Single atom catalysts (SACs) with the maximized metal atom efficiency have sparked great attention. However, it is challenging to obtain SACs with high metal loading, high catalytic activity, and ...good stability. Herein, we demonstrate a new strategy to develop a highly active and stable Ag single atom in carbon nitride (Ag‐N2C2/CN) catalyst with a unique coordination. The Ag atomic dispersion and Ag‐N2C2 configuration have been identified by aberration‐correction high‐angle‐annular‐dark‐field scanning transmission electron microscopy (AC‐HAADF‐STEM) and extended X‐ray absorption. Experiments and DFT calculations further verify that Ag‐N2C2 can reduce the H2 evolution barrier, expand the light absorption range, and improve the charge transfer of CN. As a result, the Ag‐N2C2/CN catalyst exhibits much better H2 evolution activity than the N‐coordinated Ag single atom in CN (Ag‐N4/CN), and is even superior to the Pt nanoparticle‐loaded CN (PtNP/CN). This work provides a new idea for the design and synthesis of SACs with novel configurations and excellent catalytic activity and durability.
A new Ag single atom in carbon nitride (Ag‐N2C2/CN) photocatalyst with Ag‐N2C2 configuration is developed. It affords fast charge transfer, high Ag loading, and good stability. Noteworthily, the Ag‐N2C2/CN exhibits much better hydrogen evolution activity than Ag‐N4/CN, and even superior to the platinum‐loaded CN.
Objective
Since December 2019, an outbreak of corona virus disease 2019 (COVID-19) occurred in Wuhan, and rapidly spread to almost all parts of China. This was followed by prevention programs ...recommending Chinese medicine (CM) for the prevention. In order to provide evidence for CM recommendations, we reviewed ancient classics and human studies.
Methods
Historical records on prevention and treatment of infections in CM classics, clinical evidence of CM on the prevention of severe acute respiratory syndrome (SARS) and H1N1 influenza, and CM prevention programs issued by health authorities in China since the COVID-19 outbreak were retrieved from different databases and websites till 12 February, 2020. Research evidence included data from clinical trials, cohort or other population studies using CM for preventing contagious respiratory virus diseases.
Results
The use of CM to prevent epidemics of infectious diseases was traced back to ancient Chinese practice cited in Huangdi’s Internal Classic (Huang Di Nei Jing) where preventive effects were recorded. There were 3 studies using CM for prevention of SARS and 4 studies for H1N1 influenza. None of the participants who took CM contracted SARS in the 3 studies. The infection rate of H1N1 influenza in the CM group was significantly lower than the non-CM group (relative risk 0.36, 95% confidence interval 0.24–0.52; n=4). For prevention of COVID-19, 23 provinces in China issued CM programs. The main principles of CM use were to tonify qi to protect from external pathogens, disperse wind and discharge heat, and resolve dampness. The most frequently used herbs included
Radix astragali
(Huangqi),
Radix glycyrrhizae
(Gancao),
Radix saposhnikoviae
(Fangfeng),
Rhizoma Atractylodis Macrocephalae
(Baizhu),
Lonicerae Japonicae Flos
(Jinyinhua), and
Fructus forsythia
(Lianqiao).
Conclusions
Based on historical records and human evidence of SARS and H1N1 influenza prevention, Chinese herbal formula could be an alternative approach for prevention of COVID-19 in high-risk population. Prospective, rigorous population studies are warranted to confirm the potential preventive effect of CM.
Phenolics are good natural antioxidant in human diets and contribute to formation of sensory attributes of food products. This study aimed to investigate effects of 1%–5% pomegranate juice powder ...(PJP, rich in phenolics) used as sugar in fermentation matrix on the physiochemical properties (color, sensory and total phenolic content), structure (texture and microstructure), rheology and functionality (antioxidant activity and in vitro bioaccessibility) of set yogurts during storage for 21 days. It showed that the higher PJP level, the higher sensory scores and total phenolic contents the yogurt had, the firmer in texture and compacter in microstructure became, and the better viscoelasticy and stronger antioxidant activity exhibited. But there was no significant difference (P > 0.05) in color and bioaccessibility between controls and yogurts with PJP. During the storage, except for the consistency of LD was slightly lower than that of the control on the first day and at the end of storage, the values of other quality attributes of the LD, MD, MD groups showed higher than that of the controls. Results indicated that 5% PJP has potential to improve quality attributes of set yogurt by replacing sucrose in fermentation matrix.
•1%–5% pomegranate juice powder (PJP) was used as a sugar replacer for set yogurts production.•PJP improved gel viscoelasticity, antioxidant activity and storage stability of set yogurts.•Enhancement effects on set yogurts increased with the increasing levels of PJP replacement.•PJP can replace some or all sucrose in fermentation matrix for the production of functional yogurt.
A facile impregnation combined with photo-deposition approach was adopted to deposit CdS nanoparticles on covalent-organic framework (CTF-1), which not only acted as supporter but also served as ...photocatalyst and electron-donor. The fast electron transfer rate and injection efficiency enabled the as-formed CdS-CTF-1 to show higher photocatalytic performance than CdS/CTF-1 prepared via solvothermal method.
