Inducing trained immunity in pro-metastatic macrophages to control tumor metastasis.

Metastasis is the leading cause of cancer-related deaths and myeloid cells are critical in the metastatic microenvironment. Here, we explore the implications of reprogramming pre-metastatic niche myeloid cells by inducing trained immunity with whole beta-glucan particle (WGP). WGP-trained macrophages had increased responsiveness not only to lipopolysaccharide but also to tumor-derived factors. WGP in vivo treatment led to a trained immunity phenotype in lung interstitial macrophages, resulting in inhibition of tumor metastasis and survival prolongation in multiple mouse models of metastasis. WGP-induced trained immunity is mediated by the metabolite sphingosine-1-phosphate. Adoptive transfer of WGP-trained bone marrow-derived macrophages reduced tumor lung metastasis. Blockade of sphingosine-1-phosphate synthesis and mitochondrial fission abrogated WGP-induced trained immunity and its inhibition of lung metastases. WGP also induced trained immunity in human monocytes, resulting in antitumor activity. Our study identifies the metabolic sphingolipid-mitochondrial fission pathway for WGP-induced trained immunity and control over metastasis.

Growth of 1D Carbon Nanotube@Perovskite Core-Shell van der Waals Heterostructures through Chemical Vapor Deposition.

Perovskite is an emerging material with immense potential in the field of optoelectronics. 1D perovskite nanowires are crucial building blocks for the development of optoelectronic devices. However, producing perovskite nanowires with high quality and controlled alignment is challenging. In this study, the direct epitaxial growth of perovskite on oriented carbon nanotube (CNT) templates is presented through a chemical vapor deposition method. The deposition process of lead iodide and methylammonium iodide is systematically investigated, and a layer plus island growth mechanism is proposed to interpret the experimental observations. The aligned long CNTs serve as 1D templates and allow the growth of CNT@perovskite core-shell heterostructure with a high aspect ratio to withstand large deformation. The obtained 1D perovskite materials can be easily manipulated and transferred, enabling the facile preparation of microscale flexible devices. For proof of concept, a photodetector based on an individual CNT@methylammonium lead iodide heterostructure is fabricated. This work provides a new approach to prepare 1D hetero-nanostructure and may inspire the design of novel flexible nanophotodetectors.

Doping Ability Modulated by Interlayer Coupling in AA' and AB Stacked Bilayer V-WS2 Grown with Chemical Vapor Deposition.

Doping in transition metal dichalcogenide (TMD) has received extensive attention for its prospect in the application of photoelectric devices. Currently researchers focus on the doping ability and doping distribution in monolayer TMD and have obtained a series of achievements. Bilayer TMD has more excellent properties compared with monolayer TMD. Moreover, bilayer TMD with different stacking structures presents varying performance due to the difference in interlayer coupling. Herein, this work focuses on doping ability of dopants in different bilayer stacking structures that has not been studied yet. Results of this work show that the doping ability of V atoms in bilayer AA' and AB stacked WS2 is different, and the doping concentration of V atoms in AB stacked WS2 is higher than in AA' stacked WS2. Moreover, dopants from top and bottom layer can be distinguished by scanning transmission electron microscopy (STEM) image. Density functional theory (DFT) calculation further confirms the doping rule. This study reveals the mechanism of the different doping ability caused by stacking structures in bilayer TMD and lays a foundation for further preparation of controllable-doping bilayer TMD materials.

Concentration Phase Separation of Substitution-Doped Atoms in TMDCs Monolayer.

The density and spatial distribution of substituted dopants affect the transition metal dichalcogenides (TMDCs) materials properties. Previous studies have demonstrated that the density of dopants in TMDCs increases with the amount of doping, and the phenomenon of doping concentration difference between the nucleation center and the edge is observed, but the spatial distribution law of doping atoms has not been carefully studied. Here, it is demonstrated that the spatial distribution of dopants changes at high doping concentrations. The spontaneous formation of an interface with a steep doping concentration change is named concentration phase separation (CPS). The difference in the spatial distribution of dopants on both sides of the interface can be identified by an optical microscope. This is consistent with the results of spectral analysis and microstructure characterization of scanning transmission electron microscope. According to the calculation results of density functional theory, the chemical potential has two relatively stable energies as the doping concentration increases, which leads to the spontaneous formation of CPS. Understanding the abnormal phenomena is important for the design of TMDCs devices. This work has great significance in the establishment and improvement of the doping theory and the design of the doping process for 2D materials.

