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The interfacial properties between carbon fiber (CF) and thermoplastic resin are relatively weak, which can be problematic for composites in structural applications. Improving the surface roughness of CF is regarded as an effective way to enhance the interface of composites. However, most CF modifying methods are complex and time-consuming, which cannot meet the demand for industrial production. Therefore, it is of great significance to research a fast technique of CF surface modification to strengthen the interface of composites. Herein, a one-pot reaction based on the aryl diazonium salt modification was applied to enhance the interface between CF and poly ether ether ketone (PEEK) resin. Carbon nanotubes (CNTs) were linked to CF by p-phenylenediamine (PPD) via cyclic voltammetry (CV). The surface morphology, chemical characteristics and surface energy of modified CF illustrated the effectiveness of this method, and the interfacial properties of as-prepared modified CF/PEEK demonstrated the increased tendency. All the CF was treated within 5 min and the interfacial shear strength (IFSS) of CF/PEEK was increased to the maximum of 99.62 MPa by aryl diazonium salt modification. This work may shed some light on the industrialized application of CF reinforced high-performance engineering thermoplastic composites. [ABSTRACT FROM AUTHOR]

In order to improve the inversion accuracy of stellar occultation data and to provide a reference for the selection of inversion methods with higher accuracy in the future, this study compared and analyzed the inversion effects of two different methods on the same set of data, which are the effective cross-section method and the onion-peeling method, respectively. Firstly, the inversion principle of the effective cross-section method is introduced in detail. The regularisation parameters and screening conditions for the observation data in the inversion process were clarified based on the ozone observation characteristics. Second, the algorithm was applied to invert the GOMOS observational data from 1 December 2002. The atmospheric radiative transmittance obtained from the observations was filtered, and the inversion results were compared with those obtained using the onion-peeling method. Third, the errors in the height distribution obtained by both methods were calculated using the GOMOS secondary results from 1 December 2002 as the reference value. Finally, the inversion errors of other trace components were computed to further validate the accuracy of the two methods. The results demonstrate that the effective cross-sectional method is more accurate for the inversion of ozone, particularly in low-altitude regions affected by refraction. The method achieved a maximum error of 1.2%, with an apparent magnitude of 2, an effective temperature greater than 10,000 K, and a regularisation parameter of 1015. Furthermore, when applying the same method to the inversion of nitrogen trioxide and calculating the error, it was observed that the results of both methods were comparable at altitude of 30–60 km, with an error value ranging from 0 to 2%. However, at approximately 25 km, the inversion accuracy of the onion-peeling method surpassed that of the effective cross-sectional method. This research provides a theoretical foundation for further investigation of the stellar occultation inversion method and enhancing the accuracy of inversions. [ABSTRACT FROM AUTHOR]

In this study, we analyze the accuracy of the stellar occultation technique to detect the oxygen number density and temperature in near space. Based on the validation of the algorithm related to stellar occultation using a single wavelength of 762 nm, the simulation and inversion are performed using the oxygen absorption A-band, and the results are compared with SABER observations to calculate the deviation. Then, the distribution of the detection accuracy with wavelength, latitude, and altitude is analyzed. The results show that the radiant transmittance of the basic observation varies significantly with wavelength and altitude, and it is not sensitive to a change of latitude. The inversion results of each wavelength at different latitudes can be combined, and it can be seen that the 754–769 nm band is preferred for oxygen and temperature detection. Therefore, analyzing the accuracy results of the specific wavelength 757.84 nm at different latitudes, the temperature accuracy can reach 0.1 K in the stratosphere at both low and high latitudes and 0.6–34 K at middle latitudes. The temperature detection accuracy in the mesosphere at each latitude reaches about a dozen K. The deviation of the inversion results at middle latitudes is larger in the thermosphere, and at the other two latitudes, it is about a few dozen K. From the analysis of relative deviation, excluding the deviation of 95–100 km, the deviation of other altitudes is within the ideal range, and the minimum can reach 0. The accuracy of the oxygen number density increases with latitude, and the relative deviation of the middle and high latitudes is around 10–20%. Based on the above results, it is concluded that the technique of starlight occultation exhibits high accuracy for detecting atmospheric parameters in the near space region, and the results lay the technical foundation for the independent development of stellar occultation. [ABSTRACT FROM AUTHOR]

