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Free-standing mode triboelectric nanogenerator (F-S TENG) is supposed to be a most efficient technology for harvesting low frequency sliding energy. However, the waste of half working area and the existence of contact friction largely limit its output and reduce its durability. Here, we propose a flexible halbach magnetic arrays assisted sliding mode triboelectric nanogenerator (MA-S TENG), which multiplies its energy output and greatly increases its durability. Based on flexible magnetic sheet, the horizontal movement of fully covered sliding part can be converted into the mode of periodical contact-separation. Benefiting from this working mode, the output energy and peak power during one sliding motion are 2.7 times and over 10 times larger than the free-standing mode TENG respectively. In addition, during 25 h of continuous operation, the MA-S TENG remains 60% of its initial output compared with 1.8% for the F-S TENG. This work provides a promising strategy to address the problems of efficiency and durability existing in sliding mode TENGs in practical applications. Image 1 • We propose a flexible halbach magnetic arrays assisted sliding mode triboelectric nanogenerator (MA-S TENG). • Compared to traditional free-standing mode TENG with half-covered sliding part, MA-S TENG with fully-covered sliding part can maximize the energy scavenging efficiency. • MA-S TENG also provides an effective strategy to solve the durability issue in sliding/freestanding mode TENGs. [ABSTRACT FROM AUTHOR]

Flexible, highly sensitive, easy fabricating process, low-cost pressure sensors are the trend for flexible electronic devices. Despite the tremendous progress in recent years, it is still challenging to prepare pressure sensors with high sensitivity, high stability, and fast responsiveness. In this study, we report a simple and low-cost method for the preparation of novel pressure sensors. Inspired by the pomegranate structure, a 3-D porous structure consisting of polystyrene (PS) microspheres filled with reduced graphene oxide (rGO) paper is proposed. This pressure sensor has high linear sensitivity (1.41 kPa−1 in the pressure range of 0–50 kPa), high stability (1000 cycles), and quick response time (~20 ms). Furthermore, a robotic arm interacting control system based on pressure sensor arrays is constructed, which demonstrates the far-reaching potential of pressure sensors in human–machine interaction. Therefore, this work provides a low-cost and effective method for preparing high linear sensitivity pressure sensors. [ABSTRACT FROM AUTHOR]

Due to the advantages of excellent output power, low cost and easily preparation, triboelectric nanogenerator (TENG) is developing rapidly in the field of renewable energy. The output performance of TENG is largely dependent on the surface charge density, which is closely related to the ability of the tribo-material to gain or lose electrons. To obtain higher output power, numerous efforts have been done on material modifications of the friction layer and electrodes of TENG with additional fillers or molecular modifications. In this review, advanced materials for the preparation of TENG devices to achieve high output, humidity-resisting and wear-resisting performance are presented and the working mechanisms of performance optimisation are discussed. Moreover, natural materials, recyclable materials and non-conventional electrode materials are mentioned to inspire subsequent research on TENG. [ABSTRACT FROM AUTHOR]

As a new engineering dielectric, vegetable insulating oil is widely used in electrical equipment. Small polar molecules such as alcohol and acid will be produced during the oil-immersed electrical equipment operation, which seriously affects the safety of equipment. The polar molecule can be removed by using functional fossil graphene materials. However, the structural design and group modification of graphene materials lack a theoretical basis. Therefore, in this paper, molecular dynamics (MD) and quantum mechanics theory (Dmol3) were utilized to study the adsorption kinetics and mechanism of graphene (GE), porous graphene (PGE), porous hydroxy graphene (HPGE), and porous graphene modified by hydroxyl and carboxyl groups (COOH-HPGE) on polar small molecules in vegetable oil. The results show that graphene-based materials can effectively adsorb polar small molecules in vegetable oil, and that the modification of graphene materials with carboxyl and hydroxyl groups improves their adsorption ability for polar small molecules, which is attributed to the conversion of physical adsorption to chemical adsorption by the modification of oxygen-containing groups. This study provides a theoretical basis for the design and preparation of graphene materials with high adsorption properties. [ABSTRACT FROM AUTHOR]

Moisture is a significant factor that affects the insulation performance of outdoor high-voltage insulators in power systems. Accumulation of water droplets on insulators causes severe problems such as flashover of insulators and power outage. In this study, we develop a method to fabricate a micro/nano hierarchical super hydrophobic surface. The as-prepared super hydrophobic surface exhibits a water contact angle (WCA) of 160.4 ± 2°, slide angle (SA) less than 1° and surface free energy (SFE) of 5.99 mJ/m 2 . We investigated the electrohydropdynamic behavior of water droplet on a horizontal super hydrophobic surface compared with hydrophobic RTV silicone rubber surface which was widely used as anti-pollution coating or shed material of composite insulator. Results show that water droplet tended to a self-propelled motion on the super hydrophobic surface while it tended to elongate and break up on the RTV surface. The micro/nano hierarchical surface structure and chemical components with low surface free energy of the super hydrophobic surface jointly contributed to the reduction of skin fraction drag and subsequently made it possible for the motion of water droplet driven by electric field. Furthermore, the self-propelled motion of water droplets could also sweep away contaminations along its moving trace, which provides super hydrophobic surface a promising anti-pollution prospect in power systems. [ABSTRACT FROM AUTHOR]

High‐temperature thermoelectric (TE) materials are common wide‐gap semiconductors that are used in order to prevent the bipolar effect. Here, a potential high‐temperature n‐type TE material SmS with a simple NaCl structure that demonstrates a narrow band gap of ≈0.25 eV is reported. As expected, a temperature‐dependent carrier concertation is observed, which is attributed to the thermal activation of electrons from valence band edge to conduction band. Interestingly, the intrinsic activation does not cause any sign of a bipolar effect. Density functional theory calculations suggest that the phenomenon originates from the strong electron‐hole asymmetry in the electronic structure and the electron‐to‐hole conductivity ratio is as high as 700–900. As a result, the activated minority carriers barely participate in the TE transport and the maximum power factor reaches 1.41 mW K−2 m−1 at 1123 K. By further alloying with Se to reduce lattice thermal conductivity, a peak zT of ≈1.1 is obtained in Sm1.08S0.78Se0.22 at 1123 K, which is among the best n‐type high‐temperature thermoelectrics. This study proves high‐temperature TE materials can be found in narrow‐gap semiconductors, which significantly enriches the scope of possibilities for novel TE materials. [ABSTRACT FROM AUTHOR]

