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In order to reduce the etching effect of the catalysts to carbon fibers caused by high temperature during the chemical vapor deposition (CVD) process, four multi-element catalysts, Fe–Co, Fe–Ni, Co–Ni and Fe–Co–Ni, were used to realize the low temperature growth of carbon nanotubes (CNTs) on carbon fibers at 350 °C–400 °C. The results show that the growth state of CNTs has a great relationship with the type of catalysts. The catalytic efficiency of Fe–Co catalysts is low, but the graphitization degree of CNTs is relatively high. The Fe–Co–Ni catalysts has high catalytic efficiency but low graphitization degree of CNTs. The tensile strength of carbon fiber/CNTs reinforcements prepared by Fe–Ni catalysts at 400 °C is the highest, reaching 3.99 GPa, which is 11.14% higher than that of desized fiber. The melt drop phenomenon of the catalysts was found by TEM, indicating the formation of the liquid phase catalysts during the growth of CNTs. This phenomenon can change the diffusion mode of carbon atoms in the catalyst and significantly reduce the growth activation energy of CNTs, so that CNTs can grow at lower temperatures. Based on the detailed analysis of the CVD process, a low temperature growth model of CNTs on carbon fibers was proposed. [ABSTRACT FROM AUTHOR]

Ultrathin sectioning and solvent etching were used to assess microstructural changes in polyacrylonitrile (PAN) fibrils following a dry-jet wet spinning process. Morphologic assessment revealed the coexistence of fibrils and lamellae within the PAN fibers, with a frill-like structure found on the fibrils. The size of the lamella-like layers was consistent with a crystal size of 13.2 nm as characterized by X-ray diffraction and microfibrils were composed of alternate dark lamella-like crystal layers and surrounded by bright amorphous chains. Further, fibril arrangement followed a weave-like pattern. During the post-spinning process, break-rearrangement of chain-folded lamellae had an important role in fibril structure evolution. The high stream stretching and heat treatment induced the breaking of lamellae and the formation of new lamellae through the molecular chains rotating and slipping, resulting in a decrease in voids and the coalescence of microfibrils. Consequently, the fibrils were arranged in a more orderly manner and interlinked more tightly, a process conducive for the preparation of high quality PAN fibers. [ABSTRACT FROM AUTHOR]

[Display omitted] Modulating the structure and morphology is essential in fabricating high-performance electromagnetic absorbing materials. Herein, we obtained porous Fe 3 O 4 /carbon hollow microspheres and porous Fe 4 N/carbon hollow microspheres derived from Fe-glycerol hollow microspheres. Through structure and morphology analysis, we proved the existence of porous and hollow features. By comparison, it can be found that the porous Fe 4 N/carbon hollow microspheres have electromagnetic wave absorption performance superior to that of porous Fe 3 O 4 /carbon hollow microspheres. The reflection loss value of porous Fe 4 N/carbon hollow microspheres reaches −42.2 dB at a matching thickness of merely 1.4 mm, and its effective absorbing bandwidth approaches 4.5 GHz, whereas the reflection loss of porous Fe 3 O 4 /carbon hollow microspheres in the 2–18 GHz range is over −10 dB. Reasons for the better electromagnetic wave absorption performance are revealed to be that the magnetic Fe 4 N has higher complex permittivity and complex permeability, and the porous hollow microspherical structure increases the multiple scattering and reflection of electromagnetic waves. Meanwhile, the impedance matching and attenuation constant are optimized together through the synergy of dielectric and magnetic loss. This research can provide instructive findings for thin-thickness electromagnetic wave absorbing materials based on Fe 4 N with an appropriate microstructure. [ABSTRACT FROM AUTHOR]

The mechanical properties of carbon fiber composites depend on the interfacial strength between fiber and epoxy matrix. Different poly (amido amine) (PAMAM) dendrimers were grafted onto carbon fiber to improve the interfacial strength of the resulting composites. Functional groups on the carbon fiber surface were examined by X-ray photoelectron spectroscopy. The surface morphology of the resulting materials was characterized by scanning electron microscopy and atomic force microscope. The characterization results revealed that PAMAM dendrimers were chemically grafted onto the surface of carbon fiber. More importantly, the mechanical properties of the resulting composites were enhanced owing to the presence of sufficient functional groups on the carbon fiber surface. In addition, after PAMAM containing chair conformations were grafted, the interlaminar shear strength had the highest increase of 53.13%, higher than that of the fiber grafted with PAMAM containing terminated linear amine. This work provides an alternative approach to enhance the mechanical properties of fiber composites by controlling the interface between fiber and epoxy matrix. [ABSTRACT FROM AUTHOR]

Most commercial polyacrylonitrile-based carbon fibers are microfibers derived from the wet-spinning or dry-jet wet-spinning polyacrylonitrile fiber. Nano carbon fibers made by electrospinning and post-processing have many advantages over micro carbon fibers in performance, but the research on nano carbon fibers is far from enough. In this work, polyacrylonitrile-based nano- and microfibers obtained by electrospinning and dry-jet wet spinning are converted into nano- and micro carbon fibers under the same pre-oxidation and carbonization conditions. The evolution of morphology, elemental content, functional groups and apparent crystallinity of the two size-scale fibers before and after carbonization are studied. The relationship between their structure and their electrical property is speculated. The results show that pre-oxidized nano fibers' absorption of visible light is much weaker than microfibers. The oxygen content of the pre-oxidized nanofibers is higher, and the carbon content in the carbonization process is always higher than that of microfibers. The nanofibers are more accessible to crystallize than microfibers. They can obtain better electrical properties than microfibers and have a more excellent application prospect as conductive fillers in antistatic composites. [ABSTRACT FROM AUTHOR]

Evaluating the impact of different meteorological conditions on apple yield and predicting the future yield in Yantai City is essential for production. Furthermore, it provides a scientific basis for the increase in apple yield. In this study, first, a grey relational analysis (GRA) was used to determine the quantitative relationship between different meteorological factors and meteorological yield which is defined as affected only by meteorological conditions. Then, the comprehensive meteorological factors extracted by a principal component analysis (PCA) were used as inputs for multiple linear regression (MLR). The apple yield accuracy was compared with the lasso regression prediction. Trend analysis showed that the actual apple yield increased annually, but the meteorological yield decreased annually over a long time. Correlation ranking illustrated that the meteorological yield was significantly correlated with the frost-free period, the annual mean temperature, the accumulated temperature above 10 °C, etc. The good consistency between GRA and MLR–PCA showed that the accumulated temperature above 10 °C, the March–October mean temperature, and the June–August mean temperature are key meteorological factors. In addition, it was found that the principal components F 2 ,   F 4 , and F 5 were negatively correlated with meteorological yield, while the principal components F 1 and F 3 were positively correlated with meteorological yield. Moreover, the MLR–PCA model predicted the apple yield in 2020 as 47.256 t·ha−1 with a 7.089% relative error. This work demonstrates that the principal component regression model can effectively extract information about different meteorological factors and improve the model's accuracy for analyzing key meteorological factors and predicting apple yield. [ABSTRACT FROM AUTHOR]

