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Highly conductive MXene has attracted extensive focus owing to its notable ability for electromagnetic wave dissipation, but it also suffers from impedance mismatch. Herein, flexibly MXene/rGO aerogel frames (MGs) were construct by direct ink writing (DIW) of low concentration emulsion inks. Adjustment of compositional ratio and structural design could effectively regulate their EWA performances. The results indicate that the printed aerogel frame has an effective absorption bandwidth (EAB) of 8.10 GHz (covering the majority of X-band and entire Ku-band) and a minimum reflection loss (RL min) of −56.85 dB. In addition, the printed ultralight aerogel frames integrate good mechanical performance and thermal insulation capability. The DIW technique for ultralight MXene-based absorber reveals beneficial inspiration and enlightenment for the structural design and potential application of EMA composites. [Display omitted] • DIW of ultra low-density aerogel frames using low concentration (10 mg/ml) MXene/GO emulsion ink. • Electromagnetic wave absorption properties are effectively regulated by composition ratio and structural design. • The EAB of under optimized condition can reach 8.10 (9.9–18.0) GHz at 3.5 mm, and the RL min at 2.7 mm was −56.85 dB. • The printed ultralight multifunctional integrated electromagnetic wave absorber has good thermal insulation and mechanical properties. [ABSTRACT FROM AUTHOR]

Ceramic SiCN nanocomposites modified with nanocellulose derived defect-rich carbon nanofibers (CNFs-SiCN) were developed by thermolysis of nanocelulose-polysilazane single-source precursors (SSPs). Multi-loss mechanisms (i.g. polarization loss and conductive loss) were established in the SiCN ceramic nanocomposites by employing the defect-rich structure of CNFs. Cole-Cole circle plots indicate that the CNFs-SiCN ceramics possess strong polarization capability due to the defect-rich structure of the CNFs. Dielectric loss values fitted by the Debye theory showed that the proportion of polarization loss reaches an unprecedented high value, accounting for 52.1% of the total dielectric loss. When the content of nanocellulose is 10 wt% of SSPs, the minimal reflection coefficient (RC min) and effective absorption bandwidth (EABs) of CNFs-SiCN ceramic can reach −36.3 dB and 3.0 GHz, respectively. This work may contribute new ideas for establishing multi-loss mechanisms in ceramic-based materials, finding a new application for nanocellulose, and shaping the design of novel absorbents. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work, SiC nanowires and graphitic carbon (GC) including 2D reduced graphene oxide and graphene-liked ribbons modified polymer derived SiCN (SiC/GC-SiCN) porous ceramic monoliths were prepared via catalyst assisted single-source-precursor derived ceramic route. The inclusion of absorbents (e.g. graphitic carbon and SiC nanowires) significantly improved the electrical conductivity of the materials from 1.77 × 10−8 S/cm (pristine SiCN) to 0.56 S/cm. In turn, the electromagnetic interference shielding effectiveness (EMI SE) of the ceramic increased significantly from 4.0 dB to 19.2 dB. At the highest absorbent content, the SiC/GC-SiCN ceramics exhibit a high absorption power of 0.3 nW and an SE of 48.5 dB at thickness of 2 mm, which means more than 99.998 % of the EM wave is blocked. This work finds new avenue for the design of advanced electromagnetic shielding materials possessing strong absorption capability. [ABSTRACT FROM AUTHOR]

Molybdenum carbide (β-Mo 2 C) possesses excellent electrical conductivity, good thermal and chemical stability, and is, therefore, a promising candidate material for electromagnetic (EM) shielding in diverse harsh environments. Herein, for the first time, β-Mo 2 C based ultra-thin films were prepared through in-situ growth of the carbide on a self-assembled graphene oxide (GO) film. The remaining reduced GO (RGO) layers located in between two adjacent Mo 2 C nanoparticles not only can work as flexible binder to impart the resultant films excellent flexibility but also enable the formation of heterogeneous nano-interface which is beneficial for the improvement of shielding by absorption. The amounts of β-Mo 2 C in the resultant films were adjusted through varying the Mo precursor contents. With the introduction of β-Mo 2 C phase in the resultant film, the shielding effectiveness (SE) increased significantly. At the thickness of ∼25 μm, the highest SE reaches 46.8 dB compared to 21.6 dB of the pristine RGO film. With the increase of the Mo 2 C content in the resultant materials, the density increased from 0.32 to 1.23 g/cm3. The resultant Mo 2 C film exhibit an SSE/t (specific SE by thickness) value of as high as 15,971 dB cm2 g−1. Image 1 [ABSTRACT FROM AUTHOR]

