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Electromagnetic wave (EMW)-absorbing materials, manufactured with composites of magnetic particles, are essential for maintaining a high complex permeability and modulated permittivity for impedance matching. However, commonly available EMW-absorbing materials are unsatisfactory owing to their low complex permeability in the high-frequency band. Herein, we report a thin, flexible EMW-absorbing membrane comprising shape-modulated FeCo nanobelts/boron nitride nanoparticles, which enables enhanced complex permeability in the S, C, and X bands (2-12 GHz). The boron nitride nanoparticles that are introduced to the FeCo nanobelts demonstrate control of the complex permittivity, leading to an effective impedance matching close to 1, consequently resulting in a high reflection loss value of -42.2 dB at 12.0 GHz with only 1.6 mm thickness. In addition, the incorporation of boron nitride nanoparticles improves the thermal conductivity for the heat dissipation of the absorbed electromagnetic wave energy. Overall, the comprehensive study of nanomaterial preparation and shape modulation technologies can lead to the fabrication of an excellent EMW-absorbing flexible composite membrane.

A 5G EMI shielding composite flexible film with near-zero reflection is proposed with remarkably low reflection with thin thickness compared to the previous studies. The resonant frequency can be controlled via tailored design factors of the film.

In this study, electroless nickel-plated carbon fiber (CF) was prepared with edge-selectively oxidized graphene (EOG) to reinforce the interface between nickel and CF for use in a composite for ele...

Herein, we introduce novel 1-dimensional nano-chained FeCo particles with unusually-high permeability prepared by a highly-productive thermal plasma synthesis and demonstrate an electromagnetic wave absorber with exceptionally low reflection loss in the high-frequency regime (1–26 GHz). During the thermal plasma synthesis, spherical FeCo nanoparticles are first formed through the nucleation and growth processes; then, the high temperature zone of the thermal plasma accelerates the diffusion of constituent elements, leading to surface-consolidation between the particles at the moment of collision, and 1-dimensional nano-chained particles are successfully fabricated without the need for templates or a complex directional growth process. Systematic control over the composition and magnetic properties of FexCo1−x nano-chained particles also has been accomplished by changing the mixing ratio of the Fe-to-Co precursors, i.e. from 7 : 3 to 3 : 7, leading to a remarkably high saturation magnetization of 151–227 emu g−1. In addition, a precisely-controlled and uniform surface SiO2 coating on the FeCo nano-chained particles was found to effectively modulate complex permittivity. Consequently, a composite electromagnetic wave absorber comprising Fe0.6Co0.4 nano-chained particles with 2.00 nm-thick SiO2 surface insulation exhibits dramatically intensified permeability, thereby improving electromagnetic absorption performance with the lowest reflection loss of −43.49 dB and −10 dB (90% absorbance) bandwidth of 9.28 GHz, with a minimum thickness of 0.85 mm.

Herein, we introduce novel 1-dimensional nano-chained FeCo particles with unusually-high permeability prepared by a highly-productive thermal plasma synthesis and demonstrate an electromagnetic wave absorber with exceptionally low reflection loss in the high-frequency regime (1-26 GHz). During the thermal plasma synthesis, spherical FeCo nanoparticles are first formed through the nucleation and growth processes; then, the high temperature zone of the thermal plasma accelerates the diffusion of constituent elements, leading to surface-consolidation between the particles at the moment of collision, and 1-dimensional nano-chained particles are successfully fabricated without the need for templates or a complex directional growth process. Systematic control over the composition and magnetic properties of FexCo1-x nano-chained particles also has been accomplished by changing the mixing ratio of the Fe-to-Co precursors, i.e. from 7 : 3 to 3 : 7, leading to a remarkably high saturation magnetization of 151-227 emu g-1. In addition, a precisely-controlled and uniform surface SiO2 coating on the FeCo nano-chained particles was found to effectively modulate complex permittivity. Consequently, a composite electromagnetic wave absorber comprising Fe0.6Co0.4 nano-chained particles with 2.00 nm-thick SiO2 surface insulation exhibits dramatically intensified permeability, thereby improving electromagnetic absorption performance with the lowest reflection loss of -43.49 dB and -10 dB (90% absorbance) bandwidth of 9.28 GHz, with a minimum thickness of 0.85 mm.

