Morphological and chemical composition characteristics of summertime atmospheric particles collected at Tokchok Island, Korea

Geng, H.,Jung, H.J.,Park, Y.,Hwang, H.,Kim, H.,Kim, Y.J.,Sunwoo, Y.,Ro, C.U. Pergamon Press ; Elsevier [distribution] 2009 Atmospheric environment Vol.43 No.21

Determination of the chemical compositions of atmospheric single particles in the Yellow Sea region is critical for evaluating the environmental impact caused by air pollutants emitted from mainland China and the Korean peninsula. After ambient aerosol particles were collected by the Dekati PM10 cascade impactor on July 17-23, 2007 at Tokchok Island (approximately 50 km west of the Korean coast nearby Seoul), Korea, overall 2000 particles (on stage 2 and 3 with cut-off diameters of 2.5-10 μm and 1.0-2.5 μm, respectively) in 10 samples were determined by using low-Z particle electron probe X-ray microanalysis. X-ray spectral and secondary electron image (SEI) data showed that soil-derived and sea-salt particles which had reacted or were mixed with SO<SUB>2</SUB> and NO<SUB>x</SUB> (or their acidic products) outnumbered the primary and ''genuine'' ones (59.2% vs. 19.2% in the stage 2 fraction and 41.3% vs. 9.9% in the stage 3 fraction). Moreover, particles containing nitrate in the secondary soil-derived species greatly outnumbered those containing sulfate. Organic particles, mainly consisting of marine biogenic species, were more abundant in the stage 2 fraction than in the stage 3 fraction (11.6% vs. 5.1%). Their relative abundance was greater than the sum of carbon-rich, K-containing, Fe-containing, and fly ash particles, which exhibited low frequencies in all the samples. In addition, many droplets rich in C, N, O, and S were observed. They tended to be small, exhibiting a dark round shape on SEI, and generally included 8-20 at.% C, 0-12 at.% N, 60-80 at.% O, and 4-10 at.% S (sometimes with <3 at.% Mg and Na). They were attributed to be a mixture of carbonaceous matter, H<SUB>2</SUB>SO<SUB>4</SUB>, and NH<SUB>4</SUB>HSO<SUB>4</SUB>/(NH<SUB>4</SUB>)<SUB>2</SUB>SO<SUB>4</SUB>, mostly from the reaction of atmospheric SO<SUB>2</SUB> with NH<SUB>3</SUB> under high relative humidity. The analysis of the relationship between the aerosol particle compositions and 72-h backward air-mass trajectories suggests that ambient aerosols at Tokchok Island are strongly affected not only by seawater from the Yellow Sea but also by anthropogenic pollutants emitted from China and the Seoul-Incheon metropolis, resulting in the dominance of complex secondary aerosol particles.

Structural and Maturational Covariance in Early Childhood Brain Development

Geng, X.,Li, G.,Lu, Z.,Gao, W.,Wang, L.,Shen, D.,Zhu, H.,Gilmore, J. H. Oxford University Press 2017 Cerebral Cortex Vol. No.

<P>Brain structural covariance networks (SCNs) composed of regions with correlated variation are altered in neuropsychiatric disease and change with age. Little is known about the development of SCNs in early childhood, a period of rapid cortical growth. We investigated the development of structural and maturational covariance networks, including default, dorsal attention, primary visual and sensorimotor networks in a longitudinal population of 118 children after birth to 2 years old and compared them with intrinsic functional connectivity networks. We found that structural covariance of all networks exhibit strong correlations mostly limited to their seed regions. By Age 2, default and dorsal attention structural networks are much less distributed compared with their functional maps. The maturational covariance maps, however, revealed significant couplings in rates of change between distributed regions, which partially recapitulate their functional networks. The structural and maturational covariance of the primary visual and sensorimotor networks shows similar patterns to the corresponding functional networks. Results indicate that functional networks are in place prior to structural networks, that correlated structural patterns in adultmay arise in part fromcoordinated corticalmaturation, and that regional co-activation in functional networks may guide and refine the maturation of SCNs over childhood development.</P>