This study provides an in-depth analysis of the characteristics of stellar occultation events. Using 10 target star sources, the influence of orbital elements on the number, duration, and distribution of stellar occultation events was simulated and analyzed, and the constellation configuration was designed. The results showed the following points: (1) the orbital inclination had the greatest influence on the number of occultation events, with obvious upward and downward trends in the range of 10–40° and 150–180°, and the amount of occultation data remained at about 303 times under the other angle conditions. The orbital height had an effect on the number of occultations, but the amplitude was small. (2) The use of four orbits had an impact on the occultation duration. The duration decreased with an increase in the orbit height and inclination, the distribution was symmetrical with the perigee angular distance, and it increased with an increase in the ascending intersection right ascension. (3) The higher the orbital height, the less comprehensive the longitudinal and latitudinal distribution of occultation events. With an orbital inclination of less than 150°, the greatest occultation event was covered to encompass the entire world. The other two orbital elements had negligible effects on the longitudinal and latitudinal distribution of occultation events. (4) The elevation of the occultation event increased with an increase in the orbital altitude, but the azimuth showed no obvious change trends. A considerable number of normal occultations can be obtained with an orbital inclination of less than 120°. The other two orbital elements had a negligible effect on the distribution of altitude and azimuth of occultation events. A stellar occultation constellation configuration was designed based on the simulation results, and the results showed that the following parameters of satellites can be used to realize the global distribution of occultation events: orbital height of 500 km, orbital inclination of 97.3771°, perigee angular distance of 40°, and ascending node right ascension steps of 40°. This configuration will ensure that an adequate number of normal occultations are obtained, which will ensure the quality of data inversion under the condition of 152 infrared target star sources. [ABSTRACT FROM AUTHOR]

In knowledge graph completion (KGC) and other applications, learning how to move from a source node to a target node with a given query is an important problem. It can be formulated as a reinforcement learning (RL) problem transition model under a given state. In order to overcome the challenges of sparse rewards and historical state encoding, we develop a deep agent network (graph-agent, GA), which combines temporal convolutional network (TCN) and Monte Carlo Tree Search (MCTS). Firstly, we combine MCTS with neural network to generate more positive reward trajectories, which can effectively solve the problem of sparse rewards. TCN is used to encode the history state, which is used for policy and Q-value respectively. Secondly, according to these trajectories, we use Q-Learning to improve the network and parameter sharing to enhance TCN strategy. We apply these steps repeatedly to learn the model. Thirdly, in the prediction stage of the model, Monte Carlo Tree Search combined with Q-value method is used to predict the target nodes. The experimental results on several graph-walking benchmarks show that GA is better than other RL methods based on-policy gradient. The performance of GA is also better than the traditional KGC baselines. [ABSTRACT FROM AUTHOR]

In order to improve the interfacial adhesion of stainless-steel mesh reinforced poly(ether-ether-ketone) (SSM/PEEK) heating elements (HEs) used in the resistance welding process for continuous carbon fiber reinforced PEEK composites (CF/PEEK composites), three kinds of surface treatments, sandblasting, aryl diazonium grafting and silane grafting, were adopted on SSM surfaces. The functional groups were grafted successfully according to the Fourier Transform Infrared (FTIR) results and Energy Dispersive Spectrometer (EDS) results, and the surface morphologies of SSM changed significantly after different treatments. Although the tensile performances of sandblasted stainless-steel (SS) wire and sandblasted SSM were distinctly reduced, the lap shear strength (LSS) of joints with sandblasted SSM still slightly improved. Besides, the interfacial shear strength (IFSS) increased from 28 MPa for untreated SSM to 34 MPa for diazonium grafted SSM and 38 MPa for silane grafted SSM. Furthermore, the LSS results were in agreement with this trend, representing a 9% improvement for joints with diazonium grafted SSM and a 23% improvement for joints with silane grafted SSM compared with untreated CF/PEEK joints. After comparison, silane grafting was the most suitable surface modification for resistance-welded CF/PEEK joints. The interfacial bonding mechanism of CF/PEEK joints with silane grafted SSM was compared with that of untreated CF/PEEK joints, suggesting that the mechanical interlocking contributed to improved interfacial bonding. [ABSTRACT FROM AUTHOR]

