium, and Pseudomonas were detected as the main microbial community during the fermentation with different salt concentrations. Furthermore, the correlations analysis results indicated that the salt concentration has a significant effect on the microbial community of pickled peppers (p < 0.001), and Pediococcus, Lactobacillus, Cedecca, Issatchenkia, Pichia, Kazachstania, and Hanseniaspora were significantly correlated with flavors, which played crucial roles in the unique flavor formation of pickled peppers.

Ultrasound Speckle Decorrelation Analysis-Based Velocimetry for 3D-Velocity-Components Measurement Using a 1D Transducer Array.

Ultrasound velocimetry has been widely used for blood flow imaging. However, the flow measurements are constrained to resolve the in-plane 2D flow components when using a 1D transducer array. In this work, an ultrasound speckle decorrelation analysis-based velocimetry (3C-vUS) is proposed for 3D velocity components measurement using a 1D transducer array. The 3C-vUS theory is first derived and validated with numerical simulations and phantom experiments. The in vivo testing results show that 3C-vUS can accurately measure the blood flow 3D-velocity-components of the human carotid artery at arbitrary probe-to-vessel angles throughout the cardiac cycle. With such capability, the 3C-vUS will alleviate the requirement of operators and promote disease screening for blood flow-related disorders.

Liquid Metal as Energy Conversion Sensitizers: Materials and Applications.

Energy can exist in nature in a wide range of forms. Energy conversion refers to the process in which energy is converted from one form to another, and this process will be greatly enhanced by energy conversion sensitizers. Recently, an emerging class of new materials, namely liquid metals (LMs), shows excellent prospects as highly versatile materials. Notably, in terms of energy delivery and conversion, LMs functional materials are chemical responsive, heat-responsive, photo-responsive, magnetic-responsive, microwave-responsive, and medical imaging responsive. All these intrinsic virtues enabled promising applications in energy conversion, which means LMs can act as energy sensitizers for enhancing energy conversion and transport. Herein, first the unique properties of the light, heat, magnetic and microwave converting capacity of gallium-based LMs materials are summarized. Then platforms and applications of LM-based energy conversion sensitizers are highlighted. Finally, some of the potential applications and opportunities of LMs are prospected as energy conversion sensitizers in the future, as well as unresolved challenges. Collectively, it is believed that this review provides a clear perspective for LMs mediated energy conversion, and this topic will help deepen knowledge of the physical chemistry properties of LMs functional materials.

Prognostic value of ultrasound in early arterial complications post liver transplant.

Liver transplantation is the primary therapeutic intervention for end-stage liver disease. However, vascular complications, particularly those involving the hepatic artery, pose significant risks to patients. The clinical manifestations associated with early arterial complications following liver transplantation are often nonspecific. Without timely intervention, these complications can result in graft failure or patient mortality. Therefore, early diagnosis and the formulation of an optimal treatment plan are imperative. Ultrasound examination remains the predominant imaging modality for detecting complications post liver transplantation. This article comprehensively reviews common causes and clinical presentations of early hepatic artery complications in the post-transplantation period and delineates abnormal sonographic findings for accurate diagnosis of these conditions. Overall, ultrasound offers the advantages of convenience, safety, effectiveness, and non-invasiveness. It enables real-time, dynamic, and precise evaluation, making it the preferred diagnostic method for post-liver transplantation assessments.

Time-Lagged Functional Ultrasound for Multi-Parametric Cerebral Hemodynamic Imaging.

We introduce an ultrasound speckle decorrelation-based time-lagged functional ultrasound technique (tl-fUS) for the quantification of the relative changes in cerebral blood flow speed (rCBF [Formula: see text]), cerebral blood volume (rCBV) and cerebral blood flow (rCBF) during functional stimulations. Numerical simulations, phantom validations, and in vivo mouse brain experiments were performed to test the capability of tl-fUS to parse out and quantify the ratio change of these hemodynamic parameters. The blood volume change was found to be more prominent in arterioles compared to venules and the peak blood flow changes were around 2.5 times the peak blood volume change during brain activation, agreeing with previous observations in the literature. The tl-fUS shows the ability of distinguishing the relative changes of rCBFspeed, rCBV, and rCBF, which can inform specific physiological interpretations of the fUS measurements.

Emulsion-Based Multi-Phase Integrated Microbeads with Inner Multi-Interface Structure Enable Dual-Modal Imaging for Precision Endovascular Embolization.

Microsphere-based embolic agents have gained prominence in transarterial embolization (TAE) treatment, a critical minimally invasive therapy widely applied for a variety of diseases such as hypervascular tumors and acute bleeding. However, the development of microspheres with long-term, real-time, and repeated X-ray imaging as well as ultrasound imaging remains challenging. In this study, emulsion-based dual-modal imaging microbeads with a unique internal multi-interface structure is developed for TAE treatment. The embolic microbeads are fabricated from a solidified oil-in-water (O/W) emulsion composed of crosslinked CaAlg-based aqueous matrix and dispersed radiopaque iodinated oil (IO) droplets through a droplet-based microfluidic fabrication method. The CaAlg-IO microbeads exhibit superior X-ray imaging visibility due to the incorporation of exceptionally high iodine level up to 221 mgI mL-1, excellent ultrasound imaging capability attributed to the multi-interface structure of the O/W emulsion, great microcatheter deliverability thanks to their appropriate biomechanical properties and optimal microbead density, and extended drug release behavior owing to the biodegradation nature of the embolics. Such an embolic agent presents a promising emulsion-based platform to utilize multi-phased structures for improving endovascular embolization performance and assessment capabilities.