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1.
Hua Yang Shi-Xiao Wei Han Chen Lang Chen Chak-Tong Au Ting-Liang Xie Shuang-Feng Yin 《American Institute of Chemical Engineers》2022,68(10):e17810
A high-throughput (105.5 g/h) passive four-stage asymmetric oscillating feedback microreactor using chaotic mixing mechanism was developed to prepare aggregated Barium sulfate (BaSO4) particles of high primary nanoparticle size uniformity. Three-dimensional unsteady simulations showed that chaotic mixing could be induced by three unique secondary flows (i.e., vortex, recirculation, and oscillation), and the fluid oscillation mechanism was examined in detail. Simulations and Villermaux–Dushman experiments indicate that almost complete mixing down to molecular level can be achieved and the prepared BaSO4 nanoparticles were with narrow primary particle size distribution (PSD) having geometric standard deviation, σg, less than 1.43 when the total volumetric flow rate Qtotal was larger than 10 ml/min. By selecting Qtotal and reactant concentrations, average primary particle size can be controlled from 23 to 109 nm as determined by microscopy. An average size of 26 nm with narrow primary PSD (σg = 1.22) could be achieved at Qtotal of 160 ml/min. 相似文献
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采用超高效液相色谱⁃四极杆⁃飞行时间高分辨质谱(UPLC⁃Q⁃TOF)对4类不同类型的含聚对苯二甲酸乙二醇酯(PET)材质的食品接触材料在4 %乙酸和50 %乙醇模拟物中的迁移出的非挥发性未知物进行筛查解析。结果表明,产品在4 %乙酸模拟物的迁移风险远小于50 %乙醇模拟物,主要迁移物质为聚合单体形成的寡聚物,抗氧剂、润滑剂、胶黏剂等加工助剂以及生产加工、迁移过程中形成的非有意添加物(NIAS)物质;纯PET材质的产品迁移物质较少,多层复合材料迁移物质较多。复合材质的产品中,PET材质可能在生产时添加了己二酸、癸二酸、新戊二醇等物质,进行了改性处理;此外,部分迁移物质会与模拟物中的乙醇发生反应,生成新的NIAS物质。 相似文献
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为了分析天问一号火星高分相机不同状态对性能的影响,最大限度提高使用效率,对高分相机的多状态、状态变化过程和仿真方法开展研究。首先,分析相机的组成和不同功能单元退化产生的影响。然后,分析相机在轨工作的多状态变化规律,建立转化过程模型。最后,提出基于多状态的仿真建模方法。案例仿真分析结果表明:考虑调整后实际有效数据获取概率提高评估准确性,通过敏感度分析也可有效提出调焦单元可靠性要求。多状态分析方法可有效评估火星相机或其他航天光学载荷可靠性水平,有效指导可靠性要求的制定和工程设计。 相似文献
9.
Quan-Qi Yu Juan-Juan Gao Xue-Xian Lang Hong-Yao Li Prof. Ming-Qi Wang 《Chembiochem : a European journal of chemical biology》2021,22(6):1042-1048
The development of small molecules that can selectively target G-quadruplex (G4) DNAs has drawn considerable attention due to their unique physiological and pathological functions. However, only a few molecules have been found to selectively bind a particular G4 DNA structure. We have developed a fluorescence ligand Q1 , a molecular scaffold with a carbazole–pyridine core bridged by a phenylboronic acid side chain, that acts as a selective ascaris telomere antiparallel G4 DNA ASC20 ligand with about 18 nm blue-shifted and enhanced fluorescence intensity. Photophysical properties revealed that Q1 was sensitive to the microenvironment and gave the best selectivity to ASC20 with an equilibrium binding constant Ka=6.04×105 M−1. Time-resolved fluorescence studies also demonstrated that Q1 showed a longer fluorescence lifetime in the presence of ASC20. The binding characteristics of Q1 with ASC20 were shown in detail in a fluorescent intercalator displacement (FID) assay, a 2-Ap titration experiment and by molecular docking. Ligand Q1 could adopt an appropriate pose at terminal G-quartets of ASC20 through multiple interactions including π–π stacking between aromatic rings; this led to strong fluorescence enhancement. In addition, a co-staining image showed that Q1 is mainly distributed in the cytoplasm. Accordingly, this work provides insights for the development of ligands that selectively targeting a specific G4 DNA structure. 相似文献
10.
Rui-Qi Yao Yi-Tong Zhou Hang Shi Wu-Bin Wan Qing-Hua Zhang Lin Gu Yong-Fu Zhu Zi Wen Xing-You Lang Qing Jiang 《Advanced functional materials》2021,31(10):2009613
Electrocatalytic hydrogen evolution in alkaline and neutral media offers the possibility of adopting platinum-free electrocatalysts for large-scale electrochemical production of pure hydrogen fuel, but most state-of-the-art electrocatalytic materials based on nonprecious transition metals operate at high overpotentials. Here, a monolithic nanoporous multielemental CuAlNiMoFe electrode with electroactive high-entropy CuNiMoFe surface is reported to hold great promise as cost-effective electrocatalyst for hydrogen evolution reaction (HER) in alkaline and neutral media. By virtue of a surface high-entropy alloy composed of dissimilar Cu, Ni, Mo, and Fe metals offering bifunctional electrocatalytic sites with enhanced kinetics for water dissociation and adsorption/desorption of reactive hydrogen intermediates, and hierarchical nanoporous Cu scaffold facilitating electron transfer/mass transport, the nanoporous CuAlNiMoFe electrode exhibits superior nonacidic HER electrocatalysis. It only takes overpotentials as low as ≈240 and ≈183 mV to reach current densities of ≈1840 and ≈100 mA cm−2 in 1 m KOH and pH 7 buffer electrolytes, respectively; ≈46- and ≈14-fold higher than those of ternary CuAlNi electrode with bimetallic Cu–Ni surface alloy. The outstanding electrocatalytic properties make nonprecious multielemental alloys attractive candidates as high-performance nonacidic HER electrocatalytic electrodes in water electrolysis. 相似文献