The prevailing property management philosophy in China is outdated and is therefore not useful for improving the sustainability of buildings and their facilities. However, the introduction and integration of basic ecological concepts in the existing studies of ecological property management theory has been limited. The analysis related to the methods for and the influencing factors on ecological behavior implementation has hardly been covered. Based on the use of grounded theory, this paper conducts an in-depth analysis of property management ecological behavior by setting the influencing factors as the research target. First, a literature review is conducted to identify the definition of property management ecological behavior. Based on the theory of planned behavior, a preliminary theoretical model of the factors influencing ecological behavior in property management is constructed. Then, the research framework and a data analysis scheme are designed based on grounded theory. An in-depth review is used to gather information on property management in community and public housing. The interview data are coded and analyzed with the help of NVivo11 software to identify the influencing factors of the property management ecological behavior in China. Studies have shown that factors influencing property management ecological behavior include stimulus, status, scenario, and result. The stimulus factors include government regulations , market pressure , and social supervision. The status factors include scale, nature, capabilities, value , environmental awareness of managers, and financial situation. The scenario factors include service cost, resource availability, object factor , and owner willingness. The result factors include the profits of the company and the satisfaction of the owners. This study comprehensively identifies the influencing factors of the property management ecological behavior in China and enriches the definition of property management ecological behavior. A theoretical model of influencing factors of property management ecological behavior is built and employed to systematically analyze the characteristics of the ecological behavior of property service companies. This study provides a foundation for further analysis of the mechanisms guiding ecological behavior among property management companies in China. [ABSTRACT FROM AUTHOR]

In the past decade, many efforts have been devoted to exploring the Critical Success Factors (CSFs) for Green Building (GB) projects. However, there is absence of a systematic review exploring these studies. Therefore, the paper presents a comprehensive review of publications from 2005 to 2018 on CSFs for GB projects. The results indicate there is a growing interest in the exploration of CSFs for GB projects since 2010. The main contributing contributors, institutions, countries and areas, as well as research methods in this area are summarized. The mostly identified CSFs for GB projects are "communication and cooperation between project participants", "effective project planning and control", "owner's involvement and commitment", "clear goals and objectives" and "project manager's performance". The contractors and owners were found more related to these identified CSFs. Finally, knowledge gaps are discussed and future research directions including: (1) more studies on relationships between the CSFs; (2) extending studies to cover all building types; (3) more investigation on CSFs for different project objectives; (4) more emphasis on how to implement CSFs for GB projects are proposed. The results could offer a favorable reference for researchers to obtain a thorough picture of the current research woks and facilitate further study in this area. The discussion of GB CSFs could also broaden the understanding of the best ways for implementing GB projects to practitioners thereby reducing the setbacks towards its implementation. • Studies on Critical Success Factors (CSFs) for green building projects were systematically reviewed. • Our focus was to review papers published from 2005 to 2018. • Most adopted research methods in this field were presented. • CSFs of green building projects in previous researches and their related project stakeholders were identified and discussed. • Future research directions in green building projects were proposed. [ABSTRACT FROM AUTHOR]

Waste plastics and electromagnetic radiation pollution have been two serious issues that largely affect our environment. How to solve them in a single approach is a social and scientific challenge. In this work, advanced Co/MnO@carbon nanotube composite (Co/MnO@CNTs) absorbents were prepared via pyrolysis-catalysis conversion of face masks as post-consumer plastic waste with multi-scale designed Co x Mn 3– x O 4 spinel pre-catalysts. The (nano)structure (e.g., MnO-carbon and Co-carbon hetero-interface), composition, and graphitic degree of the Co/MnO@CNTs absorbents were facilely controlled by varying the catalytic reaction temperature and the composition of spinel pre-catalysts. By constructing multi-loss mechanisms (e.g., magnetic loss, conductive loss, interface polarization loss, and defects-induced polarization loss), the largest effective absorption bandwidth (EAB) of the Co/MnO@CNTs/wax composites can reach as wide as 5.28 GHz at a thickness of 1.7 mm. When the content of the Co/MnO@CNTs absorbents is 17 wt%, the EAB and minimal reflection loss (RL min) achieves 5.04 GHz and −38.1 dB, respectively. This work is based on a sustainable and cost-effective feedstock as well as an innovative method for the large-scale production of advanced CNTs-based materials in electromagnetic absorption application. [Display omitted] [ABSTRACT FROM AUTHOR]