The effects of electrospinning parameters in a wider range on the morphology and diameters of polyacrylonitrile (PAN) fibers are studied in detail. The fibers' diameter increases from 288 to 3469 nm swiftly with the increasing PAN concentration. With the increasing voltage or prolonging gap distance, the diameter increases primarily and decreases later. The combined effects of surface tension, splitting and stretching, electric force, viscosity, and solvent volatilization are the main reasons. Ultrasonic etching method, Atomic force microscope (AFM), Scanning electron microscope (SEM) and X-ray diffraction (XRD) technology have been utilized to verify the nature structure of electrospun PAN fibers. Combining all the results, it is deduced that there are many grooves arranging nearly perpendicular to the fiber axis on the surface of electrospun PAN fibers. The thickness of relative ordered region is 40 to 190 nm and the thickness of amorphous region is 20 to 35 nm. [ABSTRACT FROM AUTHOR]

• A detail map of chemical and morphological evolution of fibers was investigated. • High stabilization temperature programs facilitated the cyclization reaction. • The radial structure difference increased firstly and then decreased in the later stage. The thermal stabilization process is a crucial stage for microstructure transformation and quality of carbon fibers, which is determined by the stabilization temperature gradient. In this work, the effect of the temperature gradient on the evolution of both chemical structures and physical morphology of polyacrylonitrile (PAN) fibers at multistage of thermal stabilization process was investigated. Combined with functional groups, oxygen element content, and aromatization index, increasing temperature reasonably shifted oxidation and cyclization reaction into early stage and the corresponding samples possessed relatively large degree of cyclization. It was worth noting that high stabilization temperature gradient could accelerate the formation of the conjugated structures at early stage and facilitate the cyclization reaction in the stabilized fibers. As for morphologies, there were aligned microfibrils and transvers lamellae in stabilized fibers. Their radial structure difference increased firstly and then decreased in the later stage. The tensile strength and tensile modulus decreased during the thermal stabilization process. Moreover, increasing temperature resulted in reduction of tensile strength and tensile modulus, which was mainly resulted by the high degree of cyclization instead of structural defects. These results guide the design and optimization of temperature program and adjusting the processing parameters for all commercially PAN fibers without any additional conditions. [ABSTRACT FROM AUTHOR]

Wearable and bicontinuous Ag-doped poly (3,4-ethylenedioxythiophene): poly (styrenesulfonate)/MnO 2 /carbon fabric was manufactured in a facile, eco-friendly, and scalable approach. The high temperature-resistant textile performed a maximum specific capacitance of 2.97 F cm−2, and delivered 113 % retention at 80 °C compared with that at room temperature. At a cooling-heating-cooling cycle, the capacitance could recover to its initial value after 10000 charge-discharge tests at 20 mA cm−2. Density function theory proves that Ag dopants and the S-containing functional group improve the adsorption ability with Na+. The maximum energy and power density achieved 19.36 mWh cm−3 and 530.50 mW cm−3 over a wide potential window of 2 V, respectively. Moreover, the fabric could be operated at low-temperature climates by multi-offset Joule heating performance and a deicing/dewatering ability. The antimicrobial capacity against typical bacteria and fungi renders robust safety to the wearable electronics. The fabric performed shielding effectiveness of 45.95 dB at 377 μm and reliable durability after 1000 times bending cycles. The reflection-dominant shielding mechanism was further revealed by COMSOL Multiphysics software. The all-in-one fabric complies with Internet of Things design and can endure extreme environments over a wide temperature range, implying great potential for energy storage, thermal management, bacteriostasis, and electromagnetic protection. [Display omitted] • Ag-doped PEDOT: PSS/MnO 2 /carbon fabric was designed in an eco-friendly approach. • The cloth displayed a high temperature-resistant electrochemical performance. • DFT simulation indicates the improved Na + affinity due to Ag dopants and S-containing functional groups. • The textile showed mechanical-tolerant electromagnetic interference shielding property. • COMSOL software shows the reflection-dominant shielding mechanism. [ABSTRACT FROM AUTHOR]

The carbon matrix composites with three-dimensional porous structure and multiple phases were prepared by heat treatment of nano-Fe and polyacrylonitrile (PAN) precursor with different content of nano-Fe. The phase and morphology changes of the samples during heat treatment were investigated, and their electromagnetic properties and microwave absorption performance were compared in the frequency range of 2–18 GHz. The Fe4N@Fe3O4@Fe/carbon composite presents a three-dimensional porous structure with an average pore size of 5 μm. Fe4N and Fe3O4 can be generated in situ by the reaction of Fe with active N and O in PAN, which is helpful to improve the dielectric and magnetic losses of the composite. PAN can be cyclized, crosslinked and pyrolyzed to form graphite carbon and amorphous carbon, and various reactions in the heat treatment process, the heterogeneous interfaces between magnetic phases and carbon matrix were formed, which can enhance the interfacial polarization relaxation. With the increase in nano-Fe content, the magnetic loss increases, and with the increase in magnetic particle content and coating thickness, the absorption peak tends to move to lower frequency. When the mass ratio of Fe/PAN in the precursor is 120%, the lowest reflection loss of the composite is − 37 dB at 13 GHz, and the effective absorption bandwidth is 3.23 GHz (11.54–14.77 GHz) with 1.5 mm thickness. When the mass ratio is 180%, the lowest reflection loss is − 33 dB at 4.7 GHz. This study not only provides a simple method to prepare porous carbon and ferromagnetic composites, but also shows that Fe4N has great potential in the application of wave absorbers. [ABSTRACT FROM AUTHOR]

Abstract: This paper investigates a novel two-step heating process to transient liquid phase (TLP) bond dissimilar steels between 45MnMoB and 30CrMnSi. The process consists of a short-time high temperature heating followed by isothermal solidification at a lower temperature. The microstructure and mechanical properties of the bonds were investigated and compared with that of conventional TLP bond made at a constant bonding temperature. The results show that the two-step heating process can change the interface morphology from planar to non-planar and increase the curvature of the non-planar interface during TLP bonding. The voids are decreased and the bending strength is increased with the increase of isothermal solidification temperature during two-step TLP bonding. Compared to conventional TLP bonding, the two-step heating can reduce the voids and improve the bond strength near similar bonding temperature within minutes. Production tests show that the two-step heating has the potential application in industry. Modeling of interface morphology and defects in the joint are also discussed. [Copyright &y& Elsevier]

[Display omitted] • Carbonaceous fibers were hydrophobically treated with hexadecyltrimethoxysilane. • Moisture resistance of fibers was improved through simple impregnation modification. • The accelerated environmental test proved the more stable resistivity of fibers. Although the general carbon fibers are very stable, low-temperature carbonized carbonaceous fibers were sensitive to moisture, which would lead to unstable electrical conductivity, and seriously endanger the antistatic properties of antistatic coating when carbonaceous fibers were used as conductive filler. In this work, a simple dipping modification is proposed to improve the stability of fiber resistivity by using a long carbon chain silane coupling agent (hexadecyltrimethoxysilane) to perform surface moisture-proof treatment on carbonaceous fibers. The modification was demonstrated to significantly improve the stability of fiber resistivity by accelerated experiments in hygrothermal and salt spray environments. After 72 h treatment in hygrothermal environment, the increase percentage of untreated carbonaceous fiber resistivity reached 70%. Nevertheless, that of CF@KH1631-6 was 40%. Good hydrophobicity was achieved at a concentration of 6 wt%, water contact angle increasing from 135.6° to 152.2°. Furthermore, the whole preparation process had the potential of large-scale industrial production and application. [ABSTRACT FROM AUTHOR]

