Abstract
Human activities and climate change threaten water quality in China’s rivers. We simulated the monthly concentrations of riverine total nitrogen (TN), ammonia-nitrogen (NH
3
-N), total ...phosphorus (TP), and chemical oxygen demand (COD
Mn
) in 613 sub-watersheds of the nation’s 10 major river basins during the 1980–2050 period based on a 16-year (2003–2018) monitoring dataset using the stacking machine-learning models. The results showed that water quality improved markedly, except for the TN concentration, which was probably due to the lack of a TN control target and assessment system. Quantitative analysis indicated that anthropogenic factors were the primary controls compared with climatic drivers and geographical drivers for TN, TP, and NH
3
-N concentrations. On the basis of all 17 sustainable development goals (SDGs) relevant to water quality in China, the water resources, water environment, aquatic ecology and water security should be considered collectively to achieve improvements in the ecological status of China’s rivers.
The application of limited hydrolysis on wheat gluten (WG) has been found to be a highly effective method for improving a wide range of functional properties associated with plant protein. However, ...the bitter peptides formed during this process have an unpleasant bitterness. To provide a theoretical framework for de-bittering techniques, this study examined the modulation of bitterness intensity in wheat gluten hydrolysates (WGHs) by manipulating enzyme cleavage sites and degree of hydrolysis (DH). It was found that the bitter peptide's release content increased significantly, and the bitterness threshold decreased markedly with increasing DH. Furthermore, the structure-bitterness threshold association of bitter peptides was investigated. The results indicated that peptide segments in molecular weights (MW) from 500 to 1000 exhibited the greatest influence on bitterness threshold compared to peptides with other MWs. The percentage of total hydrophobic amino acid content and position of some hydrophobic amino acids in the amino acid sequence had a significant effect on the bitterness threshold. Finally, 47 peptides were identified by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) analysis. These peptides were mainly small peptides with less than 13 amino acid residues and MW below 1500 Da, and most of them had Q values higher than 5855 J/mol.
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•The bitterness threshold played a leading role in bitterness evaluation.•The effect of amino acid composition on bitter taste threshold wasn't obvious.•The amino acid sequence of peptides was the most important in bitter taste threshold.•The molecular weights from 500 to 1000 was the most important in bitter taste threshold.
Salicylic acid (SA) is a hydrolysis product and an active form of aspirin, and SA is found in a range of fruits and other food products. For food and drug and analysis there is a strong desire to ...detect SA. Since SA is a very small molecule, aptamers have advantages over antibodies for its detection. In this work, we used the library‐immobilization capture‐SELEX method to isolate aptamers for SA. After 17 rounds of selection, two main families of aptamers were isolated. The SA1 aptamer from family 1 has a Kd of 5.8 μM from a thioflavin T (ThT) fluorescence assay and 26.7 μM from isothermal titration calorimetry. The binding of other sequences was weaker compared to SA1. Based on mutation studies, the two conserved regions of SA1 were connected by two stems. Using ThT as a stain, a label‐free fluorescent sensor was tested for the detection of SA with a detection limit of 2.2 μM. A few similar molecules were tested including aspirin, and only p‐hydroxybenzoic acid showed a weak binding, indicating the high specificity of the SA1 aptamer. Finally, the SA1 aptamer was also tested in tomato juice and a similar binding performance was achieved.
A short 40‐nucleotide aptamer was isolated using the library‐immobilization SELEX method, and this aptamer can selectively bind to salicylic acid but showed no binding to aspirin. A label‐free fluorescent sensor was developed using thioflavin T as a dye probe.
A good water ecological environment is crucial for the sustainable development and ecological civilization of China. However, various problems remain for China’s water ecological environment, ...including eutrophication, pollution of drinking water sources, contamination of groundwater and coastal waters, emerging pollutants, and shortage of ecological water. In this study, we analyzed the overall situation of the water ecological environment in China, pinpointed the major challenges, and proposed the strategic thinking and several basic principles. These principles focus on improving the water ecological environment and comprehensively consider water quality improvement, water ecological protection, and water environmental risk prevention and control. Three major scientific and technological projects were proposed pertaining to (1) coordinated governance and overall restoration of mountains, rivers, forests, fields, lakes, grasses, and sand in key basins, (2) overall improvement of water environment and water ecology in the Beijing-Tianjin-Hebei Collaborative Development Area, and (3) assurance of drinking water safety in the new era. Furthermore, we proposed the following four countermeasures: (1) revising the Environmental Quality Standards for Surface Water to strengthen its leading role in the construction of water ecological civilization in China; (2) evaluating the spatial and temporal differences of nitrogen and phosphorus nutrients in China’s lakes and implementing differentiated nutrients standards; (3) assessing the current status of water ecology in China and promoting water ecology monitoring and assessment; and (4) establishing an intelligent supervision platform for drinking water safety based on big data fusion.
