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SiO 2 -supported SiC/B 4 C (SiO 2 –SiC/B 4 C) nanowires were synthesized by using SiO 2 @C nanospheres, amorphous B powders and catalyst Ni(NO 3) 2 ·6H 2 O as raw materials, and exhibited remarkable microwave absorbing characteristics. The minimum reflection loss of the SiO 2 –SiC/B 4 C nanowire/paraffin composite reaches −41.33 dB with an effective absorption bandwidth up to 9.69 GHz. The broadband microwave absorption of SiO 2 –SiC/B 4 C nanowires is attributed to the synergistic effect of interfacial polarization relaxation and conduction loss. While conductive loss dominates at low frequencies within 2–8 GHz, polarization loss caused by the heterogeneous interfaces plays an important role at high frequencies, especially between 10 and 16 GHz. The movement of the polarization relaxation peaks to lower frequencies in the composites is further investigated by modeling the relaxation process as a rotating sphere in a viscous fluid. The linear relationship between relaxation time and conductivity indicates that the conductivity is an important factor that affects the electromagnetic wave (EMW) absorption performance not only on the impedance matching and attenuation constant of the materials, but also regulates the relaxation time, and this result provides a new idea for exploring the absorption mechanism of EMW absorbing materials. [ABSTRACT FROM AUTHOR]

Boron nitride nanosheets (BNNS) were mixed with rutile TiO 2 and (Al, Nb)-codoped ceramics (ANTO) powders by heteroaggregation method. Homogeneous ceramics with the single phase of rutile TiO 2 were obtained by subsequent solid-state sintering. Scanning transmission electron microscope (STEM) and X-ray photoelectron spectrometer (XPS) results show that N was doped into the crystal lattice during sintering. It is shown that the strong electron localization of the covalent N i –O bond formed between interstitial N (N i) and adjacent O atom shifts the cutoff frequency of high permittivity from ∼100 kHz to 100 MHz in both rutile TiO 2 and the ANTO systems. Particularly, the ANTO-0.6BNNS sample exhibits optimum dielectric properties with a permittivity of 1.3 × 104 and tan δ of 0.04 measured at 1 MHz. Meanwhile, the colossal permittivity of ANTO-0.6BNNS with tan δ < 0.1 shows good temperature stability in the temperature range of 200–400 K. [ABSTRACT FROM AUTHOR]

High yielding synthesis of hollow carbon cubes (HCCs) was realized by using easily available NaCl cubes as templates in a simple way. The cubic carbon shells featuring an average side length of 3.5 μm, a thickness of 22.9 nm and the presence of macro and mesopores in the material, endow the HCCs/paraffin composites with an appropriate balance between good impedance matching and strong loss capacity. Superior electromagnetic wave (EMW) absorption performance was obtained at a very low loading ratio of 1.5 wt% of the HCCs. The composite having 4.5 mm thickness gave the maximum reflection loss of −46.0 dB at 7.8 GHz. At a thickness of 2.6 mm, a maximum effective absorption bandwidth of 6.6 GHz was achieved. Further investigation on the EMW dissipation mechanism of HCCs surrounding polarization relaxation and conductive loss was conducted. The integrity of the hollow structure plays a dominant role during EMW dissipation. The present study provides easy processing, cost-effective and environment-friendly HCCs as a predominant candidate for ultralight carbon-based EMW absorbing materials. [Display omitted] • High-yielding synthesis of hollow carbon cubes using NaCl cubes as template. • Superior microwave absorption performance at a low loading ratio of 1.5 wt %. • Dipole polarization observed by measuring temperature dependence of ε′ and tanδ. • Hollow structure effect on the performance studied by damage treatment of HCCs. [ABSTRACT FROM AUTHOR]

