A Novel Cargo Delivery System-AnCar-ExoLaIMTS Ameliorates Arthritis via Specifically Targeting Pro-Inflammatory Macrophages.

Macrophages are heterogenic phagocytic cells that play distinct roles in physiological and pathological processes. Targeting different types of macrophages has shown potent therapeutic effects in many diseases. Although many approaches are developed to target anti-inflammatory macrophages, there are few researches on targeting pro-inflammatory macrophages, which is partially attributed to their non-s pecificity phagocytosis of extracellular substances. In this study, a novel recombinant protein is constructed that can be anchored on an exosome membrane with the purpose of targeting pro-inflammatory macrophages via antigen recognition, which is named AnCar-ExoLaIMTS . The data indicate that the phagocytosis efficiencies of pro-inflammatory macrophages for different AnCar-ExoLaIMTS show obvious differences. The AnCar-ExoLaIMTS3 has the best targeting ability for pro-inflammatory macrophages in vitro and in vivo. Mechanically, AnCar-ExoLaIMTS3 can specifically recognize the leucine-rich repeat domain of the TLR4 receptor, and then enter into pro-inflammatory macrophages via the TLR4-mediated receptor endocytosis pathway. Moreover, AnCar-ExoLaIMTS3 can efficiently deliver therapeutic cargo to pro-inflammatory macrophages and inhibit the synovial inflammatory response via downregulation of HIF-1α level, thus ameliorating the severity of arthritis in vivo. Collectively, the work established a novel gene/drug delivery system that can specifically target pro-inflammatory macrophages, which may be beneficial for the treatments of arthritis and other inflammatory diseases.

A Thermo-Electro-Viscoelastic Model for Dielectric Elastomers.

Dielectric elastomers (DEs) are a class of electro-active polymers (EAPs) that can deform under electric stimuli and have great application potential in bionic robots, biomedical devices, energy harvesters, and many other areas due to their outstanding deformation abilities. It has been found that stretching rate, temperature, and electric field have significant effects on the stress-strain relations of DEs, which may result in the failure of DEs in their applications. Thus, this paper aims to develop a thermo-electro-viscoelastic model for DEs at finite deformation and simulate the highly nonlinear stress-strain relations of DEs under various thermo-electro-mechanical loading conditions. To do so, a thermodynamically consistent continuum theoretical framework is developed for thermo-electro-mechanically coupling problems, and then specific constitutive equations are given to describe the thermo-electro-viscoelastic behaviors of DEs. Furthermore, the present model is fitted with the experimental data of VHB4905 to determine a temperature-dependent function of the equilibrium modulus. A comparison of the nonlinear loading-unloading curves between the model prediction and the experimental data of VHB4905 at various thermo-electro-mechanical loading conditions verifies the present model and shows its ability to simulate the thermo-electro-viscoelastic behaviors of DEs. Simultaneously, the results reveal the softening phenomena and the instant pre-stretch induced by temperature and the electric field, respectively. This work is conducive to analyzing the failure of DEs in functionalities and structures from theoretical aspects at various thermo-electro-mechanical conditions.

RuO2 electronic structure and lattice strain dual engineering for enhanced acidic oxygen evolution reaction performance.

Developing highly active and durable electrocatalysts for acidic oxygen evolution reaction remains a great challenge due to the sluggish kinetics of the four-electron transfer reaction and severe catalyst dissolution. Here we report an electrochemical lithium intercalation method to improve both the activity and stability of RuO2 for acidic oxygen evolution reaction. The lithium intercalates into the lattice interstices of RuO2, donates electrons and distorts the local structure. Therefore, the Ru valence state is lowered with formation of stable Li-O-Ru local structure, and the Ru-O covalency is weakened, which suppresses the dissolution of Ru, resulting in greatly enhanced durability. Meanwhile, the inherent lattice strain results in the surface structural distortion of LixRuO2 and activates the dangling O atom near the Ru active site as a proton acceptor, which stabilizes the OOH* and dramatically enhances the activity. This work provides an effective strategy to develop highly efficient catalyst towards water splitting.

Chemical Strain of Graphite-Based Anode during Lithiation and Delithiation at Various Temperatures.

