Hybridized Electromagnetic–Triboelectric Nanogenerator for Scavenging Air-Flow Energy to Sustainably Power Temperature Sensors

We report a hybridized nanogenerator with dimensions of 6.7 cm × 4.5 cm × 2 cm and a weight of 42.3 g that consists of two triboelectric nanogenerators (TENGs) and two electromagnetic generators (EMGs) for scavenging air-flow energy. Under an air-flow speed of about 18 m/s, the hybridized nanogenerator can deliver largest output powers of 3.5 mW for one TENG (in correspondence of power per unit mass/volume: 8.8 mW/g and 14.6 kW/m³) at a loading resistance of 3 MΩ and 1.8 mW for one EMG (in correspondence of power per unit mass/volume: 0.3 mW/g and 0.4 kW/m³) at a loading resistance of 2 kΩ, respectively. The hybridized nanogenerator can be utilized to charge a capacitor of 3300 μF to sustainably power four temperature sensors for realizing self-powered temperature sensor networks. Moreover, a wireless temperature sensor driven by a hybridized nanogenerator charged Li-ion battery can work well to send the temperature data to a receiver/computer at a distance of 1.5 m. This work takes a significant step toward air-flow energy harvesting and its potential applications in self-powered wireless sensor networks

Efficient Scavenging of Solar and Wind Energies in a Smart City

To realize the sustainable energy supply in a smart city, it is essential to maximize energy scavenging from the city environments for achieving the self-powered functions of some intelligent devices and sensors. Although the solar energy can be well harvested by using existing technologies, the large amounts of wasted wind energy in the city cannot be effectively utilized since conventional wind turbine generators can only be installed in remote areas due to their large volumes and safety issues. Here, we rationally design a hybridized nanogenerator, including a solar cell (SC) and a triboelectric nanogenerator (TENG), that can individually/simultaneously scavenge solar and wind energies, which can be extensively installed on the roofs of the city buildings. Under the same device area of about 120 mm × 22 mm, the SC can deliver a largest output power of about 8 mW, while the output power of the TENG can be up to 26 mW. Impedance matching between the SC and TENG has been achieved by using a transformer to decrease the impedance of the TENG. The hybridized nanogenerator has a larger output current and a better charging performance than that of the individual SC or TENG. This research presents a feasible approach to maximize solar and wind energies scavenging from the city environments with the aim to realize some self-powered functions in smart city

Elasto-Aerodynamics-Driven Triboelectric Nanogenerator for Scavenging Air-Flow Energy

Efficient scavenging the kinetic energy from air-flow represents a promising approach for obtaining clean, sustainable electricity. Here, we report an elasto-aerodynamics-driven triboelectric nanogenerator (TENG) based on contact electrification. The reported TENG consists of a Kapton film with two Cu electrodes at each side, fixed on two ends in an acrylic fluid channel. The relationship between the TENG output power density and its fluid channel dimensions is systematically studied. TENG with a fluid channel size of 125 × 10 × 1.6 mm³ delivers the maximum output power density of about 9 kW/m³ under a loading resistance of 2.3 MΩ. Aero-elastic flutter effect explains the air-flow induced vibration of Kapton film well. The output power scales nearly linearly with parallel wiring of multiple TENGs. Connecting 10 TENGs in parallel gives an output power of 25 mW, which allows direct powering of a globe light. The TENG is also utilized to scavenge human breath induced air-flow energy to sustainably power a human body temperature sensor

Tuning the Coordination Microenvironment to Boost the Electrocatalytic HER Activity of M₃(C₆O₃S₃)₂

It is presently imperative to find efficient and practical catalysts for the hydrogen evolution reaction (HER) for hydrogen production with high efficiency. In this work, the catalytic HER activity of a class of two-dimensional (2D) metal–organic frameworks (MOFs), i.e., M3(C6O3S3)2 with M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Tc, Ru, Ta, W, and Re, is studied by using first-principles calculations. It is found that nonmetal atoms of the first coordination sphere to the central metal atom could be the active site for HER, and V3(C6O3S3)2 (ΔGH* = 0.02 eV, on V), Cr3(C6O3S3)2 (ΔGH* = −0.02 eV, on S, and ΔGH* = −0.05 eV, on O), and Cu3(C6O3S3)2 (ΔGH* = −0.03 eV, on S) are screened out as promising HER catalysts. To complete the picture of how the metal–ligand matching affects the activity, a different coordination microenvironment is considered by regulating the first coordination shell to, for example, the central V atom. It is of interest that the newly constructed moieties present high catalytic HER activity with ΔGH* almost zero, proving the significance of metal–ligand interaction. In view of these results, we propose a descriptor Δε↑↓ that correlates the local electronic structure and the catalytic HER activity. In short, our results not only identify a series of efficient HER electrocatalysts but also unravel the underneath factors that affect the activity and thus provide new insights into the rational design of catalysts for other reactions