(1- x wt)Bi 0.0025 Nb 0.0025 Ti 0.995 O 2 - x wt Bi 2 Ti 4 O 11 composite ceramics with high permittivity were fabricated by a conventional sintering method. The sintering temperature was decreased from 1300 °C to 1130 °C, and the grain size was reduced from ~2.6 μm to ~1.5 μm by the addition of Bi 2 Ti 4 O 11 phase. When x wt = 0.2, the breakdown strength was increased from 1 kV/cm to 13 kV/cm while preserving high permittivity (ϵ' ~ 1100). Microstructure, I–V behavior, and Impedance spectroscopy studies demonstrated that the enhanced breakdown strength and excellent dielectric properties were attributed to the small grain size and the highly resistant grain boundaries. These advantages, together with its excellent DC bias stability of dielectric constant (0–1050 V/cm), give the composites a great potential in rutile TiO 2 -based high voltage MLCC applications. [ABSTRACT FROM AUTHOR]

Novel FeB/B 4 C nanowire composite was synthesized by a catalyst-assisted process. The results showed that the composite contains mainly B 4 C nanowires with diameters under 100 nm and FeB nanoparticles with a size of ~50 nm. Reflection loss value of the FeB/B 4 C nanowire-paraffin composite reaches −13.6 dB at 8.2 GHz when the thickness is 3.5 mm, and absorption bandwidth with RL below −10 dB reaches 1.6 GHz (7.5–9.1 GHz). The minimum RL value reaches −50.8 dB at 17.4 GHz when the thickness is 4.8 mm, with the absorption bandwidth increased to 2.4 GHz (15.6–18.0 GHz). Electromagnetic parameters of the composite were studied to understand its excellent microwave absorbing properties. [ABSTRACT FROM AUTHOR]

A large amount of multi-walled carbon nanotubes (MWCNTs) (10 vol%) were uniformly and intimately dispersed within ZrB 2 ceramic matrix using an aqueous hetero-coagulation approach followed by spark plasma sintering (SPS) at 1700 °C. Addition of MWCNTs inhibited grain growth, increased the relative density from 89% to 97%, and resulted in a composite with a fine, rather pore-free and uniform microstructure. Structural evolution of MWCNTs in the ZrB 2 matrix was further studied after SPS sintering at 1900 °C by XRD, Raman, scanning electron microscopy and TEM. When sintered at 1700 °C, the MWCNTs remained intact with their tubular one-dimensional structure though experiencing an expected radial elastic compression/buckling due to thermal misfit residual stresses. When sintered at 1900 °C, their unzipping into graphite nanoribbons was observed. For practical applications, MWCNTs content should however be lowered to prevent their agglomeration during grain growth. [ABSTRACT FROM AUTHOR]

Abstract: A solid state reaction of ZrH2, Si3N4 and B4C has been proposed to synthesize machinable ZrB2–SiC–BN composites. Dense ZrB2–SiC–BN composites with fine grain size and homogeneous microstructure were fabricated via spark plasma sintering at 1900°C in vacuum. The kinetics of the reaction process was studied with XRD results. SEM and TEM results showed that the in-situ formed BN phase was composed of micro-sized intergranular and nano-sized intragranular h-BN particles. The influences of the BN content on the mechanical properties as well as the thermal conductivities of the composites were studied. The composites that contained >20vol% BN exhibited excellent machinability and high strength. [Copyright &y& Elsevier]

ZrB2–SiC–ZrN composites were fabricated by reactive hot pressing using Zr, Si3N4, and B4C powders as starting materials. Sintering was conducted at temperatures of 1800 to 2000°C under a load of 20MPa in Ar atmosphere. The composite was densified at 2000°C. The in situ formed BN flakes which distributed uniformly at the grain boundaries were identified by X-ray diffraction and scanning electron microscopy. The formation of h-BN phase and its effect on the mechanical properties of the composite are discussed. [ABSTRACT FROM AUTHOR]

ZrB2–SiC–BN composites were fabricated from a powder mixture of ZrH2, Si3N4 and B4C via reactive hot pressing (RHP) and reactive spark plasma sintering (R-SPS). The phase composition, density, microstructure and mechanical properties of the final products were studied and compared. The sample fabricated by the R-SPS process showed higher density, flexural strength and fracture toughness and had a more homogeneous microstructure compared to the one fabricated by the RHP process. [Copyright &y& Elsevier]