Electrochemical lithiation/delithiation of electrodes induces chemical strain cycling that causes fatigue and other harmful influences on lithium-ion batteries. In this work, a homemade in situ measurement device was used to characterize simultaneously chemical strain and nominal state of charge, especially residual chemical strain and residual nominal state of charge, in graphite-based electrodes at various temperatures. The measurements indicate that raising the testing temperature from 20°C to 60°C decreases the chemical strain at the same nominal state of charge during cycling, while residual chemical strain and residual nominal state of charge increase with the increase of temperature. Furthermore, a novel electrochemical-mechanical model is developed to evaluate quantitatively the chemical strain caused by a solid electrolyte interface (SEI) and the partial molar volume of Li in the SEI at different temperatures. The present study will definitely stimulate future investigations on the electro-chemo-mechanics coupling behaviors in lithium-ion batteries.

Thickness- and temperature-dependent Grüneisen parameter in thin films.

The Grüneisen formula is one of the most important equations of state, in which the Grüneisen parameter plays a key role in the linkage of mechanical and thermal properties of materials. In the present work, for the first time, we investigate the dependence of the Grüneisen parameter on film-thickness and temperature via theoretical modeling and molecular dynamics (MD) simulations. The theoretical analysis gives two analytic expressions of a thickness- and temperature-dependent Grüneisen parameter, and the difference between the two analytic expressions lies in the quadratic or linear dependence on temperature. MD simulations are conducted on face-centered cubic (FCC) Ni, Cu, and Au (001) thin films and their bulk counterparts. The simulation results completely verify the theoretical results and determine the values of parameters involved in the theoretical modeling. The thickness- and temperature-dependent film heat capacity density is also investigated during the course of the Grüneisen parameter study.

Correction: Two-dimensional polar metal of a PbTe monolayer by electrostatic doping.

Correction for 'Two-dimensional polar metal of a PbTe monolayer by electrostatic doping' by Tao Xu et al., Nanoscale Horiz., 2020, 5, 1400-1406, DOI: .

Two-dimensional polar metal of a PbTe monolayer by electrostatic doping.

Polar metals characterized by the simultaneous coexistence of a polar structure and metallicity have been a long-sought goal due to the promise of novel electronic devices. Developing such materials at low dimensions remains challenging since both conducting electrons and reduced dimensions are supposed to quench the polar state. Here, based on first-principles calculations, we report the discovery of a non-centrosymmetric polar structure in two-dimensional (2D) metallic materials with electrostatic doping, even though ferroelectricity is unconventional at the atomic scale. We revealed that the PbTe monolayer is intrinsically ferroelectric with pronounced out-of-plane electric polarization originating from its non-centrosymmetric buckled structure. Moreover, the polar distortions can be preserved with carrier doping in the monolayer, which further enables the doped PbTe monolayer to act as a 2D polar metal. With an effective Hamiltonian extracted from the parametrized energy space, we found that the special elastic-polar mode interaction is of great importance for the existence of robust polar instability (i.e., soft phonon mode associated with polar distortion) in the doped system. The application of this doping strategy is not specific to the present crystal, but is rather general to other 2D ferroelectrics to bring about the fascinating non-centrosymmetric metallic state. Our findings thus change the conventional knowledge in 2D materials and will facilitate the development of multifunctional materials in low dimensions.

Superacid-doped polyaniline as a soluble polymeric active electrolyte for supercapacitors.

Using polyaniline as a soluble electrochemically active additive in an electrolyte has the advantages of high pseudocapacitance and good cycle stability of polyaniline, however, the challenge is how to make polyaniline soluble in the electrolyte. In this study, we prepare a solution of polyaniline in N-methylpyrrolidone by protonating polyaniline with trifluoromethyl sulfonic acid. Spectroscopic and electrochemical results indicate that the weak binding interaction, between trifloromethyl sulfonate ions and protonated polyaniline chains, increases the solubility of trifloromethyl sulfonic acid doped polyaniline. An active electrolyte system composed of 15 mg mL-1 polyaniline and 0.4 M trifluoromethyl sulfonic acid in N-methylpyrrolidone is developed. With the active electrolyte and reduced graphene oxide as the electrodes, the fabricated supercapacitor shows a higher specific capacitance than the corresponding electric double-layer supercapacitors. Because the volume change and hydrolyzation of polyaniline, which are the main causes of the performance degradation in polyaniline-based supercapacitors, are avoided, the present supercapacitor exhibits an excellent cycle stability of 100% capacitance retention after 10 000 cycles. This work demonstrates the possibility of directly using a conductive polymer as an active electrolyte in supercapacitors with high cycle stability.

