Reorientation of Hydrogen Bonds Renders Unusual Enhancement in Thermal Transport of Water in Nanoconfined Environments.

Liquid confined in a nanochannel or nanotube has exhibited a superfast transport phenomenon, providing an ideal heat and mass transfer platform to meet the increasingly stringent challenge of thermal management in developing high-power-density nanoelectronics and nanochips. However, understanding the thermal transport of confined liquid is currently lacking and is speculated to be fundamentally different from that of bulk counterparts due to the unprecedented thermodynamics of liquid in nanoconfined environments. Here, we report that the thermal conductivity of water confined in a silica nanotube is nearly 2-fold as that of bulk status. Further molecular dynamics simulations reveal that this unusual enhancement originates from the densification and reorientation of local hydrogen bonds close to the nanotubes. Thermal-confinement scaling law is established and quantitatively supported by comprehensive simulations with remarkable agreement. Our findings lay a theoretical foundation for designing nanofluidics-enabled cooling strategies and devices.

Ultra-High Interfacial Thermal Conductance via Double hBN Encapsulation for Efficient Thermal Management of 2D Electronics.

Heat dissipation is a major limitation of high-performance electronics. This is especially important in emerging nanoelectronic devices consisting of ultra-thin layers, heterostructures, and interfaces, where enhancement in thermal transport is highly desired. Here, ultra-high interfacial thermal conductance in encapsulated van der Waals (vdW) heterostructures with single-layer transition metal dichalcogenides MX2 (MoS2 , WSe2 , WS2 ) sandwiched between two hexagonal boron nitride (hBN) layers is reported. Through Raman spectroscopic measurements of suspended and substrate-supported hBN/MX2 /hBN heterostructures with varying laser power and temperature, the out-of-plane interfacial thermal conductance in the vertical stack is calibrated. The measured interfacial thermal conductance between MX2 and hBN reaches 74 ± 25 MW m-2 K-1 , which is at least ten times higher than the interfacial thermal conductance of MX2 in non-encapsulation structures. Molecular dynamics (MD) calculations verify and explain the experimental results, suggesting a full encapsulation by hBN layers is accounting for the high interfacial conductance. This ultra-high interfacial thermal conductance is attributed to the double heat transfer pathways and the clean and tight vdW interface between two crystalline 2D materials. The findings in this study reveal new thermal transport mechanisms in hBN/MX2 /hBN structures and shed light on building novel hBN-encapsulated nanoelectronic devices with enhanced thermal management.

Spontaneous outflow efficiency of confined liquid in hydrophobic nanopores.

The suspension of nanoporous particles in a nonwetting liquid provides a unique solution to the crux of superfluid, sensing, and energy conversion, yet is challenged by the incomplete outflow of intruded liquid out of nanopores for the system reusability. We report that a continuous and spontaneous liquid outflow from hydrophobic nanopores with high and stable efficiency can be achieved by regulating the confinement of solid-liquid interactions with functionalized nanopores or/and liquids. Full-scale molecular-dynamics simulations reveal that the grafted silyl chains on nanopore wall surfaces will promote the hydrophobic confinement of liquid molecules and facilitate the molecular outflow; by contrast, the introduction of ions in the liquid weakens the hydrophobic confinement and congests the molecular outflow. Both one-step and multistep well-designed quasistatic compression experiments on a series of nanopores/nonwetting liquid material systems have been performed, and the results confirm the outflow mechanism in remarkable agreement with simulations. This study offers a fundamental understanding of the outflow of confined liquid from hydrophobic nanopores, potentially useful for devising emerging nanoporous-liquid functional systems with reliable and robust reusability.

Capillary transfer of soft films.

