Congener-specific Mother-Fetus Distribution, Placental Retention, and Transport of C_(10-13) and C_(14-17) Chlorinated Paraffins in Pregnant Women

Short-chain chlorinated paraffins (SCCPs) and medium-chain chlorinated paraffins (MCCPs) are high-production-volume persistent and toxic industrial chemicals found ubiquitously in various environmental matrices. However, information is scarce regarding human internal exposure. The congener-specific SCCP and MCCP levels in matched maternal serum (n = 31), umbilical cord serum (n = 31), and placenta (n = 31) were studied to investigate the maternal–placenta–fetus distribution and the placental transport mechanisms of SCCPs and MCCPs. The results indicated that lower chlorinated and shorter carbon chain CPs were efficiently transported across placenta compared to highly chlorinated and longer carbon chain CPs. Meanwhile, ∑MCCP concentration followed the order of maternal sera > placentas > cord sera. The cord/maternal concentration fraction ratios (R_(CM)) of CPs exhibited similar values from C_(10) to C_(14), and then from C_(15), a decreasing trend was observed with increasing carbon chain length. The log-normalized maternal SCCP concentrations were positively correlated (P < 0.01) with that in the cord, suggesting fetus exposure to SCCPs during pregnancy. Furthermore, the placenta/maternal concentration fraction ratio (R_(PM)) values for MCCPs were relatively higher than those for SCCPs, demonstrating that MCCPs were not efficiently transported and effectively retained in placenta tissues. These findings provide a better understanding of the maternal–fetal transmission and neonatal exposure to CPs

Potential health benefits of lowering gas production and bifidogenic effect of the blends of polydextrose with inulin in a human gut model

Polydextrose is a nutrient supplement, which is widely applied in the food industry. The use of polydextrose in combination with prebiotics and probiotics has recently increased, whereas the fermentation properties of its blend have not yet been fully revealed. We evaluated the metabolic profile of polydextrose, inulin, and their blends by a batch in vitro fermentation of fifteen human fecal inocula. After 24 h of fermentation, polydextrose increased the production of gas, ammonia, and several short chain fatty acids, including propionate and butyrate, when compared to its blends, inulin, and fructo-oligosaccharides. Furthermore, polydextrose had the slowest degradation rate of all the carbohydrates tested, consistent with its partial fermentation in the distal colon. The 16S rRNA gene sequencing analysis of the gut microbiome exhibited significantly increased relative abundance of Clostridium_XVIII, Megamonas, Mitsuokella, and Erysipelotrichaceae_incertae_sedis in polydextrose compared to other carbohydrates. On the other hand, the blends of polydextrose and inulin (1:1 or 2:1) showed reduced gas production and similar bifidogenicity to inulin alone. The blends not only had similar alpha-diversity and PCoA to inulin but also had a similar abundance of beneficial bacteria, such as Faecalibacterium and Roseburia, suggesting potential health benefits. Also their low gas production was likely due to the abundance of Faecalibacterium and Anaerostipes, which were negatively correlated with gas production. Additionally, our in vitro fermentation model shows advantages in the large-scale assessment of fermentation performance

Spatiotemporal dynamic of subtropical forest carbon storage and its resistance and resilience to drought in China

Subtropical forests are rich in vegetation and have high photosynthetic capacity. China is an important area for the distribution of subtropical forests, evergreen broadleaf forests (EBFs) and evergreen needleleaf forests (ENFs) are two typical vegetation types in subtropical China. Forest carbon storage is an important indicator for measuring the basic characteristics of forest ecosystems and is of great significance for maintaining the global carbon balance. Drought can affect forest activity and may even lead to forest death and the stability characteristics of different forest ecosystems varied after drought events. Therefore, this study used meteorological data to simulate the standardized precipitation evapotranspiration index (SPEI) and the Biome-BGC model to simulate two types of forest carbon storage to quantify the resistance and resilience of EBF and ENF to drought in the subtropical region of China. The results show that: 1) from 1952 to 2019, the interannual drought in subtropical China showed an increasing trend, with five extreme droughts recorded, of which 2011 was the most severe one; 2) the simulated average carbon storage of the EBF and ENF during 1985-2019 were 130.58 t·hm-2 and 78.49 t·hm-2, respectively. The regions with higher carbon storage of EBF were mainly concentrated in central and southeastern subtropics, where those of ENF mainly distributed in the western subtropic; 3) The median of resistance of EBF was three times higher than that of ENF, indicating the EBF have stronger resistance to extreme drought than ENF. Moreover, the resilience of two typical forest to 2011 extreme drought and the continuous drought events during 2009 - 2011 were similar. The results provided a scientific basis for the response of subtropical forests to drought, and indicating that improve stand quality or expand the plantation of EBF may enhance the resistance to drought in subtropical China, which provided certain reference for forest protection and management under the increasing frequency of drought events in the future