Recent advances in fifth generation (5G) mobile communication have allowed the development of high data rates, energy efficiency, and system capacity. The demand for millimeter-wave (mmWave) frequency electromagnetic wave shielding materials is also increasing simultaneously. However, current electromagnetic interference (EMI) shielding materials, including metals and composites with dielectric or conductive fillers, typically have a high absorption shielding effectiveness (SEA) with a low reflection shielding effectiveness (SER) at mmWave frequencies. To address this inherent issue of EMI shielding materials, we introduce a metal-mesh-supported polymer composite consisting of a reflection layer and an absorbing layer. The proposed composite shielding material has a SER of only 2 dB and a SEA of 46 dB. The permittivity, permeability, and tangent loss of the absorption layer, as well as the effects of thickness and type of mesh of the mesh-supported polymer composite are discussed. The mechanism of additional absorption capacity due to destructive interference is also discussed in comparison with theoretical calculations. Its shielding efficiency is compared with previously reported values, and a superior absorbance with a thinner thickness of the proposed mesh-supported polymer composite system is observed, which is very proper for 5G EMI shielding applications.

Understanding the ion transport mechanism in nanocomposite solid polymer electrolytes is necessary to develop next-generation electrochemical devices. We investigate the role of inorganic nanoparticle on ion conduction and segmental dynamics in cross-linked epoxy-based nanocomposite solid polymer electrolytes, complexed with Li+F3CSO2NSO2CF3– (LiTFSI) salt and Al2O3 nanowire, using dielectric relaxation spectroscopy. The addition of Al2O3 not only increases the ionic conductivity σDC by up to ∼10 times but also accelerates the segmental α motion compared to the host electrolyte. Increasing Al2O3 content leads to a reduction in segmental α relaxation temperature Tα (fast dynamics), resulting in increased ion mobility as well as an enhancement in segmental α relaxation strength Δeα, lowering ion dissociation energy, as revealed by density functional theory calculations, thereby providing more mobile ions for conduction. This ion transport investigation provides insights into the design of high-conductivity ...

A novel mesoporous silica-based single-ion conductor for lithium-ion batteries was prepared via two-step selective functionalization of designated silica precursors into the inner pore wall of mesoporous silica. 2-[(Trifluoromethanesulfonylimido)-N-4-sulfonylphenyl]ethyl (TFSISPE) group was first incorporated as a silica precursor having an anionic weak-binding imide group, and a dense brush of oligo-poly(ethylene glycol) (oligo-PEG) moieties, solvating Li+, was cografted to produce functionalized mesoporous silica (FMS-TFSISPE) nanoparticles. FMS-TFSISPE showed a 2D hexagonal nanopore structure and a regular spherical shape with an average diameter of 50 nm. Poly(ethylene oxide) (PEO) was used to form a dispersion of the mesoporous silica nanoparticles into the polymer matrix. This new polymer–mesoporous silica nanohybrid solid electrolyte with the sole mobile Li ions (FMS-TFSISPE-PEO) exhibits attractive electrical, mechanical, and electrochemical properties. The ionic conductivity and storage modulus b...

Solid polymer electrolytes (SPEs) have drawn attention for promising multifunctional electrolytes requiring very good mechanical properties and ionic conductivity. To develop a safe SPE for energy storage applications, mechanically robust cross-linked epoxy matrix is combined with fast ion-diffusing ionic liquid/lithium salt electrolyte (ILE) via a simple one-pot curing process. The epoxy-rich SPEs show higher Young’s modulus (E), with higher glass transition temperature (Tg) but lower ionic conductivity (σdc) with a higher activation energy, compared to the ILE-rich SPEs. The incorporation of inorganic robust Al2O3 nanowire simultaneously provides excellent mechanical robustness (E ≈ 1 GPa at 25 °C) and good conductivity (σdc ≈ 2.9 × 10–4 S/cm at 25 °C) to the SPE. This suggests that the SPE has a bicontinuous microphase separation into ILE-rich and epoxy-rich microdomain, where ILE continuous conducting phases are intertwined with a sturdy cross-linked amorphous epoxy framework, supported by the observa...

We report the effect of epoxy adhesion layers with different mechanical or physical property on a magnetoelectric (ME) composite laminate composed of FeBSi alloy (Metglas)/single-crystal Pb(Mg1/3Nb2/3)O3-Pb(Zr,Ti)O3/Metglas to achieve an improved ME conversion performance. Through theoretical simulation, it was revealed that the Young's modulus and the thickness of interfacial adhesives were major parameters that influence the conversion efficiency in ME composites. In the experimental evaluation, we utilized three epoxy materials with a distinct Young's modulus and adjusted the average thickness of the adhesion layers to optimize the ME conversion. The experimental results show that a thin epoxy layer with a high Young's modulus provided the best performance in the inorganic-based ME conversion process. By tailoring the interfacial adhesion property, the ME laminate generated a high conversion coefficient of 328.8 V/(cm Oe), with a mechanical quality factor of 132.0 at the resonance mode. Moreover, we demonstrated a highly sensitive alternating current magnetic field sensor that had a detection resolution below 10 pT. The optimization of the epoxy layers in the ME laminate composite provided significant enhancement of the ME response in a simple manner.