Nicotinamide mononucleotide alters body composition and ameliorates metabolic disorders induced by a high-fat diet.

Obesity is caused by an imbalance between calorie intake and energy expenditure, leading to excessive adipose tissue accumulation. Nicotinamide adenine dinucleotide (NAD+ ) is an important molecule in energy and signal transduction, and NAD+ supplementation therapy is a new treatment for obesity in recent years. Liver kinase B1 (LKB1) is an energy metabolism regulator. The relationship between NAD+ and LKB1 has only been studied in the heart and has not yet been reported in obesity. Nicotinamide mononucleotide (NMN), as a direct precursor of NAD+ , can effectively enhance the level of NAD+ . In the current study, we showed that NMN intervention altered body composition in obese mice, characterized by a reduction in fat mass and an increase in lean mass. NMN reversed high-fat diet-induced blood lipid levels then contributed to reducing hepatic steatosis. NMN also improved glucose tolerance and alleviated adipose tissue inflammation. Moreover, our data suggested that NMN supplementation may be depends on the NAD+ /SIRT6/LKB1 pathway to regulate brown adipose metabolism. These results provided new evidence for NMN in obesity treatment.

Increasing coverage of mono-layer graphene grown on hexagonal boron nitride.

Graphene sitting on hexagonal boron nitride (h-BN) always exhibits excellent electrical properties. And the properties of graphene onh-BN are often dominated by its domain size and boundaries. Chemical vapor deposition (CVD) is a promising approach to achieve large size graphene crystal. However, the CVD growth of graphene onh-BN still faces challenges in increasing coverage of monolayer graphene because of a weak control on nucleation and vertical growth. Here, an auxiliary source strategy is adapted to increase the nucleation density of graphene onh-BN and synthesis continuous graphene films. It is found that both silicon carbide and organic polymer e.g. methyl methacrylate can assist the nucleation of graphene, and then increases the coverage of graphene onh-BN. By optimizing the growth temperature, vertical accumulation of graphitic materials can be greatly suppressed. This work provides an effective approach for preparing continuous graphene film onh-BN, and may bring a new sight for the growth of high quality graphene.

Principle and applications of peak force infrared microscopy.

Peak force infrared (PFIR) microscopy is an emerging atomic force microscopy (AFM)-based infrared microscopy that bypasses Abbe's diffraction limit on spatial resolution. The PFIR microscopy utilizes a nanoscopically sharp AFM tip to mechanically detect the tip-enhanced infrared photothermal response of the sample in the time domain. The time-gated mechanical signals of cantilever deflections transduce the infrared absorption of the sample, delivering infrared imaging and spectroscopy capability at sub 10 nm spatial resolution. Both the infrared absorption response and mechanical properties of the sample are obtained in parallel while preserving the surface integrity of the sample. This review describes the constructions of the PFIR microscope and several variations, including multiple-pulse excitation, total internal reflection geometry, dual-color configuration, liquid-phase operations, and integrations with simultaneous surface potential measurement. Representative applications of PFIR microscopy are also included in this review. In the outlook section, we lay out several future directions of innovations in PFIR microscopy and applications in chemical and material research.

Towards chirality control of graphene nanoribbons embedded in hexagonal boron nitride.

The integrated in-plane growth of graphene nanoribbons (GNRs) and hexagonal boron nitride (h-BN) could provide a promising route to achieve integrated circuitry of atomic thickness. However, fabrication of edge-specific GNRs in the lattice of h-BN still remains a significant challenge. Here we developed a two-step growth method and successfully achieved sub-5-nm-wide zigzag and armchair GNRs embedded in h-BN. Further transport measurements reveal that the sub-7-nm-wide zigzag GNRs exhibit openings of the bandgap inversely proportional to their width, while narrow armchair GNRs exhibit some fluctuation in the bandgap-width relationship. An obvious conductance peak is observed in the transfer curves of 8- to 10-nm-wide zigzag GNRs, while it is absent in most armchair GNRs. Zigzag GNRs exhibit a small magnetic conductance, while armchair GNRs have much higher magnetic conductance values. This integrated lateral growth of edge-specific GNRs in h-BN provides a promising route to achieve intricate nanoscale circuits.

Dual-Scale Stick-Slip Friction on Graphene/h-BN Moiré Superlattice Structure.

