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Radar is an extremely valuable sensing technology for detecting moving targets and measuring their range, velocity, and angular positions. When people are monitored at home, radar is more likely to be accepted by end-users, as they already use WiFi, is perceived as privacy-preserving compared to cameras, and does not require user compliance as wearable sensors do. Furthermore, it is not affected by lighting conditions nor requires artificial lights that could cause discomfort in the home environment. So, radar-based human activities classification in the context of assisted living can empower an aging society to live at home independently longer. However, challenges remain as to the formulation of the most effective algorithms for radar-based human activities classification and their validation. To promote the exploration and cross-evaluation of different algorithms, our dataset released in 2019 was used to benchmark various classification approaches. The challenge was open from February 2020 to December 2020. A total of 23 organizations worldwide, forming 12 teams from academia and industry, participated in the inaugural Radar Challenge, and submitted 188 valid entries to the challenge. This paper presents an overview and evaluation of the approaches used for all primary contributions in this inaugural challenge. The proposed algorithms are summarized, and the main parameters affecting their performances are analyzed.

The feasibility of industrial waste fly ash as an alternative fluxing agent for silica in carbothermal reduction of medium-low-grade phosphate ore was studied in this paper. With a series of single-factor experiments, the reduction rate of phosphate rock under different reaction temperature, reaction time, particle size, carbon excess coefficient, and silicon–calcium molar ratio was investigated with silica and fly ash as fluxing agents. Higher reduction rates were obtained with fly ash fluxing instead of silica. The optimal conditions were derived as: reaction temperature 1,300°C, reaction time 75 min, particle size 48–75 µm, carbon excess coefficient 1.2, and silicon–calcium molar ratio 1.2. The optimized process condition was verified with other two different phosphate rocks and it was proved universally. The apparent kinetics analyses demonstrated that the activation energy of fly ash fluxing is reduced by 31.57 kJ/mol as compared with that of silica. The mechanism of better fluxing effect by fly ash may be ascribed to the fact that the products formed within fly ash increase the amount of liquid phase in the reaction system and promote reduction reaction. Preliminary feasibility about the recycling of industrial waste fly ash in thermal phosphoric acid industry was elucidated in the paper.

AbstractA new polysaccharides fraction (PSF) was isolated from the extraction of flue-cured tobacco stem with hot water and purified through ethanol precipitation, deproteinization and Sepharose CL-6B column chromatography. Structural features of PSF were elucidated by a combination of FT-IR and GC-MS. The results revealed that PSF was heteropolysaccharide mainly consisted of mannose, arabinose, galactose and glucose. The molecular characteristics of PSF were examined by a multiangle laser-light scattering (MALLS) and refractive index (RI) detector system. The SEC/MALLS analysis revealed that the PSF had an average molecular weight about 3.142 × 104g/mol with the low polydispersity (Mw/Mn=1.247). The molecular shape of the PSF was a rigid sphere in the aqueous solution. The results of antioxidant assay showed that the PSF significantly scavenged hydroxyl (OH) and DPPH radical in a concentration-dependent manner. The results reveal that PSF is a useful antioxidant and might be available for relevant industrial application.

AbstractThe essential oil was isolated using the water steam distillation from the peel of Citrus maxima(Burm.) Merr. cv. Shatian Yu with a yield of 0.31% (w/w). The essential oil sample were analyzed by GC-MS and total sixty six components were identified. The major compounds were found to be identical namely D-limonene (86.4%) and nootkatone (2.11%). The essential oil displayed broad spectrum antibacterial activity against a panel of pathogenic bacteria and was most effective against Bacillus licheniformis. Thus, pummelo essential oil could be a potential antimicrobial agent.

Nickel-rich LiNi0.8Co0.15Al0.015O2(NCA) with excellent energy density is considered one of the most promising cathodes for lithium-ion batteries. Nevertheless, the stress concentration caused by Li+/Ni2+mixing and oxygen vacancies leads to the structural collapse and obvious capacity degradation of NCA. Herein, a facile codoping of anion (F–)-cation (Mg2+) strategy is proposed to address these problems. Benefiting from the synergistic effect of F–and Mg2+, the codoped material exhibits alleviated Li+/Ni2+mixing and demonstrates enhanced electrochemical performance at high voltage (≥4.5 V), outperformed the pristine and F–/Mg2+single-doped counterparts. Combined experimental and theoretical studies reveal that Mg2+and F–codoping decreases the Li+diffusion energy barrier and enhances the Li+transport kinetics. In particular, the codoping synergistically suppresses the Li+/Ni2+mixing and lattice oxygen escape, and alleviates the stress–strain accumulation, thereby inhibiting crack propagation and improving the electrochemical performance of the NCA. As a consequence, the designed Li0.99Mg0.01Ni0.8Co0.15Al0.05O0.98F0.02(Mg1+F2) demonstrates a much higher capacity retention of 82.65% than NCA (55.69%) even after 200 cycles at 2.8–4.5 V under 1 C. Furthermore, the capacity retention rate of the Mg1+F2||graphite pouch cell after 500 cycles is 89.6% compared to that of the NCA (only 79.4%).

Abstract: t-Butyl and t-pentylcalix[4]arenes bearing two 2-naphthol-1-hydrazone groups at the lower rim were synthesized, and showed excited-state intermolecular proton transfer fluorescent signal with basic anion. They are more sensitive to dihydrogen phosphate anion than to fluoride anion, although the latter has stronger basicity. Compared with t-butylcalix[4]arene bearing two 2-naphthol-1-hydrazone groups, t-pentylcalix[4]arenes derivative has a larger fluorescent difference between dihydrogen phosphate and fluoride anion. This finding may be used to analyze dihydrogen phosphate anion in the presence of fluoride anion and provide a new approach for designing fluorescence probes that are highly selective for H2PO4−.

The effects of sulfur (S) nutrition at 0.1 or 1 mM S on cadmium (Cd) toxicity measured by photosynthesis in barley (Hordeum vulgare L. cv. UC 476) seedlings were studied. Eight-day-old seedlings were treated with 25 μM Cd by adding cadmium chloride (CdCl2) to the nutrient solution. Then photosynthetic carboxylation efficiency (ACi curve) and stomatal conductance of the primary and second leaves were measured at four and eight days after Cd treatment. Fluorescence parameters were measured every 24 h for eight days after two days of Cd treatment. At 20 days, plant growth parameters were measured and dry biomass determined. The results showed that ACi was significantly reduced by Cd, but more in the low (0.1 mM) S than in the high (1 mM) S-treated plants. Stomatal conductance of plants was also decreased by Cd, but more in the low S-treated plants. Low S-treated plants exposed to Cd showed an increase in Fo and Fq, and a decrease in Fv/Fm and T1/2, indicating photoinhibitory damage to PSII. Analysis of the growth parameters showed that Cd decreased plant size and biomass, but the reduction was more severe in the low S-treated plants. These results support the hypothesis that S is a critical nutritional factor in plants which is important for the reduction of Cd toxicity.