We report the microstructures, electrical conductivity, and electromagnetic interference (EMI) shielding effectiveness of a series of hybrid cellulose papers coated alternatively with silver nanowire ...(AgNW) and multi-walled carbon nanotube (MWCNT), which are fabricated by controlling the dip-coating sequence and cycle. SEM images and EDS data reveal that AgNWs and/or MWCNTs are sequentially coated on the surfaces of the cellulose papers with increasing the dip-coating cycle and the coating density of the particles decreases gradually in thickness direction of the papers. This result is supported by the anisotropic apparent electrical conductivity of AgNW/MWCNT/cellulose hybrid papers in in-plane and thickness directions. In addition, the apparent electrical conductivity of the hybrid papers in the in-plane direction increases significantly from 0.17–0.22 S/cm to 2.55–2.83 S/cm with increasing the coating cycle from 2 to 10, although it is higher for the hybrid cellulose papers with AgNW top-coating layers than the hybrid papers with MWCNT top-coating layers at the same coating cycle. This result indicates that a highly effective and conductive AgNW/MWCNT network is formed on the cellulose fibers in a layer-by-layer manner. For the hybrid papers with 2.55–2.83 S/cm, high EMI shielding effectiveness of ∼23.8 dB at 1 GHz is achieved.
We report the structures, electrical and mechanical properties of a series of epoxy composites reinforced with multi walled carbon nanotube (MWCNT)-coated basalt fibers. For the purpose, MWCNT-coated ...basalt fibers were obtained by cyclic dip-dry coating process of neat basalt fibers in an aqueous MWCNT dispersion containing sodium dodecyl sulfate (SDS) surfactant, and they were composited with epoxy resin by hand lay-up method. The FT-IR and Raman spectroscopic analyses revealed the presence of the specific interactions between MWCNT and basalt fibers via SDS surfactant. Accordingly, the content of MWCNT coated on basalt fibers was measured to increase with the dip-dry coating cycle from 0 to 10. The electrical conductivity of the epoxy composites with MWCNT-coated basalt fibers increased significantly from 3.25 × 10−9 S/cm to 1.44 × 10−1 S/cm with increasing the dip-dry coating cycle. The composites with MWCNT-coated basalt fibers fabricated by above 2 cycles of dip-dry coating exhibited excellent electric heating performance in terms of rapid temperature responsiveness, high steady-state maximum temperature, high electric power efficiency, and stable operational stability under applied voltages. In addition, the epoxy composites with MWCNT-coated basalt fibers fabricated by one or two dip-dry coating cycle were found to have highly improved flexural mechanical properties, compared to the epoxy composite reinforced with neat basalt fibers.
Concepts of non-volatile memory to replace conventional flash memory have suffered from low material reliability and high off-state current, and the use of a thick, rigid blocking oxide layer in ...flash memory further restricts vertical scale-up. Here, we report a two-terminal floating gate memory, tunnelling random access memory fabricated by a monolayer MoS2/h-BN/monolayer graphene vertical stack. Our device uses a two-terminal electrode for current flow in the MoS2 channel and simultaneously for charging and discharging the graphene floating gate through the h-BN tunnelling barrier. By effective charge tunnelling through crystalline h-BN layer and storing charges in graphene layer, our memory device demonstrates an ultimately low off-state current of 10(-14) A, leading to ultrahigh on/off ratio over 10(9), about ∼10(3) times higher than other two-terminal memories. Furthermore, the absence of thick, rigid blocking oxides enables high stretchability (>19%) which is useful for soft electronics.
Immiscible polylactide (PLA)/maleic anhydride-grafted polypropylene (PP) blend (50/50 by wt.%) composite films filled with different pristine multi-walled carbon nanotube (MWCNT) contents of ...0.0–10.0wt.% were manufactured by an efficient and facile melt-mixing/compression technique. The electrical, mechanical and thermal properties of the PLA/PP/MWCNT composite films were investigated by considering the morphological feature as well as the MWCNT content. SEM images of the composite films confirmed that the PLA domains were well dispersed in the PP matrix of the immiscible PLA/PP blends and that the MWCNTs were localized selectively and uniformly in the PP matrix of the composite films. Accordingly, the electrical resistivity of the composite films decreased considerably from ∼1010Ωcm to ∼101Ωcm with the increment of the MWCNT content. The DSC cooling thermograms supported the fact that the MWCNTs served as effective accelerating agents for the melt-crystallization of the composite films as well as the development of the α-form crystals in the PP matrix. The dynamic storage modulus and the thermal degradation stability of the composite films were also increased significantly with the increment of the MWCNT content. Overall, high performance in the electrical conductivity, melt-crystallization rate, mechanical modulus, and thermal degradation stability of the PLA/PP/MWCNT composite films was found to stem from the selective and uniform localization of the MWCNTs in the continuous PP matrix.
Enhancement of oxygen ion conductivity in oxides is important for low-temperature (<500 °C) operation of solid oxide fuel cells, sensors and other ionotronic devices. While huge ion conductivity has ...been demonstrated in planar heterostructure films, there has been considerable debate over the origin of the conductivity enhancement, in part because of the difficulties of probing buried ion transport channels. Here we create a practical geometry for device miniaturization, consisting of highly crystalline micrometre-thick vertical nanocolumns of Sm-doped CeO2 embedded in supporting matrices of SrTiO3. The ionic conductivity is higher by one order of magnitude than plain Sm-doped CeO2 films. By using scanning probe microscopy, we show that the fast ion-conducting channels are not exclusively restricted to the interface but also are localized at the Sm-doped CeO2 nanopillars. This work offers a pathway to realize spatially localized fast ion transport in oxides of micrometre thickness.