In this paper, using Fourier transform infrared (FTIR) spectroscopy, ion conductivity measurements and first-principle density functional theory (DFT) calculations, we study intermolecular interactions between three molecules (methyl tetrahydrophthalic anhydride (MeTHPA), succinonitrile (SN) plastic crystal, and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt) constituting the lithium-ion battery electrolyte. The C–O stretching band position in MeTHPA shifts to a lower frequency in the order of MeTHPA–SN < MeTHPA < MeTHPA–LiTFSI/SN < MeTHPA–LiTFSI; the average C–O bond length in MeTHPA increases in the same order, which reveals the linear correlation between the vibration frequency shift and bond length change. Furthermore, the lithium ionic conductivities of MeTHPA–LiTFSI/SN and MeTHPA–LiTFSI are consistent with this linear relationship, which confirms that the bond length, vibration frequency and lithium-ion transport are strongly influenced by molecular-level interactions. Our results provide fundamental insights valuable for the understanding of the effect of intermolecular interactions on molecular geometry and physical quantities in different electrolytes, and could be utilized to guide the design of high-performance electrolyte materials.

Railway wheels and axles are the most critical parts of the railway rolling stock. The wheel carry axle loads and guide the vehicles on the track. Therefore, the contact surface of wheel are subjected to wear and fatigue process. The wheel damage can be divided into three types; wear, contact fatigue failure and thermal crack due to braking. Therefore, in the contact surface between the wheel and the rail, the materials are heat treated to have a specific hardness. The manufacturing quality of the wheel have a considerable influence on the formation of tread wear and damage. Also, the residual stress on wheel is formed during the manufacturing process is one of the main sources of the damage. In this paper, the mechanical characteristic and the residual stress according to wheel material have been evaluated by applying finite element analysis and conducting mechanical tests.

For the development of next-generation safe energy storage (batteries or supercapacitors), energy conversion (solar cells), and electromechanical transduction devices (ionic actuators), solid polymer electrolytes (SPEs) having good electrochemical stability are widely considered as promising materials to substitute for conventional organic liquid electrolytes that have flammability and explosion issues. The SPEs could also offer a perfect solution to the enhancement of energy or power density, due to the possibility to use lithium metal anode that has a high theoretical specific capacity, and would even enable their use in multifunctional wearable or structural energy storage systems for portable electronics or transport applications. However, the key challenge facing the development of the SPEs for energy storage applications is to achieve high mechanical performance without sacrificing the requisite ionic conductivity: increasing conductivity typically leads to a reduction of the modulus. We prepare cross-linkable epoxy-based networked SPEs including Li salts (LiTFSI) with either plastic crystals (PCs), tetraglymes (G4s) or ionic liquids (ILs). The epoxy resins are particularly attractive as polymer matrices for solid polymer electrolytes due to their high mechanical performance combined with good adhesive properties and corrosion resistance. The selected electrolyte components (PC, G4 or IL) are allowed to boost ionic conductivity owing to solvating the lithium cation and plasticizing the epoxy matrix. As a result, the thermal curing of a homogeneous mixture of epoxy and electrolyte components can generate a two-phase system in which the epoxy phase is selected to provide mechanical strength and the electrolyte phase is selected to maximize ionic conductivity, via polymerization-induced phase separation, allowing for a bicontinuous microphase separation morphology. To further improve the physical properties of the SPEs, inorganic nanoparticles such TiO2, SiO2, or Al2O3 are incorporated in the nanocomposite SPEs, allowing for the combination of the advantages of both inorganic materials and organic polymers. This can be the strategy to achieve the simultaneous improvement in both mechanical strength and ion conduction of nanocomposite SPEs. In the current investigation, we conduct an investigation of the effect of electrolyte and inorganic types and their concentration on the ion conduction and dielectric and viscoelastic response of epoxy-based networked SPEs to investigate their ion and polymer dynamics. We measure storage and loss moduli, viscosity, ionic conductivity, dielectric constant, Young’s modulus of a series of epoxy-based SPEs, where the concentration of epoxy resin, electrolyte, and inorganic filler is varied, using oscillatory and steady shear, dielectric relaxation spectroscopy, and dynamic mechanical analyzer, respectively. These results are complemented by morphological studies from FESEM, microstructural and physical interaction studies from Fourier transform infrared (FTIR) spectroscopy, intermolecular interaction from Density functional theory (DFT) calculations, and thermal properties from DSC. Our study leads to insight regarding optimal design of multifunctional solid polymer electrolytes for energy storage devices.