Existing transfer technologies in the construction of film-based electronics and devices are deeply established in the framework of native solid substrates. Here, we report a capillary approach that enables a fast, robust, and reliable transfer of soft films from liquid in a defect-free manner. This capillary transfer is underpinned by the transfer front of dynamic contact among receiver substrate, liquid, and film, and can be well controlled by a selectable motion direction of receiver substrates at a high speed. We demonstrate in extensive experiments, together with theoretical models and computational analysis, the robust capabilities of the capillary transfer using a versatile set of soft films with a broad material diversity of both film and liquid, surface-wetting properties, and complex geometric patterns of soft films onto various solid substrates in a deterministic manner.

Infectious hematopoietic necrosis virus (IHNV) nucleoprotein amino acid residues affect viral virulence and immunogenicity in rainbow trout (Oncorhynchus mykiss).

This study compared the N protein sequences of genotype J with other genotypes of IHNV to select amino acid residues that may be related to the change in viral virulence. The recombinant viruses containing different mutation sites were rescued by alanine scanning mutagenesis and the reverse genetic system. The nine recombinant virus strains obtained in this work were named rIHNV-N85, rIHNV-N102, rIHNV-N146, rIHNV-N380, rIHNV-N85-102-146, rIHNV-N85-102-380, rIHNV-N85-146-380, rIHNV-N102-146-380, and rIHNV-N85-102-146-380. Pathogenicity and immunity assays were performed to determine the role of virulence sites. The result of the pathogenicity test showed that the survival rates of rIHNV-N85, rIHNV-N102, rIHNV-N85-102-146, and rIHNV-N85-102-380 groups were 52.5%, 55%, 67.5%, and 57.5%, while the survival rate of wild-type (wt) IHNV HLJ-09 group was only 10%. The replication ability of recombinant viruses with substitutions at positions 85 and 102 was significantly inhibited in vivo and in vitro. The qRT-PCR result indicated that the cytokines of IFN1, IL-8, and IL-1ß expression levels were increased in rIHNV-N85, rIHNV-N102, rIHNV-N85-102-146, and rIHNV-N85-102-380 groups. In addition, these four recombinant viruses could cause the rainbow trout to produce anti-IHNV-specific antibodies immunoglobulin M (IgM) earlier, confirming that 85 and 102 amino acid residues of N protein affected the virulence and immunogenicity of IHNV. All these results suggest that mutations of the N protein virulence sites reduce virulence while retaining immunogenicity. This also provides a new idea for studying the virulence mechanism of rhabdoviruses and preparing attenuated vaccines.

Theoretical search for heterogeneously architected 2D structures.

Architected 2D structures are of growing interest due to their unique mechanical and physical properties for applications in stretchable electronics, controllable phononic/photonic modulators, and switchable optical/electrical devices; however, the underpinning theory of understanding their elastic properties and enabling principles in search of emerging structures with well-defined arrangements and/or bonding connections of assembled elements has yet to be established. Here, we present two theoretical frameworks in mechanics-strain energy-based theory and displacement continuity-based theory-to predict the elastic properties of 2D structures and demonstrate their application in a search for novel architected 2D structures that are composed of heterogeneously arranged, arbitrarily shaped lattice cell structures with regulatory adjacent bonding connections of cells, referred to as heterogeneously architected 2D structures (HASs). By patterning lattice cell structures and tailoring their connections, the elastic properties of HASs can span a very broad range from nearly zero to beyond those of individual lattice cells by orders of magnitude. Interface indices that represent both the pattern arrangements of basic lattice cells and local bonding disconnections in HASs are also proposed and incorporated to intelligently design HASs with on-demand Young's modulus and geometric features. This study offers a theoretical foundation toward future architected structures by design with unprecedented properties and functions.

Wafer-recyclable, environment-friendly transfer printing for large-scale thin-film nanoelectronics.

Transfer printing of thin-film nanoelectronics from their fabrication wafer commonly requires chemical etching on the sacrifice of wafer but is also limited by defects with a low yield. Here, we introduce a wafer-recyclable, environment-friendly transfer printing process that enables the wafer-scale separation of high-performance thin-film nanoelectronics from their fabrication wafer in a defect-free manner that enables multiple reuses of the wafer. The interfacial delamination is enabled through a controllable cracking phenomenon in a water environment at room temperature. The physically liberated thin-film nanoelectronics can be then pasted onto arbitrary places of interest, thereby endowing the particular surface with desirable add-on electronic features. Systematic experimental, theoretical, and computational studies reveal the underlying mechanics mechanism and guide manufacturability for the transfer printing process in terms of scalability, controllability, and reproducibility.

