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The aim of this study is to prepare epoxy/polytetrafluoroethylene (PTFE)/glass fiber (GF) composites (EPGs) with the unique characteristics of low friction and high wear resistance based on triglycidyl isocyanurate (TGIC). The tribological properties of composites with different filler ratios under different working conditions were systematically studied. At the maximum filler content of 40 wt% PTFE, the minimum coefficient of friction (COF) and wear rate reached 0.079 and 0.45 - 10°6 mm³/N-m. The hardness decreased by 44.2% and the density increased by 18.3%. The worn surfaces and transfer films were observed and analyzed by scanning electron microscopy (SEM) and x-ray photoelectron spectroscopy (XPS). The increasing tendency of velocity and amplitude is beneficial to reduce the carbon-rich region and further enhance the formation of transfer films. It is proved that the tribological properties of TGIC-based epoxy composites are higher than those of other types of epoxy composites. This study offers great insight into the tribological applications of TGIC-based epoxy composites. Highlights • Epoxy/PTFE/GF composites (EPGs) were prepared using TGIC as the base material. • EPGs have good mechanical and tribological properties. • The COF of EPG3 reaches 0.079 and the wear rate becomes 0.45 x 10°6 mm3/(N-m). • The increasing tendency of velocity and amplitude is beneficial to reduce the carbon-rich region and further enhance the formation of transfer films. [ABSTRACT FROM AUTHOR]

This study deals with the fault-tolerant control problem for a class of two independent wheeled mobile robot systems with actuator faults and unknown robot parameters. Partial loss of control effectiveness and bias-actuator faults are addressed without knowing eventually faulty information of actuators. Adaptive schemes are developed to estimate unknown faulty parameters of actuator faults and unknown robot parameters of viscous friction factor and driving gain. Then, the backstepping control technique is utilised to construct the state feed-back control strategy based on the adaptive estimations. By using the Lyapunov stability theory, it is shown that the forward speed and azimuthal angle of wheeled mobile robots can track the given trajectory asymptotically in the case of actuator faults and unknown parameters. The effectiveness of the proposed designs is illustrated via a mobile robot system. [ABSTRACT FROM AUTHOR]

Steer-by-wire (SbW) systems in road vehicles require an effective controller to provide accurate and robust steering performance. For this purpose, this study proposes an adaptive fast non-singular terminal sliding mode (AFNTSM) controller for an SbW system by combining an adaptive estimation law with a fast non-singular terminal sliding mode (FNTSM) control scheme. First, the authors present a model to identify the dynamics of the SbW system, in which the self-aligning torque and friction-related forces are treated as external disturbances. Second, the AFNTSM control design is elaborated, which is proved to be able to guarantee high tracking accuracy via effectively estimating the self-aligning torque, fast convergence rate owing to its exponential stability, strong robustness against system and road surface uncertainties, and inherently smooth control inputs. Subsequently, the selection criteria of the control parameters are given in details. Finally, experimental results are shown to demonstrate that the designed AFNTSM controller has great superiority in comparison with an FNTSM controller without adaptation and an adaptive sliding mode controller based on conventional sliding mode. [ABSTRACT FROM AUTHOR]

In this study, a robust sliding mode learning control scheme is proposed to address the congestion control problem in differentiated services (DiffServ) networks. A validated non-linear network model is based on fluid flow theory corresponding to two important services, namely, the premium traffic and the ordinary traffic. The proposed congestion controller is able to efficiently cope with both the physical network resource constraints and unknown time delays associated with networking systems. Numerical results are presented to illustrate the effectiveness of the proposed control scheme. [ABSTRACT FROM AUTHOR]

A novel atmospheric pressure plasma microjet (APPμJ) array is proposed to realize maskless parallel micropatterned etching of materials. Due to applying microfabrication technology, the dimension and distance of multiple jets in an array can be adjusted at a micro/nanoscale. However, interactions among multiple jets often lead to inconsistency of microjets and nonuniformity of sample etching. In this study, a 1 × 2 APPμJ array with 90-μm nozzles and varying jet-to-jet distance is developed. The effects of different operating factors on the consistency of the APPμJ array are investigated. The experiment results show that the consistency of the microjet array and uniformity of sample etching can be greatly improved by optimizing operating parameters, such as applied voltage, gas flow rate, and jet-to-jet distance. [ABSTRACT FROM AUTHOR]

