| 1. |
- Liu, Jun, et al.
(författare)
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Determining the influence of LC2 and FA on the iodide diffusion coefficient of in seawater and sea sand concrete: A novel modified RIM test method
- 2023
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Ingår i: Cement and Concrete Composites. - 0958-9465. ; 143
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Tidskriftsartikel (refereegranskat)abstract
- A novel modified Rapid Iodide Migration (RIM) test method was used to determine the influence of LC2 and FA on iodide ion diffusion coefficient of seawater and sea sand concrete (SSC). A 0.1 mol/L AgNO3 solution was selected as the indicator to develop the colour of iodide in SSC, and a lowered mass fraction of NaI solution was selected to improve the RIM test. An X-Ray Fluorescence (XRF) test was employed to detect the feasibility of the modified RIM test. Additionally, the effects of the w/c ratio, the type and substitution rate of supplementary cementitious materials (SCMs), and the compressive strength on the iodide ion diffusion coefficient of SSC were studied using the modified RIM test. The results show that it is completely feasible to use AgNO3 solution as an indicator. A lower mass fraction of NaI solution not only does not change the iodide ion diffusion coefficient of concrete but also reduces the test cost by 77.46% when using a 5 wt% NaI solution. Moreover, using SCMs to replace cement, liking fly ash (FA) and calcined clay and limestone (LC2), significantly reduces the iodide ion permeability of SSC, especially the use of LC2. Furthermore, there is a nonlinear relationship between the compressive strength and the iodide ion diffusion coefficient of SSC. This work is beneficial for the promotion of the application of modified RIM tests in studies of concrete contaminated with chloride and can provide a theoretical basis for the application of seawater and sea sand in engineering practices.
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| 2. |
- Chen, Shan, et al.
(författare)
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An efficient enzymatic aminolysis for kinetic resolution of aromatic alpha-hydroxyl acid in non-aqueous media
- 2016
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Ingår i: Tetrahedron Letters. - : Elsevier. - 0040-4039 .- 1359-8562. ; 57:48, s. 5312-5314
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Tidskriftsartikel (refereegranskat)abstract
- A new and highly efficient enzymatic aminolysis approach for kinetic resolution of aromatic a-hydroxy acid in non-aqueous media has been developed. The corresponding alpha-hydroxyl acid ester was employed as the substrate, and commercially available Candida antarctica lipase B is used as the biocatalyst, anhydrous ammonia is the resolving agent. Reactions can be proceeded smoothly in organic solvent at ambient temperatures. High concentration of substrate is allowed due to the application of organic media and the products are obtained in yields of up to 49% with ee values of up to 99%, and with E value of >300, representing an appealing and promising protocol for large-scale preparations.
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| 3. |
- England-Mason, Gillian, et al.
(författare)
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Postnatal BPA is associated with increasing executive function difficulties in preschool children
- 2021
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Ingår i: Pediatric Research. - : Springer Science and Business Media LLC. - 0031-3998 .- 1530-0447. ; 89, s. 686-693
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Tidskriftsartikel (refereegranskat)abstract
- Background Early bisphenol exposure may have consequences for executive function development, but less is known about potential sex effects. We hypothesized that early bisphenol A (BPA) and bisphenol S (BPS) exposures would be associated with sex-dependent changes in preschool executive function. Methods A subsample of the Alberta Pregnancy Outcomes and Nutrition (APrON) cohort (n = 312) provided maternal second trimester (prenatal) and 3-month postpartum (postnatal) urine samples, from which BPA and BPS concentrations were quantified. When children were age 2 and 4, mothers completed the Behavior Rating Inventory of Executive Function-Preschool Version (BRIEF-P). Changes in standardized T scores on the BRIEF-P indexes of inhibitory self-control, flexibility, and emergent metacognition were investigated. Results Adjusted multivariate regression analyses showed that child sex modified the associations between maternal postnatal BPA and changes in executive function. Higher maternal postnatal BPA concentrations predicted increasing difficulties from age 2 to 4 in the domains of inhibitory self-control and emergent metacognition in female, but not male children. The other bisphenol concentrations were not associated with changes in executive function. Conclusion Due to the ubiquity of BPA exposure among breastfeeding women, these findings justify further investigation on the effects of postnatal bisphenol exposure on child cognitive development. Impact Higher concentrations of maternal BPA at 3-month postpartum were associated with increasing difficulties in inhibitory self-control and emergent metacognition from age 2 to 4 in girls, but not boys. Prenatal BPA and prenatal/postnatal BPS were not significant predictors of changes in executive function in boys and girls. The current study extends previous research to show that maternal postnatal BPA could also impact child executive function. Due to the ubiquity of BPA exposure among breastfeeding women, the current findings suggest that additional precautions may be needed to protect infants' neurodevelopment from indirect exposure to BPA.
