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121.
Wenwen Yi Qiao Li Tengfei Song Lei Chen Xing-Cong Li Zhizhen Zhang Xiao-Yuan Lian 《Tetrahedron》2019,75(9):1186-1193
New indole alkaloids streptoprenylindoles A–C (1–3) and diterpenoids 18-acetyl-cyclooctatin (8), 5,18-dedihydroxy-cyclooctatin (9), and 5-dehydroxy-cyclooctatin (10) were isolated from the culture of marine-derived Streptomyces sp. ZZ820, along with known 3-cyanomethyl-6-[3-methyl-2-butenyl]indole (4), N-(2-(1H-indol-3-yl)ethylacetamide (5), 1-acetyl-β-carboline (6), indole-3-methylethanoate (7), cyclooctatin (11), and chromomycin A3 (12). Their structures were elucidated by a combination of extensive spectroscopic analyses, ECD calculation, and the Mosher's method. Streptoprenylindoles A (1) and B (2) are enantiomers that were separated through the preparation of their Mosher esters. Three new diterpenoids (8–10) showed antibacterial activities against methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli with MIC values of 24.11–55.12?μM, while chromomycin A3 (12) showed potent antibacterial activities against MRSA (MIC: 0.59?μM) and E. coli (MIC 0.04?μM). 相似文献
122.
We investigate the impact of memory effect on the evolution of cooperation in the spatial prisoner's dilemma game, in which each player will record his own strategies during the previous M game rounds (here, M is also named as the memory length). At each time step, each individual will update his current strategy according to the Fermi-like probability which will be multiplied by a pre-factor, and this factor will be correlated with the fraction of previous strategy states identical with the individual strategy to be updated. The numerical simulation results demonstrate that the memory length will largely influence the cooperation level at the stationary state, and it is clearly shown that the intermediate value of M will optimally favor the emergence of cooperation and the dynamical evolution, and characteristic patterns also support these conclusions. In addition, we depict the full cooperation phase diagrams and find that the cooperation region will be broadened under the case of moderate M values. The current results also indicate that the limited memory may be enough for us to design the effective promotion mechanism and further understand the emergency of cooperation taking place upon many networked populations. 相似文献
123.
All‐Inorganic Hetero‐Structured Cesium Tin Halide Perovskite Light‐Emitting Diodes With Current Density Over 900 A cm−2 and Its Amplified Spontaneous Emission Behaviors
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采用凝胶-燃烧法合成了LaM2VO6:Eu3+(M=Mg,Ca,Sr,Ba)系列红色纳米荧光粉。通过X射线衍射、扫描电镜及荧光光谱等检测方法,研究了不同碱土金属离子掺杂Eu3+荧光粉基质的晶体结构、形貌及其光致发光性能。结果表明:采用凝胶-燃烧法制备的LaM2VO6:Eu3+(M=Mg,Ca,Sr,Ba)红色荧光粉结晶良好、晶相单一且具有良好的发光性能;其中掺Mg基质LaMg2VO6:Eu3+荧光粉的发光性能最好。当引燃温度为800℃,保温时间1h,Eu3+的掺杂量x=0.11时所得荧光材料发光效果最优。 更多还原 相似文献
127.
基于有限脉冲响应滤波器的数字全息零级像消除 总被引:9,自引:3,他引:6
针对数字全息中零级像的存在影响数字再现像的质量,分析数字全息图的记录、再现原理及频谱特性,提出了一种利用有限脉冲响应滤波器消除全息图数字再现中零级像的方法.该方法只需记录一幅数字全息图,不需要相移器材或其他辅助设备,直接利用数字图像处理对数字全息图在空域进行预处理,消除全息再现时的零级像干扰.对比了数字模拟和实验拍摄到的全息图在应用有限脉冲响应滤波器消除零级像前后的再现结果,表明该方法可消除零级衍射像,改善重建像质量,并且算法简单. 相似文献
128.