The refined design of γ′-Fe 4 N structure plays a significant role in enhancing microwave absorption performance. γ′-Fe 4 N@iron oxides particles have been fabricated through an economical one-step gaseous nitriding method. The loss mechanism of the particles was studied, and the electromagnetic properties were also investigated in the frequency range of 2–18 GHz. The results show that γ′-Fe 4 N@iron oxides particles form a hierarchical structure with outer amorphous iron oxides, secondary outer Fe 3 O 4 , and inner γ′-Fe 4 N. Equipped with rugged surfaces and heterogeneities, the γ′-Fe 4 N@iron oxides particles feature multiple reflection and polarization characteristic, resulting in multiple relaxations in the interior of the as-fabricated particles, which enhance the microwave absorption properties. Its minimum reflection loss (RL) value can reach −38.5 dB with a thickness of 1.24 mm. We provide a facile method to fabricate particles with core-shell structure, which have great prospects for applications in microwave absorption field. [ABSTRACT FROM AUTHOR]

This article provides a method for growing carbon nanotubes(CNTs) on carbon fibers(CFs) using iron and nickel as catalysts at low temperatures. This series of experiments was conducted in a vacuum chemical vapor deposition(CVD)furnace. It is found that Fe–Ni catalysts, which have a certain thickness and can be better combined with resins when manufacturing composite materials, are more ideal for the growth of CNTs than single metal catalysts. At the same time, it is proved that the CVD process worked best at 450 °C. The mechanical property test proved the reinforcing effect of CNTs on carbon fiber, the single-filament tensile strength of CFs obtained by using Fe–Ni catalyst at 450 °C was 11% higher than that of Desized CFs. The bonding strength of carbon fiber and resin has also been significantly improved. When synthesized at low temperature, CNTs exhibited a hollow multi-wall structure. [ABSTRACT FROM AUTHOR]

Graphene (GN) is transformed into carboxylic graphene (GO-COOH) with carboxylic groups by acidizing. Carboxylic graphene/polyimide (GO-COOH/PI) composite films are prepared by in-situ polymerization. The composite films show strong intermolecular force compared to the PI films which leads to excellent tensile strength and thermal conductivity. The composite films can be transformed into carbon films and graphite films by carbonization and graphitization. The GO-COOH can induce the graphitization process and compensate the defects. The thermal conductivity of graphite films prepared by composite films graphitized at the same temperature is higher compared to that of PI films. The addition of GO-COOH has great effects on reducing carbonization and graphitization temperature and improving property of films. The graphite films treated with 2500 °C possess smoother surface and the color of graphite films turn into dark grey. The films can keep the integral state and bend to a certain extent which exhibits that the flexibility of the graphite films is improved. The thermal conductivity of graphite films prepared by composite films treated with 2500 °C is 760.386 W/mK and increases by 128% compared to that prepared by the PI films, which is suitable for the application of heat conduction. [ABSTRACT FROM AUTHOR]

Two kinds of Fe/C nanofibers were prepared by electrospinning and calcination under the same process conditions. A simple way was used to adjust the size of the Fe nanoparticles by using different spinning solvents. The one was prepared by a mixture of water and anhydrous alcohol as solvents (named as CNF water) and the other by N,N-Dimethylformamide and anhydrous alcohol (named as CNF DMF). Due to the higher solubility to iron salts and larger surface tension of water, CNF water gained a larger size of Fe nanoparticles and average diameter. In addition, the graphite layers wrapped on Fe nanoparticles which were formed during calcination were thinner in CNF water than CNF DMF. These factors endowed CNF water better microwave absorption performance. The results of XRD, SEM, HRTEM, Raman, magnetostatic and electromagnetic properties analysis revealed the influence mechanisms of solvents on the formation, microstructure and properties of Fe/C nanofibers. [ABSTRACT FROM AUTHOR]

The effect of spinning speed on the microstructures and mechanical properties of polyacrylonitrile (PAN) fibers and carbon fibers was investigated. The microstructures and mechanical properties of PAN fibers and resulted carbon fibers were characterized. When winding speed increased from 63m/min to 95m/min, the fibers still exhibited smooth surfaces, and the diameter and aspect ratio of fibrils increased. In early spinning stages, the lamellae were arranged orderly and PAN fibers had larger crystallinity at low spinning speed. After densifying process, the crystal layers were stacked regularly and their crystallinity was larger at high spinning speed, and the resulted precursor fibers had big thermal stability and large dimethylsulfoxide (DMSO) residue value. Meanwhile, the tendency of mechanical strengths of PAN fibers was in accord with their crystallinity changes. Increasing spinning speed brought the negative influence on microstructures and mechanical properties of the resulted carbon fibers, and the carbon fibers owned low tensile strength due to relatively poor crystallinity and graphitic structures. [ABSTRACT FROM AUTHOR]

Carbon fiber (CF) reinforced composite materials are highly sought after for their exceptional mechanical properties and functional capabilities, making them promising materials for applications in aerospace and other industries. In this study, we aimed to construct a medium modulus interfacial layer using the layer-by-layer construction (LBL) method. This was achieved by grafting rigid dendritic polymers onto the surface of the carbon fiber, with the branch density being adjustable based on the reaction time. The rigid branched structure of the dendritic polymer and the numerous functional groups provide physical entanglement and stronger mechanical bonding at the interface, great chemical bonding. This distinctive structure improves the interfacial compatibility of the composite and enhances its mechanical properties. Following treatment, the tensile properties of the fibres are increased by approximately 20 %, suggesting that the treatment process effectively repairs surface defects on the fiber. Compared to untreated carbon fiber composites, the tensile properties of CF-M-P3 have improved by approximately 11 %. Furthermore, the thermal weight loss of the composite material is significantly reduced due to the branching of its rigid dendritic structure. The weight loss percentage decreased from 16.84 % to 7.89 % after being held at a temperature of 350 °C for a duration of 4 h. [Display omitted] • Grafting of dendritic polymers on the surface of carbon fibers by a simple method. • Dendritic polymers grafted on the fiber surface help improve the mechanical properties of the composite. • Dendritic polymers grafted on the fiber surface help improve the temperature resistance of the composite. [ABSTRACT FROM AUTHOR]

