Optimizing Epoxy Interfacial Bonding Properties and Failure Mechanism between Carbon Textile-Reinforced Mortar Composites and Concrete Substrates.

Textile-reinforced mortar (TRM) composites have been extensively utilized in building reinforcement due to their exceptional mechanical properties. The weakest link in the entire structure is the interface between the TRM composites and the concrete; however, it plays a crucial role in effectively transferring stress. Researchers have taken measures to improve the strength of the interface, but the results are relatively scattered. In this paper, the surface treatment of the substrate, the thickness of the surfactant, and the physical doping of the surfactant on the interfacial bonding strength of the concrete were comparatively studied. The results demonstrate that the sandblasting treatment on the surface of the concrete enhances the bonding area between the mortar and the concrete of the reinforcement layer, leading to a 50% increase in the bending resistance of the structure. When the surfactant thickness increases to 0.5 kg/m2, more surfactants penetrate the mortar and concrete. This significantly inhibits the occurrence of cracks in the structure. The addition of 2.5% Al2O3 nanomaterials to the surfactant diminishes the shrinkage rate of the curing process, enhances the impact toughness, and improves the flexural and compressive properties of the bonding layer. The ultimate load of the structure increases by 65%. Physical doping of the surfactant is the most effective measure with the most apparent improvement result. It significantly enhances the bonding strength of the interface and can be widely used in construction.

Study on the Inhibition Characteristics of Coal Spontaneous Combustion by Silica Gel Foam.

The spontaneous combustion of residual coal in abandoned mining areas severely affects the safe and efficient extraction of coal, employee occupational health, and regional environmental ecology. A technical measure for preventing and controlling the spontaneous combustion of residual coal involves injecting antispontaneous combustion materials into abandoned areas. In this study, the composition, preparation, and mechanism of action of silica gel foam, a material used to suppress spontaneous combustion during coal mining, were investigated to improve the performance of materials designed to prevent spontaneous combustion in abandoned areas. The inhibitory efficiency improved, and the mechanical strength and stability of the foam liquid film increased upon adding modified antioxidants and nanosilica particles to the gel foam. Macro performance tests, microstructural characterization, and chemical inhibition mechanism analyses verified the efficacy of silica gel foam for suppressing spontaneous combustion. The air leakage resistance of the silica gel foam effectively increased the air leakage resistance of the coal samples at different pressures. New radicals formed during the spontaneous combustion of coal comprising different inhibitors, as indicated by the g-factor results of electron paramagnetic resonance (EPR) spectroscopy analysis; the formation of radicals initially decreased and then increased when the inhibitor material changed. The concentration of free radicals decreased markedly during the spontaneous combustion process of both raw and inhibited coal samples at low oxidation temperatures (∼60-100 °C), indicating a marked inhibitory effect.

Motion planning framework based on dual-agent DDPG method for dual-arm robots guided by human joint angle constraints.

Introduction: Reinforcement learning has been widely used in robot motion planning. However, for multi-step complex tasks of dual-arm robots, the trajectory planning method based on reinforcement learning still has some problems, such as ample exploration space, long training time, and uncontrollable training process. Based on the dual-agent depth deterministic strategy gradient (DADDPG) algorithm, this study proposes a motion planning framework constrained by the human joint angle, simultaneously realizing the humanization of learning content and learning style. It quickly plans the coordinated trajectory of dual-arm for complex multi-step tasks. Methods: The proposed framework mainly includes two parts: one is the modeling of human joint angle constraints. The joint angle is calculated from the human arm motion data measured by the inertial measurement unit (IMU) by establishing a human-robot dual-arm kinematic mapping model. Then, the joint angle range constraints are extracted from multiple groups of demonstration data and expressed as inequalities. Second, the segmented reward function is designed. The human joint angle constraint guides the exploratory learning process of the reinforcement learning method in the form of step reward. Therefore, the exploration space is reduced, the training speed is accelerated, and the learning process is controllable to a certain extent. Results and discussion: The effectiveness of the framework was verified in the gym simulation environment of the Baxter robot's reach-grasp-align task. The results show that in this framework, human experience knowledge has a significant impact on the guidance of learning, and this method can more quickly plan the coordinated trajectory of dual-arm for multi-step tasks.