Singing voice separation on robots faces the problem of interpreting ambiguous auditory signals. The acoustic signal, which the humanoid robot perceives through its onboard microphones, is a mixture of singing voice, music, and noise, with distortion, attenuation, and reverberation. In this paper, we used the 3D Inception-ResUNet structure in the U-shaped encoding and decoding network to improve the utilization of the spatial and spectral information of the spectrogram. Multiobjectives were used to train the model: magnitude consistency loss, phase consistency loss, and magnitude correlation consistency loss. We recorded the singing voice and accompaniment derived from the MIR-1K dataset with NAO robots and synthesized the 10-channel dataset for training the model. The experimental results show that the proposed model trained by multiple objectives reaches an average NSDR of 11.55 dB on the test dataset, which outperforms the comparison model. [ABSTRACT FROM AUTHOR]

Carbon fabric/polyphenylene sulfide (CF/PPS) composite has been used in the aircraft industry, which might suffer moisture and high temperature in service, leading to degradation and even failure. Therefore, knowledge of hydrothermal aging behavior and effects is needed to ensure service life. This work explores the water diffusion behavior, crystallization, and interfacial properties of CF/PPS composite under hydrothermal aging in continuous 3 months and periodical cycles. Diffusion coefficients were calculated through the Fickian model, crystallization behaviors were measured through differential scanning calorimetry and polarized optical microscope, and interfacial properties were characterized by interfacial shear strength, and interlaminar shear strength. The results demonstrate the crystal morphology transforms from transverse crystals to spherulites at the CF/PPS interface after recrystallization through hydrothermal aging, revealing water has a significant impact on the nucleation performance of T300 carbon fiber in the PPS matrix. Hydrothermal aging affects the crystallinity and crystal morphology of CF/PPS composite after recrystallization, and impacts the micro and macro interfacial properties. Highlights: Transverse crystals transform to spherulites at CF/PPS interface after water uptake.Water impacts on nucleation performance of T300 carbon fiber in PPS matrix.Hydrothermal aging effect can be accumulated and promotes water uptake.ILSS drop is related to water uptake content, crystallization and IFSS changes. [ABSTRACT FROM AUTHOR]

A new and convenient synthesis of 7-(3-chloropropoxy)-4-hydroxy-6-methoxyquinoline-3-carbonitrile, the key intermediate to bosutinib, is described on a hectogram scale. 5-Bromo-2-methoxyphenol is adopted as the starting material via the simple chemical process including Friedel-Crafts reaction, alkylation, bromination, cyano substitution, and so on to give the 3-amino-2-(2-bromobenzoyl)acrylonitrile compound 25, which underwent key intramolecular cyclization at K2CO3/DMF condition; the title product was obtained in 36.9% yield over 7 steps and 98.71% purity (HPLC). [ABSTRACT FROM AUTHOR]

One-dimensional porous Fe 2 O 3 nanotubes with 2 µm length, 220 nm outer diameter and 65 nm wall thickness were firstly synthesized via a low temperature hydrothermal method followed by thermal treatment. As advanced anode for lithium ion batteries, porous Fe 2 O 3 nanotubes exhibit obviously enhanced electrochemical properties in terms of lithium storage capacity (1050.1 mA h g −1 at 100 mA g −1 rate), initial coulombic efficiency (78.4%), cycle performances (90.6% capacity retention at 50th cycle), and rate capability (613.7 mA h g −1 at 1000 mA g −1 rate). This enhancement could be attributed to the one-dimensional nanostructure of porous Fe 2 O 3 nanotubes which could increase contact area between electrolyte and active materials, shorten migration path for Li + ions and electrons, and accommodate the volume variations via additional void space during cycling. [ABSTRACT FROM AUTHOR]

