PM2.5 source apportionment identified with total and soluble elements in positive matrix factorization.

Source apportionments of urban aerosols identified with positive matrix factorization (PMF) are sensitive to input variables. So far, total elements were frequently included as effective factors in PMF-based source apportionment. We investigated the advances to involve soluble parts of elements in the source apportionment with four data sets of PM2.5 composition observed at a coastal city (Qingdao) in northern China: water-soluble ions plus organic and elemental carbon (IC set), the IC set plus total elements (ICTE set), the IC set plus soluble elements (ICSE set), and the IC set plus both total elements and soluble elements (ICAE set). The apportionments of six sources, including secondary sulfate, secondary nitrate, secondary oxalate, sea salt, biomass burning and dust, were identified with the IC set. In comparison, pollutants from vehicle + coal combustion, ship emissions, waste incineration and industrial activities were also identified with the ICTE, ICSE, or ICAE sets. We found that the PMF solutions of the ICAE set could distinguish aged and fresh dust, and identify fly ash and aged pollutants from industrial sources. The profiles and corresponding time series of vehicle + coal combustion, secondary aerosols, ship emissions, sea salt, and biomass burning emissions identified with the four data sets were very similar, while discrepancies were encountered for waste incineration, dust, and industrial sources. These results indicate the benefits and potentials with total and soluble elements involved in PMF-based source apportionments.

Investigation of a haze-to-dust and dust swing process at a coastal city in northern China part I: Chemical composition and contributions of anthropogenic and natural sources.

The long retention of dust air masses in polluted areas, especially in winter, may efficiently change the physicochemical properties of aerosols, causing additional health and ecological effects. A large-scale haze-to-dust weather event occurred in the North China Plain (NCP) region during the autumn-to-winter transition period in 2018, affecting the coastal city Qingdao several times between Nov. 27th and Dec. 1st. To study the evolution of the pollution process, we analyzed the chemical characteristics of PM2.5 and PM10-2.5 and source apportionments of PM2.5 and PM10, The dust stagnated around NCP and moved out and back to the site, noted as dust swing process, promoting SO42- formation in PM2.5 and NO3- formation in PM10-2.5. Source apportionments were analyzed using the Positive Matrix Factorization (PMF) receptor model and weighted potential source contribution function (WPSCF). Before the dust invasion, Qingdao was influenced by severe haze; waste incineration and coal burning were the major contributors (~80 %) to PM2.5, and the source region was in the southwest of Shandong Province. During the initial dust event, mineral dust and the mixed factor of dust and sea salt were the major contributors (46.0 % of PM2.5 and 86.5 % of PM10). During the polluted dust period, the contributions of regional transported biomass burning (22.3 %), vehicle emissions (20.8 %), and secondary aerosols (33.8 %) to PM2.5 from the Beijing-Tianjin-Hebei region significantly increased. The secondary aerosols source was more regional than that of vehicle emissions and biomass burning and contributed considerably to PM10 (30.8 %) during the dust swing process. Our findings demonstrate that environmental managers should consider the possible adverse effects of winter dust on regional and local pollution.

Study on the Influence of Calcined Underground Ant Nest Powder on the Durability of Concrete.

Ants have strict requirements on the building materials of the nest, such as the size, weight, luster and color of soil particles. The soil of underground ant nests is composed of clay particles cemented together to form a hard brick-like material. The ant nest powder shows pozzolanic activity after calcination, which can meet the requirements for active admixture of concrete. Under the standard curing condition, the influence of calcined ant nest clay powder (CANCP) on the durability of concrete is evaluated by chloride penetration resistance, carbonization resistance and freeze-thaw resistance, and the influence of the powder content is investigated. The results show that when the content of CANCP is less than 10%, the chloride penetration resistance of concrete increases with content of CANCP. In the early stage of carbonation, the greater the content of CANCP, the higher the carbonization rate of concrete. In the middle and later stage of carbonation, the carbonation rate of CANCP concrete is significantly lower than that in the early stage, and the carbonation depth is linearly related to the carbonation time. When the content of CANCP is less than 20%, the freeze-thaw resistance of CANCP concrete is better than that of the reference concrete.

Basic Properties of Calcined Underground Ant Nest Materials and Its Influence on the Compressive Strength of Concrete.