Wenwen Zhang Gomez Escalada Margarita Di Wu Wenqin Yuan Sha Yan Suzhen Qi Xiaofeng Xue Kai Wang Liming Wu 《Molecules (Basel, Switzerland)》2022,27(5)
The antibacterial activity of propolis has long been of great interest, and the chemical composition of propolis is directly dependent on its source. We recently obtained a type of propolis from China with a red color. Firstly, the antibacterial properties of this unusual propolis were determined against Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA). Studies on its composition identified and quantified 14 main polyphenols of Chinese red propolis extracts (RPE); quantification was carried out using liquid chromatography triple quadrupole tandem mass spectrometry (LC-QQQ-MS/MS) and RPE was found to be rich in pinobanksin, pinobanksin-3-acetate, and chrysin. In vitro investigations of its antibacterial activity revealed that its activity against S. aureus and MRSA is due to disruption of the cell wall and cell membrane, which then inhibits bacterial growth. Despite its similar antibacterial activities against S. aureus and MRSA, metabolomic analysis further revealed the effects of RPE on bacteria metabolism were different. The untargeted metabolomic results showed that a total of 7 metabolites in 12 metabolic pathways had significant changes (Fold change > 2, p < 0.05 *) after RPE treatment in S. aureus, while 11 metabolites in 9 metabolic pathways had significant changes (Fold change > 2, p < 0.05 *) after RPE treated on MRSA. Furthermore, RPE downregulated several specific genes related to bacterial biofilm formation, autolysis, cell wall synthesis, and bacterial virulence in MRSA. In conclusion, the data obtained indicate that RPE may be a promising therapeutic agent against S. aureus and MRSA. 相似文献
129.
Muhammad Hilal Kabir Mahamed Lamine Guindo Rongqin Chen Fei Liu Xinmeng Luo Wenwen Kong 《Molecules (Basel, Switzerland)》2022,27(18)
Traditional Chinese herbal medicine (TCHM) plays an essential role in the international pharmaceutical industry due to its rich resources and unique curative properties. The flowers, stems, and leaves of Fritillaria contain a wide range of phytochemical compounds, including flavonoids, essential oils, saponins, and alkaloids, which may be useful for medicinal purposes. Fritillaria thunbergii Miq. Bulbs are commonly used in traditional Chinese medicine as expectorants and antitussives. In this paper, a feasibility study is presented that examines the use of hyperspectral imaging integrated with convolutional neural networks (CNN) to distinguish twelve (12) Fritillaria varieties (n = 360). The performance of support vector machines (SVM) and partial least squares-discriminant analysis (PLS-DA) was compared with that of convolutional neural network (CNN). Principal component analysis (PCA) was used to assess the presence of cluster trends in the spectral data. To optimize the performance of the models, cross-validation was used. Among all the discriminant models, CNN was the most accurate with 98.88%, 88.89% in training and test sets, followed by PLS-DA and SVM with 92.59%, 81.94% and 99.65%, 79.17%, respectively. The results obtained in the present study revealed that application of HSI in conjunction with the deep learning technique can be used for classification of Fritillaria thunbergii varieties rapidly and non-destructively. 相似文献
130.
Yihe Song Xinming Li Donglei Shi Tianyue Sun Wenwen Liu Xiaokang Li Sicong Qiao Xin Chen Yuan Guo Jian Li 《Chemical science》2022,13(40):11738
Selective elimination of senescent cells (senolysis) has become a promising therapeutic strategy for the management of chronic renal failure (CRF), but the senolytic molecular pathways towards CRF therapy are limited. Here, we present for the first time a senescence-associated β-galactosidase (SA-β-gal) activatable theragnostic prodrug strategy to pertinently and effectively treat CRF in mice with the aid of fluorescence-guided senolysis. The signs of premature senescence, including the overexpression of β-gal, have been found in kidneys of mice with CRF, making this enzyme particularly suitable as a trigger of prodrugs for CRF therapy. With this unique design, our pioneering prodrug TSPD achieved the activation of a fluorophore for tracking and the specific release of the parent drug, gemcitabine, in β-gal-enriched cells after activation with SA-β-gal. In mice with CRF, abdominal administration of TSPD was effective for improvement of the kidney functions, supporting the feasibility of the SA-β-gal-dependent senolysis therapy towards CRF.Here, we report a senescence-associated β-galactosidase activatable theragnostic prodrug to pertinently treat chronic renal failure (CRF) in mice with the aid of fluorescence-guided senolysis, providing a creative molecular approach to CRF therapy. 相似文献