In order to improve the low-temperature operational reliability of natural ester insulating oil-immersed transformers, the low-temperature property improvement on natural ester is investigated. The results show that poly alpha-olefin, hexyl naphthalene, and polymethacrylate have good effects of pour point depression, but poly alpha-olefin and hexyl naphthalene cause properties deterioration of natural ester such as acid value and dielectric dissipation factor because of their own characteristics. When the adding proportion of polymethacrylate is 1%, the pour point of natural ester is reduced to −20.5 °C, which can maintain good physicochemical and electrical insulating properties. Polyacrylate has no depression effect and reduces the insulating property. During the crystallizing fractionation (CF) process, when the stirring speed of low-temperature crystallization (II) is 3 r/min, and the temperature difference between cooling medium and natural ester is 3 °C, the pour point is reduced to −20.3 °C. However, due to the reduction of high melting point glycerides content, the oxidation resistance of natural ester decreases. The effective combination of CF process and polymethacrylate as a pour point depressant makes the pour point reduce to −27.3 °C, which also ensures good physicochemical and electrical properties. Also, the synergistic antioxidation between phenolic antioxidants and polymethacrylate enhances the antioxygenic property, which effectively expands the application conditions and ranges of natural ester. [ABSTRACT FROM AUTHOR]

The suppression of lattice thermal conductivity of thermoelectric CuInTe2 was often realized by complex micrometer-structure control. Herein, we demonstrate that simple alloying AgSbTe2 in CuInTe2 is capable of strongly strengthening lattice anharmonicity, which gives rise to an extremely low lattice thermal conductivity of ∼ 0.62 W m−1 K−1 at 823 K for (CuInTe2)0.95(AgSbTe2)0.05. In addition, the intentionally introduced copper vacancies can effectively increase the carrier concentration and dramatically improve the electrical performance of (CuInTe2)0.95(AgSbTe2)0.05. As a result, the sample with nominal composition of (Cu0.95InTe2)0.95(AgSbTe2)0.05 reaches a maximum zT value of ∼ 1.3 at 823 K. This study provides some insight into designing thermoelectric compounds in the diamond-like semiconductor family by inducing strong anharmonicity through a small amount of alloying. [ABSTRACT FROM AUTHOR]

SF6 is a common insulating medium of gas-insulated switchgear (GIS). However, it is inevitable that SF6 will be decomposed due to partial discharge (PD) in GIS, which will cause hidden dangers to the safe and stable operation of equipment. Based on the DFT method, the two-dimensional nano-composite As-doped h-BN (As-BN) monolayer was proposed. By modeling and calculating, the ability of an As-BN monolayer as a specific sensor for SO2F2 (compared with an H2O adsorption system and CO2 adsorption system) was evaluated by parameters such as the binding energy (Eb), adsorption energy (Eads), transfer charge (ΔQ), geometric structure parameters, the total density of states (TDOS), band structure, charge difference density (CDD), electron localization function (ELF), sensitivity (S), and recovery time (τ). The results showed that an As-BN monolayer showed strong adsorption specificity, high sensitivity, and short recovery time for SO2F2 gas molecules. Therefore, the As-BN monolayer sensor has great application potential in the detection of SF6 decomposition gases. [ABSTRACT FROM AUTHOR]

• The diffusion properties of POSS and H2O molecules in POSS modified insulating oil investigated by MD. • The electric field has the greatest influence on the interaction energy between POSS carbon chain and oil molecules. • The electric field reduces the interaction energy between POSS and oil molecules. • The electric field increase the interaction energy between H2O molecules and oil molecules. The use of nano-materials can effectively improve the dielectric and heat transfer properties of natural ester insulating oil. However, the migration and interaction mechanism of components in nano-modified insulating oil under electric field is still not clear. Through detailed Molecular Dynamics (MD) simulation, this study revealed the migration and interaction mechanism of Cage Polysilsesquioxane (POSS) and H 2 O molecules in natural ester insulating oil. The data indicates that POSS and H 2 O molecules have completely different diffusion properties under electric field. The existence of electric field not only makes the displacement of molecules nonlinear, but also limits the Brownian motion of H 2 O molecules. On the contrary, POSS molecules under electric field have better diffusion properties. Electric field leads to the extremely uneven distribution of electrostatic potential (ESP) of oil molecules, which makes it easier for H 2 O molecules with small volume to dissociate near the polarized oil molecular structure and be bound by it, and the interaction energy between oil molecules and POSS molecules under the action of electric field will be weakened, which is the main reason why H 2 O and POSS molecules have completely different diffusion performance under electric field. The limited displacement of H 2 O molecules can inhibit the aging of insulating oil and improve its service life. Compared with the electric field effect, temperature has a great influence on the interaction energy between POSS and oil molecules. The results provide useful guidance for the design of the next generation of natural ester nano-modified insulating oil. [ABSTRACT FROM AUTHOR]

In the post-epidemic era, industrial production has gradually recovered, and the attendant air pollution problem has attracted much attention. In this study, the Zr-doped h-BN monolayer (Zr-BN) is proposed as a new gas sensor for air pollution. Based on density functional theory (DFT), we calculated and compared the adsorption energies (Eads), geometric parameters, the shortest distance between gas and substrate (dsub/gas), density of states (DOS), electron localization function (ELF), charge density difference (CDD), band structure, band gap energy change rate (ΔEg), and sensitivity (S) of Zr-BN adsorption systems (SO2F2, SOF2, SO2, NO, and CO2 adsorption systems). The results show that Zr-BN had strong adsorption and high sensitivity to the above-mentioned polluted gases, and the sensitivity was in the order of SOF2 > SO2F2 > CO2 > SO2 > NO. Therefore, this study provides a theoretical basis for the preparation of Zr-BN gas sensors and provides new ideas and methods for the development of other gas sensors. [ABSTRACT FROM AUTHOR]

