Optimization of ultrasound-assisted enzymatic hydrolysis extraction of tea polyphenols from green tea and their antioxidant activities

Production of natural extracts requires suitable processing conditions to facilitate the accumulation and preservation of bioactive ingredients. This study aimed to optimize the conditions for extracting tea polyphenols (TPs) from green tea using ultrasound-assisted compound enzymatic extraction (UACEE) technology with response surface methodology (RSM), based on a three-level, four-variable central composite rotatable design (CCRD). Extracted TPs yields were in the range of 16.48% to 28.77%; the experimental results were fitted to a second-order quadratic polynomial model and showed a good fit to the proposed model (R2 > 0.90). Compared with other ex-traction methods, UACEE exhibited significant advantages in the TPs extraction rate and preservation of catechins composition. The antioxidant activities of these extracts were also analyzed using reducing power and DPPH radical scavenging activity; all extracts showed excellent antioxidant activity in a dose-dependent manner, and UACEE extracts showed the strongest antioxidant activity in vitro

Simulation of Drainage Capacity in a Coastal Nuclear Power Plant under Extreme Rainfall and Tropical Storm

To ensure the safety of coastal nuclear power plants, accurately simulating water depth due to flooding resulting from heavy rainfall and tropical storms is important. In this paper, a combined model is developed to analyze and simulate the drainage capacity in a coastal nuclear power plant under the combined action of extreme rainfall and wave overtopping. The combined model consist of a surface two-dimensional flood-routing model, a pipe network model, and an offshore wave model. The method of predictive correction calculation is adopted to calculate the node return flow. The inundated water depth varying with time for different design rainstorm return periods (p = 0.1 and 1%) was simulated and analyzed by the combined model. The maximum inundated water depth is calculated for the important entrances of the workshop. The model was validated and calibrated with the data of the rainfall, outflow discharge, and flow velocity measured on 23 June 2016 in plant. Modeling indicates that the simulated depths are consistent with the observed depths. The results show that the water depths in the left and right of the nuclear power plant are 0.2⁻0.4 m and 0.3⁻0.8 m, respectively. The water depth increases of Monitoring Point 22 are the largest in different design rainstorm return periods (p = 0.1 and 1%), which increase by 16% for a rainstorm once every thousand years compared to events occurring once in one hundred years. The main factor influencing water accumulation is wave overtopping, and the seawall, revetments, and pipe system play an important role in decreasing the inundated water depth. Through scientific analysis, a certain decision-making basis has been provided for flood disaster management and a certain security guarantee has also been provided for regional sustainable development

Spatiotemporal Distribution Characteristics of Nutrients in the Drowned Tidal Inlet under the Influence of Tides: A Case Study of Zhanjiang Bay, China

The tidal dynamics and the characteristics of pollutant migration in the drowned-valley tidal inlet, a typical unit of coastal tidal inlets, are strongly influenced by geomorphological features. Along with the development of society and the economy, the hydrodynamic and water quality environment of the tidal inlet is also becoming more disturbed by human activities, such as reclamation of the sea and the construction of large bridges. In this study, a typical drowned-valley tidal inlet, Zhanjiang Bay (ZJB), was selected for the establishment of a model via coupling of a tidal hydrodynamic model and water quality numerical model. This model can be used to simulate the migration and diffusion of pollutants in ZJB. The spatial and temporal variation processes of water quality factors of the bay under the influence of special geomorphic units was simulated at the tidal-inlet entrance, the flood/ebb tidal delta, and the tidal basin. The results show that ZJB has strong tidal currents that are significantly affected by the terrain. Under the influence of the terrain and tidal currents, the phosphorus and nitrogen concentration at the flood-tide and ebb-tide moments showed obvious temporal and spatial differences in the ebb-tide delta, tidal-inlet entrance, flood-tide delta, and tidal basin. In this study, we analyzed the response mechanism of the water quality environment to the drowned-valley tidal inlet, and this can provide theoretical guidance and a basis for decision-making toward protecting the ecology and water security of ZJB

Tumor microenvironment-responsive artesunate loaded Z-scheme heterostructures for synergistic photo-chemodynamic therapy of hypoxic tumor