Simple Summary: pH-responsive hydrogel microparticles have great potential as drug delivery systems of anti-cancer drugs. Here, we use microfluidics for the generation of asymmetric microgels as carriers for oral administration of 5-fluorouracil (5-FU) in colorectal cancer. Due to their anisotropic shape, they show increased on-demand loading of the drug. The pH-responsiveness is ensured by the presence of alginate methacrylate within the gel network and represents the key factor for 5-FU release at the targeted location. Empty, asymmetric microgels do not show cytotoxicity even at high concentration, while upon treatment with 5-FU loaded microparticles, the viability of tumor cells notably decreases confirming the efficacy of drug release at certain pH. In the last 20 years, the development of stimuli-responsive drug delivery systems (DDS) has received great attention. Hydrogel microparticles represent one of the candidates with the most potential. However, if the role of the cross-linking method, polymer composition, and concentration on their performance as DDS has been well-studied, still, a lot needs to be explained regarding the effect caused by the morphology. To investigate this, herein, we report the fabrication of PEGDA–ALMA-based microgels with spherical and asymmetric shapes for 5-fluorouracil (5-FU) on-demand loading and in vitro pH-triggered release. Due to anisotropic properties, the asymmetric particles showed an increased drug adsorption and higher pH responsiveness, which in turn led to a higher desorption efficacy at the target pH environment, making them an ideal candidate for oral administration of 5-FU in colorectal cancer. The cytotoxicity of empty spherical microgels was higher than the cytotoxicity of empty asymmetric microgels, suggesting that the gel network's mechanical proprieties of anisotropic particles were a better three-dimensional environment for the vital functions of cells. Upon treatment with drug-loaded microgels, the HeLa cells' viability was lower after incubation with asymmetric particles, confirming a minor release of 5-FU from spherical particles. [ABSTRACT FROM AUTHOR]

Carbon-fiber-reinforced polyimide (PI) resin composites have gained significant attention in the field of continuous-fiber-reinforced polymers, in which the interfacial bonding between carbon fiber and matrix resin has been an important research direction. This study designed and prepared a water-soluble thermoplastic polyamide acid sizing agent to improve the wettability of carbon fiber, enhance the van der Waals forces between carbon fiber and resin and strengthen the chemical bonding between the sizing agent and the alkyne-capped polyimide resin by introducing alkyne-containing functional groups into the sizing agent. This study found that the addition of a sizing layer effectively bridged the large modulus difference between the fiber and resin regions, resulting in the formation of an interfacial layer approximately 85 nm thick. This layer facilitated the transfer of stress from the matrix to the reinforced carbon fiber, leading to a significant improvement in the interfacial properties of the composites. Adjusting the concentration of the sizing agent showed that composites treated with 3% had the best interfacial properties. The interfacial shear strength increased from 82.08 MPa to 108.62 MPa (32.33%) compared to unsized carbon fiber. This research is significant for developing sizing agents suitable for carbon-fiber-reinforced polyimide composites. [ABSTRACT FROM AUTHOR]