In actual organic Rankine cycle systems (ORCs), the inclusion of lubricating oil in the working fluid is nearly unavoidable. Under the condition of high-temperature operation, the presence of lubricating oil can potentially exacerbate the thermal stability of the working fluid. The impact of polyol ester (POE) and mineral lubricant on the thermal stability of octadethyltrisiloxane (MDM) is studied. Results indicate that both POE and mineral lubricant contribute to the decomposition of MDM to a certain extent. Specifically, at a 5.0% mass fraction of POE and mineral lubricant, MDM remains its stable at 230 °C and 210 ℃, respectively. However, as the mass fraction of lubricant increases, the decomposition of MDM intensifies, with mineral lubricant exhibiting a more pronounced effect compared to POE lubricant. Regarding pyrolysis products, the presence of lubricants leads to an increase in CH 4 , C 2 H 6 and C 2 H 4 gases. Furthermore, the addition of lubricant promotes the formation of siloxane oligomers, particularly MD 5 M to MD 9 M, and enhances the production of unidentified products. Compared to MDM, both POE and mineral lubricant molecules exhibit lower bond dissociation Gibbs free energies. The free radicals generated from lubricant decomposition are prone to hydrogen abstraction reactions with MDM to promote MDM decomposition. Moreover, ReaxFF simulation results demonstrate that lubricant molecules also enhanced the activation of MDM and increased its susceptibility to Si-C bond cleavage. Following the removal of the methyl group, the Si-O bonds in the radicals are more likely to break, leading to the formation of additional siloxane oligomers through Si-O bond recombination. Kinetic analysis reveals that the apparent activation energy of MDM decomposition drops from 134.4 kJ∙mol−1 to 110.8 kJ∙mol−1 as the mass fraction of n-hexadecane (model compounds for mineral lubricant) rises from 0% to 10.30%. • Compared to MDM, both POE and mineral lubricants have poorer thermal stability. • Both POE and mineral lubricants contribute to MDM decomposition. • When doped with 5.0 wt% POE or mineral oil, MDM remains stable at approximately 230 ℃ and 210 ℃, respectively. • The decomposition mechanism of MDM under lubricant blend conditions was revealed. [ABSTRACT FROM AUTHOR]

• Drift velocities of ions increase nonlinearly under external electric fields. • Scattering determines the threshold of the ion drift. • Structural cages limit the ion drift effectively under lower electric field strength. • Electric motion replaces thermal motion under higher electric field strength. • Biological liquids facilitate the restriction of cationic electric drifts. Ionic conduction is a critical parameter to evaluate the electrical performance of biological dielectric liquids. In this work, detailed molecular dynamics (MD) simulations were carried out to reveal both drift mechanisms of ions (H 3 O+, Cu2+, OH– and Cl-) and local structure evolution characteristics in biological dielectric liquids under external electric fields. The drift velocities of all ionic species increase nonlinearly with the addition of static electric fields. At relatively low field regimes, the structural cages formed by corresponding biological dielectric molecules are found to reduce ion transport. Above certain field thresholds, the accelerated ions impart appreciable energy to the surrounding molecular segments, making the binding of the cages broken. As such, the electric motion as a replacement of the thermal motion is eventually taken place. The computed thresholds are 0.97 V/nm, 0.645 V/nm, 0.67 V/nm, and 0.77 V/nm for H 3 O+, Cu2+, OH–, and Cl-, respectively. Additionally, given the electrostatic potential feature of biological dielectric molecules, the structural cages have greater advantages in limiting cationic migration, in which the binding effect for cations is more stable and persistent. The results provide a helpful guideline for designing the next-generation biological dielectric liquids. [ABSTRACT FROM AUTHOR]

Aircraft icing poses a major threat to flight safety, and plasma anti-/de-icing becomes a new approach in the field of anti-/de-icing in recent years. In this paper, a surface dielectric barrier discharge (SDBD) plasma actuator with SiC hydrophobic coating-based quartz glass is designed and fabricated. Actuated by nanosecond high voltage pulse, its de-icing characteristics are explored experimentally and compared with the uncoated actuator. The results show that under the same actuation parameters, the discharge current peaks and the power consumption of SDBD are reduced with hydrophobic coating, which can be further verified by surface temperature distribution. Intensified CCD camera images indicate that after the adding of SiC coating, the discharge propagation process of SDBD does not change significantly. For both coated/uncoated actuators, two discharges occur during the voltage rise and fall phases respectively, while no discharge occurs during the pulse width phase, but the coated actuator exhibits slightly longer plasma dissipation time. Static de-icing results reveal that the instantaneous energy utilization rate of the coated actuator at 60 s of de-icing process is about 54% higher than that of the uncoated actuator, which can be explained by two aspects: one is to weaken the adverse effects of melted water on the discharge plasma to a maximum extent, and the other is to reduce the contact area between the ice accretion and the hydrophobic surface. [ABSTRACT FROM AUTHOR]

It is an innovation to self‐heal the microdefects inside materials by doping microcapsules. Urea‐formaldehyde resin (UF) microcapsule is widely used in self‐healing materials owing to its excellent mechanical properties. However, when it is used in electrical insulation materials, the thermal stability of the microcapsules need to be enhanced owing to the relatively high internal temperature of the material under the long‐term action of electric field. In this paper, molecular dynamics simulation is used to calculate the properties related to the thermal stability of UF microcapsule with and without nanosilica incorporation. The simulation result shows that incorporating nanosilica can increase the density and glass transition temperature, decrease the fractional free volume of UF materials. The UF microcapsules with and without nanosilica incorporation are prepared experimentally, and thermogravimetric test result shows that incorporating nanosilica can enhance the thermal stability of UF microcapsule; scanning electron microscope result shows nanocomposite microcapsule has more UF debris adhered on its surface. By establishing the interface model of UF and nanosilica to explore the internal mechanism, it is found that the interface interaction between UF and nanosilica is conducive to enhancing the thermal stability of UF material. [ABSTRACT FROM AUTHOR]