Understanding the dynamic spatial structures behind the operation of unplanned commercial areas: a case of the Liuhua Clothing Wholesale District in China

China’s post-1978 economic transition induced fundamental changes to urban space. The private economy legalization and land commercialization suddenly endowed space with capital values. To understand the formation and transformation of urban space, this research investigates the dynamic spatial structures of the Liuhua Clothing Wholesale District in Guangzhou China, by regarding spaces as actors. The advantageous location of the Liuhua District on the south of the large transportation hub Guangzhou Railway Station not only started the rapid-growth of a brand-new clothing wholesale district, but also provides an ideal opportunity to investigate the dramatic changes of urban space during economic transition. The regulation gaps of urban planning left the opportunities for the space end-users – the wholesale traders – to express their agencies of space use. The agencies rendered the Liuhua district a multi-functional and well-organized place, including business types, such as clothing wholesale shops, mannequin shops, tag shops and logistics companies, to enable the everyday operation of clothing wholesale. This research follows Actor Network Theory (ANT) and borrows concepts from Social Network Analysis (SNA) in order to understand how human and non-human actors have shaped the spatial structures in the Liuhua District. Spaces are regarded both as actors and networks; the hierarchies of spaces are understood through the concepts centrality and marginality. To engage with the research question, the empirical research adopts qualitative mixed methods including archival research, ethnographic methods (observation and semi-structured interview) and mapping. The research findings include two parts. The first part focuses on the social relationships between spaces, while the second part works with the concrete phenomena from urban scale to architectural scale. This research has found that: cooperation, competition and evolution are three types of relationships between spaces in the Liuhua District; on the urban scale, the spatial structures of clothing wholesale areas are influenced by the central actors, people flows and early actors, while to clothing wholesale service industries, the everyday practices are vital in terms of choosing business location; on the architectural scale, spatial structures are influenced by central actors and spatial practices such as sales activities, livestreaming and customers’ activities. The Liuhua District is taken as an example to understand how spaces are endowed with hierarchies and chosen for various functions. Through actor networks, it becomes possible to understand that spatial structures are not merely determined by individual spaces, but are shaped by relations among spaces and other actors which influence the value, status, and changes of spaces

Enantioseparation of napropamide by supercritical fluid chromatography: Effects of the chromatographic conditions and separation mechanism

Supercritical fluid chromatography (SFC) is already used for enantioseparation in the pharmaceutical industry, but it is rarely used for the separation of chiral pesticides. Comparing with high performence liquid chromatography, SFC uses much more environmnetal friendly and economic mobile phase, supercritical CO2. In our work, the enantioseparation of an amide herbicide, napropamide, using three different polysaccharide‐type chiral stationary phases (CSPs) in SFC was investigated. By studying the effect of different CSPs, organic modifiers, temperature, back‐pressure regulator pressures, and flow rates for the enantioseparation of napropamide, we established a rapid and green method for enantioseparation that takes less than 2 minutes: The column was CEL2, the mobile phase was CO2 with 20% 2‐propanol, and the flow rate was 2.0 mL/min. We found that CEL2 demonstrated the strongest resolution capability. Acetonitrile was favored over alcoholic solvents when the CSP was amylose and 2‐propanol was the best choice when using cellulose. When the concentration of the modifiers or the flow rate was decreased, resolutions and analysis times increased concurrently. The temperature and back‐pressure regulator pressure exhibited only minor influences on the resolution and analysis time of the napropamide enantioseparations with these chiral columns. The molecular docking analysis provided a deeper insight into the interactions between the enantiomers and the CSPs at the atomic level and partly explained the reason for the different elution orders using the different chiral columns