Partial sodiation induced laminate structure and high cycling stability of black phosphorous for sodium-ion batteries.

Black phosphorus (BP) is a promising anode material for sodium ion batteries (SIBs) due to its extremely high theoretical capacity. However, the large volume change and breaking of the layered structure result in rapid capacity decay during cycling. Herein, our in situ transmission electron microscopy (TEM) study reveals the highly anisotropic Na diffusion and the formation of alternating layered and amorphous lamellas in BP nanosheets with small volume expansion induced by partial sodiation. Inspired by these results, we investigate systematically the cyclability of BP at controlled discharge capacities using half-cell SIBs, expecting to achieve good cyclability by sacrificing some of the capacity and preserving the layered structure of BP. Our results show that the cycling stability of BP is obviously improved by controlling the capacity appropriately. When the discharge capacity is limited at 400 mA h g-1, the half-cell can sustain more than 100 cycles with an active material mass loading of ∼2 mg cm-2, which is at least 4 times longer than when the capacity is limited at 600 mA h g-1 or above. The in situ TEM and electrochemical tests indicate that maintaining the layered structure by controlling the capacity is key to improve the cyclability of BP as an anode in SIBs.

A high performance wearable strain sensor with advanced thermal management for motion monitoring.

Resistance change under mechanical stimuli arouses mass operational heat, damaging the performance, lifetime, and reliability of stretchable electronic devices, therefore rapid thermal heat dissipating is necessary. Here we report a stretchable strain sensor with outstanding thermal management. Besides a high stretchability and sensitivity testified by human motion monitoring, as well as long-term durability, an enhanced thermal conductivity from the casted thermoplastic polyurethane-boron nitride nanosheets layer helps rapid heat transmission to the environments, while the porous electrospun fibrous thermoplastic polyurethane membrane leads to thermal insulation. A 32% drop of the real time saturated temperature is achieved. For the first time we in-situ investigated the dynamic operational temperature fluctuation of stretchable electronics under repeating stretching-releasing processes. Finally, cytotoxicity test confirms that the nanofillers are tightly restricted in the nanocomposites, making it harmless to human health. All the results prove it an excellent candidate for the next-generation of wearable devices.

Out-of-plane ion transport makes nitrogenated holey graphite a promising high-rate anode for both Li and Na ion batteries.

The search for suitable anodes with good performance is a key challenge for rechargeable Li- and Na-ion batteries (LIBs and NIBs). In this work, we adopt first-principles calculations and ab initio molecular dynamics simulations to investigate the ion transport mechanism and potential of C2N stoichiometric nitrogenated holey graphite (C2N-NHG) as a promising anode material for LIBs and NIBs. Although huge in-plane diffusion barriers for both Li and Na ions restrict the application of the C2N-NHG monolayer as an effective anode, Li and Na ions are found to exhibit facile out-of-plane ion transport in the most stable layered AD stacking C2N-NHG. The fully lithiated and sodiated cases of LiC2N and Na0.67C2N show reversible specific capacities up to 587 mA h g-1 and 353 mA h g-1, low chemical potentials of 0.12 V and 0.25 V, and small volume expansions of 7.16% and 13.54%, respectively. Meanwhile, the out-of-plane collective diffusion reduces Li/Na collective migration barriers to 0.23 eV and 0.18 eV. These findings suggest that AD stacking C2N-NHG, with metallic properties after lithiation and sodiation processes, high specific capacity, low open circuit voltage, small volume expansion, and low collective migration barriers, has the potential to serve as a promising high-rate anode material for LIBs and NIBs with large energy density and power density. The calculations reveal that the novel out-of-plane diffusion behaviour plays a crucial role in Li/Na ion transport in holey layered materials.

Nanowire-Seeded Growth of Single-Crystalline (010) ß-Ga2 O3 Nanosheets with High Field-Effect Electron Mobility and On/Off Current Ratio.