A modified shadowgraph imaging setup equipped with a high-speed camera is utilized to achieve a numerical evaluation of temperature, number densities of molecules, ions and electrons to the refractive-index of negative non-breakdown streamer in rapeseed insulating oil for revealing the dynamics of streamer propagation. The non-breakdown streamer is found reaching fairly high speed of 3.01–4.66 km/s during −1.7 μs. The following 10 µs is dominated by streamer propagation with the grayscale decreasing continuously for the entire streamer. The dissipation is identified starting at ca. 11.7 μs in the stem region while the head of streamer remaining further propagation. This is followed by a dissipation expansion from the stem to the head regions. The double-unsaturated triglycerides are evidenced as the main ionization components in the non-breakdown streamer, which aid to identify the temperature variations, instead of electrons, positive ions, or dissociation of molecules, contribute mainly to the refractive index drop of the streamer. The mapping for the temperature distribution of streamer is resultantly possible and provides the insight to ascertain the inhomogeneous migration of electrons the kinetic superiority for the streamer evolution dynamics. [ABSTRACT FROM AUTHOR]

Porous nanomaterials have broad application aspects in energy storage and conversion. In this paper, the energy storage characteristics of two kinds of Metal-organic Frameworks (MOFs) nanofluids were studied through experiments and molecular simulation (MS). Firstly, UIO-67/water and UIO-67/methanol nanofluids were prepared, the structural characteristics of UIO-67 were studied, and the results showed that the Metal-organic Frameworks of UIO-67 is stable under 770 K. Then, the energy storage capacity of the two kinds of nanofluids was studied experimentally. The results indicated that the energy storage capacity of UIO-67/water nanofluids decreased with 0.83% and 3.60% mass fractions nanoparticles at 288 K-360 K. However, that of UIO-67/methanol nanofluids containing 1.60% and 5.28% mass fractions nanoparticles showed an enhancement trend at 250 K-330 K. Meanwhile, the changes of energy storage capacity are proportional to the mass fraction of UIO-67 nanoparticles. Finally, about the energy storage capacities of UIO-67/water and UIO-67/methanol nanofluids, the results retrieved by molecular simulation are in good agreement with the experimental ones, which provides an explanation for the inconsistency of the energy storage characteristics of the two kinds of nanofluids. The research method in this paper provided a reference for studying the thermophysical properties of nanofluids mixed with porous materials, and the results should have some practical interest. [ABSTRACT FROM AUTHOR]

The dielectric liquids/cellulose system has been widely employed to protect industrial devices due to its excellent insulation and heat dissipation properties. Nevertheless, the aggregation of molecules and ions on the cellulose surface has a significant influence on its physical and chemical performances. In this study, the migration characteristics and suppression mechanisms of H 2 O and H 3 O+ were studied in bio-based dielectric liquids (BDLs)/cellulose and petroleum-based dielectric liquids (PDLs)/cellulose systems via molecular dynamics (MD) simulations and quantum mechanics (QM) methods. Results indicated that the water molecule was adsorbed unavoidably on the cellulose surface in both systems even though the stronger interaction between H 2 O and BDLs molecules delayed the transport process. However, the migration suppression of H 3 O+ was found in BDLs/cellulose systems, which is entirely different from that in PDLs/cellulose systems. The self-assembled structure made the ion be far away from the cellulose surface and never trigging the "driver" procedure, which deciphered that BDLs attenuated the performance degradation of cellulose by inhibiting the transfer of ions. On the contrary, the H 3 O+ was integrated into cellulose quickly because of the repulsion interaction between PDLs and H 3 O+. As for suppression mechanisms, the polar groups in BDLs were considered to be the most effective parameter to avoid aggregation of ions on the cellulose surface, since the electrostatic potential was enough to encapsulate ions. This research can provide a more practical reference for the performance prediction and structure design of liquid-solid systems in the future. • Polar groups in bio-liquids are an effective parameter to avoid ionic aggregation. • Forming ionic clusters by self-assembly provides protection for solid materials. • For neutral molecules, the delayed migration process is also found in bio-liquids. [ABSTRACT FROM AUTHOR]

In this research, the mesomorphic properties, thermal conductivity, and dielectric strength of a liquid-crystalline epoxy resin with hybrids of cellulose nanofiber and boron nitride nanosheet are studied. The thermal conductivity of LCER with hybrid fillers at a loading of 30 wt% demonstrated approximately 387% of that of the neat LCER and 246% of that of the nanocomposites with single BNNS fillers. The hybrid nanocomposite also demonstrates comparable dielectric strength and greater water contact angles in contrast to nanocomposites with single BNNS fillers. Furthermore, the nanocomposites with hybrid fillers show greater resistance to electrical erosion during the breakdown testing due to the greater thermal conductivity induced by enhanced filler dispersion. [ABSTRACT FROM AUTHOR]

In this paper, the pollution flashover performance of a superhydrophobic surface with different coating strategies are studied. The results show that a superhydrophobic coating is effective in preventing pollution flashover under high voltage. The superhydrophobic coatings show increased pollution flashover voltage when compared to room temperature vulcanized silicone rubber and to an uncoated glass substrate. A novel suppression mechanism of the superhydrophobic coating is proposed which is driven by the electrostatic force produced by the applied voltage. The coalesced slippery slurry droplets and the expanded dry area on the superhydrophobic surface contributes to increased flashover voltage on the superhydrophobic surface. The superhydrophobic coating promises to be a prospective application in anti-pollution performance of insulators. [ABSTRACT FROM AUTHOR]

A multi-branch pre-breakdown streamer model for natural ester-based nanofluid is established in this paper to study the influence of electrons density fluctuation on the streamer branching and propagation during the pulsed discharge. The mechanism of electron density fluctuation on the streamer branching and propagation characteristics is further studied using the finite element software. Results show that the initial streamer branched more likely near the needle tip in the nanofluids than that in the pure oils, and the branching of the initial streamers in nanofluid significantly inhibit the streamer propagation. The fluctuation of carrier density and the low charge density regions caused by adsorption of electrons with nanoparticles near the needle tip are the leading causes for the initial streamer branching in the nanofluid. The repulsion of the charge with the same polarity between the streamer branches can change the propagation pattern of the streamer, resulting in the inhibition of the streamer propagation. Results provide a novel strategy for the inhibition of streamer propagation by electron density fluctuations-induced branched initial streamer in nanofluids. [ABSTRACT FROM AUTHOR]