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A facile and effective impregnation combined with photo-deposition approach was adopted to deposit cadmium sulfide (CdS) nanoparticles on CTF-1, a covalent triazine-based frameworks (CTFs). In this system, CTF-1 not only acted as supporter but also served as photocatalyst and electron donor. The performance of the obtained CdS deposited CTF-1 (CdS-CTF-1) nanocomposite was evaluated by H2 evolution reaction under visible light irradiation. As a result, CdS-CTF-1 exhibited high H2 production from water, far surpassing the CdS/CTF-1 nanocomposite, in which CdS was deposited via solvothermal method. The high activity of CdS-CTF-1 was attributed to the confined CdS nanoparticles with small size, leading to expose more active sites. In addition, time-resolved spectroscopy indicated that the superior performance of CdS-CTF-1 also can be ascribed to the fast electron transfer rate and injection efficiency (KET = 0.18 × 109 s−1, ηinj = 39.38%) between CdS and CTF-1 layers, which are 3.83 times faster and 4.84 times higher than that of CdS/CTF-1 nanocomposite. This work represents the first example on using covalent organic frameworks (COFs) as a support and electron-donor for fabricating novel CdS-COF nanocomposite system and its potential application in solar energy transformations.
Protective role of hydrogen sulfide （H2S） on seed germination and seedling growth was studied in wheat （Triticum） seeds subjected to aluminum （Al3＋） stress. We show that germination and seedling ...growth of wheat is inhibited by high concentrations of AICI3. At 30 mmol/L AICI3 germination is reduced by about 50% and seedling growth is more dramatically inhibited by this treatment. Pre-incubation of wheat seeds in the H2S donor NaHS alleviates AICI3-induced stress in a dose-dependant manner at an optimal concentration of 0.3 mmol/L. We verified that the role of NaHS in alleviating Al3＋ stress could be attributed to H2S/HS- by showing that the level of endogenous H2S increased following NaHS treatment. Furthermore, other sodium salts containing sulfur were ineffective in alleviating Al3＋ stress. NaHS pretreatment significantly increased the activities of amylases and esterases and sustained much lower levels of MDA and H2O2 in germinating seeds under Al3＋ stress. Moreover, NaHS pretreatment increased the activities of guaiacol peroxidase, ascorbate peroxidase, superoxide dismutase and catalase and decreased that of lipoxygenase. NaHS pretreatment also decreased the uptake of Al3＋ in AICI3-treated seed. Taken together these results suggest that H2S could increase antioxidant capability in wheat seeds leading to the alleviation of Al3＋ stress.
To improve the physicochemical stability of hydrophobic flavonoids, a series of protein-based nanomicelles have been developed in recent years. However, the quinoa protein (QP) nanomicelles and its ...interactions with different flavonoids were rarely reported. In this study, the QP nanomicelles (48.6 nm) were initially prepared. Then, quercetin (Que), curcumin (Cur), luteolin (Lut) and resveratrol (Res) were successfully assembled into the hydrophobic region of QP nanomicelles, giving the loading capacity of 33.9%, 8.0%, 17.8% and 6.4%, respectively. Moreover, this self-assembly significantly enhanced the solubility and stability of four flavonoids. The molecular interactions were further investigated. Results showed that hydrophobic interaction and hydrogen bonding were the main interaction driving forces between QP and hydrophobic flavonoids. The present work provided valuable evidences for the application of quinoa protein in functional foods.
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•Quinoa protein (QP) was extracted from quinoa seeds.•Hydrophobic flavonoids were successfully assembled in QP nanomicelles.•Flavonoids inducing the fluorescence quenching of QP via self-assembly.•Hydrophobic interaction and hydrogen bonding were the main molecular driving forces.
Limited by the electrostatic interaction, the oxidation reaction of cations at the anode and the reduction reaction of anions at the cathode in the electrocatalytic system nearly cannot be achieved. ...This study proposes a novel strategy to overcome electrostatic interaction via strong complexation, realizing the electrocatalytic reduction of cyanide (CN−) at the cathode and then converting the generated reduction products into nitrogen (N2) at the anode. Theoretical calculations and experimental results confirm that the polarization of the transition metal oxide cathodes under the electric field causes the strong chemisorption between CN− and cathode, inducing the preferential enrichment of CN− to the cathode. CN− is hydrogenated by atomic hydrogen at the cathode to methylamine/ammonia, which are further oxidized into N2 by free chlorine derived from the anode. This paper provides a new idea for realizing the unconventional and unrealizable reactions in the electrocatalytic system.
Electrostatic interaction could severely inhibit the selective conversion of ions. This work proposes a strategy to overcome electrostatic interaction via strong complexation, realizing the preferential hydrogenation of cyanide at the cathode, and then oxidizing the reduction products into nitrogen at the anode. The controlled mass transfer of ions provides more possibilities for their selective conversion in the electrocatalytic system.
With the enhancement of copper (Cu) stress, the germination percentage of wheat seeds decreased gradually. Pretreatment with sodium hydrosulfide (NaHS), hydrogen sulfide (H₂S) donor alleviated the ...inhibitory effect of Cu stress in a dose-dependent manner; whereas little visible symptom was observed in germinating seeds and radicle tips cultured in NaHS solutions. It was verified that H₂S or HS⁻ rather than other sulfur-containing components derived from NaHS attribute to the potential role in promoting seed germination against Cu stress. Further studies showed that NaHS could promote amylase and esterase activities, reduce Cu-induced disturbance of plasma membrane integrity in the radicle tips, and sustain lower levels of malondialdehyde and H₂O₂ in germinating seeds. Furthermore, NaHS pretreatment increased activities of superoxide dismutase and catalase and decreased that of lipoxygenase, but showed no significant effect on ascorbate peroxidase. Alternatively, NaHS prevented uptake of Cu and promoted the accumulation of free amino acids in seeds exposed to Cu. In addition, a rapid accumulation of endogenous H₂S in seeds was observed at the early stage of germination, and higher level of H₂S in NaHS-pretreated seeds. These data indicated that H₂S was involved in the mechanism of germinating seeds' responses to Cu stress.
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