| 1. |
- Cai, Jing, et al.
(författare)
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Size-segregated particle number and mass concentrations from different emission sources in urban Beijing
- 2020
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 20:21, s. 12721-12740
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Tidskriftsartikel (refereegranskat)abstract
- Although secondary particulate matter is reported to be the main contributor of PM2.5 during haze in Chinese megacities, primary particle emissions also affect particle concentrations. In order to improve estimates of the contribution of primary sources to the particle number and mass concentrations, we performed source apportionment analyses using both chemical fingerprints and particle size distributions measured at the same site in urban Beijing from April to July 2018. Both methods resolved factors related to primary emissions, including vehicular emissions and cooking emissions, which together make up 76% and 24% of total particle number and organic aerosol (OA) mass, respectively. Similar source types, including particles related to vehicular emissions (1.6 +/- 1.1 mu gm(-3); 2.4 +/- 1.8 x 10(3) cm(-3) and 5.5 +/- 2.8 x 10(3) cm(-3) for two traffic-related components), cooking emissions (2.6 +/- 1.9 mu gm(-3) and 5.5 +/- 3.3 x 10(3) cm(-3)) and secondary aerosols (51 +/- 41 mu gm(-3) and 4.2 +/- 3.0 x 10(3) cm(-3)), were resolved by both methods. Converted mass concentrations from particle size distributions components were comparable with those from chemical fingerprints. Size distribution source apportionment separated vehicular emissions into a component with a mode diameter of 20 nm (traffic-ultrafine) and a component with a mode diameter of 100 nm (traffic-fine). Consistent with similar day- and nighttime diesel vehicle PM2.5 emissions estimated for the Beijing area, traffic-fine particles, hydrocarbon-like OA (HOA, traffic-related factor resulting from source apportionment using chemical fingerprints) and black carbon (BC) showed similar diurnal patterns, with higher concentrations during the night and morning than during the afternoon when the boundary layer is higher. Traffic-ultrafine particles showed the highest concentrations during the rush-hour period, suggesting a prominent role of local gasoline vehicle emissions. In the absence of new particle formation, our re-sults show that vehicular-related emissions (14% and 30% for ultrafine and fine particles, respectively) and cooking-activity-related emissions (32 %) dominate the particle number concentration, while secondary particulate matter (over 80 %) governs PM2.5 mass during the non-heating season in Beijing.
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| 2. |
- Haslett, Sophie, 1988-, et al.
(författare)
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Nighttime NO emissions strongly suppress chlorine and nitrate radical formation during the winter in Delhi
- 2023
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Ingår i: Atmospheric Chemistry And Physics. - 1680-7316 .- 1680-7324. ; 23:16, s. 9023-9036
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Tidskriftsartikel (refereegranskat)abstract
- Atmospheric pollution in urban regions is highly influenced by oxidants due to their important role in the formation of secondary organic aerosol (SOA) and smog. These include the nitrate radical (NO3), which is typically considered a nighttime oxidant, and the chlorine radical (Cl), an extremely potent oxidant that can be released in the morning in chloride-rich environments as a result of nocturnal build-up of nitryl chloride (ClNO2). Chloride makes up a higher percentage of particulate matter in Delhi than has been observed anywhere else in the world, which results in Cl having an unusually strong influence in this city. Here, we present observations and model results revealing that atmospheric chemistry in Delhi exhibits an unusual diel cycle that is controlled by high concentrations of NO during the night. As a result of this, the formation of both NO3 and dinitrogen pentoxide (N2O5), a precursor of ClNO2 and thus Cl, are suppressed at night and increase to unusually high levels during the day. Our results indicate that a substantial reduction in nighttime NO has the potential to increase both nocturnal oxidation via NO(3 )and the production of Cl during the day.
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| 3. |
- Li, Liyuan, et al.
(författare)
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Flexible double-cross-linked cellulose-based hydrogel and aerogel membrane for supercapacitor separator
- 2018
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Ingår i: Journal of Materials Chemistry A. - : ROYAL SOC CHEMISTRY. - 2050-7488 .- 2050-7496. ; 6:47, s. 24468-24478
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Tidskriftsartikel (refereegranskat)abstract
- A cellulose-based flexible double-cross-linked hydrogel with hierarchical porosity (max. 80%) was obtained by a facile solution-phase method by using polydopamine (PDA) as a crosslinker between cellulose and polyacrylamide (PAM). The investigation on the ratio of dopamine/acrylamide (DA/AM) reveals that the - stacking of the catechol groups in PDA and the abundant hydrogen bonds distributed in the gel network exert key effects on the hydrogels mechanical properties. At the premium ratio of 0.4 (C-4-DM-40), the mechanical and self-healing properties of the hydrogel are superior to those of other hydrogels. Fe3+-functionalizing endows the hydrogel with enhanced conductivity and sensitivity, as evidenced by the 3-fold increase in resistance variation (R/R-0) in a finger-bending monitoring test. An electric double layer supercapacitor using the KOH-saturated C-4-DM-40 aerogel membrane as a polymer electrolyte presents high capacitance of 172 F g(-1) at 1.0 A g(-1) and long cycling life of 10000 cycles with 84.7% capacitance retention due to electrolyte retention of 548.6%. Remarkably, an integrated micro-supercapacitor is fabricated by directly depositing activated carbon materials onto the C-4-DM-40 hydrogel membrane. The device shows areal capacitance of 275.8 mF cm(-2) and volumetric capacitance of 394.1 F cm(-3) at 10 mV s(-1). These findings suggest that the multi-functional cellulose-based hydrogels reported in this study display various potentials for practical applications not only in human health monitoring but also in portable and energy-storage devices.
