Supercapacitors, with their superior capacity and lower space occupancy, offer inherent advantages over aluminum electrolytic capacitors (AECs) in meeting the demands of miniaturization and ...planarization of devices. However, the capacitive advantage of supercapacitors is often compromised by the limited availability of electrode materials under high‐frequency alternating current conditions. The development of electrode materials that possess both high‐frequency response and high capacity is undoubtedly critical. Herein, PEDOT:PSS/Ketjenblack holey nanosheets (PKHNs) prepared by a solvent thermal method are successfully developed as the electrode material to ensure rapid ion transport and abundant charge storage on the accessible nanosheet surfaces. The micro‐supercapacitors exhibit a high‐frequency capacitance (3089 µF cm−2 at 120 Hz, with a phase angle of −81.9°), achieved through an innovative structural design utilizing PKHNs materials. These micro‐supercapacitors demonstrate excellent frequency response with efficient 120 Hz filtering and offer volumetric advantages over the state‐of‐the‐art commercial ones during low‐voltage operations, making them an ideal choice for the next‐generation miniaturized filter capacitors.
The novel holey nanosheets are fabricated by assembling Ketjenblack nanoparticles and PEDOT:PSS nanofibrils. The unique nanostructure design and their excellent conductivity make them highly promising candidates for filter capacitors. The micro‐supercapacitors fabricated using these materials demonstrate superior AC line‐filtering and volumetric advantages compared to their commercial counterparts, thereby highlighting their potential for next‐generation miniaturized filter and energy electronics.
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•Double-layer TENG intended for self-powered and real-time sensing was constructed.•The open-circuit voltage and power density of the TENG were 440 V and 1877 mW/m2.•The ePTFE/PHB ...TENG was capable of supporting the HUVECs adhesion and growth.•The ePTFE/PHB TENG could effectively monitor the changing hemodynamic conditions.•The ePTFE/PHB TENG vascular counterpart exhibited excellent pressure sensitivity.
Being able to detect or monitor the onset of thrombosis, recurrent stenosis, or other vascular disorders in newly transplanted vascular grafts will be very beneficial for patients who received the artificial blood vessel through bypass surgeries. The inherent advantages of triboelectric nanogenerators (TENGs) in self-powered signal monitoring presents a feasible solution. In this study, a double-layer TENG intended for self-powered and real-time sensing of vascular graft applications was constructed using two biocompatible materials commonly used in tissue engineering. In particular, an electrospun poly(3-hydroxybutyrate) (PHB) membrane as a positive tribomaterial was combined with an expanded polytetrafluoroethylene (ePTFE) membrane, a strong negative tribomaterial, to construct an ePTFE/PHB TENG. While possessing power generation, charging capacities, and operation stability, the ePTFE/PHB TENG was capable of supporting the growth of human umbilical vein endothelial cells (HUVECs) and monitoring changing hemodynamic conditions. Although many challenges remain and necessary future developments are needed, this study demonstrated the feasibility of a self-powered and sensing TENG vascular graft.
For schools, the quality of teaching and learning is an important guarantee for achieving educational goals. There are very many factors affecting teaching quality, including hard and soft factors. ...Among them, the soft factors mainly refer to the teaching quality of teachers and the teaching management mechanism of schools. The teaching quality of teachers is the most critical among all factors. Traditional teaching quality evaluation (TQE) mainly adopts the way of manual scoring. This way of TQE lacks data support, and there is no evaluation mechanism based on multiple data sources. Therefore, the TQE results obtained in this way are subjective and inaccurate. Considering that the main subjects of the whole teaching session are teachers, students, and schools, each subject generates massive information in the whole teaching process. In our study, a novel evaluation method based on fuzzy classification algorithm is proposed to be applied in teaching evaluation. Firstly, this paper collects the relevant data generated by the three subjects in the teaching process, respectively. Secondly, after removing the unsuitable data, principal component analysis is used to extract the main features of the applicable data. Finally, a fuzzy support vector machine (FSVM) is used to classify and analyze the feature data in order to derive each teacher’s teaching evaluation results. The final evaluation results in this paper are divided into five grades, i.e., five categories: excellent, good, moderate, passing, and failing. The comparison with other algorithms demonstrates that the teaching evaluation model based on fuzzy comprehensive evaluation algorithm used in this paper has the advantages of high evaluation accuracy and objectivity, and we hope that this study will be useful in the field of teaching evaluation.