• Quadruple-layered nanotube array is designed as flexible binder-free electrode. • Metal oxides are confined and coated by carbon matrices via strong chemical bonds. • A stable SEI layer is formed due to the unique quadruple-layered structure. • Binder-free nanotube array electrodes exhibit excellent lithium storage capacity. Designing flexibly binder-free metal oxide electrodes, which could effectively alleviate the mechanical stress and maintain the structural integrity during the lithiation/delithiation process, is still a major challenge. Here we report a facile strategy for successfully synthesizing free-standing quadruple-layered metal oxides/nitrogen, oxygen-doped carbon nanotube array electrodes. In the quadruple-layered structure, metal oxides are protected by carbon layer to minimize the direct exposure to the electrolyte and accommodate the huge volume change during cycling, and thus form the solid-electrolyte interface layer. Besides that, the abundant oxygen and nitrogen-containing functional groups of carbon layer shows a strong interaction with metal oxides to prevent the electrode pulverization during charging and discharging. Meanwhile, carbon layer is introduced to facilitate the stable and fast electrons mobility. As a result, the as-prepared quadruple-layered electrodes show excellent electrochemical performance in terms of high reversible capacity, good rate capability, and stable cyclability. This work may pave the way for the construction of flexible binder-free lithium ion batteries with superior lithium storage properties. Image, graphical abstract [ABSTRACT FROM AUTHOR]

The toughening modification of epoxy resin has received widespread attention. The addition of the second-phase resin has a good toughening effect on epoxy resin. In order to investigate the effect of the second-phase resin on the interphase of composites, in this work the interfacial properties of carbon fiber (CF)/epoxy resin with the second-phase resin structure were investigated. Methodologies including surface structure observation, chemical characteristics, surface energy of the CF, and micro-phase structure characterization of resin were tested, followed by the micro-interfacial performance of CF/epoxy composites before and after hygrothermal treatment. The results revealed that the sizing process has the positive effect of increasing the interfacial bonding properties of CF/epoxy. From the interfacial shear strength (IFSS) test, the introduction of the second phase in the resin reduced the interfacial bonding performance between the CF and epoxy. After the hygrothermal treatment, water molecules diffused along the interfacial paths between the two resins, which in turn created defects and consequently brought about a reduction in the IFSS. [ABSTRACT FROM AUTHOR]

In this study, a passive radar system that detects flying targets is developed in order to solve the problems associated with traditional flying target detection systems (i.e., their large size, high power consumption, complex systems, and poor battlefield survivability). On the basis of target detection, the system uses the multipath signal (which is usually eliminated as an error term in navigation and positioning), enhances it by supporting information, and utilizes the multi-source characteristics of ordinary omnidirectional global navigation satellite system (GNSS) signals. The results of a validation experiment showed that the system is able to locate a passenger airplane and obtain its flight trajectory using only one GNSS receiving antenna. The system is characterized by its light weight (less than 5 kg), low power consumption, simple system, good portability, low cost, and 24/7 and all-weather work. It can be installed in large quantities and has good prospects for development. [ABSTRACT FROM AUTHOR]

To prevent the potential failure of the surface acoustic wave (SAW) atomizer caused by the concentration of thermal stresses, this study investigates the thermal elevation process inherent to the operation of the surface wave atomizer. Subsequently, a method for temperature regulation is proposed. By collecting the temperature rise data of SAW atomizers with water, olive oil, and glycerol at 5/6/7 Watts (W) of power, the temperature curves of the atomizer surface under different conditions are obtained, and the stress changes in the working process are simulated additionally. The results indicate that although the stress generated by surface acoustic wave atomizers varies for different media, there is always a problem of rapid heating during the initial working stage in all cases. To address the above issues, this study analyzed the time when the maximum stress occurred and proposed control methods based on experimental data. The simulation results show that by controlling the driving power within 4 s after the start of atomization, the problem of excessive stress during the heating stage can be avoided. Finally, the feasibility of the control method was verified through a simple power control method (limiting the driving power to 3 W in the first 2 s), proving that this method can effectively reduce the thermal stress during the working process of the atomizer and prevent the atomizer from cracking. [ABSTRACT FROM AUTHOR]

