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排序方式: 共有1000条查询结果,搜索用时 125 毫秒
1.
Katja F. Hellendahl Felix Kaspar Dr. Xinrui Zhou Zhaoyi Yang Prof. Dr. Zhen Huang Prof. Dr. Peter Neubauer Dr. Anke Kurreck 《Chembiochem : a European journal of chemical biology》2021,22(11):2002-2009
Selenium-modified nucleosides are powerful tools to study the structure and function of nucleic acids and their protein interactions. The widespread application of 2-selenopyrimidine nucleosides is currently limited by low yields in established synthetic routes. Herein, we describe the optimization of the synthesis of 2-Se-uridine and 2-Se-thymidine derivatives by thermostable nucleoside phosphorylases in transglycosylation reactions using natural uridine or thymidine as sugar donors. Reactions were performed at 60 or 80 °C and at pH 9 under hypoxic conditions to improve the solubility and stability of the 2-Se-nucleobases in aqueous media. To optimize the conversion, the reaction equilibria in analytical transglycosylation reactions were studied. The equilibrium constants of phosphorolysis of the 2-Se-pyrimidines were between 5 and 10, and therefore differ by an order of magnitude from the equilibrium constants of any other known case. Hence, the thermodynamic properties of the target nucleosides are inherently unfavorable, and this complicates their synthesis significantly. A tenfold excess of sugar donor was needed to achieve 40−48 % conversion to the target nucleoside. Scale-up of the optimized conditions provided four Se-containing nucleosides in 6–40 % isolated yield, which compares favorably to established chemical routes. 相似文献
2.
《International Journal of Hydrogen Energy》2022,47(51):21753-21759
Surface reconstruction produces metal oxyhydroxide (1OOH) active sites, and promoting surface reconstruction is essential for the design of OER electrocatalysts. In this paper, we reported that a large amount of active NiFeOOH was generated in-situ on the surface of nickel-iron sulfide selenide, thus exposing more active sites and efficiently catalyzing OER. In 1 M KOH solution, NiFeOOH(S,Se) achieves an ultra-low overpotential of 195 mV at the current density of 10 mA cm?2, and the Tafel slope is only 31.99 mV dec?1, showing excellent catalytic performance. When the current density is 100 mA cm?2, the over-potential of NiFeOOH(S,Se) in KOH + seawater solution is 239 mV, which is almost equivalent to 231 mV in KOH solution. The excellent OER stability of the NiFeOOH(S,Se) catalyst in alkaline electrolytes was confirmed, and the overpotential did not change significantly after 4 days of testing in KOH + seawater solution. 相似文献
3.
Hefei Zhao Xiaoqing Xie Paul Read Benjamin Loseke Stephen Gamet Wenkuan Li Changmou Xu 《International Journal of Food Science & Technology》2021,56(2):825-837
Enriching the micronutrients, selenium (Se) and lithium (Li), in grapes to improve their nutraceutical properties were implemented by foliar application of organic fertiliser rich in Se and Li onto five grape cultivars. The effects of this biofortification on vine vigour, fruit quality, overall micronutrients and phenolic compounds also were investigated. Agronomic biofortification was found greatly increased the Se and Li content in the whole grape by multiple times, meanwhile it did not significantly affect the vine vigour and fruit quality of grapes. However, the biofortification did impact the Ionome (including all the mineral nutrients and trace elements) and phenolic compounds in grapes and this varied among cultivars. This study demonstrated foliar spray of organic Se/Li fertiliser was a very effective strategy to biofortify these micronutrients in grape berries, particularly in the skin, and therefore might be a promising strategy to increase the consumption and awareness of these grapes. 相似文献
4.
Ana Carolina Ruberte Gustavo Gonzlez-Gaitano Arun K. Sharma Carlos Aydillo Ignacio Encío Carmen Sanmartín Daniel Plano 《International journal of molecular sciences》2020,21(23)
Aspirin (ASA) has attracted wide interest of numerous scientists worldwide thanks to its chemopreventive and chemotherapeutic effects, particularly in colorectal cancer (CRC). Incorporation of selenium (Se) atom into ASA has greatly increased their anti-tumoral efficacy in CRC compared with the organic counterparts without the Se functionality, such as the promising antitumoral methylseleno-ASA analog (1a). Nevertheless, the efficacy of compound 1a in cancer cells is compromised due to its poor solubility and volatile nature. Thus, 1a has been formulated with native α-, β- and γ-cyclodextrin (CD), a modified β-CD (hydroxypropyl β-CD, HP-β-CD) and Pluronic F127, all of them non-toxic, biodegradable and FDA approved. Water solubility of 1a is enhanced with β- and HP- β-CDs and Pluronic F127. Compound 1a forms inclusion complexes with the CDs and was incorporated in the hydrophobic core of the F127 micelles. Herein, we evaluated the cytotoxic potential of 1a, alone or formulated with β- and HP- β-CDs or Pluronic F127, against CRC cells. Remarkably, 1a formulations demonstrated more sustained antitumoral activity toward CRC cells. Hence, β-CD, HP-β-CD and Pluronic F127 might be excellent vehicles to improve pharmacological properties of organoselenium compounds with solubility issues and volatile nature. 相似文献
5.