For the first time, single-source-precursors (SSPs) were synthesized through chemical modification of a commercial poly(methylvinyl)silazane with chemically bonded graphene oxide and carbon nanotube hybrids (GO/CNTs). After pyrolysis of warm-pressed and consolidated SSP-powders at 1000 °C in Ar, monolithic SiCN ceramic nanocomposites modified with in-situ thermally reduced GO/CNTs, namely RGO/CNTs-SiCN, were successfully obtained. The SSP-derived nanocomposite exhibits significantly enhanced dielectric properties if compared with that of a physically-blended-precursor derived reference material. Moreover, the SSP-derived RGO/CNTs-SiCN composite containing 15.0 wt% GO/CNTs in the feed possesses an electromagnetic shielding effectiveness of 67.2 dB with a sample thickness of 2.00 mm, which is the highest value among all the reported graphene-based composites with comparable thickness. [ABSTRACT FROM AUTHOR]

Constructing effective photocatalysts with visible-light-driven for degrading VOCs including formaldehyde remains a challenge. The TiO 2 (B) photocatalyst with a two-dimensional lamellar structure was prepared and modified by surface engineering. The DFT calculation results showed new impurity levels appeared among the energy bands of the modified TiO 2 (B) materials. These photocatalysts exhibited different rates of HCHO degradation under visible light. A variety of characterizations demonstrated that the surface defects greatly reduced the bandgap and enhanced the absorption of visible light. And the recombination of photogenerated electron-hole (e--h+) pairs was suppressed to varying degrees in the modulated TiO 2 (B) catalysts revealed in the photoelectrochemical analysis. It is necessary to match the band structure of photocatalysts with the frontier orbital of HCHO for achieving effectual photocatalytic oxidation (PCO). Remarkably, the separation and transport of photogenerated carriers were inhibited when excessive metal Cu was doped. The results in this work provide a deeper understanding of the relationship between the surface engineering of TiO 2 (B)-based catalysts and catalytic performance. [Display omitted] • Cu was anchored on TiO 2 (B) nanosheets through in situ icing-assisted photocatalytic doping method. • TiO 2 (B)-based catalysts showed potential for photocatalytic oxidation HCHO under visible light. • Matching the electronic structure of photocatalysts with the frontline orbital of pollutant was crucial factor. • The transport and separation of photogenerated carriers was inhibited when excessive Cu was doped. [ABSTRACT FROM AUTHOR]

Abstract: Carbon nanotube reinforced carbon fiber/pyrolytic carbon composites were fabricated by precursor infiltration and pyrolysis method and their electromagnetic interference shielding effectiveness (EMI SE) was investigated over the frequency range of 8.2–12.4GHz (X-band). Carbon nanotubes (CNTs) were in situ formed through catalyzing hydrocarbon gases evaporating out of phenolic resin with nano-scaled Ni particles. The content of CNTs increased with the increase of Ni loadings (0.00, 0.50, 0.75 and 1.25wt.%) in phenolic resin. Thermal gravimetrical analysis results showed that the carbon yield of phenolic resin increased with the addition of Ni catalyst. With the formation of CNTs, the EMI SE increased from 28.3 to 75.2dB in X-band. The composite containing 5.0wt.% CNTs showed an SE higher than 70dB in the whole X-band. [Copyright &y& Elsevier]