• Hierarchical Co 3 O 4 /Co@CNFs/CNTs/CF hybrids are fabricated by a scalable approach. • Magnetic-dielectric loss and ideal impedance produce super microwave absorption. • A RL min of −60.85 dB at 1.22 mm and an EAB of 4.24 GHz at 1.38 mm are obtained. • The SRL of CFF650 outperforms many previous prominent carbon-based composites. • CST simulation results confirm the stealth potential in practical application. Aiming to solve the aggravating electromagnetic radiation issues, high-performance electromagnetic wave (EMW) absorbers are urgently required. Recently, integrating carbonaceous and magnetic materials to obtain dielectric-magnetic double EMW loss has been intensively explored. Here, Co 3 O 4 /Co@carbon nanofibers/carbon nanotubes anchored on carbon fiber (Co 3 O 4 /Co@CNFs/CNTs/CF) hybrids (CFFs) with distinctive heterostructure were synthesized by annealing ZIF-67@CF and catalytic chemical vapor deposition, and deliver great superiorities in microwave dissipation. Specifically, when at a low filling ratio of 25 wt% in paraffin wax, CFF650 acquires a superb minimum reflection loss up to −60.85 dB at only 1.22 mm together with a broad effective absorption bandwidth of 4.24 GHz at merely 1.38 mm. Remarkably, the specific reflection loss of CFF650 achieves an unexpected value, comparable to many distinguished carbon-based composites previously reported. Besides, the simulation of radar cross section values ascertains the fulfilling stealth ability of CFFs under radar detection. These excellent characteristics benefit from the diverse components and unique heterostructures, which form rich conductive networks, plentiful heterogeneous interfaces, appropriate defect polarization and dipole polarization, sufficient magnetic loss as well as optimal impedance matching. Combined with the feasible and efficient fabrication method, this work offers a significant promise of CF-based composites for practical applications in EMW absorption. [ABSTRACT FROM AUTHOR]

The low-temperature‑carbonized carbon fiber (CF) with different diameters modified with silane coupling agent was prepared as the fillers and added into silicone resin (SR) composite coatings, in order to investigate the effects of the diameter and modification of fibers on the mechanical and electronic properties of the CF/SR composite coatings. The results of surface microscopy and structural analysis showed that more coupling agents were coated on the surface of thick fibers (TCFs) with a larger diameter, which provided more chemical bonds and mechanical meshing than fine fibers (FCFs) with a smaller diameter. The mechanical test and electrical test illustrated that the decrease in the diameter of fibers cannot only increase the mechanical properties of the composite coatings but also enhanced the surface resistivity with fewer amounts of fibers, which reduced the cost of the application. In particular, the surface resistivity of 2wt%TCF/SR was 11.60 MΩ/square, which was 455.02 % higher than that of 2wt%FCF/SR (2.09 MΩ/square). In addition, the silane coupling agent treatment also increased the mechanical properties and the surface resistivity of the composite coating. The surface resistivity of 2wt.%FCF-A/SR was 24.94 MΩ/square, while that of 2wt.%TCF-A/SR was 60.42 MΩ/square. Meanwhile, reducing the fiber diameter and the silane coupling agent treatment could increase the dielectric constant and dielectric loss of the coating, while could also meet the requirements in the wave transmission performance during the application of coatings. This paper illustrates that reasonable control of diameter and modification is required to improve the comprehensive performance of silicone composite coatings. It guides the application in the electrical magnetic interference field as well as the improved functionality of the composites. • The AMT modification of TCFs increased the roughness and provided more mechanical meshing for improving the interface bond than FCFs. • The reduction of fiber diameter and the modification improved the mechanical property attributed to the more crack deflection and interface adhesion. • The surface resistivity of FCF/SR was lower than that of TCF/SR because of the more conductive network. [ABSTRACT FROM AUTHOR]

This paper provides a continuous method for grafting carbon nanotubes (CNTs) on the surface of carbon fibers by chemical vapor deposition (CVD). The control of the morphology of CNTs/CFs can be achieved by adding thiourea to the cobalt nitrate precursor. The sulfur can increase the catalytic activity of the Co catalyst. Scanning electron microscopy reveals that a uniform layer of CNTs is grafted onto the surface of carbon fibers with the presence of thiourea. Through the single-filament tensile strength test, it can be found that the tensile strength of the fiber is increased by up to about 10% compared with the desized carbon fibers after the CVD process. And the reason for the enhancement is explored through X-ray diffraction. Raman spectroscopy reveals that the sample possesses the highest degree of graphitization at a thiourea concentration of 0.02 mol/L. It is found by high-resolution transmission electron microscopy that the growth mechanism of CNTs is tip growth mechanism, and the diameter of the CNTs is about 15 nm. [ABSTRACT FROM AUTHOR]

Mechanical properties and thermal resistance reinforcement were achieved by a one-step dipping method, in which an aniline-methyl-triethoxysilane (AMT) coupling agent was grafted onto the carbonaceous fiber (CF) to fabricate CF/silicone resin (SR) composite coatings. Micromorphology and structure analysis of carbonaceous fibers showed that the AMT modification increase the roughness and the uniformity on the fiber surface, resulting in the link between AMT and fiber surface, and the polysiloxane formation by polymerization between the Si-OH groups. The AMT modification of the fiber surface introduced the AMT with a disordered structure on the fiber surface and improved the compatibility between CFs and SR. Mechanical testing showed that the tensile strength and elongation rate of the coating containing CF modified with 1wt%AMT coupling agent was increased by 45.32 % and 19.07 % compared with that of the unmodified one, respectively. The reinforcing mechanism revealed that the AMT modification improved interfacial bonding and mechanical riveting. Besides, the thermogravimetric analysis (TGA) analysis showed that the siloxane layer crosslinked at a high temperature, which was conducive to improving the thermal resistance for the long-term stability of the composite coatings. This special treatment provides an idea for simultaneously improving the mechanical properties and thermal resistance of silicone composites. [Display omitted] • A simple process to modify carbonaceous fibers (CFs) is used by an aniline-methyl-triethoxysilane coupling agent. • The siloxane layer provides stress transfer and mechanical riveting between carbonaceous fibers and silicone resin (SR). • The tensile strength of the modified CF/SR increased by 45.32 % compared with unmodified CF/SR. • The thermal resistance of the modified CF/SR for the long-term use at 350 °C increased because of the siloxane layer. [ABSTRACT FROM AUTHOR]

• A stealth coating with not only low infrared emissivity in mid and far infrared band, but also wave-transparent performance in the radar band. • The floating Al powder was firstly modified with paraffin wax (PW) and the effects of Al@PW powder on the various properties of the composite coatings were disclosed. • The composite coating can meet the multi-function requirements of airborne radome. Low Infrared (IR) emissivity coatings in military aerospace need to meet both stealth and radar transmission. At present, there are few research on this aspect, therefore how to solve the compatibility problem of low infrared emissivity and high radar wave transmission rate of materials is an important direction for the development of infrared stealth materials. A multi-functional composite coating with low IR emissivity, dielectric loss, and antistatic properties was prepared using modified floating aluminum powder (Al@PW), short-cut carbon fiber, and ethylene propylene diene monomer (EPDM) as the binder. The coating's properties were investigated, highlighting the effect of PW. The results indicate that modifying floating Al powder with PW is an effective solution to the trade-off between low IR emissivity and high wave transparency. At a dosage of 11 g (about 12.5 wt% in Al@PW), the coating demonstrated the best overall performance, including the IR emissivity of 0.582, the surface resistivity of 9.5 MΩ/□, the dielectric constant of 5.15, the dielectric loss angle tangent of 0.052, the tensile strength of 11.75 MPa, and the elongation at break of 516.10%. The composite coating may be used as a multi-functional protective coating for airborne radomes. [ABSTRACT FROM AUTHOR]