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| 4. |
- McCord, Lauren A, et al.
(författare)
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Ovarian Expression and Regulation of the Stromelysins During the Periovulatory Period in the Human and the Rat.
- 2012
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Ingår i: Biology of reproduction. - : Oxford University Press (OUP). - 1529-7268 .- 0006-3363. ; 86:3
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Tidskriftsartikel (refereegranskat)abstract
- The matrix metalloproteinases (MMPs) are postulated to facilitate follicular rupture. In the present study, expression of the stromelysins (MMP3, MMP10, MMP11) was analyzed in the periovulatory human and rat ovary. Human granulosa and theca cells were collected from the dominant follicle at various times after hCG. Intact rat ovaries, granulosa cells, and residual tissue (tissue remaining after granulosa cell collection) were isolated from eCG-hCG-primed animals. Mmp10 mRNA was highly induced in human granulosa and theca cells and intact rat ovaries, granulosa cells, and residual tissue. Localization of MMP10 to granulosa and theca cells in both human and rat ovarian follicles was confirmed by immunohistochemistry. Mmp3 mRNA was unchanged in human cells and rat granulosa cells but increased in intact rat ovaries and residual tissue. Mmp11 mRNA decreased following hCG treatment in human granulosa and theca cells as well as rat granulosa cells. Regulation of Mmp10 in cultured rat granulosa cells revealed that the EGF inhibitor AG1478 and the progesterone antagonist RU486 suppressed the induction of Mmp10 mRNA whereas the prostaglandin inhibitor NS398 had no effect. Studies on the Mmp10 promoter demonstrated forskolin plus PMA stimulated promoter activity, which was dependent upon a proximal AP1 site. In conclusion, there are divergent patterns of stromelysin expression associated with ovulation with a marked induction of Mmp10 mRNA, a decrease in Mmp11 mRNA, yet a species dependent pattern on Mmp3 mRNA expression. The induction of Mmp10 expression suggests an important role for this MMP in the follicular changes associated with ovulation and subsequent luteinization.
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| 5. |
- Rosewell, Katherine L, et al.
(författare)
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Ovarian Expression, Localization, and Function of Tissue Inhibitor of Metalloproteinase 3 (TIMP3) During the Periovulatory Period of the Human Menstrual Cycle.
- 2013
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Ingår i: Biology of reproduction. - : Oxford University Press (OUP). - 1529-7268 .- 0006-3363. ; 89:5
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Tidskriftsartikel (refereegranskat)abstract
- Ovulation involves reorganization of the extracellular matrix of the follicle. This study examines the expression, localization, and potential function of the tissue inhibitor of metalloproteinase 3 (TIMP3) during ovulation in women. The dominant follicle of the menstrual cycle was collected at specified times throughout the ovulatory process: pre-, early, late, and postovulatory. For quantitative studies, the follicle was bisected; granulosa and theca cells were separated and collected. For immunohistochemistry (IHC), the intact follicle was embedded and TIMP3 was localized. Additionally, granulosa cells were collected from women undergoing in vitro fertilization and treated with increasing concentrations of recombinant TIMP3, and cell viability was assessed. Real-time PCR for TIMP3 mRNA revealed an increase in TIMP3 mRNA expression in granulosa cells from the early to the late ovulatory stage. Thecal TIMP3 mRNA expression was constitutive across the periovulatory period. TIMP3 protein was localized by IHC to the granulosa and theca cell layers in pre-, early, and late ovulatory follicles as well as to the vascular bed. The staining was most intense in the granulosa and theca cells in the late ovulatory group. Treatment of human granulosa-lutein cells with exogenous recombinant TIMP3 for 24 h decreased cell viability by 60%. Using human follicles collected throughout the periovulatory period of the menstrual cycle, we have demonstrated that TIMP3 mRNA expression increases and that TIMP3 protein is in the appropriate cellular layers to regulate proteolytic remodeling as the follicle progresses toward ovulation. In addition, we have shown that elevated levels of TIMP3 lead to decreased cell viability.
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