2D ß-Ga2 O3 nanosheets, as fundamental materials, have great potential in next generations of ultraviolet transparent electrodes, high-temperature gas sensors, solar-blind photodetectors, and power devices, while their synthesis and growth with high crystalline quality and well-controlled orientation have not been reported yet. The present study demonstrates how to grow single-crystalline ultrathin quasi-hexagonal ß-Ga2 O3 nanosheets with nanowire seeds and proposes a hierarchy-oriented growth mechanism. The hierarchy-oriented growth is initiated by epitaxial growth of a single-crystalline ( 2 - 01 ) ß-Ga2 O3 nanowire on a GaN nanocrystal and followed by homoepitaxial growth of quasi-hexagonal (010) ß-Ga2 O3 nanosheets. The undoped 2D (010) ß-Ga2 O3 nanosheet field effect transistor has a field-effect electron mobility of 38 cm2 V-1 s-1 and an on/off current ratio of 107 with an average subthreshold swing of 150 mV dec-1 . The from-nanowires-to-nanosheets technique paves a novel way to fabricate nanosheets, which has great impact on the field of nanomaterial synthesis and growth and the area of nanoelectronics as well.

Author Correction: Evolution of the electrochemical interface in sodium ion batteries with ether electrolytes.

The original version of this Article incorrectly omitted an affiliation of Kaikai Li: 'Shenzhen Environmental Science and New Energy Technology Engineering Laboratory, Tsinghua-Berkeley Shenzhen Institute (TBSI), Tsinghua University, Shenzhen 518055, China'. This has been corrected in both the PDF and HTML versions of the Article.

Evolution of the electrochemical interface in sodium ion batteries with ether electrolytes.

Ether based electrolytes have surfaced as alternatives to conventional carbonates allowing for enhanced electrochemical performance of sodium-ion batteries; however, the primary source of the improvement remains poorly understood. Here we show that coupling titanium dioxide and other anode materials with diglyme does enable higher efficiency and reversible capacity than those for the combination involving ester electrolytes. Importantly, the electrolyte dependent performance is revealed to be the result of the different structural evolution induced by a varied sodiation depth. A suit of characterizations show that the energy barrier to charge transfer at the interface between electrolyte and electrode is the factor that dominates the interfacial electrochemical characteristics and therefore the energy storage properties. Our study proposes a reliable parameter to assess the intricate sodiation dynamics in sodium-ion batteries and could guide the design of aprotic electrolytes for next generation rechargeable batteries.

Giant magnetoelectric effect at the graphone/ferroelectric interface.

Multiferroic heterostructures combining ferromagnetic and ferroelectric layers are promising for applications in novel spintronic devices, such as memories with electrical writing and magnetic reading, assuming their magnetoelectric coupling (MEC) is strong enough. For conventional magnetic metal/ferroelectric heterostructures, however, the change of interfacial magnetic moment upon reversal of the electric polarization is often very weak. Here, by using first principles calculations, we demonstrate a new pathway towards a strong MEC at the interface between the semi-hydrogenated graphene (also called graphone) and ferroelectric PbTiO3. By reversing the polarization of PbTiO3, the magnetization of graphone can be electrically switched on and off through the change of carbon-oxygen bonding at the interface. Furthermore, a ferroelectric polarization can be preserved down to ultrathin PbTiO3 layers less than one nanometer due to an enhancement of the polarization at the interface. The predicted strong magnetoelectric effect in the ultimately thin graphone/ferroelectric layers opens a new opportunity for the electric control of magnetism in high-density devices.

Enhancing sodium ionic conductivity in tetragonal-Na3PS4 by halogen doping: a first principles investigation.