Enantioseparation of napropamide by supercritical fluid chromatography: Effects of the chromatographic conditions and separation mechanism

Supercritical fluid chromatography (SFC) is already used for enantioseparation in the pharmaceutical industry, but it is rarely used for the separation of chiral pesticides. Comparing with high performence liquid chromatography, SFC uses much more environmnetal friendly and economic mobile phase, supercritical CO2. In our work, the enantioseparation of an amide herbicide, napropamide, using three different polysaccharide‐type chiral stationary phases (CSPs) in SFC was investigated. By studying the effect of different CSPs, organic modifiers, temperature, back‐pressure regulator pressures, and flow rates for the enantioseparation of napropamide, we established a rapid and green method for enantioseparation that takes less than 2 minutes: The column was CEL2, the mobile phase was CO2 with 20% 2‐propanol, and the flow rate was 2.0 mL/min. We found that CEL2 demonstrated the strongest resolution capability. Acetonitrile was favored over alcoholic solvents when the CSP was amylose and 2‐propanol was the best choice when using cellulose. When the concentration of the modifiers or the flow rate was decreased, resolutions and analysis times increased concurrently. The temperature and back‐pressure regulator pressure exhibited only minor influences on the resolution and analysis time of the napropamide enantioseparations with these chiral columns. The molecular docking analysis provided a deeper insight into the interactions between the enantiomers and the CSPs at the atomic level and partly explained the reason for the different elution orders using the different chiral columns

Enantioselective effects of chiral amide herbicides napropamide, acetochlor and propisochlor: The more efficient R-enantiomer and its environmental friendly

Amide herbicides, which are used extensively worldwide, are often chiral. Enantiomeric selectivity comes from the different effects of the enantiomers on target and non-target organisms. In this study, the enantiomers of three amide herbicides were purified by the semi-preparative column and were used to investigate the enantioselective effects on target Echinochloa crusgalli (lowland rice weeds), and non-target Microcystis aeruginosa, and the yeast transformed with the human TRβ plasmid organisms. The results showed that (i) the R-enantiomers of the three amide herbicides exhibited the strongest activity toward weed inhibition and the lowest toxicity toward non-target organisms; (ii) napropamide was better suited for controlling root growth, while acetochlor and propisochlor were better for leaves control; (iii) herbicides at certain low concentrations (0.01 mg L^(−1) for acetochlor and propisochlor) could be utilized to promote plant growth. These findings encourage the use of R-amide herbicides instead of their racemates to increase the efficiency of weed control and reduce the risk to non-target organisms. On the other hand, the adverse effects are caused mostly by S-enantiomer, using R-enantiomer-enriched products may offer great environmental/ecological benefits

Enantioseparation of four amide herbicide stereoisomers using high-performance liquid chromatography

The chirality of herbicides has been the focus of research. However, there is little information on the enantioseparation of amide herbicides with different chiral elements. In this study, the need for different chiral stationary phases (CSPs), mobile phases, temperatures and flow rates for the separation of napropamide, acetochlor and propisochlor was discussed in detail and compared to metolachlor. Resolution of C-chiral enantiomers was easier than that of axial-chiral enantiomers. Metolachlor and acetochlor could achieve baseline separation only on AY-H and AS-H columns, respectively. Propisochlor had satisfactory separations on OD-H and AS-H columns. Napropamide was separated on OJ-H, AY-H and AS-H columns. Both the structures of the compounds and CSPs and the interactions between them played significant roles in the enantioseparations. Molecule dockings were also used to elucidate the separation mechanisms. C-chiral enantiomers had perfect symmetry in their optical properties, whereas the axial-chiral enantiomers did not. The elution order for napropamide, acetochlor and propisochlor, with a single chiral location, was R- prior to S-. These results were the first that compare the enantioseparations of four amide herbicides with different chirality, and they provided the absolute configurations for the herbicides. The paper also illustrated certain mechanisms for enantioseparations