Abstract: Carbon nanotube reinforced pyrolytic carbon/silicon nitride (CNT-PyC/Si3N4) composite ceramics were fabricated through in-situ growth of CNTs in PyC–Si3N4 ceramics by precursor infiltration and pyrolysis. CNTs were in-situ formed by the addition of nano-sized Ni into phenolic resin and Si3N4 powder blend, and the content of CNTs increased with the increase of Ni content. Due to the formation of CNTs in the inter-particle pores of CNTs/PyC–Si3N4 ceramic, the PyC wrapped Si3N4 particles were bridged by CNTs, which led to the increase of electrical conductivity. Different from the previously reported PyC–Si3N4 ceramics fabricated by chemical vapor infiltration (CVI), the PyC–Si3N4 ceramics exhibited a shielding mechanism dominated by absorption. Compared to PyC–Si3N4 ceramics prepared with same procedure, the shielding effectiveness of CNTs-PyC/Si3N4 increased significantly with the formation of CNTs. With the increase of CNT content, the shielding effectiveness of CNTs/PyC–Si3N4 ceramics increased from 25.5 to 43.6dB, in which the absorption shielding effectiveness increased from 15 to 30dB over the frequency range of 8.2–12.4GHz. [Copyright &y& Elsevier]

Abstract: Sm and Sr co-doped ceria-based electrolyte with compositions of Ce0.8(Sm1−x Sr x )0.2O2−δ (x =0, 0.3, 0.5, 0.7) are synthesized and investigated with the aim of improving the electrical properties of Ce0.8Sm0.2O2−δ . X-ray diffraction (XRD) and electron microscope (SEM and TEM) techniques are employed to characterize the microstructure of powders and sintered pellets. The ionic conductivity has been examined by the A.C. impedance spectroscopy in air. The Ce0.8(Sm0.7Sr0.3)0.2O2−δ exhibits the highest bulk conductivity among the series, which can be mainly ascribed to the increase of oxygen vacancy concentration. The specific grain-boundary conductivities are observed to increase with the Sr doping content up to x =0.5. Further increase in Sr concentration will lead to reduced specific grain-boundary conductivities. The total conductivities of all Sm and Sr co-doped ceria are higher than that of Ce0.8Sm0.2O1.9. The results indicate that Sr co-doping opens a new avenue to improve ionic conductivity in Ce0.8Sm0.2O1.9. [Copyright &y& Elsevier]

Abstract: Sm0.5Sr0.5CoO3−δ (SSC) cathode prepared by a glycine–nitrate process (GNP) is investigated for solid oxide fuel cells (SOFCs) based on Ce0.85Sm0.075Nd0.075O2−δ (SNDC) electrolyte. SSC forms cubic perovskite structure after being annealed at 1100°C for 5h. SSC cathode and SNDC electrolyte can retain their own structure and there is no reaction between the two compositions. The microstructure of the cathode and the interfaces between cathodes and SNDC electrolytes are studied by scanning electron microscopy (SEM) after sintering at various temperatures. Impedance spectroscopy measurements reveal that area specific resistances (ASRs) of SSC–SNDC30 cathode are much lower than those of SSC cathode. Kinetics of oxygen reduction reaction (ORR) on porous SSC cathode is investigated by analysis of impedance spectra. Medium-frequency conductivities show no dependency on oxygen partial pressure , which can be attributed to the oxygen ions transfer across the electrode/electrolyte interface. The dependencies of low-frequency conductivities on oxygen partial pressure vary in the range from ca. 0.31 to ca. 0.34 and increase with the increasing temperatures. The low-frequency electrode process is a mixing process involving oxygen reduction reaction related to atomic oxygen and oxygen ions conduction step together with total charge-transfer step. IR-compensated current density (i)–overpotential (η) relationship is established and the exchange current densities i o originated from high-field approximations are much higher than those of low-field approximations and a.c. impedance data under OCV state. It demonstrates the polarization overpotential has great effect on the kinetics of ORR. The polarization current is observed to increase with time in the long-term stability measurement, which can be ascribed to the propagation process of oxygen vacancies. [Copyright &y& Elsevier]

Abstract: In this work, four different methods, including polyvinyl alcohol (PVA)-assisted sol–gel process, polyethylene glycol (PEG)-assisted sol–gel process, citrate sol–gel process and oxalate coprecipitation process (OCP) are employed to synthesize the Sm and Nd co-doped ceria electrolyte with the composition of Ce0.85Sm0.075Nd0.075O2−δ (SNDC). The phase structure of the powders can be well indexed with the fluorite-type CeO2 structure. The morphology of sintered samples indicates that the ceramics can be highly densified. The relative density and the average grain size vary with the synthesis processes and the sintering temperatures. The bulk conductivities are quite close and the OCP–SNDC yields highest grain-boundary conductivities and total conductivities. The results indicate that the OCP process for the powder synthesis results in higher relative density and conductivities, lower grain-boundary resistance and activation energy. Grain-boundary space charge potentials for different specimens are calculated based on the Mott–Schottky model. The synthesis process and sintering temperature have significant effect on the space charge potential and the specific grain-boundary conductivity. [Copyright &y& Elsevier]