Using atomic force microscopy, we have shown that friction on graphene/h-BN superlattice structures may exhibit unusual moiré-scale stick slip in addition to the regular ones observed at the atomic scale. Such dual-scale slip instability will lead to unique length-scale dependent energy dissipation when the different slip mechanisms are sequentially activated. Assisted by an improved theoretical model and comparative experiments, we find that accumulation and unstable release of the in-plane strain of the graphene layer is the key mechanism underlying the moiré-scale behavior. This work highlights the distinct role of the internal state of the van der Waals interfaces in determining the rich dynamics and energy dissipation of layer-structured materials.

Imaging Dual-Moiré Lattices in Twisted Bilayer Graphene Aligned on Hexagonal Boron Nitride Using Microwave Impedance Microscopy.

Moiré superlattices (MSLs) formed in van der Waals materials have become a promising platform to realize novel two-dimensional electronic states. Angle-aligned trilayer structures can form two sets of MSLs which could potentially interfere. In this work, we directly image the moiré patterns in both monolayer and twisted bilayer graphene aligned on hexagonal boron nitride (hBN), using combined scanning microwave impedance microscopy and conductive atomic force microscopy. Correlation of the two techniques reveals the contrast mechanism for the achieved ultrahigh spatial resolution (<2 nm). We observe two sets of MSLs with different periodicities in the trilayer stack. The smaller MSL breaks the 6-fold rotational symmetry and exhibits abrupt discontinuities at the boundaries of the larger MSL. Using a rigid atomic-stacking model, we demonstrate that the hBN layer considerably modifies the MSL of twisted bilayer graphene. We further analyze its effect on the reciprocal space spectrum of the dual-moiré system.

Total Internal Reflection Peak Force Infrared Microscopy.

Total internal reflection (TIR) infrared spectroscopy is a convenient measurement tool for collecting spectra for chemical identification. However, TIR infrared microscopy lacks high spatial resolution due to the optical diffraction limit and difficulty to preserve a high-quality wave front for focus. In this article, we present the peak force infrared microscopy in the TIR geometry to achieve a 10 nm spatial resolution. Instead of optical detection, photothermal responses of the sample are collected in the peak force tapping mode of atomic force microscopy. We demonstrate the technique on two representative samples: structured polymers for soft matters and a hexagonal boron nitride flake for two-dimensional materials. As an extension of the apparatus, we also demonstrate nanoinfrared imaging with the TIR excitation for photoinduced force microscopy. The combination of TIR geometry with nanoinfrared microscopies simplifies the optical alignment, providing alternative instrument-designing principles for atomic force microscopy-based infrared microscopy.

Liquid-Phase Peak Force Infrared Microscopy for Chemical Nanoimaging and Spectroscopy.

Peak force infrared (PFIR) microscopy is an emerging atomic force microscopy that bypasses Abbe's diffraction limit in achieving chemical nanoimaging and spectroscopy. The PFIR microscopy mechanically detects the infrared photothermal responses in the dynamic tip-sample contact of peak force tapping mode and has been applied for a variety of samples, ranging from soft matters, photovoltaic heterojunctions, to polaritonic materials under the air conditions. In this article, we develop and demonstrate the PFIR microscopy in the liquid phase for soft matters and biological samples. With the capability of controlling fluid compositions on demand, the liquid-phase peak force infrared (LiPFIR) microscopy enables in situ tracking of the polymer surface reorganization in fluids and detecting the product of click chemical reaction in the aqueous phase. Both broadband spectroscopy and infrared imaging with ∼10 nm spatial resolution are benchmarked in the fluid phase, together with complementary mechanical information. We also demonstrate the LiPFIR microscopy on revealing the chemical composition of a budding site of yeast cell wall particles in water as an application on biological structures. The label-free, nondestructive chemical nanoimaging and spectroscopic capabilities of the LiPFIR microscopy will facilitate the investigations of soft matters and their transformations at the solid/liquid interface.

Biomass-Derived Carbon Materials: Controllable Preparation and Versatile Applications.