The interior microstructures of polyacrylonitrile nascent fibers is studied by the scanning electronic microscopy and the high-resolution transmission electron microscopy through ultrasonic etching and ultrathin sectioning. Due to the orientation and fold of molecular chains, the lamellae of 50-80 nm in thickness are formed. A high number of pores, ranging from dozens to two hundred nanometers in diameters exist between the lamellae, which result from residual solvent. The fibril structure is formed in the nascent fiber during the coagulation process, which are oriented along the fiber axis. An uneven tensile stress distribution leads to the formation of skin-core structures in the nascent fiber during the dry-jet wet spinning process. [ABSTRACT FROM AUTHOR]

A novel process has been successfully developed to grow carbon nanotubes (CNTs) on continuously moving carbon fibers (CF) surface by a unique open-ended chemical vapor deposition (CVD) furnace. Systematic researches were carried out under various deposition temperatures, velocities of continuous carbon fibers and catalyst concentrations. The morphologies and structures of CNTs were investigated by field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM), which indicated clearly that carbon fibers with uniformly distributed CNTs were achieved, with the optimum parameters of 650 °C deposition temperature and 6 cm min −1 velocity of continuous carbon fibers and 0.05 M catalyst concentration, respectively. By means of the single fiber push-out tests, the interfacial shear strength (IFSS) of carbon fibers growing CNTs was increased significantly by 84.4% compared to the desized carbon fibers. Furthermore, the results of single fiber tensile test verified that there is scarcely any degradation in the mechanical properties of carbon fibers after the growth of CNTs with the optimum parameters. This study provides a new and original vision for scalable manufacturing of CNTs on continuous moving substrate, when compared to the traditional batch process. [ABSTRACT FROM AUTHOR]

[Display omitted] • A simple ball milling process was used to prepare flaky FeSiAl. • Excellent low-frequency electromagnetic wave absorption performance. • Low-frequency electromagnetic wave absorption mechanism is closely related to magnetic loss. • The relationships of morphology and electromagnetic wave absorption properties were disclosed. The effect of morphology and size on electromagnetic wave (EMW) absorption performance has been a relentlessly explored issue. By grinding the spherical FeSiAl alloy powder in a planetary ball mill, a flaky FeSiAl alloy with higher saturation magnetization, dielectric constant, magnetic permeability, and better impedance matching at low frequency was prepared. The phase composition, morphology, and static magnetism of FeSiAl alloys with different morphologies were studied through X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometer (VSM). The electromagnetic parameters and absorption properties of the two kinds of powders were studied using a vector network analyzer (VNA). The results show that the crystallinity, dielectric constant, and magnetic permeability of the flaky FeSiAl powder increase compared with the spherical one. The absorption performance in the low-frequency band was remarkably improved after grinding. When the matching thickness is 6.5 mm, the reflection loss at 1 GHz reaches −16.89 dB for the flaky FeSiAl. The excellent EMW absorption performance of flaky FeSiAl alloy powder at low-frequency is mainly due to the large magnetic permeability and magnetic loss which is derived from the magnetocrystalline anisotropy brought about by lamellar morphology and appropriate impedance matching as well. This work provides a new idea for the preparation of low-frequency absorbing materials expected to be used in the L-band wave absorption field. [ABSTRACT FROM AUTHOR]

The study of infrared stealth-compatible, electromagnetic wave-transparent technology is currently receiving a lot of attention due to the functional specificity of the equipment, such as radomes. In this study, a new method of layered spraying was used to construct three-layer composite coatings, in which each layer was sprayed with a different formulation of paint. By adjusting the content of aluminum powder in each layer and keeping the content of carbon fiber (CF) at 4 wt%, the three-layer composite coatings achieved a balance of dielectric property, antistatic performance, and low infrared (IR) emissivity. The A3-A0-A0 composite coating, which matched the parameters for low IR emissivity and low dielectric property, had an IR emissivity of 0.498, a dielectric constant at 9.375 GHz of 6.23, and a dielectric loss of 0.038. The findings demonstrate that the aluminum powder content of the topmost layer had the sole significant impact on the three-layer composite coatings' IR emissivity, although the dielectric constant was strongly associated with the coating's overall aluminum powder content. The novel three-layer composite coating offers a brilliant concept for the study and development of materials that are compatible with wave transmission and infrared stealth. • A unique layering spraying procedure was used to make three-layer composite coatings. • The infrared emissivity depends on the amount of aluminum powder at the top. • Dielectric constant is correlated with the coating's overall powder concentration. • Low IR emissivity and wave transmission compatibility were attained. • Excellent performance, affordable, and easy to prepare. [ABSTRACT FROM AUTHOR]

Single-phase Fe 4 N has been synthesized by gaseous nitriding micro-sized and nano-sized Fe particles at 793 K under ammonia atmosphere. The electromagnetic properties of their wax composite with 75 wt.% magnetic particles have been investigated within the frequency range of 1–18 GHz. Both size and phase effects on the microwave absorption properties were discussed on the results of scanning electronic microscopy, X-ray diffraction, hysteresis loop, and the frequency dependence of complex permittivity and permeability. The results show that nano-sized particles have superior absorbing performance at lower frequency band than the corresponding micro-sized ones, which is mainly attributed to the higher dielectric constant caused by interfacial polarization. The Fe 4 N composites exhibit much stronger absorption in 2–8 GHz than Fe composites. The reflection loss (RL) values of less than −10 dB are observed in a wide frequency bandwidth from 1.8 to 11 GHz for nano-sized Fe 4 N composite with absorber thickness of 1.2–5.0 mm. Its minimum RL value (RL min = −33 dB) appears at 3.5 GHz with a thickness of 3.0 mm. This study demonstrates the possible application of producing thin and light absorbers from nano-sized Fe 4 N particles for microwave absorption at S and C bands (2–8 GHz). [ABSTRACT FROM AUTHOR]

• The modified EPDM significantly improved the mechanical property of the composite coatings. • Coatings with both infrared stealth and low dielectric property. • Comparison of modification effects of AA and MAH monomers. Composite coating materials or structures with low infrared emissivity and high radar transmittance are in urgent need in practical applications, among which binder is one of the important factors affecting the mechanical properties, infrared and dielectric properties of coatings. Acrylic acid (AA) and maleic anhydride (MAH) were used as graft monomers to modify ethylene propylene diene monomer (EPDM) binder. Composite coating with low infrared emissivity and low dielectric properties was prepared by using modified EPDM as binder, floating aluminum (Al) powder and antistatic carbonaceous fiber (CF) as filler. The effects of the type and amount of modified monomer on the mechanical properties, infrared emissivity and dielectric properties of the binder and the composite coating were systematically studied. The results show that the tensile strength (σ b) and elongation at break (e) of the composite coating can be increased by 32% and 18%, respectively, by appropriate grafting modification of the binder. The infrared emissivity and the dielectric properties of the composite coating has a slight change with the increase of graft monomer content. Grafting modification of the binder improves the compatibility, wettability and interfacial bonding between filler and binder, which remarkably enhanced the mechanical and comprehensive properties of the composite coating. The effect mechanism of grafting modification of AA and MAH is disclosed from the aspects of polarity, branching and crosslinking. This work increases the selection range of binders needed to prepare low infrared emissivity materials. [ABSTRACT FROM AUTHOR]