Abstract: Using elemental Zr, B, Mo and Si as raw materials, partially textured ZrB2–MoSi2 composites with in situ platelet ZrB2 grains were fabricated by reactive hot pressing. Synthesized by a combustion reaction, the in situ formed ZrB2 phase had unique characteristics to grow up to platelet grains, on the surroundings of Mo–Si–B ternary liquid phase at high temperature. Mechanical properties were dependent on grain size and aspect ratio of the ZrB2 platelets. The rotation and realignment of the platelet ZrB2 grains under hot pressing led to a partially textured microstructure, which showed anisotropic mechanical properties on different directions of the as-sintered samples. A roadmap of the reaction process, microstructure evolution and texture formation was given to describe the preparation of partially textured ZrB2–MoSi2 composites by reactive hot pressing. [Copyright &y& Elsevier]

ZrB2–20 vol.% MoSi2 composites with elongated ZrB2 grains were prepared by reactive hot pressing using Zr, Si, B and Mo as raw materials. The ductile behavior of MoSi2 at high temperature helped the rod-like ZrB2 grains align under the applied pressure during sintering, resulting in a partly textured composite. The anisotropic growth of ZrB2 grains improved the toughness of the composite remarkably. [Copyright &y& Elsevier]

Four kinds of composites, ZrB2–SiC, ZrB2–SiC–ZrC, ZrB2–SiC–ZrN and ZrB2–SiC–AlN, were synthesized in situ via reactive hot pressing (RHP) and reactive spark plasma sintering (R-SPS), using Zr, Si, B4C, BN and Al as raw materials. The synthesis process plays a critical role in the microstructural features of the composites obtained. The R-SPS process can lead to a more homogeneous and finer microstructure due to its high heating rates and short holding time, while the RHP process is likely to result in coarse microstructures due to a long enough holding time for grains growth. [Copyright &y& Elsevier]

Abstract: ZrB2–SiC composite powders have been synthesized by combustion synthesis in air, using a mixture of Zr, B4C and Si as raw materials. It was found that the air atmosphere has played an important role in the ignition process of the SHS reaction. Three other kinds of ZrB2–SiC–ZrC composite powders with different ZrC content were also synthesized, and the ignition time has been measured for better understanding the ignition mechanism. As a result, the composite powders with particle size smaller than 1 µm and oxygen content as low as 0.4 wt.% were obtained. [Copyright &y& Elsevier]

Liver fibrosis is characterized by an increased and altered deposition of extracellular matrix (ECM) proteins that make up excessive tissue scarring and promote chronic liver injury. Activation of hepatic stellate cells (HSCs) is a pivotal cellular event in the progression of liver fibrosis. However, the mechanisms involved in the development of liver fibrosis are only now beginning to be unveiled. The Notch pathway is a fundamental and highly conserved pathway able to control cell-fate, including cell proliferation, differentiation, apoptosis, regeneration and other cellular activities. Recently, the deregulation of Notch cascade has been found involved in many pathological processes, including liver fibrosis. These data give evidence for a role for Notch signaling in liver fibrosis. In addition，more and more date are available on the role of Notch pathways in the process. Therefore, this review focuses on the current knowledge about the Notch signaling pathway, which dramatically takes part in HSC activation and liver fibrosis, and look ahead on new perspectives of Notch signaling pathway research. Furthermore, we will summarize this new evidence on the different interactions in Notch signaling pathway-regulated liver fibrosis, and support the potentiality of putative biomarkers and unique therapeutic targets. [ABSTRACT FROM AUTHOR]

Abstract: Binderless WC ceramics were prepared by reactive spark plasma sintering, using tungsten trioxide, tungsten and carbon black as the starting materials. Phase assemblages and microstructure of the as-sintered ceramics were investigated. It was found that graphite existed as an impurity phase due to the volatilization of WO3, and W could compensate for the WO3 loss to form WC with a single phase. Benefiting from the enhanced sinterability, WC ceramics with high relative density and good hardness could be obtained at temperature as low as 1500°C. [Copyright &y& Elsevier]