Rational design on microstructure of magnetic material provides new opportunity to enhance the electromagnetic absorption performance. Herein, we demonstrate the successful preparation of spindle-cone of Fe/Fe 2 O 3 and Fe 3 O 4 samples with an average size of ∼1.2 μm, using a facile two-steps method. The well-defined spindle-cone shaped α-Fe 2 O 3 was developed first by a solvothermal route and then reduced by H 2 or NaBH 4 , respectively. The morphologies, phase compositions and magnetization of these as-prepared samples are analyzed by Field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and X-ray photoelectron spectrum (XPS) and vibrating sample magnetometer (VSM). Meanwhile, the electromagnetic (EM) absorption performance of Fe/Fe 2 O 3 and Fe 3 O 4 spindle-cones-paraffin composites with various filling ratios are also studied. The results reveal that Fe/Fe 2 O 3 with a filling ratio of 50 wt% achieves the smallest reflection loss value of −26.2 dB at a thickness of 1.4 mm. At thinner thickness (1.0 mm), the bandwidth (RL < −10 dB) equals to 4.5 GHz (13.5–18 GHz). The excellent absorption mechanism was discussed in this work, which attributed to the unique nanostructure and moderate impedance matching and EM loss ability. • Spindle-cone shaped magnetic hybrid was prepared by a simple two-steps method. • Fe 3 O 4 and Fe/Fe 2 O 3 could be achieved using different reduction regent. • The effective absorption frequency of Fe/Fe 2 O 3 absorber was up to 4.5 GHz with a thickness of 1.4 mm. • Such a spindle-cone shape attributed to the performance. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The Co 1.11 Te 2 /C nanostructure was synthesized via a CVD method for the first time. • The N-doped carbon framework is contributed to improve the HER performance. • The Co 1.11 Te 2 /C exhibits the better HER activity, compared with CoTe/C and CoTe 2 /C. • Component control is a significant method to improve the HER performance. Abstract Rational structure design and component-controlled synthesis are attractive and challenging methods to develop materials with unique function for renewable energy conversion such as hydrogen production via water splitting. The earth-abundant and affordable transition metals have been regarded as ideal alternatives to precious platinum. Herein, we report the designed synthesis of component-modified cobalt telluride nanoparticles encapsulated in the nitrogen-doped carbon frameworks with the feature of high surface area and great electron conductivity. Compared with CoTe 2 /C and CoTe/C, the Co 1.11 Te 2 /C presents the highest catalytic activity for HER in 1M KOH due to its structural and component advantages. After a continuous reaction for 20 h or cycling for 1000 cycles, Co 1.11 Te 2 /C shows only a little performance loss. This work provides an effective approach to synthesize low-cost and efficient electrocatalysts for HER via rational structural and component design. [ABSTRACT FROM AUTHOR]

To achieve polymer-based composites for electronic packaging with high thermal conductivity, Al2O3 nanoplatelets were introduced into polytetrafluoroethylene (PTFE) matrix via a cold pressing and sintering method. The effect of mass content of the Al2O3 platelets on the morphology, mechanical properties, thermal conductivity and dielectric properties of the composites was investigated. The results revealed that the Al2O3/PTFE nanocomposites exhibited higher thermal conductivities, better thermal stabilities, enhanced mechanical properties with considerable dielectric properties. The largest thermal conductivity of the Al2O3/PTFE nanocomposites filled with 25 wt.% Al2O3 platelets was 0.461 W m − 1 K − 1 , increased by 85% compared with that of pure PTFE. The improved thermal conductivity of Al2O3/PTFE can be attributed to the formation of effective thermal conductance network within the PTFE matrix due to the interconnectivity of Al2O3 platelets. Al2O3 platelets play an important role in forming thermally conductive networks. It observes that when the filler loading beyond 10 wt.%, the thermal conductivity of the Al2O3/PTFE nanocomposites obviously increased. It also indicates that the interconnectivity of the Al2O3 nanoplatelets increased and thermally conductive path networks formed. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Atomic-layered graphene is synthesized by chemical vapor deposition. • The epitaxial graphene on the special surface of V 8 C 7 is synthesized for HER. • The electronic interactions between V 8 C 7 and graphene could improve HER activity. • The high activity and stability of material are existed in acid and alkaline media. Abstract Exploring low-cost, non-noble hydrogen evolution reaction (HER) catalysts with remarkable activity in both acidic and alkaline media still remains an enormous challenge. Herein, a novel V 8 C 7 NMs/GR heterogeneous catalyst has been synthesized by epitaxial growth of graphene as efficient acidic and alkaline HER electrocatalyst, for the first time. Electrochemical tests and DFT calculations indicate that high-activity of the exposed facet and low barrier energy for hydrogen adsorption and water dissociation could facilitate hydrogen evolution reaction. Owing to the electronic interactions between V 8 C 7 and graphene at active hybrid interfaces, this catalyst shows high HER activity with a low overpotential at 10 mA cm−2 (156 mV in 1 M KOH and 52 mV in 0.5 M H 2 SO 4), a small Tafel slope (89.4 mV dec−1 in 1 M KOH and 48.3 mV dec−1 in 0.5 M H 2 SO 4), and preferable durability in both acidic and alkaline media. This work opens up a new avenue for the epitaxial growth of graphene and exploring new-type active heterogeneous catalysts with advanced performance for HER. [ABSTRACT FROM AUTHOR]