Deterministic Nanoassembly of Quasi-Three-Dimensional Plasmonic Nanoarrays with Arbitrary Substrate Materials and Structures.

Guided manipulation of light through periodic nanoarrays of three-dimensional (3D) metal-dielectric patterns provides remarkable opportunities to harness light in a way that cannot be obtained with conventional optics yet its practical implementation remains hindered by a lack of effective methodology. Here we report a novel 3D nanoassembly method that enables deterministic integration of quasi-3D plasmonic nanoarrays with a foreign substrate composed of arbitrary materials and structures. This method is versatile to arrange a variety of types of metal-dielectric composite nanoarrays in lateral and vertical configurations, providing a route to generate heterogeneous material compositions, complex device layouts, and tailored functionalities. Experimental, computational, and theoretical studies reveal the essential design features of this approach and, taken together with implementation of automated equipment, provide a technical guidance for large-scale manufacturability. Pilot assembly of specifically engineered quasi-3D plasmonic nanoarrays with a model hybrid pixel detector for deterministic enhancement of the detection performances demonstrates the utility of this method.

Two- and three-dimensional self-folding of free-standing graphene by liquid evaporation.

Two-dimensional (2-D) atomically thin graphene has exhibited overwhelming excellent properties over its bulk counterpart graphite, yet the broad applications and explorations of its unprecedented properties require a diversity of its geometric morphologies, beyond its inherently planar structures. In this study, we present a self-folding approach for converting 2-D planar free-standing graphene to 2-D and 3-D folded structures through the evaporation of its liquid solutions. This approach involves competition between the surface energy of the liquid, and the deformation energy and van der Waals energy of graphene. An energy-based theoretical model is developed to describe the self-folding process during liquid evaporation by incorporating both graphene dimensions and surface wettability. The critical elastocapillary length by liquid evaporation is extracted and exemplified by investigating three typical graphene geometries with rectangular, circular and triangular shapes. After the complete evaporation of the liquid, the critical self-folding length of graphene that can enable a stable folded pattern by van der Waals energy is also obtained. In parallel, full-scale molecular dynamics (MD) simulations are performed to monitor the evolution of deformation energies and folded patterns with liquid evaporation. The simulation results demonstrate the formation of 2-D folded racket-like and 3-D folded cone-like patterns and show remarkable agreement with theoretical predictions in both energy variations and folded patterns. This work offers quantitative guidance for controlling the self-folding of graphene and other 2-D materials into complex structures by liquid evaporation.

Actuating Water Droplets on Graphene via Surface Wettability Gradients.

A surface wettability gradient can break the equilibrium status of a liquid droplet and drives its unidirectional movement on the surface. We propose a conceptual design of the driving water droplet on a graphene surface and demonstrate that both speed and direction of the movement can be controlled via a continuous gradient of surface wettability using comprehensive molecular dynamics (MD) simulations. Controlling the water droplet toward linear and nonlinear arc paths is exemplified in one- and two-dimensional gradients of surface wettability, respectively. Unbalanced Young's equation is extended to understand the speed of the droplet movement, and the predications agree well with MD simulations.

Spongy Ag Foam for Soft and Stretchable Strain Gauges.