Abstract: Zirconium carbide and hafnium carbide ceramics were prepared by reactive spark plasma sintering, using oxides and carbon black as the raw materials. The phase and microstructure evolution during the sintering process was investigated. It was found that ZrC and HfC powder intermediates were formed at 1750 and 1800°C, respectively. Due to the high sinterability of the in situ formed carbide particles, samples with a fine microstructure could be densified at a relatively low temperature. [Copyright &y& Elsevier]

Abstract Due to dramatic growth of the aging population worldwide, there has been an urgent call for a public health strategy to manage healthy aging, with the ultimate goal being advancement of aging research. Considerable progress has been made in uncovering the mystery of aging process using multidisciplinary methods. There is a growing consensus in the field that aging traits which were originally thought to be disparate are likely to be interconnected. Thus, emerging research is needed to incorporate current findings of aging by building multiscale network models. This study reported the network of healthy aging research using bibliometric approaches. Based on the results, aging of the brain and muscle is a primary research focus which is a critical part of the multiscale network regulating the aging process. Among aging-associated diseases, Alzheimer's disease and frailty are among the main research focuses, and emerging work has focused on developing diagnostic tools for these diseases. For research on anti-aging interventions, calorie restriction, physical activity, and anti-aging pharmacology are the main interventions, of which the underlying mechanisms have been comprehensively studied in animal models. Highlights • A comprehensive and integrative view of current research findings on healthy aging • Brain and muscle aging is the research focus and regulating aging throughout the body • Alzheimer's disease and frailty are the intensively studied aging-associated diseases • Calorie restriction, exercise, and drugs are the majority anti-aging interventions [ABSTRACT FROM AUTHOR]

This is the first comprehensive review on inherent anisotropic features of transition metal diboride (MB 2 ) and their implementation for tailoring the microstructure and properties of MB 2 -based Ultra-high temperature Ceramics (UHTCs). The emphasis is on the processing approaches, microstructures, and properties of self-reinforced and/or textured MB 2 -based composites with elongated MB 2 grains. The crystal structure characteristics and grain growth behaviour of MB 2 are also critically reviewed. Benefiting from the tailored microstructure, the MB 2 -based ceramics exhibit some improved properties. Considering the success of Si 3 N 4 ceramics in the field of structural ceramics, it is expected that the potential MB 2 -based ceramic composites with abundant elongated MB 2 grains, textured structures, and controlled grain boundaries would possess improved fracture toughness, thermal shock resistance, and reliable high-temperature properties, which are desired for their practical applications. Accordingly, microstructure designing and tailoring provide an important perspective for the future development of UHTCs. [ABSTRACT FROM AUTHOR]

Despite of good oxidation resistance and ablation resistance, challenge to densify and tendency to loss high temperature (H.T.) strength have limited its potential applications in aerospace for HfB 2 –SiC ceramic. In this work, dense HfB 2 –SiC ceramic with improved H.T. flexural strength was prepared using WC as sintering aid. Pure HfB 2 –SiC ceramic exhibited creep deformation at 1600 °C with measured strength value of 389 ± 82 MPa, whereas WC doped sample showed much higher flexural strength of 658 ± 69 MPa with linear elastic behavior prior to fracture. In addition to clean grain boundary, the addition of 5 vol.%WC into HfB 2 –SiC ceramic promoted the formation of fine (Hf,W)B 2 , (Hf,W)C and WB precipitates. This combinative effect is responsible for its excellent H.T. mechanical property of WC doped HfB 2 –SiC ceramic. [ABSTRACT FROM AUTHOR]

Textured and platelet-reinforced ZrB2-based ultra-high-temperature ceramics (UHTCs) are prepared via reactive hot pressing and successive hot forging. The textured materials display significantly anisotropic mechanical properties, and the flexural strength has been improved by 52% owing to the orderly arrangement of platelet ZrB2 grains. The texturing of ZrB2-based platelet composites should open up an effective approach to optimizing the properties of ZrB2-based UHTCs. [Copyright &y& Elsevier]