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The semiconducting metal phosphorus trichalcogenides (MPX3, X = S, Se), a new family of layered atomic materials similar to the transition‐metal dichalcogenides, have recently attracted great attention owing to their 2D magnetic properties as well as their wide range of tunable bandgaps, which can lead to promising applications in spintronic and optoelectronic devices. Herein, an uncooled bolometer based on FePSe3 atomic layers is reported, on which a competitive temperature coefficient of resistance (TCR) of ≈−2.96% K−1 at room temperature is observed. In detecting infrared radiation (980–1550 nm) at room temperature using the FePSe3 bolometer, high responsivity exceeding 108 V W−1 and specific detectivity up to 109 Jones are achieved, which can be attributed to the combined advantages of the competitive room‐temperature TCR and natural thermal isolation between the inner layers of FePSe3 and the environment. This result reveals a remarkable property of FePSe3 atomic layers and paves the way toward new types of bolometers with high sensitivities. [ABSTRACT FROM AUTHOR]

Hybrids comprising hollow mesoporous nitrogen‐doped carbon (HMC) nanospheres and metal‐oxide nanoparticles were prepared through a hydrothermal synthesis. These materials exhibit excellent bifunctional catalytic activity in the oxygen reduction and evolution reactions (ORR and OER, respectively) that are core to the efficient operation of Zn‐air batteries. When incorporated into prototype devices, Co3O4 and MnCo2O4 nanoparticle‐decorated HMC exhibited discharge potentials of 1.26 and 1.28 V at 10 mA cm−2, respectively. 'CoFeNiO'‐decorated HMC exhibited a charging potential of 1.96 V at 10 mA cm−2. These metrics are far superior to benchmark Pt−Ru, which displayed discharge and charging potentials of 1.25 and 2.01 V, respectively, at the same current density. The battery equipped with Co3O4‐decorated HMC demonstrated 63 % initial efficiency before cycling. After cycling at 10 mA cm−2 for 100 hours, the battery efficiency was maintained at 56.5 %, outperforming the battery with Pt−Ru (50.2 % after 50 h). [ABSTRACT FROM AUTHOR]

BACKGROUND Citrus aurantium L. (Aurantii fructus) is a multi‐purpose citrus fruit with high medicinal and nutritional value, but currently there are no data that can be used to investigate the appropriate harvest time to obtain high‐quality citrus bioactive ingredients from it. RESULTS: Phytochemicals and the levels of the main bioactive ingredients were investigated by ultra high performance liquid chromatography electrospray ionization quadrupole time‐of‐flight mass spectrometry (UHPLC‐ESI‐Q‐TOF/MS). The flavanone, polymethoxyflavone, coumarin, synephrine, and limonin content in the citrus fruit was analyzed at different harvest periods, and significant differences, ranging from 0.03 ± 0.01 to 116.26 ± 40.20 g kg−1 (DW), were shown. These compounds were present in higher amounts in June and then decreased gradually, while the biomass accumulation of most of them showed an increasing tendency around harvest time. The H2O2‐induced RIN‐m5F cells model was employed to evaluate their antioxidant capacity. Citrus fruit harvested from June 11 to July 7 possessed an excellent antioxidant capacity by inhibiting the intensity of intracellular reactive oxygen species (ROS) (P < 0.01) and improving superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH) activity (P < 0.01). The chemical composition and antioxidant capacity of citrus leaves, stems, and roots were also evaluated, and these showed great variation compared with other citrus fruits. Multivariate statistical analysis indicated that harvesting time was related closely to the phytochemical contents and antioxidant capacity. CONCLUSION: Citrus fruit can be appropriately harvested from June to early July when the levels of bioactive ingredients and antioxidant activity reach higher values. This research provides practical information for producing high‐quality citrus products. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The stabilization of silicon(II) and germanium(II) dihydrides by an intramolecular Frustrated Lewis Pair (FLP) ligand, PB, iPr2P(C6H4)BCy2 (Cy=cyclohexyl) is reported. The resulting hydride complexes [PB{SiH2}] and [PB{GeH2}] are indefinitely stable at room temperature, yet can deposit films of silicon and germanium, respectively, upon mild thermolysis in solution. Hallmarks of this work include: 1) the ability to recycle the FLP phosphine‐borane ligand (PB) after element deposition, and 2) the single‐source precursor [PB{SiH2}] deposits Si films at a record low temperature from solution (110 °C). The dialkylsilicon(II) adduct [PB{SiMe2}] was also prepared, and shown to release poly(dimethylsilane) [SiMe2]n upon heating. Overall, this study introduces a "closed loop" deposition strategy for semiconductors that steers materials science away from the use of harsh reagents or high temperatures. [ABSTRACT FROM AUTHOR]