6.
探讨了原子荧光仪测试岩石矿物中硒元素试验研究。运用原子荧光仪测试岩石矿物中硒元素,结果显示:原子荧光仪测试岩石矿物中方法硒元素的回收率、相对标准偏差、方法检出限分别为98.2%-103.0%、0.95%-5.80%、3.5×10^-11g/m L。原子荧光仪方法测试岩石矿物中硒元素具有较为快捷的速度、较高的灵敏度,且简便易行等,值得推广。 相似文献
7.
铁硒共沉淀法去除原水中的硒 总被引:3,自引:0,他引:3
受微量硒污染的原水处理目前尚无现成的处理工艺或方法套用,为此考察了铁硒共沉淀法的除硒效果。结果表明,当原水硒浓度为50μg/L、FeCl3投量为5~80mg/L时,对硒的去除率为83.84%~98.39%,出水硒浓度为0.81~8.08μg/L,完全满足生活饮用水水质标准中对硒含量的规定。研究中还发现,FeCl3的除硒效果比FeSO4好。 相似文献
8.
使用气固瞬时反应装置在700~1100℃下对不同氧化物(氧化镁、氧化铁、氧化铝、氧化钙)的硒捕集性能进行研究,确定吸附产物性质。基于此选取相应的典型矿物及双组分抗烧结吸附剂改善硒高温吸附能力。结果表明:900℃前氧化钙捕集效果最好,但1100℃时其吸附量迅速降低到167.59μg/g;γ-氧化铝在高温下捕集效果较好,1100℃时吸附量可达415.04μg/g,这与其优异的孔隙结构有关。钙基矿物方解石因其具有一定的抗烧结能力和发达的孔隙结构,表现出更好的高温捕集能力,1100℃时吸附量可提高到1064.97μg/g。双组分吸附剂高温捕集能力展现出不同程度的提高。钙-铝基吸附剂高温捕集性能提高相对较小;而钙-硅基吸附剂在高温下效果远高于单组分吸附剂,与氧化钙相比,1100℃时可提高1787.21μg/g。 相似文献
9.
Chaoqun Xia Shi Liu Baining Cui Mingjun Li Hongshui Wang Chunyong Liang Phong A. Tran Yan Wang Huan Zhou Lei Yang 《International Journal of Applied Ceramic Technology》2022,19(5):2437-2449
Development of reliable ultraviolet (UV) blockers is crucial for UV radiation protection applications such as sunscreen and UV-resistant fabric. To date, zinc oxide (ZnO) has been extensively used as a physical UV blocker worldwide but has also been criticized for with its unfavored UV-induced reactive oxygen species (ROS) generation phenomena. As an attempt to suppress the photocatalytic activity of ZnO without compromising its UV absorbance property, amorphous selenium (Se) nanoparticles (NPs) were incorporated to ZnO using a facile and cost-effective coprecipitation method. Additionally, this process also enables an economical synthesis route for harvesting amorphous Se NPs from an aqueous medium. The ZnO–Se composites were thoroughly characterized to confirm its enhanced UV absorptivity combined with high transparency in the visible light range and to understand the interaction between ZnO and Se. Besides, Se-induced photocatalytic activity suppression of ZnO was demonstrated using methylene orange as an indicator. In vitro study revealed that ZnO–Se composite had improved biocompatibility over ZnO but comparable bacteriostasis ability under full-spectrum light irradiation. These results suggest that ZnO–Se composite is a promising UV blocker with advantages of facile synthesis, UV-induced ROS generation diminishment and biocompatibility. 相似文献
10.
Dr. Andrea Angeli Prof. Marta Ferraroni Prof. Antonella Capperucci Dr. Damiano Tanini Prof. Gabriele Costantino Prof. Claudiu T. Supuran 《ChemMedChem》2022,17(11):e202200085
A study on the activity of selenocarbamates as a novel chemotype acting as carbonic anhydrase (CA, EC 4.2.1.1) inhibitors is reported. Undergoing CA-mediated hydrolysis, selenocarbamates release selenolates behaving as zinc binding groups and effectively inhibiting CAs. A series of selenocarbamates characterised by high molecular diversity and complexity have been studied against different human CA isoforms such as hCA I, II, IX and XII. Selenocarbamates behave as masked selenols with potential biological applications as prodrugs for CAs inhibition-based strategies. X-ray studies provided insights into the binding mode of this novel class of CA inhibitors. 相似文献