Patterned Manipulated Surface Based on Femtosecond Laser with Adjustable Wetting Speed and Directional Fluid Delivery.

Recently, due to the crucial roles of multifunctional liquid manipulation surfaces in biomedical transportation, microfluidics, and chemical engineering, the demand for controllable and functional aspects of directed liquid transportation has increased significantly. However, designing an intelligent manipulation surface that is easy to manufacture and fully functional remains an immense challenge. To address this challenge, a smart surface that can regulate the rate of liquid transport within a patterned channel by temperature is reported. A synergistically controlled approach of poly(N-isopropylacrylamide) and micropillar shape-memory polymers (SMPs) was used to modulate the wetting rate of liquids on surfaces. By femtosecond laser direct writing, temperature-responsive composite surfaces are embedded in the microstructure of shape-memory polymers (SMPs) in a patterned manner, resulting in the preparation of novel programmable liquid manipulation surfaces incorporating boundaries possessing asymmetric wettability. Since the smart surface is based on SMP, the superhydrophobic part in the superhydrophobic/controllable wettability patterning platform is also programmed for droplet directional transport, which takes advantage of the difference in wettability between the rewritable indentation track and the periphery to allow droplets to flow into the temperature-controlled velocity track, enriching the functionality of the surface. In addition, based on its excellent controllability and patterning, the surface has been shown to be used in microfluidic circuit chips with self-cleaning properties, which provides new ideas for circuit timing control. This study provides promising prospects for the effective development of multifunctional liquid steering surfaces, lab-on-a-chip, and microfluidic devices.

Interface Bonding Properties and Mechanism of Steel Fiber and Hot Melt Adhesive via Interface Design Engineering.

Steel fiber textile, which is composed of steel fibers and glass fibers, has a support layer impregnated with hot melt adhesive (HMA). During long-term service, the bonding force between the steel fiber/HMA system interfaces is poor. In order to improve the bond strength and durability of the interface, this paper introduced sandblasting, acid-etching, and phosphating treatments on the surface of the steel fibers. Also, the effects of these three pretreatment methods on the bond strength of the steel fiber/HMA interface were investigated. The results indicate that the interfacial bond strength of composites made from steel fibers is improved via surface treatment. Under a hydrothermal and simulated concrete pore solution environment, the durability of the steel fiber/HMA interface after sandblasting and acid-etching pretreatment is not as good as that after phosphating pretreatment. The mechanical properties of the phosphating/HMA composite were maintained at 4.56 and 2.24 times compared to those of the untreated/HMA composite, respectively. This is because the pinning effect formed by the phosphating film on the surface of steel fibers at the interface of steel fiber/HMA can serve as a physical barrier against corrosion, preventing the invasion of chloride ions and water vapor and improving the durability of the interface.

Smart Surfaces with pH-Responsiveness Enhanced by Multiscale Hierarchical Structures Fabricated by Laser Direct Writing.