Single‐phase multilevel neutral‐point‐clamped (NPC) voltage source inverter has been widely applied in AC traction drive system, the carrier‐based pulse width modulation (CBPWM) method and the space vector pulse width modulation (SVPWM) method are mainly two modulation methods for single‐phase NPC multilevel converters, and there is a certain relationship between these two modulation strategies. In this study, the unified relationship between SVPWM and CBPWM in single‐phase three‐level and five‐level NPC has been analysed. Then by injecting the zero‐sequence component into the initial modulation wave, the same switching state and output current as SVPWM can be achieved through modulation waves decomposed under the CBPWM strategy. Finally, the unified theory of SVPWM and CBPWM in an N‐level inverter with an arbitrary number of segments sequence was deduced. The simulation and experimental results illustrate that the unified theory between CBPWM and SVPWM is correct. With the zero‐sequence injected, CBPWM can realise the same effect as SVPWM, but the former is simpler than the latter, which is easy to promote for higher‐level applications. [ABSTRACT FROM AUTHOR]

The chemical constituents of the Siraitia grosvenorii leaf extract were studied. Firstly, high‐speed counter‐current chromatography was applied to the one‐step separation of four compounds from S. grosvenorii leaf extract with the solvent system composed of 0.01% acetic acid water/n‐butanol/n‐hexane/methanol (5:3:1:1, v/v/v/v). In this work, 270 mg of crude sample yielded four compounds, a new kaempferol O‐glycoside derivative, kaempferol 3‐O‐α‐L‐[4‐O‐(4‐carboxy‐3‐hydroxy‐3‐methylbutanoyl)]‐rhamnopyranoside‐7‐O‐α‐L‐rhamnopyranoside, named kaempferitrin A (2.1 mg, 90%), and three known compounds, grosvenorine (3.4 mg, 93%), kaempferitrin (14.4 mg, 99%) and afzelin (4 mg, 98%), and the structures of these compounds were identified by NMR spectroscopy and mass spectrometry. Then, ultra high performance liquid chromatography with electrospray ionization quadrupole time‐of‐flight mass spectrometry was used to illustrate the dominant flavonoids in S. grosvenorii leaf extract. 34 flavonoids including 19 kaempferol O‐glycosides, 4 quercetin O‐glycosides, 6 flavanone derivatives, and 5 polymethoxyflavones, were accurately or tentatively identified by carefully comparing their retention times, UV data, precise masses, the typical fragments of the standards and literature data. Most of these compounds were reported for the first time. This study establishes a foundation for the further development and utilization of S. grosvenorii leaves in future. [ABSTRACT FROM AUTHOR]

Based on the back electromotive force (back‐EMF) detection, a novel rotor position estimation strategy with adjustable turn on/off angle is proposed for the high‐speed hybrid switched reluctance motor (SRM). The minimum back‐EMF position is captured in every electrical cycle for rotor position estimation. The current comparator is employed to send out a turn‐off signal for phase winding when the maximum inductance position is detected in the first electrical cycle. By providing sufficient current rise time to the phase winding, the proposed sensorless control system enables the motor to run in high‐speed application. Besides the straightforward estimation principle, the proposed strategy has the implemental feasibility by eliminating extensive calculations and complicated look‐up tables. The experimental results of a prototype are demonstrated to verify the proposed sensorless control system. [ABSTRACT FROM AUTHOR]

Front Cover: Hollow Mesoporous Carbon Nanospheres Decorated with Metal Oxide Nanoparticles as Efficient Earth-Abundant Zinc-Air Battery Catalysts (ChemElectroChem 8/2021) Keywords: batteries; carbon; heterogeneous catalysis; nanoparticles; transition metals EN batteries carbon heterogeneous catalysis nanoparticles transition metals 1388 1388 1 04/30/21 20210412 NES 210412 B The Front Cover b shows an artistic representation of a new class of bifunctional zinc-air battery catalysts that consist of hollow mesoporous carbon nanospheres decorated with various precious-metal-free transition-metal oxide nanoparticles. Batteries, carbon, heterogeneous catalysis, nanoparticles, transition metals. [Extracted from the article]