Characterisation of individual aerosol particles collected during a haze episode in Incheon, Korea using the quantitative ED-EPMA technique

Geng, H.,Ryu, J. Y.,Maskey, S.,Jung, H.-J.,Ro, C.-U. Copernicus GmbH 2011 Atmospheric chemistry and physics Vol.11 No.3

<P>Abstract. A quantitative energy-dispersive electron probe X-ray microanalysis (ED-EPMA), called low-Z particle EPMA, was used to analyse individual aerosol particles collected in Incheon, Korea on 13-18 October 2008 (a typical haze episode occurred from 15 to 18 October). Overall 3600 individual particles in PM2.5-10 and PM1.0-2.5 fractions from 12 aerosol samples collected on haze and non-haze days were analysed. The analysed particles were classified, based on their X-ray spectral data together with their secondary electron images. The major particle types included organic carbon (OC), elemental carbon (EC), sea-salt, mineral dust (such as aluminosilicate, SiO2, CaCO3/CaMgCO3, etc.), (NH4)2SO4/NH4HSO4-containing, K-containing, Fe-rich and fly ash particles. Their relative number abundance results showed that OC particles were significantly increased while sea-salts and mineral dust particles were significantly decreased (especially in PM1.0-2.5 fraction) when haze occurred. For the other particle types (except Fe-rich particles in PM2.5-10 fraction), there were no significant differences in their relative abundances between haze and non-haze samples. On non-haze days, the nitrate-containing reacted sea-salt and mineral dust particles in PM1.0-2.5 fraction significantly outnumbered the sulfate-containing ones, whereas it was the reverse on haze days, implying that on haze days there were special sources or formation mechanisms for fine aerosol particles (≤2.5 μm in aerodynamic diameter). The emission of air pollutants from motor vehicles and stagnant meteorological conditions, such as low wind speed and high relative humidity, might be responsible for the elevated level of OC particles on haze days. </P>

Elevated nitrogen-containing particles observed in Asian dust aerosol samples collected at the marine boundary layer of the Bohai Sea and the Yellow Sea

Geng, H.,Park, Y.,Hwang, H.,Kang, S.,Ro, C.-U. Copernicus GmbH 2009 Atmospheric Chemistry and Physics Vol.9 No.18

<P>Abstract. Low-Z particle electron probe X-ray microanalysis (low-Z particle EPMA) shows powerful advantages for the characterization of ambient particulate matter in environmental and geological applications. By the application of the low-Z particle EPMA single particle analysis, an overall examination of 1800 coarse and fine particles (aerodynamic diameters: 2.5-10 μm and 1.0-2.5 μm, respectively) in six samples collected on 28 April-1 May 2006 in the marine boundary layer (MBL) of the Bohai Sea and Yellow Sea was conducted. Three samples (D1, D2, and D3) were collected along the Bohai Bay, Bohai Straits, and Yellow Sea near Korea during an Asian dust storm event while the other three samples (N3, N2, and N1) were collected on non-Asian dust (NAD) days. Based on X-ray spectral and secondary electron image data, 15 different types of particles were identified, in which soil-derived particles were encountered with the largest frequency, followed by (C, N, O)-rich droplets (likely the mixture of organic matter and NH4NO3), particles of marine origin, and carbonaceous, Fe-rich, fly ash, and (C, N, O, S)-rich droplet particles. Results show that during the Asian dust storm event relative abundances of the (C, N, O)-rich droplets and the nitrate-containing secondary soil-derived particles were markedly increased (on average by a factor of 4.5 and 2, respectively in PM2.5−10 fraction and by a factor of 1.9 and 1.5, respectively in PM1.0−2.5 fraction) in the MBL of the Bohai Sea and Yellow Sea, implying that Asian dust aerosols in springtime are an important carrier of gaseous inorganic nitrogen species, especially NOx (or HNO3) and NH3. </P>

