Microbial Fermentation Enhances the Effect of Black Tea on Hyperlipidemia by Mediating Bile Acid Metabolism and Remodeling Intestinal Microbes.

Black tea (BT), the most consumed tea worldwide, can alleviate hyperlipidemia which is a serious threat to human health. However, the quality of summer BT is poor. It was improved by microbial fermentation in a previous study, but whether it affects hypolipidemic activity is unknown. Therefore, we compared the hypolipidemic activity of BT and microbially fermented black tea (EFT). The results demonstrated that BT inhibited weight gain and improved lipid and total bile acid (TBA) levels, and microbial fermentation reinforced this activity. Mechanistically, both BT and EFT mediate bile acid circulation to relieve hyperlipidemia. In addition, BT and EFT improve dyslipidemia by modifying the gut microbiota. Specifically, the increase in Lactobacillus johnsonii by BT, and the increase in Mucispirillum and Colidextribacter by EFT may also be potential causes for alleviation of hyperlipidemia. In summary, we demonstrated that microbial fermentation strengthened the hypolipidemic activity of BT and increased the added value of BT.

Metabolome and Microbiome Analysis to Study the Flavor of Summer Black Tea Improved by Stuck Fermentation.

Tea is the most popular and widely consumed beverage worldwide, especially black tea. Summer tea has a bitter and astringent taste and low aroma compared to spring tea due to the higher content of polyphenols and lower content of amino acids. Microbial fermentation is routinely used to improve the flavor of various foods. This study analyzed the relationship between the quality of black tea, metabolic characteristics, and microbial communities after microbial stuck fermentation in summer black tea. Stuck fermentation decreased the bitterness, astringency sourness, and freshness, and increased the sweetness, mellowness, and smoothness of summer black tea. The aroma also changed from sweet and floral to fungal, with a significant improvement in overall quality. Metabolomics analysis revealed significant changes in 551 non-volatile and 345 volatile metabolites after fermentation. The contents of compounds with bitter and astringent taste were decreased. Sweet flavor saccharides and aromatic lipids, and acetophenone and isophorone that impart fungal aroma showed a marked increase. These changes are the result of microbial activities, especially the secretion of extracellular enzymes. Aspergillus, Pullululanibacillus, and Bacillus contribute to the reduction of bitterness and astringency in summer black teas after stuck fermentation, and Paenibacillus and Basidiomycota_gen_Incertae_sedis contribute positively to sweetness. In addition, Aspergillus was associated with the formation of fungal aroma. In summary, our research will provide a suitable method for the improvement of tea quality and utilization of summer tea, as well as provide a reference for innovation and improvement in the food industry.

The Role of Catechins in Regulating Diabetes: An Update Review.

Catechins are key functional components in tea and have many health benefits, including relieving diabetes. Glucose is necessary for maintaining life. However, when the glucose in the serum exceeds the threshold, it will lead to hyperglycemia. Hyperglycemia is mainly caused by insufficient insulin secretion or insulin resistance. Persistent hyperglycemia can cause various disorders, including retinopathy, nephropathy, neurodegenerative diseases, cardiovascular disease, and diabetes. In this paper, we summarize the research on the underlying mechanisms of catechins in regulating diabetes and elaborate on the mechanisms of catechins in alleviating hyperglycemia by improving insulin resistance, alleviating oxidative stress, regulating mitochondrial function, alleviating endoplasmic reticulum stress, producing anti-inflammatory effects, reducing blood sugar source, and regulating intestinal function. This review will provide scientific direction for future research on catechin alleviating diabetes.

Multi-mode surface plasmon resonance absorber based on dart-type single-layer graphene.

In this paper, a multi-mode surface plasmon resonance absorber based on dart-type single-layer graphene is proposed, which has the advantages of polarization independence, tunability, high sensitivity, high figure of merit, etc. The device consists of a top layer dart-like patterned single-layer graphene array, a thicker silicon dioxide spacer layer and a metal reflector layer, and has simple structural characteristics. The numerical results show that the device achieves the perfect polarization-independent absorption at the resonance wavelengths of λ I = 3369.55 nm, λ II = 3508.35 nm, λ III = 3689.09 nm and λ IV = 4257.72 nm, with the absorption efficiencies of 99.78%, 99.40%, 99.04% and 99.91%, respectively. The absorption effect of the absorber can be effectively regulated and controlled by adjusting the numerical values such as the geometric parameters and the structural period p of the single-layer graphene array. In addition, by controlling the chemical potential and the relaxation time of the graphene layer, the resonant wavelength and the absorption efficiency of the mode can be dynamically tuned. And can keep high absorption in a wide incident angle range of 0° to 50°. At last, we exposed the structure to different environmental refractive indices, and obtained the corresponding maximum sensitivities in four resonance modes, which are S I = 635.75 nm RIU-1, S II = 695.13 nm RIU-1, S III = 775.38 nm RIU-1 and S IV = 839.39 nm RIU-1. Maximum figure of merit are 54.03 RIU-1, 51.49 RIU-1, 43.56 RIU-1, and 52.14 RIU-1, respectively. Therefore, this study has provided a new inspiration for the design of the graphene-based tunable multi-band perfect metamaterial absorber, which can be applied to the fields such as photodetectors and chemical sensors.