This paper develops the brushless dc (BLDC) motor sensorless control system for an automotive fuel pump. The sensorless techniques that are based on a hysteresis comparator and a potential start-up ...method with a high starting torque are suggested. The hysteresis comparator is used to compensate for the phase delay of the back EMFs due to a low-pass filter (LPF) and also prevent multiple output transitions from noise or ripple in the terminal voltages. The rotor position is aligned at standstill for maximum starting torque without an additional sensor and any information of motor parameters. Also, the stator current can be easily adjusted by modulating the pulse width of the switching devices during alignment. Some experiments are implemented on a single chip DSP controller to demonstrate the feasibility of the suggested sensorless and start-up techniques.
This year, France banned the application of titanium dioxide nanoparticles as a food additive (hereafter, E171) based on the insufficient oral toxicity data. Here, we investigated the subchronic ...toxic responses of E171 (0, 10, 100, and 1,000 mg/kg) and tried to elucidate the possible toxic mechanism using AGS cells, a human stomach epithelial cell line. There were no dose‐related changes in the Organisation for Economic Cooperation and Development test guideline‐related endpoints. Meanwhile, E171 deeply penetrated cells lining the stomach tissues of rats, and the IgM and granulocyte‐macrophage colony‐stimulating factor levels were significantly lower in the blood from rats exposed to E171 compared with the control. The colonic antioxidant protein level decreased with increasing Ti accumulation. Additionally, after 24‐h exposure, E171 located in the perinuclear region of AGS cells and affected expression of endoplasmic reticulum stress‐related proteins. However, cell death was not observed up to the used maximum concentration. A gene profile analysis also showed that immune response‐related microRNAs were most strongly affected by E171 exposure. Collectively, we concluded that the NOAEL of E171 for 90 days repeated oral administration is between 100 and 1,000 mg/kg for both male and female rats. Additionally, further study is needed to clarify the possible carcinogenesis following the chronic accumulation in the colon.
In this study, we found that E171 did not induce any dose‐related changes in the OECD test guideline‐related endpoints. Meanwhile, E171 deeply penetrated cells lining the stomach tissues of rats, and the colonic antioxidant protein level decreased with increasing Ti accumulation. After 24‐h exposure, E171 also located in the perinuclear region of AGS cells and affected expression of ER stress‐related proteins. Additionally, a gene profile analysis showed that immune response‐related microRNAs were most strongly affected by E171 exposure.
ObjectiveThis study aims to explore the association between physical activity and high-sensitivity C reactive protein, based on different types of physical activity—occupational and leisure ...time.MethodsUsing cross-sectional data from the Korea National Health and Nutrition Examination Survey 2015–2018, we explored the association between different types of self-reported physical activity and high levels of high-sensitivity C reactive protein (>3 mg/L). We estimated the ORs for high-level high-sensitivity C reactive protein using multiple logistic regression models after adjusting for covariates from 12 970 eligible subjects (mean age 44.8).ResultsCompared with subjects who did not engage in moderate-to-vigorous level of occupational physical activity (OPA), the group that engaged in moderate-to-vigorous level of OPA showed a significantly high OR (1.32, 95% CI (1.03 to 1.69)), whereas the group that engaged in moderate-to-vigorous level of leisure-time physical activity (LPA) yielded a low OR (0.84, 95% CI (0.69 to 1.01)). The group that engaged in moderate-to-vigorous level of OPA but not LPA showed a significantly high OR (1.76, 95% CI (1.27 to 2.45)) compared with subjects who engaged in moderate-to-vigorous level of LPA but not in OPA.ConclusionsOPA is directly associated with high C reactive protein levels, suggesting that it increases the risk of inflammation.
Room-temperature-operable all-solid-state Na-ion batteries (ASNBs) using sulfide Na-ion solid electrolytes (SEs) are promising because of their potential for greater safety, lower cost, and ...acceptable performance. Despite extensive developments in the area of sulfide Na-ion SEs, their poor chemical stability and prospects for wet-chemical synthesis have been overlooked to date. Herein, the scalable synthesis of Na3SbS4via aqueous-solution routes using precursors of Na2S, Sb2S3, and elemental sulfur for ASNBs is described. With no concerns about the evolution of toxic H2S gas, the aqueous-solution-synthesized Na3SbS4 exhibits high ionic conductivities (0.1–0.2 mS cm−1 at 25 °C). Importantly, the homogeneity of the aqueous solutions enables the creation of uniform Na3SbS4 coatings on FeS2. Fe2S/Na–Sn ASNBs, employing the aqueous-solution-synthesized Na3SbS4 and the Na3SbS4-coated FeS2 for the SE layer and positive electrode, respectively, demonstrate a high charge capacity of 256 or 346 mA h g−1 with good reversibility at 30 °C, highlighting their potential for practical applications.
Utilizing the optimal capacity of a battery in wind-battery hybrid power systems is crucial to minimize costs. In this paper, we modify the min-max dispatch method to effectively integrate wind power ...into the grid. In line with the dispatch principle, we define a lifetime cost function, which indicates the battery energy storage system cost of dispatching 1 kWh of wind energy, to determine the optimal battery capacity. By using the optimal battery capacity, the operation costs are minimized, and the hybrid system is able to dispatch the scheduled power at any dispatching time. Moreover, the short-term power dispatch control is also considered; we smooth the transient power between two consecutive dispatching intervals and control the state of charge of the battery by an online control algorithm. To evaluate the performance of the proposed optimization method and the short-term power dispatch control, we perform several numerical studies with a 3-MW wind turbine generator and real wind speed data.
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