[Display omitted] • Construction of correct and effective SnO 2 -MoS 2 monolayer model. • The changes and effects of electronic properties of each adsorption system. • The application of SnO 2 -MoS 2 monolayer in the field of gas sensing. • New ways for the exploration of other gas sensing materials. Selective monitoring and capture of some gases (CH 4 , C 2 H 2 , NO 2 , H 2 S, SO 2 , SO 2 F 2 , CO, H 2 , CO 2) are helpful to discover and warn the problems such as dangerous accidents and gas pollution caused by too low or too high specific gas content. In this letter, the first-principles density functional theory (DFT) was used to calculate and analyze the geometric structure parameters of the adsorption systems composed of SnO 2 -MoS 2 monolayer and the above gases. The electronic structure parameters and adsorption parameters such as binding energy (E b), adsorption energy (E ads), transfer charge (Δ Q), total density of states (TDOS), energy band structure, the change rate of band gap energy (Δ E g), sensitivity (S), and recovery time (τ) were used to obtain the optimal adsorption configuration and microscopic gas sensing mechanism. The results show that the SnO 2 -MoS 2 monolayer has strong adsorption on CH 4 , C 2 H 2 , and NO 2 gas molecules, mainly chemical adsorption. Gas-sensitive response to other gases is relatively insensitive, mainly for weak physical adsorption. The adsorption strength of each adsorption system was CH 4 > NO 2 > C 2 H 2 > H 2 S > SO 2 > SO 2 F 2 > CO > H 2 > CO 2. This letter provides a theoretical basis for the application of SnO 2 -MoS 2 monolayer in the field of gas sensing and provides new ideas and ways for the exploration of other gas sensing materials. [ABSTRACT FROM AUTHOR]

We report the influence of Ni substituting for Fe on the phase stability and thermoelectric properties of Yb x Fe 4- y Ni y Sb 12 (x = 0.6, 0.7, 0.8, 0.9, 1.0; y = 1.0, 0.8, 0.6). Ni substituting can efficiently enhance phase stability but reduces band gap, which establishes an optimum Ni substituting content to keep the balance. Meanwhile, the atomic disorder caused by Ni substituting together with Yb-filling leads to a significant reduction in lattice thermal conductivity. The most marked reduction in lattice thermal conductivity is achieved in the Yb 0.9 Fe 3.4 Ni 0.6 Sb 12 compound with a minimum value of 0.71 W m−1 K−1 at about 650 K. Finally, a peak zT of 0.85 is attained at 673 K in the Yb 0.9 Fe 3.4 Ni 0.6 Sb 12 compound, which is comparable to other p-type skutterudites at the same temperature. This work highlights the importance of considering the competition between phase stability and band gap when designing high thermoelectric performance cobalt-free skutterudites. • Importance of considering the competition between phase stability and band gap. • The atomic disorder reduces lattice thermal conductivity greatly for 0.71 W m−1 K−1. • A maximum zT value of 0.85 is achieved in Yb 0.9 Fe 3.4 Ni 0.6 Sb 12 and YbFe 3.4 Ni 0.6 Sb 12. [ABSTRACT FROM AUTHOR]

Designing nanostructure of electrode materials for boosting their electrochemical activity is a crucial issue to further development in the renewable energy industry. Here we have synthesized three NiCo 2 O 4 crystals with different morphologies by simply adjusting hydrothermal reaction conditions. The NiCo 2 O 4 nanoflake array grown on Ni foam is found to possess highly ordered structure with large specific surface area, providing vast reactive sites and facilitating the transfer of electrons and electrolyte ions. As a result, NiCo 2 O 4 nanoflake array displays an improved specific capacitance of 854.7 F g−1 at 1 A g−1 and even kept it as high as 745.1 F g−1 at 10 A g−1. Furthermore, the final capacitance remains 82.9% after 10,000 charge-discharge process at 20 A g−1. An asymmetric supercapacitor (ASC) composed of NiCo 2 O 4 nanoflake array and active carbon enables maximum energy density of 25.7 Wh kg−1 at a power density of 765.5 W kg−1. In addition, this work will broaden our vision to improve the performance of electrodes for supercapacitor by ingeniously constructing their structure. [Display omitted] • Three NiCo 2 O 4 crystals with different structures are made by a hydrothermal method. • NiCo 2 O 4 nanoflake array has highly ordered structure and good conductivity. • The shape of an individual NiCo 2 O 4 nanoflake is orthohexagonal. • NiCo 2 O 4 nanoflake array shows excellent electrochemical performance. • The energy storage mechanism of electrode materials is discussed in detail. [ABSTRACT FROM AUTHOR]

• Plasmonic photothermal films are designed for defogging, anti-icing, and deicing. • The surface temperature of films could increase more than 25 °C under light illuminating at 3 suns. • A very small amount (~3%) of metal nanoparticles were mixed in this plasmonic photothermal films. The heat generated by surface plasmon in metal nanoparticles is an interesting topic in recent research on nano-optics. In this work, Au/TiO 2 plasmonic photothermal films are obtained on the Polytetrafluoroethylene (PTFE) surface by a simple fabrication method for defogging and anti-icing/deicing. The experimental data demonstrates that the temperature of these plasmonic photothermal films increased by more than 25 ° C under light illuminating at 3 suns (300 mW / cm 2 ). The evaporation and deicing process of a water droplet on these plasmonic photothermal films are observed and analyzed, which exhibits their excellent ability of defogging and anti-icing/deicing. Furthermore, the influence of the Au/TiO 2 concentration on plasmonic photothermal effect is also studied. The results point out that the film with a much small amount of Au nanoparticles (~ 3 %) has the best performance, which is discussed based on the surface plasmon resonance. The novel plasmonic photothermal films with a simple fabrication method, low production cost, good photothermal effect, less heavy metal ions pollution, and insulation property, have broad potential applications in defogging, anti-icing, and deicing, etc. [ABSTRACT FROM AUTHOR]

• The thermal stability of HFO-1336mzz(Z) with lubricant was investigated. • The decomposition temperature of HFO-1336mzz(Z) with lubricant was measured. • The decomposition mechanism of HFO-1336mzz(Z) with PEC4 was illustrated. • HF, CO 2 and C 2 H 4 were the main decomposition products. Thermal stability and decomposition mechanism of HFO-1336mzz(Z) with polyol ester (POE) lubricant were experimentally and theoretically investigated. The experimental results showed that the dissociation temperature range of HFO-1336mzz(Z) with lubricant at 4 MPa was 250-270℃. ReaxFF force field was carried out to investigate the thermal decomposition mechanism of HFO-1336mzz(Z) with lubricant (PEC4). The breakage of C O bond in PEC4 molecule to generate the oleic acid chain (C 4 H 7 O 2 radical) was the dominant initiation reaction and then C 4 H 7 O 2 radical was decomposed to form CO 2 molecule and hydrocarbon radicals. These hydrocarbon radicals will continue to decompose or react with other radicals to generate more small molecular products. The radicals obtained from the dissociation of PEC4 will react with HFO-1336mzz(Z) to dissociate HFO-1336mzz(Z). HF, CO 2 and C 2 H 4 were the main decomposition products obtained from ReaxFF simulations. The reaction temperature and lubricant content promotes the thermal decomposition of HFO-1336mzz(Z) and the formation of decomposition products. [ABSTRACT FROM AUTHOR]