Binder-Free Porous 3D-ZnO Hexagonal-Cubes for Electrochemical Energy Storage Applications.

Considerable efforts are underway to rationally design and synthesize novel electrode materials for high-performance supercapacitors (SCs). However, the creation of suitable materials with high capacitance remains a big challenge for energy storage devices. Herein, unique three-dimensional (3D) ZnO hexagonal cubes on carbon cloth (ZnO@CC) were synthesized by invoking a facile and economical hydrothermal method. The mesoporous ZnO@CC electrode, by virtue of its high surface area, offers rich electroactive sites for the fast diffusion of electrolyte ions, resulting in the enhancement of the SC's performance. The ZnO@CC electrode demonstrated a high specific capacitance of 352.5 and 250 F g-1 at 2 and 20 A g-1, respectively. The ZnO@CC electrode revealed a decent stability of 84% over 5000 cycles at 20 A g-1 and an outstanding rate-capability of 71% at a 10-fold high current density with respect to 2 A g-1. Thus, the ZnO@CC electrode demonstrated improved electrochemical performance, signifying that ZnO as is promising candidate for SCs applications.

Coupled dynamic reaction force study of a large-aperture piezoelectric fast steering mirror.

The reaction force of a large-aperture piezoelectric fast steering mirror (PFSM) has adverse coupling interference for the stability and pointing accuracy of laser beams, and the dynamic characteristics of the reaction force are coupled with the inner components of the PFSM. In order to compensate for and eliminate the reaction force, it is essential to accurately analyze the dynamic characteristics. In this paper, a simplified piezoelectric-coupling model of PFSM is established. The coupling mathematical equations for investigating the characteristics of the reaction force are deducted based on the piezoelectric constitutive equation and Hamiltonian's principle. Then the coupling characteristics of the reaction force are probed by a finite element (FE) piezoelectric-coupling method. The simulations for three large apertures' (250, 320, and 400 mm) FE models show that the reaction force has a linear positive correlation with the actuating voltage, and coupled with the materials of the central flexure hinge, the relationship between the reaction force and driving frequency is not completely quadratic. Experiments with the 320 mm aperture are completed, and the testing results are consistent with the mathematical model and the FE piezoelectric-coupling simulation. The dynamic characteristics of the reaction force demonstrated in this paper are significance for the accurate estimation of the reaction force, the design of compensation structure, and the optimization of algorithm for beam jitter controlling.

Occlusion-aware light field depth estimation using side window angular coherence.

Depth estimation is crucial in many light field applications. However, the accuracy of light field depth estimation is prone to be affected by occlusions. In this paper, a method of side window angular coherence is proposed to handle different types of occlusions, and the ability of the proposed method to resist occlusions is theoretically analyzed. The angular patch is divided into several discrete side window subsets. These subsets are a pure occluder-type subset, a pure object point-type subset, and a hybrid-type subset. The photo-consistency of the pure object point-type subset can reflect the true depth. Meanwhile, the occlusion edges can be detected to identify occluded points and nonoccluded points so the robustness of the algorithm can be further enhanced by processing the two types of points. Moreover, fast guided filtering is applied to cost volume for improving the accuracy of depth estimation. Experimental results demonstrate that our method outperforms the state-of-the-art depth estimation methods on both synthetic and real scenes, especially near occlusion boundaries.

Design and analysis of a reactionless large-aperture fast steering mirror with piezoelectric actuators.

The reaction force of a fast steering mirror (FSM) directly transmits to the FSM's base, leading to dynamic coupling interference to the optical platform and degradation of laser beam quality in an adaptive optics system. In this paper a $\Phi {320}\;{\rm mm}$Φ320mm aperture symmetrically arranged reactionless FSM actuated by piezoelectric actuators was proposed. The corresponding dynamic equation about reaction force was established by rotational equation of Newton's second law, and the equilibrium condition of reaction force compensation was deduced. Then, the finite element (FE) piezoelectric-coupling method was used to simulate dynamic characteristics, which shows that the elimination ratios of the reaction force are 99% at low frequency (at 50 Hz) and 94.1% at high frequency (at 120 Hz). The experimental results show that the first resonance frequency of the FSM is 159.82 Hz, the tilting angle is $\pm {1.3}^\prime$±1.3', the reaction force at high frequency (at 120 Hz) is 112.95 N, and the elimination ratio of reaction force is 90.14%. The simulation and corresponding test results indicate that the developed reactionless FSM significantly eliminates reaction force and therefore improve the FSM's stability and pointing accuracy.

Vibration identification based on Levenberg-Marquardt optimization for mitigation in adaptive optics systems.

When high performance is expected, vibrations are becoming a burning issue in adaptive optics systems. For mitigation of these vibrations, in this paper, we propose a method to identify the vibration model. The nonlinear least squares algorithm named the Levenberg-Marquardt method is adapted to acquire the model parameters. The experimental validation of the high performance of vibration mitigation associated with our identification method has been accomplished. Benefiting from this method, vibrations have been significantly suppressed using linear quadratic Gaussian control, where the root-mean-square of the residual vibrations has been reduced down to a portion of a microradian. Moreover, the experimental results show that with the model identified, vibrations ranging from wide low-frequency perturbation to high-frequency vibration peaks can be dramatically mitigated, which is superior to classical control strategies.