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| 4. |
- England-Mason, Gillian, et al.
(författare)
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White matter microstructure mediates the association between prenatal exposure to phthalates and behavior problems in preschool children
- 2020
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Ingår i: Environmental Research. - : Elsevier BV. - 0013-9351 .- 1096-0953. ; 182
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Tidskriftsartikel (refereegranskat)abstract
- Background: Previous research reports associations between prenatal exposure to phthalates and childhood behavior problems; however, the neural mechanisms that may underlie these associations are relatively unexplored. Objective: This study examined microstructural white matter as a possible mediator of the associations between prenatal phthalate exposure and behavior problems in preschool-aged children. Methods: Data are from a subsample of a prospective pregnancy cohort, the Alberta Pregnancy Outcomes and Nutrition (APrON) study (n = 76). Mother-child pairs were included if mothers provided a second trimester urine sample, if the child completed a successful magnetic resonance imaging (MRI) scan at age 3-5 years, and if the Child Behavior Checklist was completed within 6 months of the MRI scan. Molar sums of high (HMWP) and low molecular weight phthalates (LMWP) were calculated from levels in urine samples. Associations between prenatal phthalate concentrations, fractional anisotropy (FA) and mean diffusivity (MD) in 10 major white matter tracts, and preschool behavior problems were investigated. Results: Maternal prenatal phthalate concentrations were associated with MD of the right inferior fronto-occipital fasciculus (IFO), right pyramidal fibers, left and right uncinate fasciculus (UF), and FA of the left inferior longitudinal fasciculus (ILF). Mediation analyses showed that prenatal exposure to HMWP was indirectly associated with Internalizing (path ab = 0.09, CI.95 = 0.02, 0.20) and Externalizing Problems (path ab = 0.09, CI.95 = 0.01, 0.19) through MD of the right IFO, and to Internalizing Problems (path ab = 0.11, CI.95 = 0.01, 0.23) through MD of the right pyramidal fibers. Discussion: This study provides the first evidence of childhood neural correlates of prenatal phthalate exposure. Results suggest that prenatal phthalate exposure may be related to microstructural white matter in the IFO, pyramidal fibers, UF, and ILF. Further, MD of the right IFO and pyramidal fibers may transmit childhood risk for behavioral problems.
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| 5. |
- Grohs, Melody N., et al.
(författare)
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Prenatal maternal and childhood bisphenol a exposure and brain structure and behavior of young children
- 2019
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Ingår i: Environmental Health. - : Springer Science and Business Media LLC. - 1476-069X. ; 18:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Bisphenol A (BPA) is commonly used in the manufacture of plastics and epoxy resins. In North America, over 90% of the population has detectable levels of urinary BPA. Human epidemiological studies have reported adverse behavioral outcomes with BPA exposure in children, however, corresponding effects on children's brain structure have not yet been investigated. The current study examined the association between prenatal maternal and childhood BPA exposure and white matter microstructure in children aged 2 to 5 years, and investigated whether brain structure mediated the association between BPA exposure and child behavior.Methods: Participants were 98 mother-child pairs who were recruited between January 2009 and December 2012. Total BPA concentrations in spot urine samples obtained from mothers in the second trimester of pregnancy and from children at 3-4 years of age were analyzed. Children participated in a diffusion magnetic resonance imaging (MRI) scan at age 2-5 years (3.7 +/- 0.8 years). Associations between prenatal maternal and childhood BPA and children's fractional anisotropy and mean diffusivity of 10 isolated white matter tracts were investigated, controlling for urinary creatinine, child sex, and age at the time of MRI. Post-hoc analyses examined if alterations in white matter mediated the relationship of BPA and children's scores on the Child Behavior Checklist (CBCL).Results: Prenatal maternal urinary BPA was significantly associated with child mean diffusivity in the splenium and right inferior longitudinal fasciculus. Splenium diffusivity mediated the relationship between maternal prenatal BPA levels and children's internalizing behavior (indirect effect: beta = 0.213, CI [0.0167, 0.564]). No significant associations were found between childhood BPA and white matter microstructure.Conclusions: This study provides preliminary evidence for the neural correlates of BPA exposure in humans. Our findings suggest that prenatal maternal exposure to BPA may lead to alterations in white matter microstructure in preschool aged children, and that such alterations mediate the relationship between early life exposure to BPA and internalizing problems.