Tetragonal Na3PS4 (t-Na3PS4) has been demonstrated as a very promising candidate for a solid-state sodium-ion electrolyte with high Na ionic conductivity at ambient temperature. In this paper, we systematically investigated the Na ionic conductivity in pristine and halogen (F, Cl, Br, and I) doped tetragonal-Na3PS4 superionic conductors using first-principles calculations. The Na ionic conductivity of pristine t-Na3PS4 is calculated to be about 0.01 mS cm-1, while much higher Na ionic conductivities could be achieved by introducing Na ion vacancies via a halogen doping strategy. The calculated Na ionic conductivity of t-Na3PS4 doped with 1.56% Cl is 1.07 mS cm-1 at ambient temperature. Among different halogen-doped t-Na3PS4, Br-doped t-Na3PS4 shows the lowest activation energy and the highest Na ionic conductivity, which reaches 2.37 mS cm-1 at 300 K. The low activation energy and high Na ionic conductivity in Br-doped t-Na3PS4 are due to a relatively lower defect binding energy of the defect pair of halogen substitution and a Na ion vacancy. Our results suggest Br-doped t-Na3PS4 may serve as a very promising Na-ion solid-state superionic conductor.

Scanning distortion correction in STEM images.

Various disturbances do exist in the image taking process of scanning transmission electron microscopes (STEM), which seriously reduces the resolution and accuracy of STEM images. In this paper, a deep understanding of the scanning distortion influence on the real and reciprocal spaces of STEM images is achieved via theoretical modeling and simulation. A scanning distortion correction algorithm is further developed based on two images scanned along perpendicular directions, which is able to effectively correct scanning distortion induced deviations and significantly increase the signal to noise ratio of STEM images.

Ultrafast-Charging and Long-Life Li-Ion Battery Anodes of TiO2-B and Anatase Dual-Phase Nanowires.

Ideal lithium-ion batteries (LIBs) should possess a high power density, be charged extremely fast (e.g., 100C), and have a long service life. To achieve them all, all battery components, including anodes, cathodes, and electrolytes should have excellent structural and functional characteristics. The present work reports ultrafast-charging and long-life LIB anodes made from TiO2-B/anatase dual-phase nanowires. The dual-phase nanowires are fabricated with anatase TiO2 nanoparticles through a facile and cost-effective hydrothermal process, which can be easily scaled up for mass production. The anodes exhibit remarkable electrochemical performance with reversible capacities of ∼225, 172, and 140 mAh g-1 at current rates of 1C, 10C, and 60C, respectively. They deliver exceptional capacity retention of not less than 126 and 93 mAh g-1 after 1000 cycles at 60C and 100C, respectively, potentially worthwhile for high-power applications. These values are among the best when the high-rate capabilities are compared with the literature data for similar TiO2-based anodes. The Ragone plot confirms both the exceptionally high energy and power densities of the devices prepared using the dual-phase nanowires. The electrochemical tests and operando Raman spectra present fast electrochemical kinetics for both Li+ and electron transports in the TiO2 dual-phase nanowires than in anatase nanoparticles due to the excellent Li+ diffusion coefficient and electronic conductivity of nanowires.

Stress-Induced Cubic-to-Hexagonal Phase Transformation in Perovskite Nanothin Films.

The strong coupling between crystal structure and mechanical deformation can stabilize low-symmetry phases from high-symmetry phases or induce novel phase transformation in oxide thin films. Stress-induced structural phase transformation in oxide thin films has drawn more and more attention due to its significant influence on the functionalities of the materials. Here, we discovered experimentally a novel stress-induced cubic-to-hexagonal phase transformation in the perovskite nanothin films of barium titanate (BaTiO3) with a special thermomechanical treatment (TMT), where BaTiO3 nanothin films under various stresses are annealed at temperature of 575 °C. Both high-resolution transmission electron microscopy and Raman spectroscopy show a higher density of hexagonal phase in the perovskite thin film under higher tensile stress. Both X-ray photoelectron spectroscopy and electron energy loss spectroscopy does not detect any change in the valence state of Ti atoms, thereby excluding the mechanism of oxygen vacancy induced cubic-to-hexagonal (c-to-h) phase transformation. First-principles calculations show that the c-to-h phase transformation can be completed by lattice shear at elevated temperature, which is consistent with the experimental observation. The applied bending plus the residual tensile stress produces shear stress in the nanothin film. The thermal energy at the elevated temperature assists the shear stress to overcome the energy barriers during the c-to-h phase transformation. The stress-induced phase transformation in perovskite nanothin films with TMT provides materials scientists and engineers a novel approach to tailor nano/microstructures and properties of ferroelectric materials.