Strain gauges, particularly for wearable sensing applications, require a high degree of stretchability, softness, sensitivity, selectivity, and linearity. They must also steer clear of challenges such as mechanical and electrical hysteresis, overshoot behavior, and slow response/recovery times. However, current strain gauges face challenges in satisfying all of these requirements at once due to the inevitable trade-offs between these properties. Here, we present an innovative method for creating strain gauges from spongy Ag foam through a steam-etching process. This method simplifies the traditional, more complex, and costly manufacturing techniques, presenting an eco-friendly alternative. Uniquely, the strain gauges crafted from this method achieve an unparalleled gauge factor greater than 8 × 103 at strains exceeding 100%, successfully meeting all required attributes without notable trade-offs. Our work includes systematic investigations that reveal the intricate structure-property-performance relationship of the spongy Ag foam with practical demonstrations in areas such as human motion monitoring and human-robot interaction. These breakthroughs pave the way for highly sensitive and selective strain gauges, showing immediate applicability across a wide range of wearable sensing applications.

Electrical-driven transport of endohedral fullerene encapsulating a single water molecule.

Encapsulating a single water molecule inside an endohedral fullerene provides an opportunity for manipulating the H2O@C60 through the encapsulated polar H2O molecule. Using molecular dynamic simulations, we propose a strategy of electrical-driven transport of H2O@C60 inside a channel, underpinned by the unique behavior of a water molecule free from a hydrogen-bonding environment. When an external electrical field is applied along the channel's axial direction, steady-state transport of H2O@C60 can be reached. The transport direction and rate depend on the applied electrical intensity as well as the polar orientation of the encapsulated H2O molecule.

Liquid flow-induced energy harvesting in carbon nanotubes: a molecular dynamics study.

Energy harvesting by the flow of a hydrochloric acid-water solution through a carbon nanotube (CNT) is explored using atomistic simulations. Through ion configurations near the CNT wall, the ion drifting velocity is obtained, and the induced voltage along the axial direction is obtained as a function of key material and system parameters, including the applied flow rate, ambient temperature, solution concentration and nanotube diameter. The molecular mechanism of ion hopping and motion is elucidated and related to the variation of material and system parameters.

Elastocapillary rolling transfer weaves soft materials to spatial structures.

Spatial structures of soft materials have attracted great attention because of emerging applications in wearable electronics, biomedical devices, and soft robotics, but there are no facile technologies available to assemble the soft materials into spatial structures. Here, we report a mechanical transfer route enabled by the rotational motion of curved substrates relative to the soft materials on liquid surface. This transfer can weave soft materials into a broad variety of spatial structures with controllable global weaving chirality and orders and could also produce local ear-like folds with programmable numbers and distributions. We further prove that multiple pieces of soft materials in different forms including wire, ribbon, and large-area film can be woven onto curved substrates with various three-dimensional geometry shapes. Application demonstrations on the woven freestanding spatial structures with on-demand weaving patterns and orders have been conducted to show the temperature-driven multimodal actuating functionalities for programmable robotic postures.

Fabrication of gold-doped crystalline-silicon nanomembrane-based wearable temperature sensor.

Wearable temperature sensors with high thermal sensitivity are required for precise and continuous body temperature monitoring. Here, we present a protocol for fabricating a thin, stretchable, and ultrahigh thermal-sensitive wearable sensor based on gold-doped crystalline-silicon nanomembrane (SiNM). We provide detailed steps of gold doping technique to SiNM and fabrication processes for gold-doped crystalline-SiNM based wearable temperature sensor. For complete details on the use and execution of this protocol, please refer to Sang et al. (2022).1.

Mechanical Janus Structures by Soft-Hard Material Integration.

Engineering Janus structures that possess anisotropic features in functions have attracted growing attention for a wide range of applications in sensors, catalysis, and biomedicine, and are yet usually designed at the nanoscale with distinct physical or chemical functionalities in their opposite sides. Inspired by the seamless integration of soft and hard materials in biological structures, here a mechanical Janus structure composed of soft and hard materials with a dramatic difference in mechanical properties at an additively manufacturable macroscale is presented. In the combination of extensive experimental, theoretical, and computational studies, the design principle of soft-hard materials integrated mechanical Janus structures is established and their unique rotation mechanism is addressed. The systematic studies of assembling the Janus structure units into superstructures with well-ordered organizations by programming the local rotations are further shown, providing a direct route of designing superstructures by leveraging mechanical Janus structures with unique soft-hard material integration. Applications are conducted to demonstrate the features and functionalities of assembled superstructures with local ordered organizations in regulating and filtering acoustic wave propagations, thereby providing exemplification applications of mechanical Janus design in functional structures and devices.

