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To study the difference in the contents of phenolics and the antioxidant activities between two kinds of Hawk tea of different maturity levels, and to evaluate their qualities, the contents of 15 phenolic compounds were determined using LC-MS/MS method. Then, the antioxidant activities of two types of tea were evaluated using DPPH radical scavenging rate, ABTS+ radical scavenging rate, and Fe3+ ferric reducing antioxidant power (FRAP). And then, the contents of 15 phenolic compounds and the antioxidant activities between two kinds of Hawk tea of different maturity levels were analyzed by analysis of variance (ANOVA). Based on the contents of 15 phenolic compounds, hierarchical cluster analysis (HCA), principal component analysis (PCA), and orthogonal partial least square-discriminant analysis (OPLS-DA) were used to classify two kinds of Hawk tea. Finally, the contribution of different phenolic compounds in Hawk tea to antioxidation was discussed by partial least square regression analysis (PLSR). The results were as follows: (1) The contents of catechin, p-coumaric acid, isoquercitrin, hyperoside, nicotiflorin, astragalin, kaempferol, quercetin, and afzelin in tender leaf tea were significantly higher than those in old leaf tea, among which the average contents of catechin, isoquercitrin, and astragalin were higher than those in old leaf tea by 1 039.43, 169.12 and 257.35 mg·100 g-1, respectively. The results of HCA, PCA, and OPLS-DA could distinguish two kinds of Hawk tea. (2) The ANOVA showed significant differences in DPPH radical scavenging rate, ABTS+ radical scavenging rate, and FRAP between two kinds of tea, with the tender leaf tea superior to the old leaf tea. (3) The PLSR suggested that isoquercitrin, catechin, astragalin, chlorogenic acid, hyperoside, p-coumaric acid, and kaempferol were the main phenolic compounds those contributed to the antioxidant activity of Hawk tea. This study can provide a reference for Hawk tea's quality control and application promotion.

【Objective】 The geometry of side ventilation windows is an important design parameter of greenhouse and this paper investigates the impact of their aspect ratio on air circulation in terraced greenhouses. 【Method】 The study is based on butterfly windows of terraced greenhouses in Guangzhou, using numerical simulation and experimental data measured from a greenhouse (Window C). We modelled five aspect ratios and compared the numerical simulations with experimental data. Air circulation in the greenhouse is quantified using non-uniformity coefficients. 【Result】 The average errors between the simulated and measured temperature and wind speed are 2.48% and 8.76% respectively, and their associated root mean square errors are 1.10 ℃ and 2.1×10-3 m/s, respectively. Changes in the aspect ratio do not result in significant effect on average temperature in the greenhouses, but affect temperature variation noticeably. Among the five aspect ratios we compared, Window A gives the greatest average wind speed and highest wind uniformity coefficient. Compared with Window C, it increase average wind speed by 23% and the wind speed uniformity coefficient by 41%. 【Conclusion】 Our results show that reducing the aspect ratio of the side ventilation window as currently used by local farmers can effectively increase the uniformity of both temperature and wind speed in the greenhouse.

TEOS-OTMS sols were prepared by sol-gel method using tetraethyl orthosilicate (TEOS) and octyl trimethoxysilane (OTMS) as raw materials.Hydrophobic coatings were prepared on a smooth glass substrate and an etched glass substrate by one-step immersion method.The effects of hydrolysis time on the hydrophobicity and hardness of the coating were studied.The formation mechanisms of TEOS-OTMS sol and hydrophobic coating were proposed.Results showed that colloidal particles with SiO2 particles as the glue core and octylsilane as the cover could be prepared through TEOS-OTMS in-situ hydrolysis polymerization.And a low surface hydrophobic film modified by an octyl chain could take shape on the glass substrate.When TEOS was treated with pre-hydrolysis polymerization for 4 h and the TEOS-OTMS was treated with co-hydrolysis polymerization for 20 min,the hydrophobic angle of the coating reached (124.01±2.00)° and the pencil hardness reached 6 H.The result of an microstructure analysis by scanning electron microscope showed that the glass substrate was etched to form micro protrusions with a spacing of 6.36 nm and an average size of 16.75 nm,which enhanced the entanglement and aggregation of TEOS and OTMS,and pores of 150～200 nm formed in the coating.This “micro roughness”was the key to the formation of superhydrophobic coating,and the hydrophobic angle of the TEOS-OTMS coating reached (160.08±2.00)°.

The characteristics of ion-scale turbulence in the presence of a magnetic island are numerically investigated using a gyrokinetic model in fusion plasma. We observe that in the absence of the usual ion temperature gradient (ITG) drive gradient, a magnetic island and its flatten effect could drive ITG instability. The magnetic island (MI) not only drives high-n modes of ITG instability but also induces low-n modes of vortex flow. Moreover, as the magnetic island width increases, the width of the vortex flow also increases. This implies that wider islands may more easily induce vortex flows. The study further indicates that the saturated amplitude and transport level of MI-induced ITG turbulence vary with different magnetic island widths. In general, larger magnetic islands enhance both particle and heat transport. When the magnetic island width reaches to 21ρi, the turbulence-driven transport becomes the same level with the cases that ITG is driven by pressure gradients. Our findings indicate the presence of intricate nonlinear effects in the modulation of plasma turbulence by MIs. These effects are of significant importance for comprehending the phenomenon of nonlinear coupling in forthcoming tokamaks such as ITER. [ABSTRACT FROM AUTHOR]

The shuttle behavior and sluggish conversion kinetics of polysulfides (LiPSs) significantly hinder sulfur utilization and cycle stability of lithium–sulfur (Li–S) batteries. Herein, iron hexadecafluorophthalocyanine (FePcF16) nanoparticles were in situ tailored on oxidized apple pomace carbon (OAPC) with a 3D porous structure to construct a high-performance FePcF16/OAPC sulfur host for advanced Li–S batteries. The designed FePcF16 nanoparticles have strong adsorption and catalytic conversion capabilities, which can reduce the redox reaction energy barrier, accelerate the conversion rate, and inhibit the LiPS shuttle. Meanwhile, the unique porous structure of OAPC effectively realizes the sulfur accommodation and rapid transport of substances. The average capacities of batteries with FePcF16/OAPC were 926.83, 847.11, and 782.63 mA h/g after 500 cycles at 1, 2, and 3C current densities, with capacity decay rates of only 0.020%, 0.031%, and 0.043% per cycle, respectively. Furthermore, it delivers favorable cycling stability at a sulfur load of 4.32 mg/cm2. [ABSTRACT FROM AUTHOR]

21 cm cosmology is a promising new probe of the evolution of visible matter in our universe, especially during the poorly constrained Cosmic Dawn and Epoch of Reionization. However, in order to separate the 21 cm signal from bright astrophysical foregrounds, we need an exquisite understanding of our telescopes so as to avoid adding spectral structure to spectrally smooth foregrounds. One powerful calibration method relies on repeated simultaneous measurements of the same interferometric baseline to solve for the sky signal and for instrumental parameters simultaneously. However, certain degrees of freedom are not constrained by asserting internal consistency between redundant measurements. In this paper, we review the origin of these degeneracies of redundant-baseline calibration and demonstrate how they can source unwanted spectral structure in our measurement and show how to eliminate that additional, artificial structure. We also generalize redundant calibration to dual-polarization instruments, derive the degeneracy structure, and explore the unique challenges to calibration and preserving spectral smoothness presented by a polarized measurement.