In contemporary applications, smart surfaces capable of altering their properties in response to external stimuli have garnered significant attention. Nonetheless, the efficient creation of smart surfaces exhibiting robust and rapid responsiveness and meticulous controllability on a large scale remains a challenge. This paper introduces an innovative approach to fabricate smart surfaces with strong pH-responsiveness, combining femtosecond laser direct writing (LDW) processing technology with stimulus-responsive polymer grafting. The proposed model involves the grafting of poly(2-diethylaminoethyl methacrylate) (PDEAEMA) onto rough and patterned Au/polystyrene (PS) bilayer surfaces through Au-SH bonding. The incorporation of LDW processing technology extends the choice of microstructures and roughness achievable on material surfaces, while PDEAEMA imparts pH responsiveness. Our findings revealed that the difference in contact angle between acidic and basic droplets on the rough PDEAEMA-g-Au surface (∼118°) greatly surpasses that on the flat PDEAEMA-g-Au surface (∼72°). Next, by leveraging the precision control over surface microstructures enabled by the LDW processing technique, this difference was further augmented to ∼127° on the optimized patterned PDEAEMA-g-Au surface. Further, we created two distinct combined smart surfaces with varying wettability profiles on which the hydrophilic-hydrophobic boundaries exhibit reliable asymmetric wettability for acidic and basic droplets. Additionally, we prepared a separator, realizing a better visual distinction between acid and base and collecting them separately. Given the effective abilities found in this study, we postulate that our smart surfaces hold substantial potential across diverse applications, encompassing microfluidic devices, intelligent sensors, and biomedicine.

Targeted Elimination of Surface Defects in Carbon Fibers: Formation of a Hybrid Structure Combining Rigidity with Flexibility from Sonochemical-Induced Directional Growth of Nano-ZIF-8 and Subsequent Annealing.

Currently, the mechanical performance of carbon fibers (CFs) has yet to fully realize its theoretical potential. This is predominantly attributed to the significant constraints posed by surface defects, greatly impeding the widespread application of carbon fibers. In order to address this issue, we employed a sonochemical-induced approach in this study to achieve in situ growth of nanoscale zeolitic imidazolate framework-8 (ZIF-8) at the surface defects of carbon fibers. After high-temperature treatment, the structure of ZIF-8 decomposed into ZnO and inorganic carbon, reinforcing the carbon fiber structure from both flexible and rigid aspects. Our research indicates that when the temperature reaches 500 °C, a substantial portion of ZIF-8 undergoes thermal decomposition, giving rise to zinc oxide and inorganic carbon. The flexible inorganic carbon and rigid ZnO form a meshlike structure, which welds to the surface defects of carbon fibers, resulting in strong interactions and contributing to the delay of fiber fracture. Compared to unmodified carbon fibers, the mechanical performance increased by approximately 15.86%. Based on the aforementioned analysis, this method can be considered a direct and effective approach for reinforcing carbon fiber structures, presenting a novel approach for the precise elimination of surface defects on carbon fibers.

Classification-Based Evaluation of Multi-Ingredient Dish Using Graphene-Modified Interdigital Electrodes.

A taste sensor with global selectivity can be used to discriminate taste of foods and provide evaluations. Interfaces that could interact with broad food ingredients are beneficial for data collection. Here, we prepared electrochemically reduced graphene oxide (ERGO)-modified interdigital electrodes. The interfaces of modified electrodes showed good sensitivity towards cooking condiments in mixed multi-ingredients solutions under electrochemical impedance spectroscopy (EIS). A database of EIS of cooking condiments was established. Based on the principal component analysis (PCA), subsets of three taste dimensions were classified, which could distinguish an unknown dish from a standard dish. Further, we demonstrated the effectiveness of the electrodes on a typical dish of scrambled eggs with tomato. Our kind of electronic tongue did not measure the quantitation of each ingredient, instead relying on the database and classification algorithm. This method is facile and offers a universal approach to simultaneously identifying multiple ingredients.

DLX5 regulates the osteogenic differentiation of spinal ligaments cells derived from ossification of the posterior longitudinal ligament patients via NOTCH signaling.