The rise in global average surface temperature has promoted the advancement of spring vegetation phenology. However, the response of spring vegetation phenology to different temperature parameters varies. The Mongolian Plateau, one of the largest grasslands in the world, has green-up dates (GUDs) with unclear sensitivity to different temperature parameters. To address this issue, we investigated the responses of GUDs to different temperature parameters in the Mongolian Plateau grasslands. The results show that GUDs responded significantly differently to changes in near-surface temperature (TMP), near-surface temperature maximum (TMX), near-surface temperature minimum (TMN), and diurnal temperature range (DTR). GUDs advanced as TMP, TMX, and TMN increased, with TMN having a more significant effect, whereas increases in DTR inhibited the advancement of GUDs. GUDs were more sensitive to TMX and TMN than to TMP. The sensitivity of GUDs to DTR showed an increasing trend from 1982 to 2015 and showed this parameter's great importance to GUDs. Our results also show that the spatial and temporal distributions of temperature sensitivity are only related to temperature conditions in climatic zones instead of whether they are arid. [ABSTRACT FROM AUTHOR]

This research aims to analyze the impact of the Earth-Space link on the Automatic Identification System (AIS) signals of ships. To achieve this, we established a simulation system that measures the receiving power of AIS signals via satellite platforms. We validated the system by utilizing observation data from Tiantuo-5. Through this simulation, we quantitatively analyzed the effects of ionospheric TEC (Total Electron Content) and space loss on the received power. During the processing of observation data, we construct a geometric propagation model utilizing the measured positions of both the satellite and the ship. We then calculate the antenna gain and remove any system errors. Additionally, we eliminate the deviation of elevation and azimuth angles caused by satellite motion. This allows us to determine the actual power of different ships reaching the receiving platform. Upon comparing the measured power data with the simulated power, it was noted that both exhibited an increasing trend as the elevation angle increased. This led to an RMSE (Root Mean Square Error) result of approximately one, indicating the accuracy of the simulation system. These findings hold significant implications for analyzing interference factors in satellite-ground links. [ABSTRACT FROM AUTHOR]

Accurate prediction of rain attenuation is critical for the design of terrestrial line‐of‐sight link systems above 5 GHz, particularly for millimetre‐wave frequency. Anomalous behaviour in the adjustment factor in existing rain attenuation prediction models is significantly greater than 1 at short distances and has been reported. To solve this problem and improve the accuracy, a rain attenuation prediction model for terrestrial line‐of‐sight links is proposed. The total rain attenuation described in the model accounts for the contributions of wet antenna attenuation and path rain attenuation. In addition, a rainfall rate adjustment factor is proposed. The proposed model has a root‐mean‐square error of 21.54% in prediction, which is an improvement compared to other existing models. Because the rainfall rate adjustment factor used in the model approaches 1 at short distances, the model can be applied to rain attenuation prediction for short‐distance links. The results will assist designers to design link margins more accurately. [ABSTRACT FROM AUTHOR]

Carbon fiber (CF) reinforced polyphenylene sulfide (PPS) composite shows extraordinary thermal stability, chemical resistance, and processability. The interface between CF and PPS transfers the load, and its properties are crucial to determine composite properties such as mechanical performance, reliability, and so forth. This work explores the relationship between surface properties of CFs (with/without sizing layer) and the interfacial properties of CF/PPS composite. X‐ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscope were employed to evaluate surface physicochemical properties of CFs, and reveal the increasing roughness and decreasing content of functional groups on the CF surface after desizing. Inverse gas chromatography and dynamic contact angle tests were adopted to characterize the surface energy of CFs, and present that the dispersive component of surface energy increases, while the polar component decreases, and the total surface energy is barely changed after desizing. Differential scanning calorimetry measurement reveals the increasing crystallinity of CF/PPS after CF desizing. Microbond test was performed to analyze interfacial shear strength (IFSS) of CF/PPS, displays that IFSS keeps almost constant after CF desizing. The results demonstrate that the surface energy of CF is important to the interfacial crystallinity, but not the critical factor for interfacial strength of CF/PPS composite. [ABSTRACT FROM AUTHOR]