• The novel Re 3 P 4 @NPVC and Re 2 P@NPVC catalysts were designed by a novel strategy. • Coupling metal Re and P is able to promote the HER pathway. • The electronic coupling of NPVC layer and nanoparticles efficiently promotes the electron-transfer process for HER. • The Re 3 P 4 @NPVC exhibit remarkable catalytic activity for HER at all pH, which rivals the commercial Pt/C. Considering the great application prospect of noble metal rhenium (Re) in the catalytic field derived from its intrinsic properties, exploring more novel and highly effective Re-based catalysts becomes an important topic. Herein, for the first time, we design a novel strategy for fabrication of Re 2 P and Re 3 P 4 nanoparticles anchored in N, P doped vesicular carbon (NPVC) via pyrolyzing ammonium perrhenate (NH 4 ReO 4), 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) and melamine on the surface of SiO 2 spheres. Choosing hydrogen evolution as a probe reaction, Re 3 P 4 @NPVC heterostructure exhibits highly efficient catalytic activity compared with as-synthesized samples, which rivals the commercial Pt/C. Concretely, the Tafel slope is 38, 77 and 62 mV dec−1, and overpotential is 40, 70 and 61 mV at 10 mA cm−2 in 0.5 M H 2 SO 4 , 1 M phosphate buffer solution and 1 M KOH, respectively. Both experiment and DFT calculation unambiguously validate that Coupling metal Re and P is able to promote the HER pathway by tuning the ΔG H* value close to the optimum, balancing adsorption and desorption of hydrogen. Besides, the electronic coupling of NPVC layer and NPs synergistically enhances the proton adsorption and reduction kinetics. [ABSTRACT FROM AUTHOR]

Improving the output energy and durability of triboelectric nanogenerators (TENGs) remains a considerable challenge for their practical applications. Owing to the interface effect of triboelectrification and electrostatic induction, thinner films with higher dielectric constants yield a higher output; however, they are not durable for practical applications. Herein, the dielectric surface effect is changed into a volume effect by adopting a millimeter-thick dielectric film with an inner porous network structure so that charges can hop in the surface state of the network. Charge migration inside the dielectric film is the key factor affecting the output of the triboelectric nanogenerator (TENG) with a thick film, based on which each working stage follows the energy-maximization principle in the voltage-charge plot. The maximum peak and average power densities of the TENG with polyurethane foam film in 1 mm thickness reach 40.9 and 20.7 W m -2  Hz -1 , respectively, under environmental conditions, and the output charge density is 5.14 times that of TENGs with a poly(tetrafluoroethylene) film of the same thickness. Superdurability is achieved in the rotary-mode TENG after 200 000 operation cycles. This study identifies the physical mechanism of the thick dielectric film used in TENGs and provides a new approach to promote the output and durability of TENGs., (© 2023 Wiley-VCH GmbH.)

Digital light processing three-dimensional (DLP 3D) printing, as a promising manufacturing technology with the capability of fabricating 3D objects with complex shapes, typically develops inconsistent material properties due to the stair-stepping effect caused by weak layer-interface compatibility. Here, we report the regulation of the interface compatibility of the 3D-printing resin with versatile photocuring characteristics and the subsequent mechanical, thermal, and dielectric performances by introducing the interpenetration network (IPN). The preparation procedures, interface structure, flexural and tensile strength, modulus, and dielectric performances of the IPN are presented. The greater penetration depth in 3D printing and the subsequently thermocured epoxy network passing through the printing interface synergistically enhance the interface compatibility of 3D-printing samples, with an unobvious printing texture on the surface of the 3D-printing objects. The mechanical performances of the IPN demonstrate little anisotropy, with a bending strength twice as much as the photosensitive resin. Dynamic mechanical analysis of the IPN indicates that the storage modulus increases by 70% at room temperature and the glass transition temperature ( T g ) increases by 57%. The dielectric performance of the IPN demonstrates a 36% decrease in dielectric constant and a 28.4% increase in breakdown strength. Molecular dynamics studies have shown that the IPN takes on higher nonbonded energies and hydrogen bonds than the photosensitive resin, indicating a stronger bonding force between molecular chains, thus leading to better physical properties. These results illustrate the effectiveness of the IPN toward enhanced 3D-printing interlayer compatibility for excellent mechanical, thermal, and electrical performances.

Two-dimensional (2D) materials composed of pentagon and Janus motifs usually exhibit unique mechanical and electronic properties. In this work, a class of ternary carbon-based 2D materials, C m X n Y 6- m - n ( m = 2, 3; n = 1, 2; X, Y = B, N, Al, Si, P), are systematically studied by first-principles calculations. Six of 21 Janus penta-C m X n Y 6- m - n monolayers are dynamically and thermally stable. The Janus penta-C 2 B 2 Al 2 and Janus penta-Si 2 C 2 N 2 exhibit auxeticity. More strikingly, Janus penta-Si 2 C 2 N 2 exhibits an omnidirectional negative Poisson ratio (NPR) with values ranging from -0.13 to -0.15; in other words, it is auxetic under stretch in any direction. The calculations of piezoelectricity reveal that the out-of-plane piezoelectric strain coefficient ( d 32 ) of Janus panta-C 2 B 2 Al 2 is up to 0.63 pm/V and increases to 1 pm/V after a strain engineering. These omnidirectional NPR, giant piezoelectric coefficients endow the Janus pentagonal ternary carbon-based monolayers as potential candidates in the future nanoelectronics, especially in the electromechanical devices.