Arsenic (As) is a highly toxic metalloid, and its widespread contamination of water is a serious threat to human health. This study explored As removal using Fe(II)-oxidizing bacteria. The strain Fe7 ...isolated from iron mine soil was classified as the genus
based on 16S rRNA gene sequence similarities and phylogenetic analyses. The strain Fe7 was identified as a strain of Gram-positive, rod-shaped, aerobic bacteria that can oxidize Fe(II) and produce iron mineral precipitates. X-ray diffraction, X-ray photoelectron spectroscopy, and energy-dispersive X-ray spectroscopy patterns showed that the iron mineral precipitates with poor crystallinity consisted of Fe(III) and numerous biological impurities. In the co-cultivation of the strain Fe7 with arsenite (As(III)), 100% of the total Fe and 99.9% of the total As were removed after 72 h. During the co-cultivation of the strain Fe7 with arsenate (As(V)), 98.4% of the total Fe and 96.9% of the total As were removed after 72 h. Additionally, the iron precipitates produced by the strain Fe7 removed 100% of the total As after 3 h in both the As(III) and As(V) pollution systems. Furthermore, enzyme activity experiments revealed that the strain Fe7 oxidized Fe(II) by producing extracellular enzymes. When 2% (
/
) extracellular enzyme liquid of the strain Fe7 was added to the As(III) or As(V) pollution system, the total As removal rates were 98.6% and 99.4%, respectively, after 2 h, which increased to 100% when 5% (
/
) and 10% (
/
) extracellular enzyme liquid of the strain Fe7 were, respectively, added to the As(III) and As(V) pollution systems. Therefore, iron biomineralized using a co-culture of the strain Fe7 and As, iron precipitates produced by the strain Fe7, and the extracellular enzymes of the strain Fe7 could remove As(III) and As(V) efficiently. This study provides new insights and strategies for the efficient remediation of arsenic pollution in aquatic environments.
To assess the quantification accuracy of pulmonary nodules using virtual monoenergetic images (VMIs) derived from spectral-detector computed tomography (CT) under an ultra-low-dose scan protocol.
A ...chest phantom consisting of 12 pulmonary nodules was scanned using spectral-detector CT at 100 kVp/10 mAs, 100 kVp/20 mAs, 120 kVp/10 mAs, and 120 kVp/30 mAs. Each scanning protocol was repeated three times. Each CT scan was reconstructed utilizing filtered back projection, hybrid iterative reconstruction, iterative model reconstruction (IMR), and VMIs of 40-100 keV. The signal-to-noise ratio and air noise of images, absolute differences, and absolute percentage measurement errors (APEs) of the diameter, density, and volume of the 4 scan protocols and 10 reconstruction images were compared.
With each fixed reconstruction image, the four scanning protocols exhibited no significant differences in APEs for diameter and density (all
> 0.05). Of the 4 scan protocols and 10 reconstruction images, APEs for nodule volume had no significant differences (all
> 0.05). At 100 kVp/10 mAs, APEs for density using IMR were the lowest (APE
: 6.69), but no significant difference was detected between VMIs at 50 keV (APE
: 11.69) and IMR (
= 0.666). In the subgroup analysis, at 100 kVp/10 mAs, there were no significant differences between VMIs at 50 keV and IMR in diameter and density (all
> 0.05). The radiation dose at 100 kVp/10 mAs was reduced by 77.8% compared with that at 120 kVp/30 mAs.
Compared with IMR, reconstruction at 100 kVp/10 mAs and 50 keV provides a more accurate quantification of pulmonary nodules, and the radiation dose is reduced by 77.8% compared with that at 120 kVp/30 mAs, demonstrating great potential for ultra-low-dose spectral-detector CT.
High-temperature and high-light are the main adversity stresses faced by strawberry seedlings and open-field cultivation in summer. Chitosan (CTS) is widely used in agriculture as a soil amendment, ...plant growth regulator, and promoter of cold resistance. However, the effects of CTS on strawberry seedlings under the combined stress of high-temperature and high-light are unclear. This study aimed to determine the effect of CTS on strawberry seedlings under the combined stress of high-temperature and high-light. In this study, Xuelixiang strawberry was used as the experimental plant material. The leaves were sprayed with 100 mg/Kg CTS or deionized aqueous solution and placed under high-temperature and high-light (38 °C, 1800 μ mol·m−2·s−1, respectively) for 8 h. In addition, a suitable temperature and light (23 °C, 400 μ mol·m−2·s−1, respectively) was sprayed with deionized water as a control. The results showed that compared with non-CTS treatment, the chlorophyll (Chl) content in strawberry plants increased by 16.9% after CTS treatment; the net CO2 exchange (Pn) increased by 74.9%; and the maximum photochemical efficiency increased by 20.1%. In addition, CTS treatment increased the content of antioxidants; increased osmotic adjustment substances; improved the activity of reduced glutathione with reduced ascorbic acid (AsA-GSH) circulating antioxidant enzymes; removed reactive oxygen species in plants in time; and reduced the damage of reactive oxygen species to photosynthetic organs and cell membranes, thereby reducing high-temperature and high-light injury to strawberry seedlings. This study shows that CTS can improve the negative effects of high-temperature and high-light stress on strawberry seedlings.
The antifungal activity of cinnamon (
Presl), litsea
(Lour.) Pers., clove (
L.), thyme (
Ronn.) and citronella (
Jowitt) essential oils (EOs) against the dominant fungi isolated from moldy peanuts ...was investigated in this research. Firstly, strain YQM was isolated and identified by morphological characterization and 18S rRNA gene sequence analysis to be
(
.
). Next, antifungal effects of single or mixed EOs on strain YQM were evaluated by the inhibition zone test. The cinnamon-litsea combined essential oil (CLCEO, V
:V
= 3:5) displayed the best antifungal effect on strain YQM. The chemical composition of CLCEO was identified and quantified by gas chromatograph-mass spectrometry (GC-MS), and results revealed that the major components of CLCEO were cinnamaldehyde and citral. Finally, the effect of EOs on the microstructure of strain YQM mycelia was observed under scanning electron microscope (SEM). The mycelia exposed to cinnamon essential oil (CEO) and litsea essential oil (LEO) were partly deformed and collapsed, while the mycelia treated with CLCEO were seriously damaged and the deformation phenomena such as shrinking, shriveling and sinking occurred. Therefore, CLCEO has great potential for using as anti-mildew agents during peanut storage.
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