Carboxylic acid accumulation and secretion contribute to the alkali-stress tolerance of halophyte Leymus chinensis.

Leymus chinensis is a dominant halophytic grass in alkalized grasslands of Northeast China. To explore the alkali-tolerance mechanism of L. chinensis, we applied a widely targeted metabolomic approach to analyze metabolic responses of its root exudates, root tissues and leaves under alkali-stress conditions. L. chinensis extensively secreted organic acids, phenolic acids, free fatty acids and other substances having -COOH or phosphate groups when grown under alkali-stress conditions. The buffering capacity of these secreted substances promoted pH regulation in the rhizosphere during responses to alkali stress. L. chinensis leaves exhibited enhanced accumulations of free fatty acids, lipids, amino acids, organic acids, phenolic acids and alkaloids, which play important roles in maintaining cell membrane stability, regulating osmotic pressure and providing substrates for the alkali-stress responses of roots. The accumulations of numerous flavonoids, saccharides and alcohols were extensively enhanced in the roots of L. chinensis, but rarely enhanced in the leaves, under alkali-stress conditions. Enhanced accumulations of flavonoids, saccharides and alcohols increased the removal of reactive oxygen species and alleviated oxygen damage caused by alkali stress. In this study, we revealed the metabolic response mechanisms of L. chinensis under alkali-stress conditions, emphasizing important roles for the accumulation and secretion of organic acids, amino acids, fatty acids and other substances in alkali tolerance.

Ultraviolet-Irradiated All-Organic Nanocomposites with Polymer Dots for High-Temperature Capacitive Energy Storage.

Polymer dielectrics capable of operating efficiently at high electric fields and elevated temperatures are urgently demanded by next-generation electronics and electrical power systems. While inorganic fillers have been extensively utilized to improved high-temperature capacitive performance of dielectric polymers, the presence of thermodynamically incompatible organic and inorganic components may lead to concern about the long-term stability and also complicate film processing. Herein, zero-dimensional polymer dots with high electron affinity are introduced into photoactive allyl-containing poly(aryl ether sulfone) to form the all-organic polymer composites for high-temperature capacitive energy storage. Upon ultraviolet irradiation, the crosslinked polymer composites with polymer dots are efficient in suppressing electrical conduction at high electric fields and elevated temperatures, which significantly reduces the high-field energy loss of the composites at 200 °C. Accordingly, the ultraviolet-irradiated composite film exhibits a discharged energy density of 4.2 J cm-3 at 200 °C. Along with outstanding cyclic stability of capacitive performance at 200 °C, this work provides a promising class of dielectric materials for robust high-performance all-organic dielectric nanocomposites.

In-Wheel Motor Control System for Four-Wheel Drive Electric Vehicle Based on CR-GWO-PID Control.

In order to improve the driving performance of four-wheel drive electric vehicles and realize precise control of their speed, a Chaotic Random Grey Wolf Optimization-based PID in-wheel motor control algorithm is proposed in this paper. Based on an analysis of the structural principles of electric vehicles, mathematical and simulation models for the whole vehicle are established. In order to improve the control performance of the hub motor, the traditional Grey Wolf Optimization algorithm is improved. In particular, an enhanced population initialization strategy integrating sine and cosine random distribution factors into a Kent chaotic map is proposed, the weight factor of the algorithm is improved using a sine-based non-linear decreasing strategy, and the population position is improved using the random proportional movement strategy. These strategies effectively enhance the global optimization ability, convergence speed, and optimization accuracy of the traditional Grey Wolf Optimization algorithm. On this basis, the CR-GWO-PID control algorithm is established. Then, the software and hardware of an in-wheel motor controller are designed and an in-wheel motor bench test system is built. The simulation and bench test results demonstrate the significantly improved response speed and control accuracy of the proposed in-wheel motor control system.

Improved 2†µm broadband luminescence in Tm3+/Ho3+ doping tellurite glass.

