Waves are seen in the atmosphere, oceans, etc. As one of the most common natural phenomena, water waves attract the attention of researchers. For the shallow water waves, a (3+1)-dimensional ...generalized nonlinear evolution equation is hereby investigated via the symbolic computation. Based on the Hirota method, we present three bilinear auto-Bäcklund transformations, along with some soliton solutions. Our results depend on the water-wave coefficients in that equation.
Pseudocapacitance holds great promise for improving energy densities of electrochemical supercapacitors, but state-of-the-art pseudocapacitive materials show capacitances far below their theoretical ...values and deliver much lower levels of electrical power than carbon-based materials due to poor cation accessibility and/or long-range electron transferability. Here we show that in situ corundum-to-rutile phase transformation in electron-correlated vanadium sesquioxide can yield nonstoichiometric rutile vanadium dioxide layers that are composed of highly sodium ion accessible oxygen-deficiency quasi-hexagonal tunnels sandwiched between conductive rutile slabs. This unique structure serves to boost redox and intercalation kinetics for extraordinary pseudocapacitive energy storage in hierarchical isomeric vanadium oxides, leading to a high specific capacitance of ~1856 F g
(almost sixfold that of the pristine vanadium sesquioxide and dioxide) and a bipolar charge/discharge capability at ultrafast rates in aqueous electrolyte. Symmetric wide voltage window pseudocapacitors of vanadium oxides deliver a power density of ~280 W cm
together with an exceptionally high volumetric energy density of ~110 mWh cm
as well as long-term cycling stability.
Rechargeable aqueous Zn-ion batteries (ZIBs) are regarded as one of the most promising energy storage devices due to their intrinsic safety and the extensive stockpile of Zn. It is still challenging ...to prepare ultrafast flexible devices with high energy/power density and satisfactory stability. Herein, two-dimensional ultrathin vanadium pentoxide (V2O5) nanosheets grown directly on titanium (Ti) substrate (V2O5–Ti) are prepared as a novel flexible cathode with high energy density for ultrafast aqueous and flexible ZIBs. Benefiting from the merits of exposed active sites and increased electrical conductivity, our optimized V2O5–Ti cathode exhibits a remarkable discharge capacity of 503.1 mAh g−1 at 100 mA g−1 and long-term stability with 86% retention after over 700 cycles at 500 mA g−1 in the aqueous coin cell. The charge storage mechanism of this V2O5–Ti cathode is investigated by in-situ Raman spectroscopy, ex-situ X-ray diffraction, and X-ray photoelectron spectroscopy. Remarkably, based on this flexible cathode, we designed an ultrafast and flexible quasi-solid-state zinc ion battery (f-V2O5–Ti//Zn), which can achieve the capacity of 377.5 mAh g−1 and energy density of 622 Wh kg−1 when charged at 4 A g−1 for less than 6 min. It also exhibits the power density of 6.4 kW kg−1 at an ultrahigh current density of 20 A g−1, which outperforms most previously reported aqueous/flexible ZIBs. As a result of superior performance, our ultrafast flexible quasi-solid-state ZIB is believed to be a promising candidate for flexible and wearable energy storage systems.
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•The binder-free V2O5–Ti cathode exhibits remarkable discharge capacity and long-term stability in aqueous electrolyte.•In-situ Raman spectroscopy are revealed to understand the charge storage mechanism of V2O5–Ti cathode.•Flexible solid-state ZIB exhibits ultrafast charge-storage property with high capacity, energy density and stability.
Due to the limitations of the existing atmospheric surface layer (ASL) turbulence prediction models during dust storms, therefore, this paper uses multi-scale signal reconstruction and HSM as the ...basic framework to propose a prediction model of streamwise and vertical wind speed fluctuation during dust storms in near-neutral ASL. The input of this model is only friction wind speed. In the reconstruction of large-scale signals, the random phase control and the introduction of structural inclination angle reflect the coherence of large-scale turbulent structures. Through the modification of the HSM method, turbulence events in different quadrants are introduced into the prediction model. The introduction of the influence of dust particles on turbulent fluctuation is achieved by modifying the characterization parameters of the Kaimal spectrum. The model proposed in this paper can not only reflect the coherence and inclination of large-scale turbulent structures, but also reflect the contribution of different turbulent events. In addition, the power spectrum predicted by the model, the event contribution ratio of different quadrants, and the turbulence intensity are in good agreement with the field observation results both qualitatively and quantitatively. These results show that the model can be used to predict the streamwise and vertical wind speed fluctuation.
•Turbulence events in different quadrants are introduced into the prediction model.•The model can reflect the coherence and inclination of large-scale turbulent structures.•Predicted results are in good agreement with the field observation.