Background: Ossification of the posterior longitudinal ligaments (OPLL) is common disorder characterized by heterotopic ossification of the spinal ligaments. Mechanical stimulation (MS) plays an important role in OPLL. DLX5 is an essential transcription factor required for osteoblast differentiation. However, the role of DLX5 during in OPLL is unclear. This study aims to investigate whether DLX5 is associated with OPLL progression under MS. Methods: Stretch stimulation was applied to spinal ligaments cells derived from OPLL (OPLL cells) and non-OPLL (non-OPLL cells) patients. Expression of DLX5 and osteogenesis-related genes were determined by quantitative real-time polymerase chain reaction and Western blot. The osteogenic differentiation ability of the cells was measured using alkaline phosphatase (ALP) staining and alizarin red staining. The protein expression of DLX5 in the tissues and the nuclear translocation of NOTCH intracellular domain (NICD) was examined by immunofluorescence. Results: Compared with non-OPLL cells, OPLL cells expressed higher levels of DLX5 in vitro and vivo (p < 0.01). Upregulated expression of DLX5 and osteogenesis-related genes (OSX, RUNX2, and OCN) were observed in OPLL cells induced with stretch stimulation and osteogenic medium, whereas there was no change in the non-OPLL cells (p < 0.01). Cytoplasmic NICD protein translocated from the cytoplasm to the nucleus inducing DLX5 under stretch stimulation, which was reduced by the NOTCH signaling inhibitors (DAPT) (p < 0.01). Conclusions: These data suggest that DLX5 play a critical role in MS-induced progression of OPLL through NOTCH signaling, which provides a new insight into the pathogenesis of OPLL.

Graphene oxide membranes with a confined mass transfer effect for Li+/Mg2+ separation: a molecular dynamics study.

Membrane separation technology represented by graphene oxide (GO) membranes has been widely used in lithium extraction from salt lakes. It is extraordinary to study the extraction of Li+ by GO membranes from the perspective of the confined mass transfer effect. This study establishes a GO channel model with the confined mass transfer effect to closely fit the actual mass transfer process. Meanwhile, this study investigates the dynamic fluid characteristics in the separation of Li+/Mg2+ by GO membranes using molecular dynamics simulations. The results showed that the Li+/Mg2+ separation ratio is maximum at 1.0 nm layer spacing and 10% oxidation degree of the GO membrane. Water molecules form a bilayer within the channel at the appropriate interlayer channel (1 nm) and oxidation level (10%), which accelerates the ion transport rate. Furthermore, the GO oxidation group has the weakest hydrogen bonding effect on water which promotes the passage of water. Finally, the maximum separation ratio is reached due to the fact that the binding force of Li+ to water molecules in the channel is lower than that of Mg2+. The results of this study will provide theoretical consideration for the design of high-performance Li+/Mg2+ separation membranes.

Upconverted persistent luminescent Zn3Ga2SnO8: Cr3+, Yb3+, Er3+ phosphor for composite anti-counterfeiting ink.

Herein, a novel colorless anti-counterfeiting luminous ink composite material, to the best of our knowledge, was prepared by incorporating upconverted persistent luminescent Zn3Ga2SnO8:1%Cr3+, 5%Yb3+, 0.5%Er3+ (ZGSO: Cr,Yb,Er) phosphors into a resin solution, followed by stirring. Owing to its small particle size and uniform distribution, ZGSO: Cr, Yb, Er exhibits long-lasting, persistent near-infrared emission at 696 nm following the stoppage of excitation by a 274 nm ultraviolet light and a 980 nm excitation. ZGSO: Cr, Yb, Er composites were prepared and exhibited characteristic peaks corresponding to upconversion and an afterglow curve following excitation at 980 nm. With various special luminescent modes, sharp emission peaks, and emission intensity varying over time, the emission light of composite ink is easy to detect and not easily confused. Furthermore, the prepared composite ink can be calligraphic, visualized, and observable, and has good light-emitting performance following UV excitation. Our work provides a meaningful way to fabricate multifunctional anti-counterfeiting luminous ink composites with an intense persistent luminescence for use in anti-counterfeiting signs, inspection imaging, and other complex industrial applications.

Micro-flower like Core-shell structured ZnCo@C@1T-2H-MoS2 composites for broadband electromagnetic wave absorption and photothermal performance.

