Optimizing the flood limit water level (FLWL) of reservoirs in sediment-laden rivers under changing water and sediment conditions is an important research topic that could improve comprehensive utilization benefits. Because reservoir operation has multiple objectives in sediment-laden rivers, this study established a water–sediment mathematical model, a comprehensive benefit evaluation model, and an evaluation index system. Taking the Xiaolangdi Reservoir of the Yellow River as an example, the operation mode of the FLWL under changing water and sediment conditions was studied. Under the scenarios of incoming sediment amounts of 300–800 million tons, when using the operation mode of gradually raising the FLWL, the sediment retention period was 4–13 years longer; the lower average annual siltation of the downstream channel and minimum bank-full discharge of the downstream channel after 50 years was larger by 150–260 m3/s than the operation mode of raising the FLWL at one time. However, with enhanced benefits of sediment blocking and siltation reduction, other benefits such as water resources supply, hydropower generation, and ecological improvement are reduced. The average annual number of days that do not meet the downstream water resources supply requirements, irrigation, and ecological improvement was increased by 0.64–2.16 days, and 91–197 million kW·h reduced average annual hydropower generation. The critical amount of incoming sediment was 350 million for conversion between the two FLWL operation modes, and it will increase to 450 million tons if the incoming runoff of the Yellow River increases by 20%. After constructing the Guxian Reservoir in the middle of the Yellow River, the critical amount of incoming sediment will increase to 600 million tons. This study is of great significance for improving the utilization efficiency of water resources and promoting the socio-economic development of river basins.
A novel strategy for preparing highly sensitive molecularly imprinted sensors based on the electro-polymerization of o-phenylenediamine (o-PD) on a columnar-structured platinum (CSPt) electrode was proposed for β2-agonist determination. The CSPt electrode was used as a working electrode to increase the specific surface area and to extend the linear range. The sensor surface morphology was characterized by scanning electron microscopy. The preparation process of the sensor was characterized by an electrochemical quartz crystal microbalance. The electrochemical performance of the sensor was investigated by electrochemical impedance spectroscopy and cyclic voltammetry. Additionally, sodium dodecyl sulfonate, which was used in the electro-polymerization reaction of o-PD, prevented the hydrolysis degradation of poly-o-phenylenediamine (PoPD) and enhanced the stability of the PoPD film in the anionic micellar media. The recognition and determination of the sensor were carried out by measuring the changes of the amperometric response of [Fe(CN)6]3−/4−. The proposed sensor was successfully applied to detect β2-agonists in real human serum samples.
Chiral iminophosphoranes organocatalyzed the enantioselective synthesis of 3-hydroxymethyl-2-oxindoles in 81–98% yields and up to 94% ee under mild conditions. Of note is that readily available and easily usable paraformaldehyde was employed as a hydroxymethylation C1 unit in the reaction.
A nickel-catalyzed reductive cross-coupling between industrial chemical CF3CH2Cl and (hetero)aryl bromides and chlorides has been reported. The reaction is synthetically simple without the preparation of arylmetals and exhibits high functional group tolerance. The utility of this protocol has been demonstrated by the late-stage modification of pharmaceuticals, providing a facile route for medicinal chemistry.
Difluoroalkylated compounds have important applications in pharmaceutical, agrochemical, and materials science. However, efficient methods to construct the alkylCF2-alkyl bond are very limited, and the site-selective introduction of a difluoromethylene (CF2) group into an aliphatic chain at the desired position remains challenging. Here, we report an unprecedented example of alkylzirconocene promoted difluoroalkylation of alkyl- and silyl-alkenes with a variety of unactivated difluoroalkyl iodides and bromides under the irradiation of visible light without a catalyst. The resulting difluoroalkylated compounds can serve as versatile synthons in organic synthesis. The reaction can also be applied to activated difluoroalkyl, trifluoromethyl, perfluoroalkyl, monofluoroalkyl, and nonfluorinated alkyl halides, providing a general method to controllably access fluorinated compounds. Preliminary mechanistic studies reveal that a single electron transfer (SET) pathway induced by a Zr(iii) species is involved in the reaction, in which the Zr(iii) species is generated by the photolysis of alkylzirconocene with blue light.
Rf, atmospheric-pressure glow discharge (APGD) plasmas with bare metal electrodes have promising prospects in the fields of plasma-aided etching, thin film deposition, disinfection and sterilization, etc. In this paper, the discharge characteristics are presented for the rf APGD plasmas generated with pure argon or argon-ethanol mixture as the plasma-forming gas and using water-cooled, bare copper electrodes. The experimental results show that the breakdown voltage can be reduced significantly when a small amount of ethanol is added into argon, probably due to the fact that the Penning ionization process is involved, and a pure α-mode discharge can be produced more easily with the help of ethanol. The uniformity of the rf APGDs of pure argon or argon-ethanol mixtures using bare metallic electrodes is identified with the aid of the intensified charge coupled device images.
Aim/Background: Cervical cancer is a common gynecologic malignant tumor, its occurrence and development are related to genetic and environmental factors. Recent studies have shown that Programmed Cell Death 4 (PDCD4) and Transcription Factor EB (TFEB) plays crucial roles in the pathogenesis of cervical cancer. The interaction between PDCD4 and TFEB and their regulatory mechanism on cellular functions in cervical cancer have not been fully explored. Materials and Methods: Therefore, this study utilized the Hela cell line as a cervical cancer model to investigate the changes in TFEB expression levels and the proliferation, migration, invasion and EMT processes of cervical cancer cells through the silencing of PDCD4. Real-time quantitative PCR and Western blot were employed to assess the expression levels of PDCD4 and TFEB, while CCK-8, scratch assay, Transwell invasion assay and Western blot were used to evaluate changes in cell proliferation, migration, invasion capabilities and EMT processes. Results: The experimental results demonstrated that silencing PDCD4 significantly increased the expression level of TFEB. Simultaneously, silencing PDCD4 also significantly accelerated the proliferation rate of Hela cells, enhanced the cells' migration, invasion capabilities and promoted the EMT processes. Further experimental results showed that silencing TFEB could partially reverse the promoting effects of PDCD4 silencing on cell proliferation, migration and invasion. In cervical cancer, silencing PDCD4 can lead to TFEB overexpression, thereby promoting the proliferation, migration and invasion of Hela cells. Conclusion: These findings provide crucial clues for the in-depth study of molecular mechanisms in cervical cancer and indicate that the PDCD4-TFEB pathway could potentially serve as a target for the treatment and prevention of this disease.
A nickel-catalyzed carbonylative difluoroalkylation reaction with arylboronic acids under 1 atm of CO has been developed. The reaction proceeds under mild reaction conditions with high efficiency and high functional group tolerance. Preliminary mechanistic studies reveal that the arylacyl nickel complex is the key intermediate to circumvent the formation of labile fluoroacyl nickel, and bimetallic oxidative addition is likely the key step to facilitate the catalytic cycle.
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