The existence of nontrivial solutions of Kirchhoff type equations is an important nonlocal quasilinear problem; in this paper we use minimax methods and invariant sets of descent flow to prove two ...interesting existence theorems for the following 4-superlinear Kirchhoff type problems without the P.S. condition, one concerning the existence of a nontrivial solution and the other one concerning the existence of sign-changing solutions and multiple solutions,
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Since the discovery of conjugated polymers in the 1970s, they have attracted considerable interest in light of their advantages of having a tunable bandgap, high electroactivity, high flexibility, ...and good processability compared to inorganic conducting materials. The above combined advantages make them promising for effective energy harvesting and storage, which have been widely studied in recent decades. Herein, the key advancements in the use of conjugated polymers for flexible energy harvesting and storage are reviewed. The synthesis, structure, and properties of conjugated polymers are first summarized. Then, their applications in flexible polymer solar cells, thermoelectric generators, supercapacitors, and lithium‐ion batteries are described. The remaining challenges are then discussed to highlight the future direction in the development of conjugated polymers.
The key advancements in the use of conjugated polymers for flexible energy harvesting and storage are reviewed. Such flexible energy devices may open up a new direction in multidisciplinary fields across chemistry, physics, biology, and engineering.
The construction of lightweight, flexible and stretchable power systems for modern electronic devices without using elastic polymer substrates is critical but remains challenging. We have developed a ...new and general strategy to produce both freestanding, stretchable, and flexible supercapacitors and lithium‐ion batteries with remarkable electrochemical properties by designing novel carbon nanotube fiber springs as electrodes. These springlike electrodes can be stretched by over 300 %. In addition, the supercapacitors and lithium‐ion batteries have a flexible fiber shape that enables promising applications in electronic textiles.
My flexible friend: Springlike electrodes with remarkable electrochemical properties have been used to create flexible and stretchable fiber‐shaped supercapacitors and lithium‐ion batteries. The electrodes, which are made from twisted aligned multiwalled carbon nanotubes (see picture), can be stretched by over 300 %, and the devices show stable performance under bending and stretching deformations.
An electrochromic fiber‐shaped supercapacitor is developed by winding aligned carbon nanotube/polyaniline composite sheets on an elastic fiber. The fiber‐shaped supercapacitors demonstrate rapid and ...reversible chromatic transitions under different working states, which can be directly observed by the naked eye. They are also stretchable and flexible, and are woven into textiles to display designed signals in addition to storing energy.
In the present study, simultaneous flue gas desulfurization and denitrification are achieved with ·OH radicals generated from O2 + reacting with water vapor in a duct. The O2 + ions are generated by ...a strong ionization dielectric barrier discharge and then injected into the duct. Compared with conventional gas discharge treatment, the present method does not need a plasma reaction reactor, additional catalysts, reductants, or oxidants. The main recovered products are the liquids H2SO4 and HNO3, which can be used in many processes. Removal rates of 97% for NO and 82% for SO2 are obtained under the following optimal experimental conditions: molar ratio of reactive oxygen species (O2 +, O3) to SO2 and NO, 5; inlet flue gas temperature, 65 °C; reaction time, 0.94 s; and H2O volume fraction, 8%. Production of O2 + and the plasma reaction mechanisms are discussed, and the recovered acid is characterized. The experimental results show that the present method performs better for denitrification than for desulfurization. Compared with conventional air discharge flue gas treatments, the present method has lower initial investment and operating costs, and the equipment is more compact.
An all‐solid‐state, coaxial and self‐powered “energy fiber” is demonstrated that simultaneously converts solar energy to electric energy and further stores it. The “energy fiber” is flexible and can ...be scaled up for the practical application by the well‐developed textile technology, and may open a new avenue to future photoelectronics and electronics.
Twisted, aligned carbon nanotube/silicon composite fibers with remarkable mechanical and electronic properties are designed to develop novel flexible lithium‐ion batteries with a high cyclic ...stability. The core‐sheath architecture and the aligned structure of the composite nanotube offer excellent combined properties.
Metal-organic frameworks (MOFs) have so far been highlighted for their potential roles in catalysis, gas storage and separation. However, the realization of high electrical conductivity (>10
S cm
) ...and magnetic ordering in MOFs will afford them new functions for spintronics, which remains relatively unexplored. Here, we demonstrate the synthesis of a two-dimensional MOF by solvothermal methods using perthiolated coronene as a ligand and planar iron-bis(dithiolene) as linkages enabling a full π-d conjugation. This 2D MOF exhibits a high electrical conductivity of ~10 S cm
at 300 K, which decreases upon cooling, suggesting a typical semiconductor nature. Magnetization and
Fe Mössbauer experiments reveal the evolution of ferromagnetism within nanoscale magnetic clusters below 20 K, thus evidencing exchange interactions between the intermediate spin S = 3/2 iron(III) centers via the delocalized π electrons. Our results illustrate that conjugated 2D MOFs have potential as ferromagnetic semiconductors for application in spintronics.
Rapid and accurate monitoring of crop plant height (PH), canopy coverage (CC), and leaf nitrogen concentration (LNC) is essential for precision management of irrigation and fertilisation. The ...objectives of this study were to estimate summer maize PH by selecting optimal percentile height of point cloud; extract CC from images by using point cloud method; and determine if the combination of PH and CC with visible vegetation index (VI) could improve estimation accuracy of LNC. Images of maize field with three irrigation and four nitrogen fertiliser levels were captured using an unmanned aerial vehicle (UAV) platform with an RGB camera at summer maize grain filling stage in 2018, 2019 and 2020. The result showed that the 99.9th percentile height of point cloud was optimal for PH estimation. Image-based point cloud method could accurately estimate CC. Normalised redness intensity (NRI) had a potential for estimating LNC (R2 = 0.474) compared with the green red ratio VI, green red VI, and atmospherically resistant VI. The relationships between four integrated VIs (PH, CC and NRI combination of two or three: NRICC, NRIH, CC∗H and NRICCH) and LNC were established based on gathered dataset of 2018 and 2019, and NRICCH exhibited the highest correlation with maize LNC (R2 = 0.716). An independent dataset from 2020 was used to evaluate the feasibility of LNC estimation model. The result showed that the model could accurately estimate LNC (R2 = 0.758, RMSE = 0.147%). Therefore, combining crop agronomy variables and visible VIs from UAV-based RGB images possesses the potential for estimating LNC.
•A low-cost UAV-based RGB imaging system was used to estimate PH, CC and LNC.•The 99.9th percentile height of point cloud has the highest correlation with PH.•Image-based point cloud method can accurately estimate CC.•Visible VIs of UAV-based RGB images have low accuracy in estimating LNC.•Combining PH, CC and visible VIs can accurately estimate summer maize LNC.
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