Underground ant nests are typically made of soil and rubble mixed with dead plant bodies, ant secretions, and other organic substances. The clay content is high, and the natural clay materials show pozzolanic activity after calcination. In this study, the underground ant nest materials of Iridomyrmex anceps, which is a common ant in the Shanghai area, are calcined and ground, and the material properties of calcined ant nest clay powder (CANCP) are characterized from six aspects: chemical composition, particle morphology, specific gravity, specific surface area, particle size distribution and pozzolanic activity index. The pozzolanic activity of CANCP is evaluated by the strength contribution rate of pozzolanic activity, revealing that CANCP is beneficial to the strength of the mortar system from an early age. The influence of CANCP on the compressive strength of concrete is analyzed using three aspects, namely, content, curing age and calcination temperature, and it is found that the three aspects of CANCP have a strong influence on the compressive strength of concrete.

Exploring the binding interaction between copper ions and Candida rugosa lipase.

The wide range of applications of copper have caused widespread concern about its toxicity. However, few studies have reported the mechanism of the binding interaction between copper ions and digestive enzymes, which play an important role in physiological health and industrial production. In this study, the effects of copper ions on the conformation and activity of Candida rugosa lipase (CRL) were evaluated by isothermal titration calorimetry (ITC), multiple spectral techniques, molecular simulation and enzyme activity assays. The results showed that copper ions can be combined with lipase, the binding affinity constant (K) was (2.91 ± 0.619) × 10-3 M-1, the binding process was a spontaneous process, and the main force was the hydrophobic force. Rather than increasing the hydrophobicity of the amino acid microenvironment of CRL, the spectral methods demonstrated that copper can also make the protein peptide bond structure compact, changing its secondary structure. In addition, molecular simulation results showed that copper ions opened the "lid" of the CRL and entered the active center, which consequently changed the conformation of the CRL molecule. Structural changes may cause changes in enzyme activity. The increased activity of CRL with the addition of copper ions was verified by enzyme activity assay. In summary, copper showed an effect on CRL at the molecular level, which means its toxicity should receive more attention.

[Absorption enhancing effects and safety of PAMAM dendrimers on liquiritin].

PAMAM dendrimer is one of the most widely studied dendrimers in recent years, which has a large number of functional groups on the surface and cavities inside, specific three-dimensional structure and good biocompatibility, permeability and stability. It has been widely applied in drug and gene carrier fields and may become a new absorption enhancer. In order to study the absorption enhancing effects of PAMAM dendrimers, liquiritin was selected as the model drug, with the protection of spleen and liver, detoxification and other functions, but it had not been widely used in clinical application because of its difficult absorption, first pass effect, and low bioavailability. This topic was based on the two main determinants (solubility and permeability) of intestinal absorption in the body, researched the physicochemical properties of liquiritin, analyzed the transport volume of liquiritin with or without PAMAM dendrimers by using Caco-2 cell model, and analyzed the cytotoxicity of PAMAM dendrimers on Caco-2 cells by MTT experiments. These results showed that 0.1% of the G4 generation PAG can promote the absorption of liquiritin safely and effectively, and it was suitable for further development into a new type of pharmaceutical excipients.

[Biopharmaceutics classification and absorption mechanisms primary study on four kinds of flavonoids].

The solubility and permeability on four kinds of flavonoids (kaempferol, hesperidin, apigenin, genistein) were test according to the theory of biopharmaceutics classification system (BCS), and their absorption mechanism. The solubility was investigated by the method in determination of solubility of "Chinese Pharmacopoeia 2010". To detect appearance permeability of compounds mentioned above, the appropriate concentrations were selected by the MTT method in cell transfer experiments in Caco-2 cell model, which established by in vitro cell culture method. Therefore, these compounds were classified with BCS according to solubility and permeability. In addition, to explore absorption mechanisms, the experiments in three different concentrations of compounds in high, medium and low in bidirectional transformation methods in Caco-2 cell model contacted. The study indicated that all of kaempferol, hesperidin, apigenin, genistein have the characteristics in low solubility and high permeability, which belong to BCSⅡ, and the absorption mechanism of kaempferol was active transportation. Whereas, hesperidin, apigenin, genistein were passive transportation. In this study, it carried out initial explorations on establishment of determination for solubility and permeability in flavonoids, and provided theoretical reference for further research on BCS in traditional Chinese medicine.

[Variation of atmospheric particle number concentrations in Qingdao and its impact on visibility].