Ternary CoNi 2 S 4 one-dimensional nanorods with the average diameter of 200 nm were synthesized by a simple hydrothermal method without any surfactant or template. One-dimensional geometry could improve the utilization of electrode material, shorten electron diffusion path, and accommodate the volume change during cycling. As an anode for lithium ion batteries, the CoNi 2 S 4 nanorod material exhibits a remarkably improved electrochemical performances in terms of lithium storage capacity (1575.1 mA h g −1 at 100 mA g −1 rate), initial coulombic efficiency (79%), cycling stability (76% capacity retention after 50 cycles). The enhanced lithium storage capacities can be mainly attributed to the designed nanostructure of ternary CoNi 2 S 4 , good conductivity, and the synergistic effects between cobalt sulfides and nickel sulfides. [ABSTRACT FROM AUTHOR]

Pre-trained Language Models (PLMs) have been shown to inherit and even amplify the social biases contained in the training corpus, leading to undesired stereotype in real-world applications. Existing techniques for mitigating the social biases of PLMs mainly rely on data augmentation with manually designed prior knowledge or fine-tuning with abundant external corpora to debias. However, these methods are not only limited by artificial experience, but also consume a lot of resources to access all the parameters of the PLMs and are prone to introduce new external biases when fine-tuning with external corpora. In this paper, we propose a C ontrastive Self- D ebiasing Model with D ouble D ata Augmentation (named CD3) for mitigating social biases of PLMs. Specifically, CD3 consists of two stages: double data augmentation and contrastive self-debiasing. First, we build on counterfactual data augmentation to perform a secondary augmentation using biased prompts that are automatically searched by maximizing the differences in PLMs' encoding across demographic groups. Double data augmentation further amplifies the biases between sample pairs to break the limitations of previous debiasing models that heavily rely on prior knowledge in data augmentation. We then leverage the augmented data for contrastive learning to train a plug-and-play adapter to mitigate the social biases in PLMs' encoding without tuning the PLMs. Extensive experimental results on BERT, ALBERT, and RoBERTa on several real-world datasets and fairness metrics show that CD3 outperforms baseline models on gender debiasing and race debiasing while retaining the language modeling capabilities of PLMs. [ABSTRACT FROM AUTHOR]

The preparation of continuous carbon fiber reinforced polyether ether ketone (PEEK) composites by the powder slurry method has many advantages, but the stability of PEEK suspension is required to be high. So far, there is a lack of in‐depth studies on the aqueous suspension of PEEK. In this study, two non‐ionic surfactants were selected for compounding. Then PEEK aqueous suspension and continuous carbon fiber reinforced PEEK composites were prepared. The stability mechanism of PEEK aqueous suspension with different surfactants was analyzed. Studies have shown that in the PEEK aqueous suspension, Triton X‐100 can help to infiltrate the PEEK powder. The steric hindrance of polyethylene glycol contributes to the stability of the suspension. The synergistic steric hindrance effect of the two surfactants can increase the stability time of PEEK suspension from 5 min to more than 50 min. The PEEK composites prepared by the powder slurry method has good quality stability, the fiber volume fraction is about 60%, the flexural strength of the composites can reach 1336 MPa, and the interlayer shear strength can reach 106 MPa. This study provides useful insights for the stability mechanism of PEEK aqueous suspension, and can guide the preparation process of thermoplastic composites by powder slurry method. [ABSTRACT FROM AUTHOR]

