Impact of size distributions of major chemical components in fine particles on light extinction in urban Guangzhou

Background: Gentianella acuta (Michx.) Hulten is an important type of medicinal plant found in several Chinese provinces. It has been widely used in folk medicine to treat various illnesses. However, there is not enough detailed information about the chemical constituents of this plant or methods for their content determination. Objective: The focus of this work is the isolation and characterization of the major chemical constituents of Gentianella acuta, and developing an analytical method for their determination. Methods: The components of Gentianella acuta were isolated using (1) ethanol extraction and adsorption on macroporous resin. (2) and ethyl acetate extraction and high speed countercurrent chromatography. A HPLC-DAD method was developed using a C18 column and water-acetonitrile as the mobile phase. Based on compound polarities, both isocratic and gradient elution methods were developed. Results: A total of 29 compounds were isolated from this plant, of which 17 compounds were isolated from this genus for the first time. The main components in this plant were found to be xanthones. The HPLC-DAD method was developed and validated for their determination, and found to show good sensitivity and reliability. Conclusion: The results of this work add to the limited body of work available on this important medicinal plant. The findings will be useful for further investigation and development of Gentianella acuta for its valuable medicinal properties.

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Size-resolved characterization of organic aerosol in the North China Plain: new insights from high resolution spectral analysis

Environmental Science: Atmospheres ◽

10.1039/d1ea00025j ◽

2021 ◽

Author(s):

Weiqi Xu ◽

Chun Chen ◽

Yanmei Qiu ◽

Conghui Xie ◽

Yunle Chen ◽

...

Keyword(s):

Radiative Forcing ◽

North China Plain ◽

North China ◽

Fine Particles ◽

Large Fraction ◽

Organic Aerosol ◽

Size Distributions ◽

The North ◽

The Impact

Organic aerosol (OA), a large fraction of fine particles, has a large impact on climate radiative forcing and human health, and the impact depends strongly on size distributions. Here we...

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Flow Characteristics and Grain Size Distribution of Granular Gangue Mineral by Compaction Treatment

Advances in Materials Science and Engineering ◽

10.1155/2017/2509286 ◽

2017 ◽

Vol 2017 ◽

pp. 1-7 ◽

Cited By ~ 1

Author(s):

Ran Yuan ◽

Dan Ma ◽

Hongwei Zhang

Keyword(s):

Weight Loss ◽

Grain Size ◽

Size Distribution ◽

Grain Size Distribution ◽

Water Flow ◽

Fine Particles ◽

Flow Characteristics ◽

Test System ◽

Chemical Components ◽

Gangue Mineral

A test system for water flow in granular gangue mineral was designed to study the flow characteristics by compaction treatment. With the increase of the compaction displacement, the porosity decreases and void in granular gangue becomes less. The main reason causing initial porosity decrease is that the void of larger size is filled with small particles. Permeability tends to decrease and non-Darcy flow factor increases under the compaction treatment. The change trend of flow characteristics shows twists and turns, which indicate that flow characteristics of granular gangue mineral are related to compaction level, grain size distribution, crushing, and fracture structure. During compaction, larger particles are crushed, which in turn causes the weight of smaller particles to increase, and water flow induces fine particles to migrate (weight loss); meanwhile, a sample with more weight of size (0–2.5 mm) has a higher amount of weight loss. Water seepage will cause the decrease of some chemical components, where SiO2 decreased the highest in these components; the components decreased are more likely locked at fragments rather than the defect of the minerals. The variation of the chemical components has an opposite trend when compared with permeability.

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Seasonal characteristics, formation mechanisms and source origins of PM<sub>2.5</sub> in two megacities in Sichuan Basin, China

10.5194/acp-2017-258 ◽

2017 ◽

Author(s):

Huanbo Wang ◽

Mi Tian ◽

Yang Chen ◽

Guangming Shi ◽

Yuan Liu ◽

...

Keyword(s):

Sichuan Basin ◽

Urban Site ◽

Chemical Components ◽

Formation Mechanisms ◽

Major Mechanism ◽

Inorganic Aerosols ◽

Seasonal Characteristics ◽

Geographical Regions ◽

Secondary Aerosols ◽

Major Chemical

Abstract. To investigate the characteristics of PM2.5 and its major chemical components, formation mechanisms, and geographical origins in the two biggest cities, Chengdu (CD) and Chongqing (CQ) in Sichuan Basin, the most densely populated basin in China, daily PM2.5 samples were collected simultaneously at one urban site in each city from October 2014 to July 2015. Annual mean concentrations of PM2.5 were 67.0 ± 43.4 and 70.9 ± 41.4 μg m−3 at CD and CQ, respectively. Secondary inorganic aerosols (SNA) and organic matter (OM) accounted for 41.1 % and 26.1 %, respectively, of PM2.5 mass at CD, and 37.4 % and 29.6 % at CQ. Seasonal variations of PM2.5 and its major chemical components were significant, usually with the highest values in winter and the lowest in summer. SNA and OM were 1.7–3.4 times higher on polluted days than on clean days at both sites, whereas their percentage contributions to PM2.5 varied differently among the components and between the two sites. Gas-phase oxidation probably played an important role on the formation of secondary aerosols when PM2.5 mass varied in the range of 75–150 μg m−3, while heterogeneous transformation was likely the major mechanism on the heavy polluted days. Geographical regions causing high PM2.5 were identified to mainly distribute within the basin at both sites based on potential source contribution function (PSCF) analysis.

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