• Floating aluminum powder coated with SiO 2 was prepared using tetraethyl orthosilicate (TEOS) as raw material by sol-gel method. • The composite coating was prepared using modified Al powder and antistatic carbonaceous fiber (CF) as filler, EPDM as binder. • The composite coating that we prepared has low infrared emissivity compatible with high radar wave transmittance. Low infrared emissivity coatings have been widely used in many fields. At present, there are few researches on coatings that are compatible with low infrared emissivity and high radar wave transmittance. In this paper, floating aluminum (Al) powder coated with SiO 2 was prepared using tetraethyl orthosilicate (TEOS) as raw material by sol-gel method. The composite coating was prepared using modified Al powder and antistatic carbonaceous fiber (CF) as filler, EPDM as binder. The surface morphology, infrared absorption properties of the modified Al powder and the infrared emissivity, surface resistivity, electromagnetic properties and mechanical properties of the composite coating were analyzed. The results show that with the increase of TEOS addition amount, more SiO 2 was covered to the surface of floating Al powder. By adjusting the thickness of the surface modification layer of floating Al powder, the dielectric constant (ε) and dielectric loss tangent values (tanδ) of the composite coating were significantly reduced. When the addition amount of TEOS is 1 g for Al@SiO 2 , the ε and tanδ can be significantly reduced, and the infrared emissivity was less than 0.6, the tensile strength (σ b) and elongation rate at break (e) decreased slightly. This suggests that the composite coating has low infrared emissivity compatible with high radar wave transmittance was obtained, which is expected to be applied to the surface of aircraft radome. [ABSTRACT FROM AUTHOR]

• Metal catalyst is uniformly constructed on the fiber surface under mild condition. • Controllable and stable assembly of CNTs on the fiber surface is realized. • PDA slows down the diffusion of metal catalyst into fiber. • PDA gives full play to the advantage of CNTs in strengthening and toughening CFRP. Based on the Platform effect of polydopamine (PDA), the distribution of metal catalyst on the surface of carbon fiber was investigated in this study. Through PDA-based carbon coating, directional Carbon nanotubes (CNTs) are grown on the high strength carbon fiber body without damaging the interface structure and properties of Carbon fiber reinforced plastic (CFRP) by Chemical vapor deposition (CVD) approach. The results indicated that the PDA coating endows CNTs with a uniform distribution on the fiber surface, which effectively mitigate the corrosion of the fiber body by the high temperature and metal catalyst during the CVD process, thus augmenting the mechanical properties of the carbon fibers and their composites. The failure mechanism of the composite under stress was clarified by the transverse and longitudinal fracture morphology, which further developed the interface theory of CFRP. [ABSTRACT FROM AUTHOR]

Abstract: The reverse atom transfer radical polymerization (RATRP) technique using FeCl3/iminodiacetic acid (IMA) complex as a catalyst was applied to the living radical polymerization of acrylonitrile (AN). A hexa-substituted ethane thermal initiator, diethyl 2,3-dicyano-2,3-diphenylsuccinate (DCDPS), was firstly used as the initiator in this iron-based RATRP system. The polymerization in N,N-dimethylformamide not only shows the best control of molecular weight and its distribution but also provides rather rapid reaction rate with the ratio of [AN]:[DCDPS]:[FeCl3]:[IMA] at 500:1:2:4. The rate of polymerization increases with increasing the polymerization temperature and the apparent activation energy was calculated to be 49.9kJmol−1. The polymers obtained were end-functionalized by chlorine atom, and they were used as macroinitiators to proceed the chain extension polymerization in the presence of FeCl2/IMA catalyst system via a conventional ATRP process. The resultant polyacrylonitrile fibers were obtained with the fineness at 1.16dtex and the tenacity at 6.01cNdtex−1. [Copyright &y& Elsevier]

• SiO 2 shell improves the impedance matching and microwave absorption performance. • Core-shell structure damages the conductive network between the Fe 4 N particles. • The minimal reflection loss can reach −27.8 dB with 2.0 mm and −23.7 dB with 1.5 mm. The flaky porous Fe 4 N@SiO 2 particles were prepared by nitriding Fe 2 O 3 @SiO 2 which was fabricated by hydrothermal synthesis and sol-gel coating treatment. The structure, morphology, magnetostatic and electromagnetic properties of the Fe 4 N@SiO 2 particles were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), high resolution transmission electron microscope (HRTEM), vibrating sample magnetometer (VSM) and vector network analyzer (VNA). For comparison, the flaky Fe 4 N particles without SiO 2 shell were prepared by nitriding Fe 2 O 3 and characterized by the same technologies. The results show that the SiO 2 shell enhances the interface polarization effect on Fe 4 N and effectively adjusts the relative permittivity, which brings a much better impedance matching for Fe 4 N@SiO 2 than Fe 4 N. The minimal reflection loss (RL) of the Fe 4 N@SiO 2 can reach −27.8 dB with a thickness of 2.0 mm and −23.7 dB with a thickness of only 1.5 mm. By contrast, the RL values of Fe 4 N without SiO 2 shell are more than −2.2 dB at the whole frequency range of 2 ~ 18 GHz. The influence mechanism of SiO 2 dielectric shell on the microstructure and properties was revealed. This work gives a remarkable proof that coating a dielectric shell on the high conductive ferromagnetic cores is an effective way to obtain microwave absorbers with enhanced absorption performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hierarchically porous chicken bone-derived carbon scaffold was adopted as PIBs anode. • The anode exerted outstanding initial capacity and superior cyclic performance. • The increased interlayer spacing and heteroatom doping facilitated capacity stability. As a potential candidate of current power supply, potassium ion batteries (PIBs) based on biomass-derived porous carbons are endowed with advantages of low cost, improved energy density, high safety, and long cycling lifespan. Herein, endeavors addressing biomass bone-based anodes for PIBs were devoted to enhance the intercalation chemistry of K+. Through a direct pyrolysis of biomass chicken bones without adding any activation agent, 3D porous carbon scaffold (3D-HPCS) with hierarchical nanostructure and heteroatoms doping was adopted as PIBs anode to realize excellent rate capability and cycle life. The prepared 3D-HPCS anode exerted an outstanding initial capacity of 470 mA h g−1 as well as a rate capacity of 113 mA h g-1 at 2.0 C. Meanwhile, it remained 205 mA h g-1 after 450 cycles at a current density of 0.2 C, which demonstrated superior rate performance and cyclic stability during K+ insertion/extraction. The remarkable performances could be mainly attributed to the comprehensively synergistic contributions of increased interlayer spacing, active heteroatom doping, and intricate porous structures of 3D-HPCS electrode, thereby improving electronic conductivity and ion diffusion kinetics. [ABSTRACT FROM AUTHOR]