Biomass-derived carbon materials (BCMs) are encountering the most flourishing moment because of their versatile properties and wide potential applications. Numerous BCMs, including 0D carbon spheres and dots, 1D carbon fibers and tubes, 2D carbon sheets, 3D carbon aerogel, and hierarchical carbon materials have been prepared. At the same time, their structure-property relationship and applications have been widely studied. This paper aims to present a review on the recent advances in the controllable preparation and potential applications of BCMs, providing a reference for future work. First, the chemical compositions of typical biomass and their thermal degradation mechanisms are presented. Then, the typical preparation methods of BCMs are summarized and the relevant structural management rules are discussed. Besides, the strategies for improving the structural diversity of BCMs are also presented and discussed. Furthermore, the applications of BCMs in energy, sensing, environment, and other areas are reviewed. Finally, the remaining challenges and opportunities in the field of BCMs are discussed.

Biomimetic Mechanically Enhanced Carbon Nanotube Fibers by Silk Fibroin Infiltration.

Natural materials, such as silk, nacre, and bone, possess superior mechanical properties which are derived from their unique hierarchical structures. Individual carbon nanotubes (CNTs) are considered as one of the strongest materials. However, macroscopic CNT fibers usually have breaking strength far below that of individual CNTs. In this work, by mimicking the structure of natural silk fibers, strong and stiff CNT fibers are prepared by infiltrating silk fibroin (SF) into CNT fibers. There are abundant hydrogen bonds in SF, contributing to the enhanced interactions between neighboring CNTs. Glycerol is selected to promote the formation of ß-sheet conformation in SF, leading to further enhanced strength and modulus. Remarkably, the SF infiltrated CNT fibers show breaking strength of 1023 MPa, toughness of 10.3 MJ m-3 , and Young's modulus of 81.3 GPa, which are 250%, 132%, and 442% of the pristine CNT fibers. The structure of the SF and the interactions between CNTs and SF are studied via Fourier transformed infrared spectroscopy and molecular dynamics simulation. Mimicking the hierarchical structures of natural silk fibers and enhance the interfacial load transfer by infiltrating SF are effective for reinforcing CNT fibers, which may be useful in the design and preparation of other structural materials.

Sustainable Silk-Derived Multimode Carbon Dots.

Carbon dots (CDs) are widely studied for years due to their unique luminescent properties and potential applications in many fields. However, aggregation-caused quenching, monotonous emission modes, and unsustainable preparation impose restrictions on their performance and practical applications. Here, this work reports the facile synthesis of sustainable silk-derived multimode emitting CDs with dispersed-state fluorescence (DSF), aggregation-induced fluorescence (AIF), and aggregation-induced room temperature phosphorescence (AIRTP) through radiating sericin proteins in a household microwave oven (800 W, 2.5 min). The structure, luminescent properties, and the mechanism are investigated and discussed. The sericin-derived CDs have graphitized cores and heteroatom-cluster-rich surfaces. The DSF corresponds to the graphitized cores and the AIF origins from the aggregation-induced abundant orbital energy levels on the heteroatom-cluster-rich surfaces. The presence of abundant hydrogen bonds and small gap between the lowest singlet and triplet excited states induces AIRTP. Finally, based on the unique multimode emission of the prepared CDs, their applications in high-performance white-light-emitting diode, information encryption, anti-counterfeiting, and visual humidity sensors are demonstrated.

Toward photoswitchable electronic pre-resonance stimulated Raman probes.

Reversibly photoswitchable probes allow for a wide variety of optical imaging applications. In particular, photoswitchable fluorescent probes have significantly facilitated the development of super-resolution microscopy. Recently, stimulated Raman scattering (SRS) imaging, a sensitive and chemical-specific optical microscopy, has proven to be a powerful live-cell imaging strategy. Driven by the advances of newly developed Raman probes, in particular the pre-resonance enhanced narrow-band vibrational probes, electronic pre-resonance SRS (epr-SRS) has achieved super-multiplex imaging with sensitivity down to 250 nM and multiplexity up to 24 colors. However, despite the high demand, photoswitchable Raman probes have yet to be developed. Here, we propose a general strategy for devising photoswitchable epr-SRS probes. Toward this goal, we exploit the molecular electronic and vibrational coupling, in which we switch the electronic states of the molecules to four different states to turn their ground-state epr-SRS signals on and off. First, we showed that inducing transitions to both the electronic excited state and triplet state can effectively diminish the SRS peaks. Second, we revealed that the epr-SRS signals can be effectively switched off in red-absorbing organic molecules through light-facilitated transitions to a reduced state. Third, we identified that photoswitchable proteins with near-infrared photoswitchable absorbance, whose states are modulable with their electronic resonances detunable toward and away from the pump photon energy, can function as the photoswitchable epr-SRS probes with desirable sensitivity (<1 µM) and low photofatigue (>40 cycles). These photophysical characterizations and proof-of-concept demonstrations should advance the development of novel photoswitchable Raman probes and open up the unexplored Raman imaging capabilities.