Deliberate engineering of built-in electric fields (BEFs) can facilitate electron transfer and promote asymmetrical charge distribution, thereby regulating the adsorption/desorption of reaction ...intermediates. Herein, an oxygen-deficiency-rich MnO-CeO 2 is synthetized supported on a carbon sphere (MnO-CeO 2 @Cs), adeptly crafted with a prominent work function difference (Δ Φ ) and robust BEF, targeting the electrocatalytic oxygen reduction reaction (ORR). Empirical and theoretical results substantiate that the BEF triggers interfacial charge redistribution, fine-tuning the adsorption energy of oxygen intermediates and hastening reaction kinetics. Consequently, the MnO-CeO 2 @Cs showcases commendable performance ( E 1/2 = 0.80 V and j L = 5.5 mA cm −2 ), outshining its single-component counterparts. Impressively, the MnO-CeO 2 @Cs-based zinc–air batteries (ZABs) boast an exemplary power density of 202.7 mW cm −2 and enduring stability of 297 h. Additionally, the solid-state ZAB commands a peak power density of 67.4 mW cm −2 , underscoring its potential in flexible ZAB applications. This work delineates a strategic avenue to harness interfacial charge redistribution, aiming to enhance the catalytic performance and longevity of energy conversion/storage apparatuses.
Deliberate engineering of built-in electric fields (BEFs) can facilitate electron transfer and promote asymmetrical charge distribution, thereby regulating the adsorption/desorption of reaction ...intermediates. Herein, an oxygen-deficiency-rich MnO-CeO
2
is synthetized supported on a carbon sphere (MnO-CeO
2
@Cs), adeptly crafted with a prominent work function difference (Δ
Φ
) and robust BEF, targeting the electrocatalytic oxygen reduction reaction (ORR). Empirical and theoretical results substantiate that the BEF triggers interfacial charge redistribution, fine-tuning the adsorption energy of oxygen intermediates and hastening reaction kinetics. Consequently, the MnO-CeO
2
@Cs showcases commendable performance (
E
1/2
= 0.80 V and
j
L
= 5.5 mA cm
−2
), outshining its single-component counterparts. Impressively, the MnO-CeO
2
@Cs-based zinc-air batteries (ZABs) boast an exemplary power density of 202.7 mW cm
−2
and enduring stability of 297 h. Additionally, the solid-state ZAB commands a peak power density of 67.4 mW cm
−2
, underscoring its potential in flexible ZAB applications. This work delineates a strategic avenue to harness interfacial charge redistribution, aiming to enhance the catalytic performance and longevity of energy conversion/storage apparatuses.
An oxygen-deficient MnO-CeO
2
@Cs catalyst, due to its high work function and strong built-in electric field, can effectively regulate charge redistribution and adsorption/desorption energies with reaction intermediates, thereby improving ORR activity.
In forests in Mongolia, tree roots and ectomycorrhizal fungi must survive several months of soil freezing in winter. To investigate the ectomycorrhizal community after winter, we collected fine roots ...of Scots pine (Pinus sylvestris) and Siberian pine (Pinus sibirica) and associated soil from Nukht forest in the Bogd-Khan National Reserve, Mongolia. Soil samples were collected from frozen soil at the end of April 2016. We described the ectomycorrhizal community, and determined on ectomycorrhizal roots tips and in soils the potential activity of enzymes involved in the degradation of soil organic matter. In order to assess the temperature sensitivity of enzyme activity, potential soil enzyme activities were assayed at temperatures from 5 to 20 °C. We detected 24 different ectomycorrhizal morphotypes associated with Pinus sylvestris and Pinus sibirica, and 18 morphotypes were identified to taxa. The two Pinus species had dissimilar ectomycorrhizal communities, and only 2 ectomycorrhizal fungal taxa were common to both species. Most ectomycorrhizal taxa had measurable activity of at least one extracellular enzyme. A high contribution to the community extracellular enzyme activity was shown for both abundant and less abundant taxa. Among the eight tested soil enzymes, only the activity of leucine amino peptidase showed consistent higher Q10 values at 5–15 °C than at 10–20 °C, suggesting that the enzyme is adapted to colder temperatures. Total soil N was the strongest factor explaining differences in soil enzyme potential activity. A positive relationship was found between soil N and the soil potential enzyme activity of acid phosphatase. We suggest that viable ectomycorrhizas during winter provide an advantage to Pinus sibirica and Pinus sylvestris in acquiring nutrients as soil thaws in spring.
•Ectomycorrhizas remain vital in soils frozen for several months.•Ectomycorrhizal communities differ in co-occurring pine species.•Soil leucine amino peptidase activity is cold adapted.
With the rapid development of portable microelectronic devices, materials with tunable electromagnetic shielding (EMI) performance and comfort of use have become urgently necessary. A lightweight, ...conductive thermoplastic polyurethane/multi-walled carbon nanotube (TPU/MWCNT) composite foam with a continuous gradient cell structure has been developed to impede electromagnetic wave reflection induced by excessive impedance mismatch. The continuous gradient distribution of cell structure and conductivity provides the TPU/MWCNT composite foams with distinct shielding effects of electromagnetic waves in both front and back gradient directions. The maximum front absorption coefficient (A) reached 0.93, which is higher than any foam with a uniform cell size within the cell size range of the gradient composite foams. At the same time, the gradient composite foams possess the characteristics of lightweight, high elasticity, and extensibility. The weight was decreased by 67.27–85.45 %, the elastic recovery ratio of compression reached 95 %, and the toughness was also excellent. Numerical simulation of the gradient foam model was conducted using CST Microwave Studio to uncover the gradient asymptotic dissipation mechanisms. The lightweight and stretchable continuous gradient foams show great promises for the next-generation portable electronic devices that generate no radiation pollution.