Core-shell structure has been receiving extensive attention to enhance the electromagnetic wave (EMW) absorption performance due to its unique interface effect. In this paper, a micro-flower like ZnCo@C@1T-2H-MoS2 was prepared through MOF self-template method. The introduction 1T-2H-MoS2 shell helps optimize impedance matching of the CoZn@C particles to improve the EMW absorption ability. The minimal reflection loss (RLmin) value of ZnCo@C@1T-2H-MoS2 is -35.83 dB with a thickness of 5.0 mm at 5.83 GHz and the effective absorption (RL < -10 dB) bandwidth up to 4.56 GHz at 2.0 mm thickness. Meanwhile, the overall effective absorption bandwidth (OEAB) can reach up to 13.44 GHz from 4.56 to 18.0 GHz. Moreover, ultrafast photothermal performances are also achieved, which can guarantee the normal functioning of ZnCo@C@1T-2H-MoS2 materials in cold conditions. The excellent EMW absorption and photothermal performance are attributed to the unique structure designed with the core of magnetic ZnCo@C rhombic dodecahedral and the shell of dielectric micro-flower like 1T-2H-MoS2 optimize impedance matching.

Experimental Study on Ultra-Precision Polishing of Ti-6Al-4V by Ultraviolet-Induced Nanoparticle Colloid Jet Machining.

Ti-6Al-4V is widely used in various fields of modern industry, but it is difficult to obtain an ultra-smooth surface of Ti-6Al-4V due to its poor machinability. In this article, ultraviolet-induced (UV-induced) nanoparticle colloid jet machining was utilized to carry out ultra-precision polishing of Ti-6Al-4V to improve the surface quality. The results of infrared differential spectroscopy before and after polishing show that new chemical bonds such as Ti-O-Ti (Al-O-Ti and V-O-Ti) appear on the Ti-6Al-4V workpiece surface, which indicates that the material of Ti-6Al-4V workpiece is removed through the chemical interaction between TiO2 nanoparticles and workpiece surface in the process of UV-induced nanoparticle colloid jet machining. The comparison of metallographic structure of Ti-6Al-4V before and after polishing shows that the chemical activity and material removal rate of the primary α phase in Ti-6Al-4V is higher than that of the remnant ß phase in UV-induced nanoparticle colloid jet machining, which lead to the well-distributed nano-scale surface peaks and valleys at regular intervals on the polished Ti-6Al-4V workpiece surface. After polishing, the longitudinal residual stress on the surface of Ti-6Al-4V workpiece decreases from 75 MPa to 67 MPa and the transverse stress decreases from 13 MPa to 3 MPa. The surface roughness of Ti-6Al-4V workpiece is reduced from Sa 76.7 nm to Sa 2.87 nm by UV-induced nanoparticle colloid jet machining.

Experimental Investigation on the Effects of Photocatalysis in Ultraviolet-Induced Nanoparticle Colloid Jet Machining.

In this paper, ultraviolet (UV)-induced nanoparticle colloid jet machining is proposed to achieve ultrasmooth surface polishing by using the interaction between nanoparticles and the workpiece surface under the action of the ultraviolet field and the hydrodynamic pressure field. In the process of UV-induced nanoparticle colloid jet machining, the effects of photocatalysis on the interaction between nanoparticles and the workpiece surface need to be further studied in order to better understand the polishing process. This paper presents the interaction between TiO2 nanoparticles and a Si workpiece surface with and without ultraviolet irradiation. Scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS) were applied to investigate the differences in the interaction of TiO2 nanoparticles with Si workpieces. The SEM and XPS results indicate that the photocatalysis of UV light can promote the interaction between TiO2 nanoparticles and a Si surface by creating more interfacial reaction active centers between the TiO2 nanoparticles and the Si workpiece. The FT-IR and XPS spectra show that TiO2 nanoparticles are chemically bonded to the Si workpiece by oxygen-bridging atoms in Ti-O-Si bonds. Due to the effects of photocatalysis, UV-induced nanoparticle colloid jet machining has a higher polishing efficiency than nanoparticle colloid jet machining with the same polishing parameters.