Tumor microenvironment (TME) with the particular features of severe hypoxia, insufficient endogenous H2O2, and overexpression of glutathione (GSH) markedly reduced the antitumor efficacy of monotherapy. Herein, a TME-responsive multifunctional nanoplatform (Bi2S3@Bi@PDA-HA/Art NRs) was presented for synergistic photothermal therapy (PTT), chemodynamic therapy (CDT), and photodynamic therapy (PDT) to achieve better therapeutic outcomes. The Z-scheme heterostructured bismuth sulfide@bismuth nanorods (Bi2S3@Bi NRs) guaranteed excellent photothermal performance of the nanoplatform. Moreover, its ability to produce O2 and reactive oxygen species (ROS) synchronously could relieve tumor hypoxia and improve PDT outcomes. The densely coated polydopamine/ammonium bicarbonate (PDA/ABC) and hyaluronic acid (HA) layers on the surface of the nanoplatform enhanced the cancer-targeting capacity and induced the acidic TME-triggered in situ “bomb-like” release of Art. The CDT treatment was achieved by activating the released Art through intracellular Fe2+ ions in an H2O2-independent manner. Furthermore, decreasing the glutathione peroxidase 4 (GPX4) levels by Art could also increase the PDT efficiency of Bi2S3@Bi NRs. Owing to the synergistic effect, this nanoplatform displayed improved antitumor efficacy with minimal toxicity both in vitro and in vivo. Our design sheds light on the application of phototherapy combined with the traditional Chinese medicine monomer-artesunate in treating the hypoxic tumor

Detecting Surface Oil Slicks Using VIIRS Nighttime Imagery under Moon Glint: A Case Study in the Gulf of Mexico

Using data collected over the Gulf of Mexico during night between May 2012 and September 2013 by the Visible Infrared Imager Radiometer Suite (VIIRS), we demonstrate a new application from its day-and-night band (DNB). Under cloud free and moon glint conditions, the DNB revealed surface oil slicks from natural oil seeps. This is despite the fact that the signal-to-noise ratio (SNR) of this wide band (505–890 nm) under moon glint is much lower (30:1–50:1) and its resolution is also coarser (750 m) than the VIIRS imaging bands (375 m) under daytime solar illumination. The DNB was designed to map light sources at night. Similar to its predecessor, the Defense Meteorological Satellite Program Operational Linescan System (OLS), the VIIRS DNB should be suitable to identifying bioluminescence at night. However, with its finer resolution and higher SNR than OLS, the VIIRS DNB is demonstrated here to be also able to complement other sensors in the detection and mapping of oil spills

BTH Treatment Delays the Senescence of Postharvest Pitaya Fruit in Relation to Enhancing Antioxidant System and Phenylpropanoid Pathway

The plant resistance elicitor Benzo (1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH) can enhance disease resistance of harvested fruit. Nonetheless, it is still unknown whether BTH plays a role in regulating fruit senescence. In this study, exogenous BTH treatment efficiently delayed the senescence of postharvest pitaya fruit with lower lipid peroxidation level. Furthermore, BTH-treated fruit exhibited lower hydrogen peroxide (H2O2) content, higher contents of reduced ascorbic acid (AsA) and reduced glutathione (GSH) levels and higher ratios of reduced to oxidized glutathione (GSH/GSSG) and ascorbic acid (AsA/DHA), as well as higher activities of ROS scavenging enzymes, including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), peroxidase (POD) and glutathione reductase (GR) in comparison with control fruit. Moreover, BTH treatment enhanced the activities of phenylpropanoid pathway-related enzymes, including cinnamate-4-hydroxylase (C4H), phenylalanine ammonia-lyase (PAL) and 4-coumarate/coenzyme A ligase (4CL) and the levels of phenolics, flavonoids and lignin. In addition, BTH treatment upregulated the expression of HuSOD1/3/4, HuCAT2, HuAPX1/2 and HuPOD1/2/4 genes. These results suggested that application of BTH delayed the senescence of harvested pitaya fruit in relation to enhanced antioxidant system and phenylpropanoid pathway

Effects of S and Mineral Elements (Ca, Al, Si and Fe) on Thermochemical Behaviors of Zn during Co-Pyrolysis of Coal and Waste Tire: A Combined Experimental and Thermodynamic Simulation Study

The transformation behaviors of Zn during co-pyrolysis of waste tires and coal were studied in a fixed-bed reaction system. The effects of pyrolysis temperature and the Zn content of coal mixture on the Zn distributions in the pyrolytic products (coke, tar and gas) were investigated in detail. It is found that the relative percentages of Zn in the pyrolytic products are closely related to the contents of S and mineral elements (Ca, Al, Si and Fe) in the coal. The thermodynamic equilibrium simulations conducted using FactSage 8.0 show that S, Al and Si can interact with Zn to inhibit the volatilization of Zn from coke. The reaction sequence with Zn is S > Al > Si, and the thermal stability of products is in the order of ZnS > ZnAl2O4 > Zn2SiO4. These results provide insights into the migration characteristics of Zn during co-pyrolysis of coal and waste tires, which is vital to the prevention and control of Zn emissions to reduce the environmental burden