• This work reviews advances of bio-carbon KIBs anode with diverse microstructures. • A discussion on biomass carbons and biomass carbon-metal composites are presented. • The geometries, synthesis, and electrochemical characteristics are both summarized. • Investigations on the electrochemical kinetics of bio-carbon KIBs anode are provided. • Perspectives to achieve structurally-tuned bio-carbon KIBs anode are highlighted. Pursuit of advanced batteries with high energy density and low cost is the eternal goal for electrochemists. Potassium-ion batteries (KIBs) become a core focus to meet the need for scalable power sources in both academic and industrial energy-harvesting area. As the key to boosting development of KIBs, the advancement of high-performance anode materials helps to increase their competitiveness and feasibility. In this sense, biomass-based carbon materials with elaborate biological structures, strong physicochemical adsorptions, environmental benignity and cost effectiveness tick almost all the right boxes as a material for biocompatible energy-storage systems. More importantly, their intrinsic diversity of bio-microstructures provide considerable merits involving rapid ion/electron channels, strengthened mechanical substrates as well as in-situ templates for further electrode designs, allowing for achieving structurally-tuned surface chemistry in KIBs anodes. In this review, by focusing on the aspects of pure biomass carbons and biomass carbon-metal composites, a rapid glimpse at biomass carbon-based anode materials with various micro-architectures is provided, covering the architectural geometries, synthetic strategies, energy-storing mechanisms and electrochemical characteristics. In addition, a brief perspective on the imminent challenges and future directions of bio-carbon anodes in KIBs is also highlighted. We hope to cast a valuable outlook for structurally-controlled biomass-based anode materials in KIBs. [ABSTRACT FROM AUTHOR]

Potassium-sulfur (K–S) battery benefits from high specific capacities and natural abundance, which is deemed to be a rational choice to realize large-scale energy-storing applications. Here, a free-standing activated carbon fiber (ACF)@sulfur composite cathode (ACF@S) is designed for K–S batteries through a simple impregnation of melted sulfur into hierarchically porous ACF cloth. Taking advantages of the microstructural diversity manifested as various specific surface area, pore size and morphology, the ACF@S yields remarkable energy-storing capability due to effective dispersion, adsorption and physicochemical anchoring of soluble polysulfides. More importantly, their fiber geometries endow them with continuous channels which facilitate fast reaction kinetics. The relationships between specific surface area of ACF and electrochemical performance are also probed. Compared with ACF-1000@S (1000 is denoted as SSA = 1000 m2 g−1 and so on) and ACF-1200@S, the ACF-1500@S electrode with high content of mesopores delivers high reversible capacity of 310 mA h g−1, indicating great promise for shuttle suppression. Besides, quantitative investigations prove that surface capacitive-controlled processes play crucial role and K 2 S n (n = 1,2,3) is verified as the final discharging products through multiple characterizations, including ex situ XPS and HRTEM. Our findings aim to provide essential designs and electrochemistry interpretations of structurally-controlled ACF-based composite cathode for high-performance K–S batteries. Image 1 • A free-standing carbon cloth/sulfur composite (ACF@S) was designed as cathode for K–S battery. • The relationships between specific surface area of ACF and capacity performance were probed. • A quantitative discussion on the surface diffusion/capacitive-controlled mechanism was presented. • A qualitative investigation on the electrochemistry pathway of K–S system was traced. [ABSTRACT FROM AUTHOR]

The high-quality polyacrylonitrile (PAN) precursor fibers are indispensable for the manufacture of high-performance carbon fibers. For the purpose of regulating microfibril structures and improving fiber quality, scanning electron microscopy, high-resolution transmission electron microscopy and the nitrogen adsorption measurement were carried out to investigate the microfibril alignment evolution in PAN fibers, which was obtained by different stretching fields during dry-jet wet spinning process. The interconnected microfibrillar network forming in coagulation bath was plastically elongated and gradually developed into the oriented microfibrils while the transverse lamellae formed. Then break-reorganization of the lamellae brought the remarkable enhancement of fiber crystallinity during the hot-treatment process. Finally, the well-aligned and regular microfibrils appeared due to the deep plastic deformation. There were three stages in the total evolution of microfibril alignment: the plastic deformation of microfibrillar network, the fragmentation of the original lamella, and the formation and development of regular microfibrils. The microfibrils in PAN fibers were stacked by crystal layers in an order and tightly manner. Served as excellent reinforcing elements, aligned microfibrils could efficiently improve the fiber mechanical properties. Compared with nascent fiber, the tensile strength of PAN precursor fiber increased by 1492% and its tensile modulus enhanced by 574%. Image 1 • The interconnected network was plastically elongated and rearranged to develop into well-aligned and regular microfibrils. • The well-aligned and regular microfibrils were superposed by the regular arrangement of crystal layers. • Served as excellent reinforcing elements, aligned microfibrils could efficiently improve the fiber mechanical properties. • PAN fibers' tensile strength increased by 1492% and tensile modulus enhanced by 574%. [ABSTRACT FROM AUTHOR]

The present study provides a facile one-pot pyrolysis strategy to prepare serial nitrogen-doped (N-doped) metal/carbon composites derived from six types of metal ethylenediaminetetraacetic acid (EDTA-M, M = Co, Cu, Mn, Fe, Mg, and Ca). N-doped Co/C composite integrated carbonaceous with magnetic components to attain dielectric-magnetic double loss mechanisms. The minimum reflection loss and effective absorption bandwidth reached -57.6 dB at 1.75 mm and 4.64 GHz at 1.52 mm, respectively. The electromagnetic simulation further confirms that the dissipation ability increases with the improvement of carbonization temperature. Results show that altering the metal species of precursors can significantly improve the electrochemical performance of the composites using the identical strategy. N-doped Cu/C composite performed a maximum specific capacitance of 2383.3 F g -1 at 0.5 A g -1 -1 , and maintained 86.3% cycling stability at 20 A g -1 after 5000 cycles. The energy density of a symmetrical two-electrode configuration achieved 350.13 Wh kg -1 at a power density of 4000.04 W kg -1 . Density functional theory calculations indicate that nitrogen dopants cause faster ion transport and stronger adsorption capacity. Moreover, the bifunctionality of other composites types are also systematically characterized., (© 2024 Wiley‐VCH GmbH.)

Developing composite materials with the synergistic effects of heterogeneous structures and multiple components is considered as a promising strategy to achieve high-performance electromagnetic wave (EMW) absorbers. To further satisfy the demand of broadband and strong microwave absorption, a novel NiS/carbon nanofibers (CNFs)/porous carbon composite is successfully synthesized by hydrothermal and chemical vapor deposition using lotus leaves as a biomass carbon source. A few carbon nanotubes (CNTs) and uniformly dispersed Ni nanocrystals have also been found in the hybrid. Benefiting from the porous structure derived from lotus leaves, the combination of dielectric NiS, conductive carbon nanomaterials, and magnetic Ni nanoparticles, together with the three-dimensional conductive network of CNFs and CNTs, the remarkable EMW absorption properties with a minimum reflection loss up to -67.65 dB have been achieved at merely 2.32 mm. Besides, the widest effective absorption band can reach 5.9 GHz with a thin thickness of 2.07 mm, covering almost the entire Ku band. In addition, under the incident angle of 31°, the radar cross-section reduction value of LNSF-600 can reach 42.88 dBm2. Therefore, this work provides an efficient and facile method for manufacturing outstanding biomass-derived EMW absorbers., (© 2023 Wiley-VCH GmbH.)