Characterization of individual insoluble particles in ice core

H. Hwang,M.A. Malek,H.-J. Eom,C.-U. Ro,J.-H. Kang,S.D. Hur,H. Geng,S. Hou 대한지질학회 2015 대한지질학회 학술대회 Vol.2015 No.10

On Phylogenetic Relationships Among Native Goat Populations Along the Middle and Lower Yellow River Valley

Chang, H.,Nozawa, K.,Liu, X.L.,Geng, S.M.,Ren, Z.J.,Qin, G.Q.,Li, X.G.,Sun, J.M.,Zheng, H.L.,Song, J.Z.,Kurosawa, Y.,Sano, A.,Jia, Q.,Chen, G.H. Asian Australasian Association of Animal Productio 2000 Animal Bioscience Vol.13 No.2

This paper is based on the 9 goat colonies along the middle and lower Yellow River valley and 7 local goat colonies in the Northeast, Tibet and the Yangtze valley. After collecting the same data about the 22 goat colonies in China and other countries, it establishes and composes the matrix of fuzzy similarity relation describing the genetic similarities of different colonies. It also clusters 38 colonies according to their phylogenetic relationship. The establishment of the matrix and the cluster are effected in terms of the frequency of 18 loci and 43 allelomorphs in blood enzyme and other protein variations. The study proves that the middle Yellow River valley is one of the taming and disseminating centers of domestic goats in the South and East of Central Asia. Compared with other goat populations in this vast area, the native goat populations in the west of Mongolian Plateau, the Qinghai-Tibet Plateau and the middle Yellow River valley share the same origin. The colonies in the lower Yellow River valley and those in the middle valley, however, are relatively remote in their phylogenetic relationship. The native goat colonies in the southeast of Central Asia can be classified into two genetic groups: "East Asia" and "South Asia" and the colonies in Southeast Asia belong to either group.

Genetic Diversity of 10 Indigenous Pig Breeds in China by Using Microsatellite Markers

Wang, X.,Cao, H.H.,Geng, S.M.,Li, H.B. Asian Australasian Association of Animal Productio 2004 Animal Bioscience Vol.17 No.9

The genetic diversities of 10 Chinese pig populations were analyzed by using microsatellite DNA polymorphisms. The results showed that the mean heterozygosities of the 10 populations were between 0.4561 and 0.6446, the mean polymorphism information contents were 0.4241-0.6184 and the mean effective number of alleles were 2.4295-3.7573. These indicated that the genetic diversity of local Chinese pigs was high. The clustering of the 10 populations was nearly inaccordance with their geographical distributions.

Study on Phylogenetic Relationship Between Wild Japanese Quails in the Weishan Lake Area and Domestic Quails

Chang, G.B.,Chang, H.,Zhen, H.L.,Liu, X.P.,Sun, W.,Geng, R.Q.,Yu, Y.M.,Wang, S.C.,Geng, S.M.,Liu, X.L.,Qin, G.Q.,Shen, W. Asian Australasian Association of Animal Productio 2001 Animal Bioscience Vol.14 No.5

This paper is based on the 36 wild Japanese quails which migrated to and settled in the Weishan Lake area. The gene frequency of 10 loci encoding the enzymes in viscera and muscle was detected. After collecting the same data about 20 quail colonies in China and other countries, it clusters the 21 quail populations by fuzzy cluster analysis. The study indicates that the wild Japanese quail in the Weishan Lake area is closer to domestic quail for phylogenetic system than wild Japanese quails in Japanese Islands. The paper supports the thesis that the quail domestication area should be further studied.