DDosTC: A Transformer-Based Network Attack Detection Hybrid Mechanism in SDN.

Software-defined networking (SDN) has emerged in recent years as a form of Internet architecture. Its scalability, dynamics, and programmability simplify the traditional Internet structure. This architecture realizes centralized management by separating the control plane and the data-forwarding plane of the network. However, due to this feature, SDN is more vulnerable to attacks than traditional networks and can cause the entire network to collapse. DDoS attacks, also known as distributed denial-of-service attacks, are the most aggressive of all attacks. These attacks generate many packets (or requests) and ultimately overwhelm the target system, causing it to crash. In this article, we designed a hybrid neural network DDosTC structure, combining efficient and scalable transformers and a convolutional neural network (CNN) to detect distributed denial-of-service (DDoS) attacks on SDN, tested on the latest dataset, CICDDoS2019. For better verification, several experiments were conducted by dividing the dataset and comparisons were made with the latest deep learning detection algorithm applied in the field of DDoS intrusion detection. The experimental results show that the average AUC of DDosTC is 2.52% higher than the current optimal model and that DDosTC is more successful than the current optimal model in terms of average accuracy, average recall, and F1 score.

Probing Mid-Infrared Phonon Polaritons in the Aqueous Phase.

Phonon polaritons (PhPs) are collective phonon oscillations with hybridized electromagnetic fields, which concentrate mid-infrared optical fields that can match molecular vibrations. The utilization of PhPs holds the promise for chemical sensing tools and polariton-enhanced nanospectroscopy. However, investigations and innovations on PhPs in the aqueous phase remain stagnant because of the lack of in situ mid-infrared nanoimaging methods in water. Strong infrared absorption from water prohibits optical delivery and detection in the mid-infrared for scattering-type near-field microscopy. Here, we present our solution: the detection of photothermal responses caused by the excitation of PhPs by liquid phase peak force infrared (LiPFIR) microscopy. Characteristic interference fringes of PhPs in 10B isotope-enriched h-BN were measured in the aqueous phase and their dispersion relationship extracted. LiPFIR enables the measurement of mid-infrared PhPs in the fluid phase, opening possibilities and facilitating the development of mid-IR phonon polaritonics in water.

Microscopically analyzed interface behavior characteristics of acid precipitation on asphalt surface.

It is generally believed that the interaction between acid precipitation and asphalt has an effect on the performance of drainage asphalt pavement, but studies on the interface behavior characteristics from microscopic analysis are rare. Therefore, molecular dynamics (MD) was used to simulate the interfacial transition zone of precipitation (neutral and acid) and asphalt in the study, and the interfacial behavior characteristics of precipitation on asphalt surface were microscopically analyzed. Additionally, the composition of acid precipitation was configured in the laboratory, and the contact angles of precipitation solutions (SO42- and NO3-) on asphalt surface also verified the interface behavior characteristics between acid precipitation and asphalt. The results showed that the interaction of acid precipitation and asphalt is stronger than that of neutral precipitation, which makes it more difficult to remove from the surface of drainage asphalt pavement. With the increase of service temperature for drainage asphalt pavement, the interaction energy increases. Under the coupling effect of acid precipitation and low service temperature, water damage to the drainage asphalt pavement is more easily induced. The results revealed the micro-effect of acid precipitation and service temperature on drainage efficiency of an asphalt surface, which has certain theoretical significance and practical value for the application and exploration of drainage asphalt pavement.

Geometry-Directed Self-Assembly of Polymeric Molecular Frameworks.

Despite the significant advances in creating assembled structures from polymers, engineering the assembly of polymeric materials into framework structures remains an outstanding challenge. In this work, we present a facile strategy to construct polymeric molecular frameworks through the assembly of T-shape polymer-rod-sphere amphiphiles in the bulk state. Various frameworks are yielded as a result of delicate interplays among three components of the T-shape amphiphiles. The internal structure of frameworks was revealed by combining experimental investigations and computational simulations. The frameworks display good solution-processability, thermal stability, and uniform pore-forming capability, which endow the resultant frameworks with great potential in scalable fabrications.