Abstract: Ti3SiC2 is one of the most promising materials belonging to M n +1AX n phases, which exhibit good damage tolerance, thermal stability and mechanical properties. Recently, in the frame of research on future gas cooled fast nuclear reactors, Ti3SiC2 has been considered as an innovative candidate material, which could be incorporated in some core components such as fuel cladding. At the present time, however, very few data are available concerning the behaviour of this material after irradiation. In this work, Ti3Si0.90Al0.10C2 samples were irradiated with high energy Kr and Xe ions and characterized by X-ray diffraction. Patterns were analysed in terms of change in peak intensity, peak position and width. Rietveld refinements were also performed. Increase in micro-strains and lattice parameter with irradiation dose was highlighted. The formation of β-Ti3SiC2, which has never been observed by experimental XRD on non irradiated material, was proposed for the highly irradiated samples. A partial recovery of the microstructure with temperature was found. [Copyright &y& Elsevier]

A novel and sustainable paper template-based method was developed for the fabrication of advanced niobium carbide (NbC)-based free-standing films for electromagnetic interference (EMI) shielding application. Through employing the porous structure of paper template, the simultaneous optimization of thickness, flexibility, density and shielding effectiveness (SE) of NbC-based films was facilely achieved. The pyrolytic carbon (PyC) derived from paper worked as a carbon source for the growth of the NbC phase. A hierarchically porous structure with a porosity of ∼80 vol % was established to optimize the flexibility and density of the resultant films. Adjusted heterogeneous NbC-PyC nano-interfaces were formed by controlling the amount of NbC and the remaining PyC phase in the films, which significantly improved the absorption capability of EM waves. At the highest NbC content, the film possesses shielding effectiveness of 50 and 86 dB when the sample thickness is ∼55 and ∼220 μm, respectively compared to 32 dB of pristine paper-derived PyC film (∼55 μm). These results provide guidance to explore more eco-friendly and commercially effective routes for the recycling of used paper through developing their application in the EM field. [Display omitted] [ABSTRACT FROM AUTHOR]

A nuclear heating system integrated with a heat storage tank (HST-NHS) is a promising technical solution for countries with large-scale heating demand. HST-NHS can greatly curtail carbon dioxide emissions and contribute to sustainable development. Appropriate control strategies are not only crucial to realize the real-time matching between HST-NHS heat supply and heat demand, but also ensure the stable and safe operation of HST-NHS. Until now, control strategies for HST-NHS have received limited attention. A refined dynamic simulation model for HST-NHS is established based on APROS software. The verification of the built model in steady state and transient state is completed. Two basic control strategies for the primary heating network (PHN) of HST-NHS, constant supply water temperature and variable flow rate (CT-VF) and variable supply water temperature and constant flow rate (VT-CF) are presented in detail. Based on various typical working conditions of a central heating region in Liaoyuan City, the control effects of two control strategies are investigated. Additionally, a comprehensive performance comparison between the two strategies is explored. Simulation results indicated that under the two control strategies, the indoor temperature can be effectively controlled at a high comfort level. During the same typical day, the total energy consumption cost under the VT-CF control strategy is 0.5 × 105 yuan lower than that under the CT-VF control strategy. • Dynamic model of nuclear heating system with heat storage is developed. • The verification of the built model in steady and transient state is completed. • Control effects of two basic control strategies during typical days are evaluated. • A performance comparison of two basic control strategies is conducted. [ABSTRACT FROM AUTHOR]