Graphene with unique physical and chemical properties has shown various potential applications in biomedicine. In this work, a photosensitizer molecule, Chlorin e6 (Ce6), is loaded on polyethylene ...glycol (PEG)-functionalized graphene oxide (GO) via supramolecular π–π stacking. The obtained GO-PEG-Ce6 complex shows excellent water solubility and is able to generate cytotoxic singlet oxygen under light excitation for photodynamic therapy (PDT). Owing to the significantly enhanced intracellular trafficking of photosensitizers, our GO-PEG-Ce6 complex offers a remarkably improved cancer cell photodynamic destruction effect compared to free Ce6. More importantly, we show that the photothermal effect of graphene can be utilized to promote the delivery of Ce6 molecules by mild local heating when exposed to a near-infrared laser at a low power density, further enhancing the PDT efficacy against cancer cells. Our work highlights the promise of using graphene for potential multifunctional cancer therapies.
The observation data in the development stage of dust storms induced by cold front were analyzed. The results showed that the contribution of outward and inward interaction to dust and heat transport ...were less than that of ejection and sweep events. That is, the transportation of dust and heat was not dominated by interactions. In the ejection events, the low- and high-frequency fluctuations dominate the upward transportation of high- and low-concentration dust micro-elements and cold air, respectively. In the sweep events, the low- and high-frequency fluctuations dominate the downward transportation of low- and high-concentration dust micro-elements and hot air. For dust transportation, although the flux directions of the low- and high-frequency fluctuations are opposite, the flux contribution of the low-frequency fluctuation is larger than that of the high-frequency fluctuation. Therefore, directions of dust transportation during dust storms are towards the second-quadrant direction. For heat transport, since the directions of the heat flux of low- and high-frequency fluctuations are the same, the direction of heat transport is towards the fourth quadrant direction.
●Transportation of dust and heat is not dominated by outward and inward interaction.●Dust transportation during the dust storm is towards to the second-quadrant direction.●Heat transport is towards to the fourth quadrant direction.●Providing a foundation for the mechanism of charged particle stratification during CFDS.
Circle-to-circle amplification (C2CA) is a specific and precise cascade nucleic acid amplification method consisting of more than one round of padlock probe ligation and rolling circle amplification ...(RCA). Although C2CA provides a high amplification efficiency with a negligible increase of false-positive risk, it contains several step-by-step operation processes. We herein demonstrate a homogeneous and isothermal nucleic acid quantification strategy based on C2CA and optomagnetic analysis of magnetic nanoparticle (MNP) assembly. The proposed homogeneous circle-to-circle amplification eliminates the need for additional monomerization and ligation steps after the first round of RCA, and combines two amplification rounds in a one-pot reaction. The second round of RCA produces amplicon coils that anneal to detection probes grafted onto MNPs, resulting in MNP assembly that can be detected in real-time using an optomagnetic sensor. The proposed methodology was applied for the detection of a synthetic complementary DNA of SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2, also known as 2019-nCoV) RdRp (RNA-dependent RNA polymerase) coding sequence, achieving a detection limit of 0.4 fM with a dynamic detection range of 3 orders of magnitude and a total assay time of ca. 100 min. A mathematical model was set up and validated to predict the assay performance. Moreover, the proposed method was specific to distinguish SARS-CoV and SARS-CoV-2 sequences with high similarity.
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•A homogeneous and isothermal circle-to-circle amplification strategy was designed.•The cascade amplification was performed in one-pot with real-time sensing.•A sub-femtomolar detection limit was achieved with a total assay time of 100 min.
Power electronic converters are one of the most fragile components in wind turbines. This paper proposes a two-dimensional (2-D) case temperature-based real-time aging monitoring method for ...insulated-gate bipolar transistor (IGBT) modules in power converters. By placing two thermal sensors for each switch at the interface between the baseplate of an IGBT module and the cold plate, the thermal parameters containing the aging information of the IGBT module can be obtained to monitor various major aging processes of the IGBT module in real time separately. The proposed method has a low cost and is easy to implement. Simulation and experimental results on a commercial IGBT module are provided to verify the effectiveness of the proposed method.
This paper reveals a stability-constrained approach for designing an odd-order recursive digital filter whose frequency bandwidths are freely tunable. The tunable filter has a cascade structure, and ...it also has definitely ensured stability. The odd-order tunable-bandwidth (OO-TBW) filter consists of a single first-order (1st-order) recursive section and a few second-order (2nd-order) recursive sections. Those sections are cascaded together to form the overall OO-TBW filter. To ensure that the cascade-form OO-TBW filter is definitely stable, a strategic technique is adopted, which expresses the coefficients of both the single 1st-order and multiple 2nd-order sections as a kind of specifically-defined composite functions. With such specific parameterizations, the resulting cascade-form OO-TBW filter is able to meet the stability requirement definitely. As a result, the resulting OO-TBW filter not only has an odd-order cascade structure, but its stability issue is resolved. To demonstrate the ensured stability and also the significantly high accuracy of the resultant OO-TBW filter, a lowpass OO-TBW filter (tunable-bandwidth lowpass filter) is designed, and the simulation results are detailed and analyzed.
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