Background: Quantitative muscle and fat data obtained through body composition analysis are expected to be a new stable biomarker for the early and accurate prediction of treatment-related toxicity, treatment response, and prognosis in patients with lung cancer. The use of these biomarkers can enable the adjustment of individualized treatment regimens in a timely manner, which is critical to further improving patient prognosis and quality of life. We aimed to develop a deep learning model based on attention for fully automated segmentation of the abdomen from computed tomography (CT) to quantify body composition., Methods: A fully automatic segmentation deep learning model was designed based on the attention mechanism and using U-Net as the framework. Subcutaneous fat, skeletal muscle, and visceral fat were manually segmented by two experts to serve as ground truth labels. The performance of the model was evaluated using Dice similarity coefficients (DSCs) and Hausdorff distance at 95th percentile (HD95)., Results: The mean DSC for subcutaneous fat and skeletal muscle were high for both the enhanced CT test set (0.93±0.06 and 0.96±0.02, respectively) and the plain CT test set (0.90±0.09 and 0.95±0.01, respectively). Nevertheless, the model did not perform well in the segmentation performance of visceral fat, especially for the enhanced CT test set. The mean DSC for the enhanced CT test set was 0.87±0.11, while the mean DSC for the plain CT test set was 0.92±0.03. We discuss the reasons for this result., Conclusions: This work demonstrates a method for the automatic outlining of subcutaneous fat, skeletal muscle, and visceral fat areas at L3., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-22-330/coif). The authors have no conflicts of interest to declare., (2023 Quantitative Imaging in Medicine and Surgery. All rights reserved.)

Dual-energy computed tomography (CT) can be used for material decomposition, allowing for the precise quantitative mapping of body substances; this has a wide range of clinical applications, including disease diagnosis, treatment response evaluation and prognosis prediction. However, dual-energy CT has not yet become the mainstream technique in most clinical settings due to its limited accessibility. To fully take advantage of material quantification, researchers have attempted to use deep learning to generate material decomposition maps from conventional single-energy CT images, mainly by synthesizing another single-energy CT image from a conventional single-energy CT image to form a dual-energy CT image first and then generate material decomposition maps. This is not a straightforward process, and it potentially introduces many inaccuracies after multiple steps. In this work, we proposed a generative adversarial network (GAN) framework as the base and improved its generator; this approach combines convolutional neural networks (CNNs) and a transformer module to directly generate material decomposition maps from conventional single-energy CT images. Our model pays attention to both local and global information. Then, we compared our method with 6 competitive deep learning methods on water (calcium) and calcium (water) substrate density image datasets. The average PSNR, SSIM, MAE, and RMSE of the generated and ground truth of the water (calcium) substrate density images were 32.7207, 0.9685, 0.0323, and 0.0555, respectively. Furthermore, the average PSNR, SSIM, MAE, and RMSE of the generated and ground truth of the calcium (water) substrate density images were 30.2823, 0.9449, 0.0652, and 0.0715, respectively. Our model achieved better performance and stronger stability than competing approaches., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Nasopharyngeal carcinoma (NPC) is a malignant tumor, and the main treatment is radiotherapy. Accurate delineation of the target tumor is essential for radiotherapy of NPC. NPC tumors are small in size and vary widely in shape and structure, making it a time-consuming and laborious task for even experienced radiologists to manually outline tumors. However, the segmentation performance of current deep learning models is not satisfactory, mainly manifested by poor segmentation boundaries. To solve this problem, this paper proposes a segmentation method for nasopharyngeal carcinoma based on dynamic PET-CT image data, whose input data include CT, PET, and parametric images (Ki images). This method uses a generative adversarial network with a modified UNet integrated with a Transformer as the generator (TG-Net) to achieve automatic segmentation of NPC on combined CT-PET-Ki images. In the coding stage, TG-Net uses moving windows to replace traditional pooling operations to obtain patches of different sizes, which can reduce information loss in the coding process. Moreover, the introduction of Transformer can make the network learn more representative features and improve the discriminant ability of the model, especially for tumor boundaries. Finally, the results of fivefold cross validation with an average Dice similarity coefficient score of 0.9135 show that our method has good segmentation performance. Comparative experiments also show that our network structure is superior to the most advanced methods in the segmentation of NPC. In addition, this work is the first to use Ki images to assist tumor segmentation. We also demonstrated the usefulness of adding Ki images to aid in tumor segmentation., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Heat dissipation is necessary for the safer operation of high-power electronic devices and high-capacity batteries. Thermal meta-materials can efficiently manipulate heat flow by molding natural materials into specific structures. In this study, we construct a three-dimensional-printed meta-material structure with efficient and deterministic heat conduction through combining the 2D boron nitride (BN) with nano-diamond (DM) bridging. A research of thermal conductivity and dielectric properties exhibits that the nanosized diamond-bridged and oriented 2D boron nitride endows efficient heat transfer and maintains low dielectric loss with low filler loading. The composites loaded with 19 wt% BN platelets and 1 wt% DM have the highest thermal conductivity of 3.687 W/(m·K) in the heat flow orientation, while the thermal conductivity is only 0.632 W/(m·K) in the vertical heading of heat flow. The thermal conductive networks with thermal meta-materials based on the structural characteristics have been designed to secure critical device components from the heat source and dissipate heat flow in a definite way. The infrared images show that the temperature difference of monitoring points in different directions on the BN-oriented composite substrate is 9 °C, which realizes the protection of the heat source and key components. This study shows the latent capacity of 3D-printed structured materials for critical device component protection and heat administration applications in electronic devices and electric equipment.

Herein, a unique ganoderma-like MoS 2 /NiS 2 hetero-nanostructure with isolated Pt atoms anchored is reported. This novel ganoderma-like heterostructure can not only efficiently disperse and confine the few-layer MoS 2 nanosheets to fully expose the edge sites of MoS 2 , and provide more opportunity to capture the Pt atoms, but also tune the electronic structure to modify the catalytic activity. Because of the favorable dispersibility and exposed large specific surface area, single Pt atoms can be easily anchored on MoS 2 nanosheets with ultrahigh loading of 1.8 at% (the highest is 1.3 at% to date). Owing to the ganoderma-like structure and platinum atoms doping, this catalyst shows Pt-like catalytic activity for the hydrogen evolution reaction with an ultralow overpotential of 34 mV and excellent durability of only 2% increase in overpotential for 72 h under the constant current density of 10 mA cm -2 ., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)