The PyC/Al 2 O 3 ceramics with micro-channels were prepared by the 3D printing, which realized the tailored microwave absorption properties via designing meta-structures with diverse micro-channels to tailor the permittivity of the ceramic. The permittivity of the ceramics can be effectively controlled by micro-channels with different orientations and sizes, which could be particular for designing multi-layer impedance matching meta-structures with different dielectric properties. The absorption bandwidth of PyC/Al 2 O 3 ceramics is effectively expanded, which realized great than 90 % EM wave absorption in the frequency range of 6–18 GHz, indicating an efficient absorption band of 12 GHz. Therefore, this study put forward a new strategy to tailor the permittivity of 3D printed ceramics by introducing micro-channels with sizes of sub-wavelength, which could enlarge the design freedoms for 3D printed microwave absorbing ceramics. • An 3D printed PyC/Al 2 O 3 ceramic metamaterials is proposed. • The permittivity of PyC/Al 2 O 3 can be effectively tailored by the micro-channels. • The proposed meta-structure can achieve strong absorption at thinner thickness. [ABSTRACT FROM AUTHOR]

Integrating heat storage devices with the pool-type low-temperature heating reactor (PLTHR) can improve the flexibility of PLTHR for load following. A novel low-temperature nuclear heating system (HST-NHS) is proposed, which combines the DHR-400 heating reactor system, a heat storage tank (HST), and a gas boiler (GB) to achieve real-time matching between heating supply and demand. A mixed integer nonlinear programming (MINLP) optimization model with the annual cost (AC) as the optimization objective is established. An operation strategy that considers the device priority is proposed. The capacity and operation of HST-NHS are simultaneously optimized using the CPLEX solver. The optimization results indicate that an HST with a rated capacity of 1324.14 MWh and a GB with a rated capacity of 201.69 MW can provide the operational flexibility needed for the HST-NHS throughout the heating period. When compared with comparison schemes 1 (DHR-400 and HST), 2 (DHR-400 and GB), and 3 (pure gas boiler heating system), HST-NHS achieves significant annual cost savings. Finally, a sensitivity analysis of device price and fuel price is conducted, revealing that the unit price of the DHR-400 heating reactor system and natural gas price are the main factors affecting the AC and dynamic payback period (DPP) of HST-NHS. This work offers theoretical guidance for the subsequent engineering application of the DHR-400 heating reactor system. • A novel nuclear heating system considering heat storage is proposed. • Operation strategy follows device priority is proposed. • The capacity and operation plan are optimized simultaneously by a MINLP model. • The nuclear heating system significantly reduces costs and CO 2 emissions. • Sensitivity analysis of device price and fuel price is carried out. [ABSTRACT FROM AUTHOR]

In this work, a tungsten carbide (WC)-containing silicon oxycarbide (SiOC) glass-ceramic was prepared from WC-filled polysiloxane via pyrolysis and subsequent spark plasma sintering (SPS). The sintering behavior of SiOC was investigated by monitoring the densification temperature and shrinkage displacement. The phase composition and microstructure of ceramics were characterized by using FTIR, XRD, SEM, Raman spectrum, and optical microscope. It was shown that upon increasing the sintering temperature from 1400 °C to 1600 °C, the densification of ceramics was further improved, and the disorder of free carbon in SiOC was linearly decreased with sintering temperature. In addition, it was found that the incorporation of WC particles was effective to reinforce the mechanical properties of ceramics, and relevant strengthening mechanisms were discussed here. Finally, a correlation between phase composition, microstructure, and macroscopic performances of SiOC glass-ceramics was successfully derived. [ABSTRACT FROM AUTHOR]

[Display omitted] • The acid-base bifunctional Y/ g- C 3 N 4 is employed to catalyze the cycloaddition of CO 2 to epoxide efficiently under halogen-free conditions. • Y-species is function well as preferred Lewis acid sites for epoxide ring opening and butene carbonate desorption. • A synergistic mechanism based on acid-base duality for cycloaddition of CO 2 to epoxide is proposed. Cycloaddition reaction of CO 2 to epoxides is an important procedure for both CO 2 conversion and cyclic carbonate synthesis. Homogeneous alkali halide and quaternary ammonium salt are the general catalysts, while they have the problems of halogen corrosion and residue, intricate separation, and catalyst recycling. Here, a series of heterogenous and halogen-free bifunctional yttrium-coordinated g- C 3 N 4 were synthesized and employed to catalyze the cycloaddition of CO 2 to butylene oxide. Excellent butylene oxide conversion (94.5%) and butene carbonate selectivity (95.0%) were achieved over the typical Y/g-C 3 N 4 -0.5 catalyst without any halogen addition. The characterizations demonstrate that the coordinated Y species function well as the preferred Lewis acid sites for epoxide ring opening and butene carbonate desorption, and the uncondensed amino groups are supplied as Lewis base sites to activate CO 2. It is the synergistic effect based on acid-base duality that enhances the catalytic performance of Y/g-C 3 N 4 to cycloaddition of CO 2 with epoxide. [ABSTRACT FROM AUTHOR]