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•A time-varying pressure foaming process was developed by changing the foaming pressure.•A lightweight, conductive TPU/MWCNT composite foam with a continuous gradient cell structure has been developed.•The maximum front absorption coefficient was 0.93, which is higher than any foam with a uniform cell size in the range.•Gradient composite foam effectively alleviates the impedance mismatch between the ambient air and foam.
Synopsis: The composite foam developed in this paper mitigates impedance mismatch significantly, ensuring the quality of specific signal and the health of biological systems.
Low‐toxicity tin halide perovskites with excellent optoelectronic properties are promising candidates for photodetection. However, tin halide perovskite photodetectors have suffered from high dark ...current owing to uncontrollable Sn2+ oxidation. Here, 2‐cyanoethan‐1‐aminium iodide (CNI) is introduced in CH(NH2)2SnI3 (FASnI3) perovskite films to inhibit Sn2+ oxidation by the strong coordination interaction between the cyano group (C≡N) and Sn2+. Consequently, FASnI3‐CNI films exhibit reduced nonradiative recombination and lower trap density. The self‐powered photodetector based on FASnI3‐CNI exhibits low dark current (1.04 × 10−9 A cm−2), high detectivity (2.2 × 1013 Jones at 785 nm), fast response speed (2.62 µs), and good stability. Mechanism studies show the increase in the activation energy required for thermal emission and generated carriers, leading to a lower dark current in the FASnI3‐CNI photodetector. In addition, flexible photodetectors based on FASnI3‐CNI, exhibiting high detectivity and fast response speed, are employed in wearable electronics to monitor the human heart rate under weak light and zero bias conditions. Finally, the FASnI3‐CNI perovskite photodetectors are integrated with a 32 × 32 thin‐film transistor backplane, capable of ultraweak light (170 nW cm−2) real‐time imaging with high contrast, and zero power consumption, demonstrating the great potential for image sensor applications.
2‐Cyanoethan‐1‐aminium iodide (CNI) is introduced to inhibit Sn2+ oxidation via strong coordination interaction. Self‐powered photodetectors based on the CH(NH2)2SnI3 (FASnI3) perovskite film with CNI exhibit low dark current, high detectivity, fast response speed, and good stability. Consequently, wearable health monitoring and weak light imaging with zero power consumption are successfully demonstrated.
With the rapid development of electronic technology and the integration of electronic chips, electromagnetic wave pollution and thermal management have become two critical issues hindering the growth ...of electronic equipment. In this work, an effective strategy has been developed for the synthesis of well-designed core-shell layered structures with hydroxylated boron nitride (HO-BNNS) core and Fe3O4 shell. The as-prepared HO-BNNS@Fe3O4 composites have both microwave absorption and thermal management properties. Moreover, these two performances show a synergistic effect. It is worth noting that the minimum reflection loss (RLmin) of HO-BNNS@Fe3O4 composite materials are −45.31 dB at 8.64 GHz with a thickness of 2 mm. Additionally, the thermal conductivity of HO-BNNS@Fe3O4 composites are 1.75 W m−1K−1 at an HO-BNNS weight of 30%, which increases approximately 400% than the initial Fe3O4. These comprehensive properties of HO-BNNS@Fe3O4 composites make it have potential applications in the field of electronic equipment packaging.
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The highlights of this paper are list below:●An effective strategy has been developed for the synthesis of well-designed core-shell layered structures with hydroxylated boron nitride (HO-BNNS) core and Fe3O4 shell.●The as-prepared HO-BNNS@Fe3O4 composites have both microwave absorption and thermal management properties.●The microwave absorption and thermal management performance of the HO-BNNS@Fe3O4 composites show a synergistic effect.
Polystyrene-wrapped boron nitride/commercial polystyrene (BN@PS/CPS) composites with high thermal conductivity were fabricated by a novel approach. The route included two steps, BN@PS core-shell ...structured fillers were prepared by using modified BN and styrene (St) as the raw materials via suspension polymerization, and then the BN@PS were kneaded with the CPS by mechanically mixed method. The composite achieves a high thermal conductivity of 0.692W/mK containing 30wt% BN@PS (∼15.9wt% BN), which is 3.72 times higher than that of pure CPS of ∼0.186W/mK and 1.78 times higher than that BN/CPS blend composite with at the same BN loading of 0.332W/mK. Compared with traditional routes, the novel preparation process requires less BN fillers when improving the same thermal conductivity. Importantly, other polymers can also encapsulate BN through this strategy, which paves a new way for preparing thermally conductive polymer-matrix composites.
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