Investigation of aged Asian dust particles by the combined use of quantitative ED-EPMA and ATR-FTIR imaging

Song, Y.-C.,Eom, H.-J.,Jung, H.-J.,Malek, M. A.,Kim, H. K.,Geng, H.,Ro, C.-U. Copernicus GmbH 2013 Atmospheric Chemistry and Physics Vol.13 No.6

<P>Abstract. In our previous works, it was demonstrated that the combined use of quantitative energy-dispersive electron probe X-ray microanalysis (ED-EPMA), which is also known as low-Z particle EPMA, and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) imaging has great potential for a detailed characterization of individual aerosol particles. In this study, extensively chemically modified (aged) individual Asian dust particles collected during an Asian dust storm event on 11 November 2002 in Korea were characterized by the combined use of low-Z particle EPMA and ATR-FTIR imaging. Overall, 109 individual particles were classified into four particle types based on their morphology, elemental concentrations, and molecular species and/or functional groups of individual particles available from the two analytical techniques: Ca-containing (38%), NaNO3-containing (30%), silicate (22%), and miscellaneous particles (10%). Among the 41 Ca-containing particles, 10, 8, and 14 particles contained nitrate, sulfate, and both, respectively, whereas only two particles contained unreacted CaCO3. Airborne amorphous calcium carbonate (ACC) particles were observed in this Asian dust sample for the first time, where their IR peaks for the insufficient symmetric environment of CO32− ions of ACC were clearly differentiated from those of crystalline CaCO3. This paper also reports the first inland field observation of CaCl2 particles probably converted from CaCO3 through the reaction with HCl(g). HCl(g) was likely released from the reaction of sea salt with NOx/HNO3, as all 33 particles of marine origin contained NaNO3 (no genuine sea salt particle was encountered). Some silicate particles with minor amounts of calcium were observed to be mixed with nitrate, sulfate, and water. Among 24 silicate particles, 10 particles are mixed with water, the presence of which could facilitate atmospheric heterogeneous reactions of silicate particles including swelling minerals, such as montmorillonite and vermiculite, and nonswelling ones, such as feldspar and quartz. This paper provides detailed information on the physicochemical characteristics of these aged individual Asia dust particles through the combined use of the two single-particle analytical techniques, and using this analytical methodology it is clearly shown that internal mixing states of the aged particles are highly complicated. </P>

<i>DLEC1</i> is a functional 3p22.3 tumour suppressor silenced by promoter CpG methylation in colon and gastric cancers

Ying, J,Poon, F F,Yu, J,Geng, H,Wong, A H Y,Qiu, G-H,Goh, H K,Rha, S Y,Tian, L,Chan, A T C,Sung, J J Y,Tao, Q Nature Publishing Group 2009 The British journal of cancer Vol.100 No.4

<P>Promoter CpG methylation of tumour suppressor genes (TSGs) is an epigenetic biomarker for TSG identification and molecular diagnosis. We screened genome wide for novel methylated genes through methylation subtraction of a genetic demethylation model of colon cancer (double knockout of <I>DNMT1</I> and <I>DNMT3B</I> in HCT116) and identified <I>DLEC1</I> (Deleted in lung and oesophageal cancer 1), a major 3p22.3 TSG, as one of the methylated targets. We further found that <I>DLEC1</I> was downregulated or silenced in most colorectal and gastric cell lines due to promoter methylation, whereas broadly expressed in normal tissues including colon and stomach, and unmethylated in expressing cell lines and immortalised normal colon epithelial cells. <I>DLEC1</I> expression was reactivated through pharmacologic or genetic demethylation, indicating a DNMT1/DNMT3B-mediated methylation silencing. Aberrant methylation was further detected in primary colorectal (10 out of 34, 29%) and gastric tumours (30 out of 89, 34%), but seldom in paired normal colon (0 out of 17) and gastric (1 out of 20, 5%) samples. No correlation between <I>DLEC1</I> methylation and clinical parameters of gastric cancers was found. Ectopic expression of <I>DLEC1</I> in silenced HCT116 and MKN45 cells strongly inhibited their clonogenicity. Thus, <I>DLEC1</I> is a functional tumour suppressor, being frequently silenced by epigenetic mechanism in gastrointestinal tumours.</P>