In this study, Y-Al-Si-O(YAS) glass-ceramic environmental barrier coatings were prepared after modifying CVI-SiC f /SiC composites with microcrystalline glass. The resistance of both SiCf/SiC and SiC f /SiC with YAS-EBC to thermal shock was systematically examined using a water quenching method. The findings demonstrate that the SiC f /SiC composites with YAS-EBC exhibits outstanding thermal shock resistance. The coefficient of thermal expansion (CTE) of the YAS coating exhibits minimal deviation from that of SiC f /SiC and possesses a low modulus of elasticity. Upon experiencing thermal shock, the YAS coating is subjected to tensile stress, with an average thermal stress of merely ∼4.4 MPa. After undergoing 100 cycles, there was no evidence of debonding between the coating and the substrate, nor was a thermally grown oxide (TGO) layer observed at the interface. This research provides a credible method and theoretical foundation for enhancing the thermal shock resistance behavior of CVI-SiC f /SiC composites. [ABSTRACT FROM AUTHOR]

The traditional wearable sensor has the problem of insufficient sensing coefficient and sensing range. In order to solve these problems, this paper innovatively prepared CNTs and MXene monodisperse waterborne slurry mixed with waterborne thermoplastic polyurethane and nanocellulose to prepare composite ink. The monodisperse CNTs and MXene have good conductive network construction ability, so that when the content of CNTs and MXene in the ink is as low as 0.08%, a stable sensing conductive network can still be formed (conductivity 127s/cm). The low addition of nanomaterials are cost saving along with the influence in conductivity which made the experiment to implement the bonding strength and viscous attributes of the inkjet in printing. The mechanical properties of the composite ink film sensor assembled by ink and medical fabric can be carried out by digital spraying printing technology. The results show that the sensitivity of the MXene/CNTs/WPU/CNFs ink sensor in the tensile test is up to 43.61, and the sensor resistance still shows a linear change under the strain of 0–89%. At the same time, after 2100 fatigue tests, the sensor resistance change remains stable. Finally, the MXene/CNTs/WPU/CNFs ink sensor has also been successful in human monitoring. From monitoring small changes such as finger bending and cervical spine bending to monitoring large movements such as arm flexion and knee bending, the corresponding electrical response can be obtained in time respectively. Therefore, the MXene/CNTs/WPU/CNFs ink sensor has the characteristics of high sensitivity, real-time monitoring and recording, which shows that the research has broad application prospects in the future development. [ABSTRACT FROM AUTHOR]

• The transient thermal–hydraulic behavior of LOFA in DPNR is analyzed. • The effects of flap valve opening criteria on LOFA are revealed. • The effects of FRC in connection pipe on LOFA are revealed. • The core flow oscillation caused by inertia tank is alleviated by opening flap valve. Deep pool nuclear reactor (DPNR) is a novel pool-type reactor, which has shown great potential in seawater desalination and district heating. In this paper, the thermal–hydraulic behavior of loss-of-flow accident (LOFA) in DPNR were investigated by RELAP5. The parametric analyses were also carried out to reveal the effects of flow resistance coefficient (FRC) in connection pipe and flap valve opening criteria on thermal–hydraulic behavior of LOFA in DPNR. The results showed that the LOFA process could be divided into coast-down phase, oscillation phase and natural circulation phase, and two peaks of clad peak temperature appeared. Besides, the parametric analysis showed that increasing FRC in connection pipe and failure of flap valve can make the first and second peak of clad peak temperature larger, respectively. The decrease of flap valve opening criteria made flap valve open earlier, and inertia tank performance was weakened when flap valve opened in coast-down phase. [ABSTRACT FROM AUTHOR]