Nanoparticle-based combination therapy strategy of photothermal therapy (PTT) and immunotherapy is an attractive cancer treatment for ablating tumors and eliciting host immune responses. However, this strategy is often hampered by tedious treatment process and limited immune response, and usually needs to be combined with checkpoint blockades to enhance therapeutic effect. Herein, a nanoplatform with mesoporous silica nanoparticles (MSNs) as a vector, which integrated photothermal agent polydopamine (PDA), model antigen ovalbumin (OVA), and antigen release promoter ammonium bicarbonate (ABC) in an easy way for melanoma PTT-immunotherapy is designed. The formulated MSNs-ABC@PDA-OVA nanovaccine exhibits excellent photothermal properties and effectively eliminates primary tumors. Under laser irradiation, the MSNs-ABC@PDA-OVA nanovaccine realizes rapid antigen release and endosome escape, enhances dendritic cells activation and maturation, facilitates migration to tumor-draining lymph nodes, and induces robust antitumor immune responses. Impressively, single injection of MSNs-ABC@PDA-OVA combines with single round of PTT successfully eradicates melanoma tumors with a cure rate of 75% and generates strong immunological memory to inhibit tumor recurrence and lung metastasis. Hence, the research offers a simple and promising strategy of synergistic PTT-immunotherapy to effectively treat cancer. [ABSTRACT FROM AUTHOR]

The reconstruction of large bone defects remains a significant challenge for orthopedists. Three-dimensional-printed (3DP) scaffold is considered a promising repair material. Static magnetic field (SMF) treatment is an effective and noninvasive therapeutic method to improve bone regeneration. However, the osteogenic effect of SMF on human bone-derived mesenchymal stem cells (hBMSCs) in 3DP scaffolds, as well as its potential mechanism, are unclear. In this study, the osteogenic effect of SMF on hBMSCs in a 3DP scaffold was investigated in vitro and in vivo. In addition, the potential mechanism for promoting osteogenesis was investigated by proteomic analysis. The results showed that SMF promoted osteogenic differentiation of hBMSCs in vitro. A total of 185 differential proteins were identified under SMF conditions by proteomic analysis. The osteogenic effect might be associated with bone morphogenetic protein-Smad1/5/8-signaling pathway and increased transport of phosphorylated Smad1/5/8 and phosphorylated Smad2/3 to the nucleus by up-regulating Smad4 under SMF conditions. The in vivo experiment showed that bone regeneration and osseointegration was enhanced by SMF in the rat model of bone defect. In conclusion, moderate SMF was a safe and effective method for enhancing osteogenesis in 3DP scaffolds in vitro and in vivo. [ABSTRACT FROM AUTHOR]

1. Different types of steppes could provide heterogeneous habitat environments for underground microorganisms, but much less is known about how soil microbes fit the distinct habitats and what are the underlying mechanisms in shaping their community patterns. 2. We simultaneously examined the community compositions and structures of soil bacteria, fungi, and diazotrophs across desert, typical, and meadow steppes in Inner Mongolia using high‐throughput sequencing. 3. The results showed that soil bacteria, fungi, and diazotrophs exhibited different distribution patterns across steppe types. Although different steppes displayed obvious differences in climate conditions, plant traits, and soil properties, most of bacterial species were shared by all the steppes while only a few species were unique, indicating that the soil bacterial compositions were hardly influenced by the steppe types. Nevertheless, the habitat heterogeneity could cause shifts in the relative abundance of some bacterial groups, which resulted in significant changes in the community structure of soil bacteria across steppes. However, the fungal community compositions and structures were similar in typical and meadow steppes but that in desert steppe were significantly different. Whereas, the community compositions and structures of diazotrophs were strongly related to the steppe types. In this study, the similar parent material backgrounds of the steppe soils might be the important factor in shaping the homologous bacterial compositions. However, the variations in soil fertility, soil water repellency, and plant species across steppes would be the major driving forces in regulating the compositions and structures of fungal communities, while the diazotrophic communities would be more closely related to the changes in plant traits and soil fertility among steppes. 4. Our results provided evidence of habitat specificity for different microbial groups and their underlying drivers. [ABSTRACT FROM AUTHOR]