Atmospheric particle number concentrations were measured from September 2010 to August 2011 with potable light house laser particle counter to study the variation of atmospheric particle concentrations and its impact on visibility in Qingdao. Backward trajectory was calculated by Hysplit model. Statistical analysis was done to discuss the influence of meteorological factors on the atmospheric particle number concentrations and visibility. It was shown that the atmospheric particle number concentrations were the highest in winter and spring, followed by autumn, and the lowest in summer. Air mass from Xinjiang and Gansu regions resulted in higher particle concentrations, while the atmospheric particles from the northeast and the ocean had lower concentrations. The variation of atmospheric particle number concentrations presented a good negative correlation with the variation of wind speed, relative humidity and mixed-layer height. When the air mass came from west or northwest, the surface wind direction was south or southeast and the mixed-layer height was low, the number concentration of fine particles was likely to be higher, which tended to cause low visibility phenomenon.

Seasonal variation, source, and regional representativeness of the background aerosol from two remote sites in western China.

Using observations from two remote sites during July 2004 to March 2005, we show that at Akdala (AKD, 47 degrees 06' N, 87 degrees 58' E, 562 m asl) in northern Xinjiang Province, there were high wintertime loadings of organic carbon (OC), elemental carbon (EC), and water-soluble (WS) SO4(2-), NO3(2-), and NH4+, which is similar to the general pattern in most areas of China and East Asia. However, at Zhuzhang (ZUZ, 28 degrees 00' N, 99 degrees 43' E, 3,583 m asl) in northwestern Yunnan Province, the aerosol concentrations and compositions showed little seasonal variation except for a decreasing trend of OC from August to autumn-winter. Additionally, the OC variations dominated the seasonal variation of PM10 (particles

Comparison of volatile profiles of nine litchi (Litchi chinensis Sonn.) cultivars from Southern China.

Volatile components of nine litchi cultivars (10 samples) with high commercial value from Southern China were investigated by means of gas chromatography-mass spectrometry combined with headspace solid phase microextraction. A total of 96 volatiles were detected, of which 43 were identified. Seventeen common volatiles in all the samples included linalool, cis-rose oxide, alpha-terpineol, beta-citronellol, geraniol, p-cymene, ethanol, 3-methyl-3-buten-1-ol, 3-methyl-2-buten-1-ol, 1-hexanol, (E)-2-hexen-1-ol, 2-ethyl-1-hexanol, 1-octen-3-ol, 1-octanol, ethyl acetate, p,alpha-dimethylstyrene and 3-tert-butyl-4-hydroxyanisole. Although the volatile composition and concentration varied between these cultivars, the components with the highest OAVs in most cultivars were still cis-rose oxide, trans-rose oxide, 1-octen-3-ol, and geraniol. Two Huaizhi samples from two producing areas exhibited similar volatile profiles, and significantly different from other cultivars according to cluster analysis performed on amounts of major volatile components.

Aerosol background at two remote CAWNET sites in western China.

The frequency distributions and some statistical features of background aerosol concentrations were investigated at two remote China Atmosphere Watch Network (CAWNET) stations. The estimated elemental carbon (EC) background at Akdala (AKD) in the mid-latitudes of northwestern China (approximately 0.15 microg m(-3)) was only half of that at Zhuzhang (ZUZ) in low-latitude southwestern China (approximately 0.30 microg m(-3)). The contributions of EC to the aerosol mass also differed between sites: EC contributed 3.5% of the PM(10) mass at AKD versus 5.1% at ZUZ. Large percentages of the total organic carbon (OC) apparently were secondary organic carbon (SOC); SOC/OC averaged 81% at ZUZ and 68% at AKD. The OC/EC ratios in PM(10) (ZUZ: 11.9, AKD: 12.2) were comparable with other global background sites, and the OC/EC ratios were used to distinguish polluted periods from background conditions. The SO(4)(2)(-), NH(4)(+) and soil dust loadings at AKD were higher and more variable than at ZUZ, probably due to impacts of pollution from Russia and soil dust from the Gobi and adjacent deserts. In contrast to ZUZ, where the influences from pollution were weaker, the real-time PM(10) mass concentrations at AKD were strongly skew right and the arithmetic mean concentrations of the aerosol populations were higher than their medians. Differences in the aerosol backgrounds between the sites need to be considered when evaluating the aerosol's regional climate effects.