Abstract: In order to enhance the dielectric and electromagnetic interference shielding (EMI) properties, the SiC/C composite ceramics were fabricated by pyrolysis of ferrocene-modified polycarbosilane. The microstructure evolutions, dielectric properties, EMI and microwave absorption properties of SiC/C composite ceramics were investigated. The increases of both ferrocene contents and annealing temperatures led to the increases of crystallizations of SiC and carbons. Crystallized carbons including carbon nanowires, turbostratic carbons, onion-like carbons and graphene-like carbons were obtained in the materials. The carbon nanowires were longest when the 5wt.% ferrocene-modified polycarbosilane was annealed at 1250°C. These carbons played a more important role than SiC in the increases of dielectric and EMI properties. The average real and imaginary permittivities of materials increased from 4.4 and 0.7 to 38.9 and 39.6, respectively. The materials exhibited high total shielding effectiveness, high absorption shielding effectiveness and low reflection shielding effectiveness, which were 36.6, 30.1 and 6.5dB, respectively. [Copyright &y& Elsevier]

Abstract: By using a catalytic growth procedure, carbon nanotubes (CNTs) are in situ formed on reduced graphene oxide (RGO) sheet at 600°C. CNTs growing on RGO planes through covalent C–C bond possess lower interfacial contact electrical resistance. As a hybrid structure, the CNTs/graphene (CNT/G) are well dispersed into poly (dimethyl siloxane). The hybrid combining electrically lossy CNTs and RGO, which disperses in electrically insulating matrix, constructs an electromagnetic wave (EM) absorbing material with ternary hierarchical architecture. The interfacial polarization in heterogeneous interface plays an important role in absorbing EM power. When the filler loading is 5wt.% and thickness of absorber is 2.75mm, the minimum value of reflection coefficient and the corresponding frequency are −55dB and 10.1GHz, and the effective absorption bandwidth reaches 3.5GHz. Therefore, combining the CNTs and graphene sheet into three-dimensional structures produces CNT/G hybrids that can be considered as an effective route to design light weight and high-performance EM absorbing material, while the effective EM absorption frequency can be designed. [Copyright &y& Elsevier]

Abstract: Porous SiCN ceramics were successfully fabricated by pyrolysis of a kind of polysilazane. The effects of annealing temperature on the microstructure evolution, direct-current electrical conductivity, dielectric properties, and microwave absorption properties of SiCN in the frequency range 8.2–12.4GHz (X-band) were investigated. With the increase of annealing temperature, SiC, Si3N4 and free carbon nanodomains are gradually formed in the SiCN. Both the SiC and free carbon nanodomains lead to the increases of the complex relative permittivity and loss tangent of SiCN. With the increase of the annealing temperature, the average real permittivity, imaginary permittivity and loss tangent increase from 4.4, 0.2 and 0.05 to 13.8, 6.3 and 0.46, respectively. The minimum reflection coefficient and the frequency bandwidth below −10dB for SiCN annealed at 1500°C are −53dB and 3.02GHz, indicating good microwave absorption properties. [Copyright &y& Elsevier]

Abstract: Silicon carbide nanowires (SiC NWs) reinforced SiOC ceramics were fabricated through in situ growth of SiC NWs in SiOC ceramics by pyrolysis of polysiloxane. SiC NWs were in situ formed by the addition of ferrocene, the content of SiC NWs increased with the increases of annealing temperature and ferrocene content. Due to the formation of SiC NWs in the inter-particle pores of SiOC ceramics, the SiOC particles were bridged by SiC NWs, which led to the increase of electrical conductivity. With the increase of SiC NWs content, the real permittivity and the imaginary permittivity increased from 3.63 and 0.14 to 10.72 and 12.17, respectively, and the minimum reflection coefficient decreased from −1.22dB to −20.01dB, demonstrating the SiOC ceramics with SiC NWs had a superior microwave-absorbing ability. [Copyright &y& Elsevier]

Abstract: SiO2 reinforced with both multi-wall carbon nanotubes (MWCNTs) and ZnO particles was prepared. Owing to the consumption of an amorphous carbon layer on the outer surface of MWCNTs and the generation of oxygen vacancies in ZnO during sintering, the contact resistance between MWCNTs is lowered and a higher concentration of charge carriers is produced in ZnO. The permittivity of the composite is improved by both changes. The composite containing 15wt% ZnO particles and 3wt% MWCNTs exhibits a wider effective absorption bandwidth and lower minimum reflection coefficient than both SiO2 reinforced with 15wt% ZnO particles and SiO2 reinforced with 3wt% MWCNTs. [Copyright &y& Elsevier]