Accurate Determination of the CO₂–Brine Interfacial Tension Using Graphical Alternating Conditional Expectation

A newly developed CO₂–brine interfacial tension (IFT) correlation based on the alternating condition expectation (ACE) algorithm has been successfully proposed to more accurately estimate the CO₂–brine IFT for a wide range of reservoir pressure, temperature, formation water salinity and injected gas composition. The new CO₂–brine correlation is expressed as a function of reservoir pressure, temperature, monovalent cation molalities (Na⁺ and K⁺), bivalent cation molalities (Ca²⁺ and Mg²⁺), N₂ mole fraction and CH₄ mole fraction in injected gas. This prediction model is originated from a CO₂–brine IFT database from the literature that covers 1609 CO₂–brine IFT data for pure and impure CO₂ streams. To test the validity and accuracy of the developed CO₂–brine IFT model, the entire dataset was divided into two groups: a training database consisting of 805 points and a testing dataset consisting of 804 points, which was arbitrarily selected from the total database. To further examine its predicted capacity, the new CO₂–brine IFT correlation is validated with four commonly used pure CO₂–pure water IFT correlations in the literature, it is found that the new CO₂–brine IFT correlation provides the comprehensive and accurate reproduction of the literature pure CO₂–pure water IFT data with an average absolute relative error (% AARE) of 12.45% and standard deviation (% SD) of 18.57%, respectively. In addition, the newly developed CO₂–brine IFT correlation results in the accurate prediction of the CO₂–brine IFT with a % AARE of 10.19% and % SD of 13.16%, respectively, compared to two CO₂–brine IFT correlations. Furthermore, sensitivity analysis was performed based on the Spearman correlation coefficients (rank correlation coefficients). The major factor influenced on the CO₂–brine IFT is reservoir pressure, which has a major negative impact on the CO₂–brine IFT. In contrast, the effects of CO₂ impurities and salt components in the water on the CO₂–brine IFT are in the following order in terms of their positive impact: bivalent cation molalities (Ca²⁺ and Mg²⁺), CH₄, N₂, and monovalent cation molalities (Na⁺ and K⁺)

Additional file 2: of Efficacy and safety assessment of acupuncture and nimodipine to treat mild cognitive impairment after cerebral infarction: a randomized controlled trial

Patients' MoCA score. (XLSX 90 kb

Additional file 1: of Efficacy and safety assessment of acupuncture and nimodipine to treat mild cognitive impairment after cerebral infarction: a randomized controlled trial

MoCA test in Chinese. (PDF 947 kb

Brønsted Basicity in Metal–Organic Framework-808 and Its Application in Base-Free Catalysis

The Brønsted basicity in activated metal–organic framework-808 (hereinafter denoted as MOF-808a) was confirmed by the analyses of CO₂-TPD-MS, in situ DRIFTS, and acid–base titration. MOF-808a exhibited efficient recyclable catalytic activities for Heck coupling and oxidation of alcohol as a one-pot tandem reaction in base-free catalysis. It is the first evidence of the Brønsted basicity in zirconium metal–organic frameworks (Zr-MOFs) and gave rise to a new opportunity to extend the catalytic application of Zr-MOFs

Engineering of Pore Design and Oxygen Vacancy on High-Entropy Oxides by a Microenvironment Tailoring Strategy

High-entropy oxides (HEOs) exhibit abundant structural diversity due to cationic and anionic sublattices with independence, rendering them superior in catalytic applications compared to monometallic oxides. Nevertheless, the conventional high-temperature calcination approach undermines the porosity and reduces the exposure of active sites (such as oxygen vacancies, OVs) in HEOs, leading to diminished catalytic efficiency. Herein, we fabricate a series of HEOs with a large surface area utilizing a microenvironment modulation strategy (m-NiMgCuZnCo: 86 m2/g, m-MnCuCoNiFe: 67 m2/g, and m-FeCrCoNiMn: 54 m2/g). The enhanced porosity in m-NiMgCuZnCo facilitates the presentation of numerous OVs, exhibiting an exceptional catalytic performance. This tactic creates inspiration for designing HEOs with rich porosity and active species with vast potential applications