A Nanoconfined Water-Ion Coordination Network for Flexible Energy-Dissipation Devices.

Water-ion interaction in a nanoconfined environment that deeply constrains spatial freedoms of local atomistic motion with unconventional coupling mechanisms beyond that in a free, bulk state is essential to spark designs of a broad spectrum of nanofluidic devices with unique properties and functionalities. Here, it is reported that the interaction between ions and water molecules in a hydrophobic nanopore forms a coordination network with an interaction density that is nearly fourfold that of the bulk counterpart. Such strong interaction facilitates the connectivity of the water-ion network and is uncovered by corroborating the formation of ion clusters and the reduction of particle dynamics. A liquid-nanopore energy-dissipation system is designed and demonstrated in both molecular simulations and experiments that the formed coordination network controls the outflow of confined electrolytes along with a pressure reduction, capable of providing flexible protection for personnel and devices and instrumentations against external mechanical impact and attack.

SAV Nsp2 regulates NF-κB signaling to induce inflammatory responses by targeting host DDX3.

Salmon alphavirus (SAV) infection leads to severe pancreas disease (PD) with typical inflammatory responses in Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss). Nsp2, an important nonstructural protein of SAV, can activate NF-κB signaling pathway to reduce inflammatory responses. However, the molecular mechanism remains unclear. In this study, the ML (279-421aa) of Nsp2 was revealed to be the key domain for activating NF-κB. We focused on a host protein, DEAD-box RNA helicase 3 (DDX3), that may interact with Nsp2 to regulate NF-κB-induced inflammatory. The interaction between DDX3 and Nsp2 was confirmed in vitro. Overexpression of DDX3 inhibited the activation of NF-κB by Nsp2. SAV Nsp2 relieves the inhibitory effect of DDX3 on NF-κB, thereby initiating the innate immune response. This study revealed the molecular mechanism of Nsp2-induced inflammatory response by targeting DDX3 to activate NF-κB, providing a theoretical basis for revealing the underlying infection mechanism and pathogenesis of SAV.

Temperature dependence of fluid transport in nanopores.

Understanding the temperature-dependent nanofluidic transport behavior is critical for developing thermomechanical nanodevices. By using non-equilibrium molecular dynamics simulations, the thermally responsive transport resistance of liquids in model carbon nanotubes is explored as a function of the nanopore size, the transport rate, and the liquid properties. Both the effective shear stress and the nominal viscosity decrease with the increase of temperature, and the temperature effect is coupled with other non-thermal factors. The molecular-level mechanisms are revealed through the study of the radial density profile and hydrogen bonding of confined liquid molecules. The findings are verified qualitatively with an experiment on nanoporous carbon.

Electrically Suppressed Outflow of Confined Liquid in Hydrophobic Nanopores.

Confining liquid in a hydrophobic nanoenvironment has enabled a broad spectrum of applications in biomedical sensors, mechanical actuators, and energy storage and converters, where the outflow of confined liquid is spontaneous and fast due to the intrinsic hydrophobic nature of nanopores with extremely low interfacial friction, challenging design capacity and control tolerance of structures and devices. Here, we present a facile approach of suppressing the outflow of water confined in hydrophobic nanopores with an electric field. Extensive molecular dynamics simulations show that the presence of an electric field could significantly strengthen hydrogen bonds and retard degradations of the associated networks during the outflow. The outflow deformation and strength are extracted to quantitatively characterize the electrical suppression to outflow and agree well with simulations. This study proposes a practical means of impeding the fast liquid outflow in hydrophobic nanopores, potentially useful for devising nanofluidics-based functional structures and devices with controllable performance.