In order to reduce the etching effect of the catalysts to carbon fibers caused by high temperature during the chemical vapor deposition (CVD) process, four multi-element catalysts, Fe-Co, Fe-Ni, Co-Ni and Fe-Co-Ni, were used to realize the low temperature growth of carbon nanotubes (CNTs) on carbon fibers at 350 °C-400 °C. The results show that the growth state of CNTs has a great relationship with the type of catalysts. The catalytic efficiency of Fe-Co catalysts is low, but the graphitization degree of CNTs is relatively high. The Fe-Co-Ni catalysts has high catalytic efficiency but low graphitization degree of CNTs. The tensile strength of carbon fiber/CNTs reinforcements prepared by Fe-Ni catalysts at 400 °C is the highest, reaching 3.99 GPa, which is 11.14% higher than that of desized fiber. The melt drop phenomenon of the catalysts was found by TEM, indicating the formation of the liquid phase catalysts during the growth of CNTs. This phenomenon can change the diffusion mode of carbon atoms in the catalyst and significantly reduce the growth activation energy of CNTs, so that CNTs can grow at lower temperatures. Based on the detailed analysis of the CVD process, a low temperature growth model of CNTs on carbon fibers was proposed., (© 2023 IOP Publishing Ltd.)

Zeolite supported amorphous metal oxide nanolayers with high specific surface area, abundant adsorption sites, and excellent reusability hold a bright prospect in the efficient removal of contaminants, yet it is proven to be still challenging to precisely regulate and control their synthesis. Herein, we reported a facile synthetic strategy for rational design and achieving the uniform and firm in situ growth of an amorphous ZrO 2 layer decorated on the surface of zeolite (ZEO@AZ) for enhanced phosphate adsorption. The Langmuir isotherm model and pseudo-second order kinetic equation well described the adsorption process towards phosphate solution, and the synthetized ZEO@AZ exhibited an excellent maximum adsorption amount of 24.98 mg P g -1 . Furthermore, the adsorption of phosphates on ZEO@AZ was confirmed to be chemisorption, endothermic and spontaneous. This approach for fabricating amorphous metal oxide nanolayers on a robust matrix may provide a new route for constructing composites with superb phosphate adsorption performance., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Two kinds of carbon nanoproducts with different microstructures, namely, carbon nanotubes (CNTs) and carbon nanofibers (CNFs), were grown on the surface of carbon fibers (CFs) by chemical vapor deposition (CVD) at low temperatures to improve the interface bonding between fibers and resins. The short-beam method and the micro-debonding method were used to test the interlaminar shear strength (ILSS) and interfacial shear strength (IFSS) of the composites. The results showed that the contribution of CNTs to the improvement of interfacial properties was better than that of CNFs. Specifically, the ILSS and IFSS of the CF-CNFs/epoxy composites increased by 18.59 and 24.39%, respectively, while the ILSS and IFSS of the CF-CNTs/epoxy composites increased by 26.97 and 47.79%, respectively. Compared with CNFs, the high degree of graphitization of CNTs and the π-interactions with the resin can better induce the formation of an interphase between the fiber and the resin, which suppressed the initiation of cracks and extended the propagation path of the cracks in the composites.

To date, elemental sulfur has been considered as a prospective cathode material for exploring high-energy power systems with low cost and sustainability. However, its practical commercialization has been impeded by inherent drawbacks of notorious capacity decay, unsatisfied insulating nature, and sluggish conversion chemistry. To address these issues, for the first time, freestanding nanofibrous networks with hierarchical nanostructures are facilely constructed by inlaying electrocatalytic bimetallic chalcogenides (Fe x Mn 1- x S nanoparticles) into conductive graphene nanosheet (GN)-doped sulfurized polyacrylonitrile (SPAN) fiber matrices. Covalent-bonded SPAN featuring an insoluble mechanism serves as a reliable cathode substrate with enhanced electrostability and high sulfur utilization, while high-surface-area GN dopants promote conductivity improvement and rapid electron transfer. Meanwhile, the results prove that sulfiphilic Fe x Mn 1- x S nanoparticles with abundant electrochemically active sites facilitate construction of uniform deposition interfaces and efficient electrocatalysis conversion toward lithium polysufides. This feasible catalytic-insoluble cathode strategy drives the Li-S battery, which exhibits excellent electrochemical performances with a remarkable reversible discharge capacity of 967 mA h g -1 and a capacity retention of 623 mA h g -1 after 500 cycles. Moreover, the corresponding lithiation/delithiation mechanisms are systematically investigated through complementary morphological and spectral analyses, providing valuable insights into advanced metal-sulfur batteries.

Carbon nanotubes (CNTs) were continuously grown on the surface of the moving carbon fiber by chemical vapor deposition method using a custom-designed production line to prepare composite reinforcements on a large-scale. The systematic study of different parameters affecting the CNT growth revealed simple growth kinetics, which helps to control the surface morphology and structural quality of CNTs. Since hydrogen maintains the activity of the catalyst, it promotes the growth of CNTs in a continuous process. The increase of acetylene partial pressure promotes the accumulation of amorphous or graphite carbon on the catalyst surface, resulting in the decrease of CNT growth rate when acetylene concentration reaches 40%. The growth temperature significantly affects the CNT diameter and structural quality. As the temperature increases, the crystallinity of the tube wall increases obviously, and the CNT diameter increases due to the aggregate growth of the catalyst particles. According to the Arrhenius formula, the apparent activation energy is observed to be 0.67 eV, which proves that both bulk diffusion and surface diffusion exist when activated carbon passes through the catalyst to form CNTs., (© 2021 IOP Publishing Ltd.)

As important regulators of chromatin, histone deacetylases (HDACs) are involved in silencing tumor suppressor genes. HDAC2, a member of HDACs, has been demonstrated to be implicated in the development and progression of various human malignancies; however, its expression and role in human primary gallbladder carcinoma (PGC) are not fully understood. Therefore, we conducted this study to address this problem. The subjects were 136 patients underwent resection for PGC. Immunostainings for HDAC2 were performed on these archival tissues. The correlation of HDAC2 expression with clinicopathological characteristics including survival was analyzed. HDAC2 was positively expressed in the nucleus of tumor cells in 86.0 % (117/136) of PGC but not in the normal epithelium of the gallbladder. Additionally, there was a significant difference in the incidence of positive nodal metastasis between high and low HDAC2 expression groups (P = 0.001). The incidences of advanced clinical stage (P = 0.005) and pathologic T stage (P < 0.001), and higher histologic grade (P < 0.001) were respectively higher in the high HDAC2 expression group than in the low group. Moreover, univariate and multivariate analyses revealed the high HDAC2 expression to be an independent prognostic factor for both overall and disease-free survival of patients with PGC. High HDAC2 expression was correlated with a high incidence of lymph node metastasis and aggressive tumor progression of PGC. It also was an independent prognostic factor for poorer overall and disease-free survival in patients. Therefore, detection of HDAC2 expression may help us screen patients at increased risk of malignant behavior for PGC.