For advanced energy storage (batteries and supercapacitors), energy conversion (fuel cells and solar cells), and electromechanical transduction devices (electroactive ionic actuators and sensors), it is vital to utilize single-ion polymer conductors (ionomers) that have been designed by covalently attaching anions (or cations) to the polymer chains. This allows the high lithium transference number in lithium polymer batteries as well as the fast response time under low voltage operating conditions in ionic polymer actuators. However, current single-ion conductors exhibit relatively low conductivities, precluding use of these materials in potential applications. This is predominantly due to relatively slow polymer segmental motion, resulting in decreased ion mobility, and large ion dissociation energy, lowering the number of simultaneous charge carries. In order to overcome the issues, we have synthesized porous silica-based lithium single-ion conducting nanoparticles containing anions with lithium counter ions. These nanoparticles are then introduced into poly(ethylene oxide) matrix, allowing us to prepare nanocomposite polymer electrolytes. Anion functionalized mesoporous silica (FMS-TFSISPE) nanoparticles were prepared by the two-step selective functionalization method. Poly(ethylene glycol) group was attached using sol-gel method on mesoporous silica particles. Trifluoromethanesulfonimide group functionalized to silica particles for binding lithium cation. The particles are uniformly distributed with an average size of 50 nm. HRTEM measurement further suggests that the clear mesoporous structure is observed. In order to extensively investigate the structural information on FMS-TFSISPE, the N2 adsorption/desorption isotherm is obtained as shown, where FMS-TFSISPE shows type IV isotherms of typical mesoporous materials, and the BET surface area is 995 m2 g- 1. The average pore size of the FMS-TFSISPE nanoparticles is about 3 nm which is close to that observed by the HRTEM measurement. The small angle XRD analysis shows three resolved peaks from which the pore structure corresponds to a 2D hexagonal (P6mm) structure. From the structure analysis, we successfully synthesized the FMS-TFSISPE nanoparticles with well-ordered hexagonal arrays of mesopore channels and exceptionally high surface area and pore volume. It is apparent that FMS-TFSISPE nanoparticles have a considerable effect on the enhancement of the ionic conductivity of these electrolytes, and their conductivities increase monotonically with increasing FMS-TFSISPE content. The maximum enhancement in conductivity is found for the nanohybrid electrolyte containing 30 wt % FMS-TFSISPE and order of sDC ~ 10- 3 S/cm at 25 oC, 10 times higher than the minimum practical requirement for single-ion conductors. We develop a novel nanohybrid single-ion conductor based porous silica structure. These systems display exceptional ionic conductivity and lithium transference number. It is shown that such nanohybrid electrolytes significantly immobilize the anion movement and pave the way for fast lithium ion-only conducting pathway. Provided that the optimization of the nanohybrid electrolytes with high-energy and -power electrodes is realized, the use of our highly conducting single-ion conductor in practical polymer electrolyte batteries will be envisaged.

Background In dental intravenous sedation, continuous intravenous infusion of a low-dose drug requires an infusion pump such as a syringe pump. To develop a new syringe pump for clinical use, the functions of the pump must meet certain international standards. Various safety and efficacy tests must be performed on the syringe pump, as stipulated by these standards, and an approval must be received from the approving agency based on such test results. Methods The authors of the present study developed a novel syringe pump and performed efficacy evaluation by testing its infusion speed at 1 and 25 ml/h, and infusion performance testing at 2 and 24 h. Moreover, performance evaluation was conducted by comparing the novel pump to an existing pump with the infusion speed varied from 1 to 5 ml/h. Results In the efficacy testing on the newly developed syringe pump, infusion with the infusion speed initially set to 1 ml/h resulted in infusion speeds of 1.00 and 0.99 ml/h in the 2- and 24-h assessment, respectively. Changing the infusion speed setting to 25 ml/h resulted in an infusion speed of 25.09 and 23.92 ml/h in the 2- and 24-h assessment, respectively. These results show no significant differences when compared with other commercially available pumps. Conclusions The efficacy testing of the newly developed syringe pump showed the accuracy to be within tolerance. Based on these findings, we believe that the newly developed syringe pump is suitable for clinical use.

Background Patients were subjected to post-discharge follow-up (by telephone) in order to investigate the potential complications of outpatient general anesthesia or deep sedation that could develop in disabled dental patients discharged from the hospital. The ultimate aim of this study was to establish an appropriate response measure for such complications. Methods The caregivers of 79 disabled patients who underwent dental procedures under general anesthesia at our outpatient clinic were interviewed over telephone. Necessary care instructions were provided during the phone calls when required. The patient satisfaction level regarding the telephonic follow-up care was surveyed by additional telephone calls. Results Most of the patients did not suffer any serious complications; however, some reported fever and bleeding. The data obtained in this study can be utilized towards the development of caregiver education pertaining to the ambulatory general anesthesia of dental patients with disabilities. Conclusions Additionally, we hope that the findings of this study will help minimize the effects of complications experienced by disabled dental patients undergoing ambulatory general anesthesia, as well as increase the overall patient satisfaction level.