Tm3+/Ho3+ doping tellurite glasses (TeO2-ZnO-La2O3) were prepared by applying melt-quenching technique, and the ∼2.0 µm band luminescence characteristics were examined. A broadband and relatively flat luminescence at 1600 to 2200 nm was observed in the tellurite glass co-doped by 1.0 mol% Tm2O3 and 0.085 mol% Ho2O3 under the excitation of 808 nm laser diode (LD), which is the result of spectral overlapping of 1.83 µm band of Tm3+ ions and 2.0 µm band of Ho3+ ions. Further, about 103% enhancement was acquired after the introduction of 0.1 mol% CeO2 and 7.5 mol% WO3 at the same time, which is primarily caused by the cross-relaxation between Tm3+ and Ce3+ ions together with the enhanced energy transfer from the Tm3+:3F4 level to Ho3+:5I7 level due to the increase in phonon energy. Spectral characteristics associated with the radiative transition of Ho3+ and Tm3+ ions on the basis of Judd-Ofelt theory, and the fluorescence decay behaviors after the addition of Ce3+ ions and WO3 component were analyzed to understand the broadband and luminescence enhancement. The findings in this work indicate that tellurite glass with optimal Tm3+-Ho3+-Ce3+ tri-doping combination and appropriate amount of WO3 is a prospective candidate for broadband optoelectronic devices operated in the infrared bands.

Tetra (C60) lanthanum phthalocyanine: design, synthesis and investigation of the third-order nonlinear optical properties.

The construction of molecules with effective photoinduced intramolecular electron transfer (PET) and energy transfer (ET) processes is critical for the enhancement of the nonlinear optical (NLO) properties. A novel D-π-A type compound, namely tetra (C60)-LaPc, has been constructed from a molecular design perspective, wherein tetra-formyl phthalocyanine is used as a donor, four C60 as acceptors and the phenylacetylene group is introduced into it as π-electron bridge, which can increase the molecular conjugation, reduce the spatial site resistance and expand the coplanarity of the molecule, thus making the intramolecular charge transfer easier. Tetra (C60)-LaPc achieves excellent NLO properties with a giant nonlinear absorption coefficient (45 cm GW-1 and large third-order susceptibility (4.05 × 10-10 esu), which are superior to those of LaPc and C60. In addition to exhibiting a superior nonlinear optical response at 532 nm compared to the single component, tetra (C60)-LaPc also broadens the limiting range to the near-infrared region, showing a significant enhancement of the optical nonlinearity at 1064 nm. This can be attributed to the synergistic effect of the different non-linear absorption mechanisms between C60 and LaPc and the efficient PET process.

Enhanced ultra-wide NIR fluorescence in tellurite glass doped with Er3+-Tm3+-Nd3+-Ag NPs.

Tellurite glasses with combination of Er3+/Tm3+/Nd3+ ions and silver nanoparticles (Ag NPs) were prepared by using single-step melt-quenching technology, and the enhanced effect of Ag NPs on the ultra-broadband near-infrared (NIR) fluorescence was studied. Under the 808 nm LD excitation, two ultra-broadband NIR fluorescence of 1300-1600 nm and 1600-2100 nm underwent an obvious enhancement of about 52% compared to the tri-doping tellurite glass free of Ag NPs. The intensified local electric field induced by Ag NPs together with the energy transfer from Ag species to doped ions is responsible for this enhancement. The enhanced ultra-broadband NIR fluorescence of 1300-1600 nm with the full width at half maximum (FWHM) of 230 nm, originating from the spectral overlapping of 1.34 µm (4F3/2→4I13/2 of Nd3+), 1.47 µm (3H4→3F4 of Tm3+) and 1.53 µm (4I13/2→4I15/2 of Er3+) three bands, is promising in developing new ultra-broadband photonic devices such as fiber amplifiers and tunable lasers.

Optimizing electric field distribution via tuning cross-linked point size for improving the dielectric properties of polymer nanocomposites.

Polymer nanocomposites containing high K ceramics have been developed for boosting the energy density of dielectric capacitors. However, there are numerous challenges in the research about how to optimize the electric field distribution and improve the interfacial structure of nanocomposites for overcoming dielectric mismatches between high K nanofillers and low K polymers. Herein, all-chemical bonding cross-linked nanocomposites were designed and nano-BT with different sizes were regarded as cross-linked points rather than a free dispersed phase in polymers. In addition, the cross-linking degree could be controlled by changing the nano-BT sizes. 60 nm BT-BCB@DPAES nanocomposites possess the most excellent mechanical and thermal properties as well as the highest theoretical breakdown strength. In fact, 100 nm BT-BCB@DPAES nanocomposites have the most perfect dielectric performance combined with the experimental data and finite element simulation, particularly at 150 °C, the highest breakdown strength of 442 MV m-1 and greatest discharged energy density of 3.1 J cm-3 were obtained. This is attributed to the proper cross-linking degree and uniform electric field distribution. Overall, this kind of cross-linked structure can effectively enhance dielectric performance, particularly at elevated temperatures. This provides an idea for developing high temperature polymer nanocomposites for dielectric energy storage applications.