Abstract The weak binding force of oxygenated species on metal-nitrogen-carbon catalytic sites severely restricts the catalytic activities towards the oxygen reduction reaction. Herein, we report a one-step method for the in-situ immobilization of poly(p -phenylenediamine-formaldehyde) on the Co, Zn-zeolitic imidazolate frameworks to construct pyrrolic/graphitic N-rich Co-N-C structures. Pyrrolic/graphitic N species derived from poly(p -phenylenediamine-formaldehyde) reduce the electron localization around the Co centers for increasing the charge polarization between Co and neighboring N atoms, leading to strengthening the adsorption of oxygenated species and improving the intrinsic activity. What's more, pyrrolic/graphitic N-rich Co-N-C structures conserve the characteristics of zeolitic imidazolate frameworks-derived catalysts, such as, large surface area, high pore volume, and atomically dispersed Co species, to fully expose efficient Co-N-C catalytic sites. Hence, the resultants as precious-metal-free catalysts demonstrate excellent catalytic activities in acidic and alkaline media, and are even superior to that of the state-of-the-art Pt/C catalyst in an alkaline environment. Moreover, doping S atoms into carbon lattice induces the asymmetric electron and spin densities of adjacent carbon atoms for providing for more oxygen adsorption sites and facilitating the formation of the OOH species, resulting in synergistically boosting the ORR activity in an acidic environment with efficient Co-N-C sites. Graphical abstract Image 1 Highlights • A facile one-step method is proposed to prepare the Co, Zn-ZIF/P p PDF complex. • P p PDF-derived N-doped carbon contains rich pyyrolic and graphitic N species. • Pyrrolic/graphitic N species weaken the electron localization around the Co centers. • The electron depletion strengthens the oxygen adsorption and ORR intrinsic activity. • The ORR activity in acidic media is improved with doping S species into the Co-N-C. [ABSTRACT FROM AUTHOR]

Abstract The long-debated intrinsic nature, less exposed active sites, as well as the tedious fabrication process of the metal-nitrogen-carbon structures severely impede the applications in the energy storage and conversion devices. Herein, we report a facile Ostwald ripening-assisted template method to controllably synthesize one-dimensional S-doped Co/N/C mesoporous nanorods as electrode materials for electrocatalytic oxygen reduction and Li-ions batteries. Introducing the S doping into the Co/N/C structure increases the intrinsic activity and electrochemically active surface area, and the structural characteristics (e.g. , the surface area, pore structure) of mesoporous nanorods are optimized on the basis of the Ostwald ripening effect for sufficiently exposing active centres and facilitating fast ion transport. Hence, it demonstrates efficient catalytic activity towards the oxygen reduction reaction in alkaline medium with the half-wave potential of 0.890 V vs. RHE, and even outerperforms the state-of-the-art Pt/C catalyst. In addition, as the anode material for Li-ion batteries, it also exhibits superior electrochemical performance with the specific capacity of 623.3 mAh g−1 after 500 cycles at 1.0 A g−1. Graphical abstract Image 1 Highlights • A facile template method is reported to synthesize S-doped Co/N/C MNR. • The MNR structure is controlled on the basis of the Ostwald ripening effect. • Highly dispersed Co/N/C active sites are formed to inhibit the self-aggregation. • Introducing the S doping in the Co/N/C structure enhances the intrinsic activity. • It demonstrates excellent ORR activity and enhanced Li storage performance. [ABSTRACT FROM AUTHOR]

Ideally, excellent heat-insulating material should have low thermal conductivity, low density, excellent resistance to high and low temperatures and good mechanical properties. But few materials can meet all the above requirements at the same time. Take polyimide (PI) aerogel as an example. Although it has the advantages of lightweight, good mechanical properties and excellent temperature resistance, the value of its thermal conductivity is often unsatisfactory. To solve this problem, a series of mesoporous polyimide aerogels using aminated SiO 2 nanoparticles as cross-linker have been prepared. By changing the content of SiO 2 and the synthetic methods, the key properties of PI aerogels such as the density and thermal conductivity were effectively tuned. These aerogels have low density, high specific modulus, significantly low thermal conductivity (~20 mW m−1 K−1), and excellent high temperature resistance. Their general properties (shrinkage, density, compression performances, specific surface area, pore size distribution, high temperature resistance) and their application potential as lightweight, high-performance thermal insulation materials in harsh environments are discussed. [Display omitted] • Aminated SiO 2 nanoparticles used as cross-linker to prepare mesoporous polyimide aerogels. • The aerogels prepared in this work have a low density (~0.08g/cm3) and a very low thermal conductivity (20.1mW/m·K). • These aerogels have excellent thermal insulation performance at 80, 120 and 160°C. • The PI-20 aerogel still has great thermal insulation performance and thermal stability after the heat treatment at 160°C. [ABSTRACT FROM AUTHOR]