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| 6. |
- Lin, Yen-Hung, et al.
(författare)
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A piperidinium salt stabilizes efficient metal-halide perovskite solar cells
- 2020
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Ingår i: Science. - : AMER ASSOC ADVANCEMENT SCIENCE. - 0036-8075 .- 1095-9203. ; 369:6499, s. 96-
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Tidskriftsartikel (refereegranskat)abstract
- Longevity has been a long-standing concern for hybrid perovskite photovoltaics. We demonstrate high-resilience positive-intrinsic-negative perovskite solar cells by incorporating a piperidinium-based ionic compound into the formamidinium-cesium lead-trihalide perovskite absorber. With the bandgap tuned to be well suited for perovskite-on-silicon tandem cells, this piperidinium additive enhances the open-circuit voltage and cell efficiency. This additive also retards compositional segregation into impurity phases and pinhole formation in the perovskite absorber layer during aggressive aging. Under full-spectrum simulated sunlight in ambient atmosphere, our unencapsulated and encapsulated cells retain 80 and 95% of their peak and post-burn-in efficiencies for 1010 and 1200 hours at 60 degrees and 85 degrees C, respectively. Our analysis reveals detailed degradation routes that contribute to the failure of aged cells.
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| 7. |
- Liu, Jiaying, et al.
(författare)
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Comparison of Bisphenol A and Bisphenol S Percutaneous Absorption and Biotransformation
- 2019
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Ingår i: Journal of Environmental Health Perspectives. - 0091-6765 .- 1552-9924. ; 127:6
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Bisphenol S (BPS) has been widely substituted for bisphenol A (BPA) on thermal papers, but little is known about its skin absorption.OBJECTIVES: We compared the percutaneous absorption and biotransformation of BPS and BPA in vitro and in a controlled human trial.METHODS: Absorption and biotransformation of BPS and BPA were monitored across reconstructed human epidermis at two environmentally relevant doses over 25 h. In the human trial, five male participants handled thermal receipts containing BPS and washed their hands after 2 h. Urine (0-48 h) and serum (0-7.5h) were analyzed for target bisphenols, and one participant repeated the experiment with extended monitoring. BPS data were compared with published data for isotope-labeled BPA (BPA-d(16)) in the same participants.RESULTS: At doses of 1.5 and 7.7 mu g/cm(2) applied to reconstructed human epidermis, the permeability coefficient of BPS (0.009 and 0.003 cm/h, respectively) was significantly lower than for BPA (0.036 and 0.033 cm/h, respectively), and metabolism of both bisphenols was negligible. In participants handling thermal receipts, the quantities of BPS and BPA-d(1)(6) on hands was significantly correlated with maximum urinary event flux (lag), but the slope was lower for BPS than BPA (beta=0.12 and 1.1, respectively). As a proportion of total urinary bisphenol, free BPS [mean +/- standard deviation (SD): 6.9 +/- 2.8%] was higher than for free BPA (2.7 +/- 1.9%). Postexposure maximum urinary BPS concentrations (0.93 to 3.0 ng/mL; n = 5) were in the 93-98th percentile range of BPS in background Canadians (0.91-3.2 ng/mL; n =467).CONCLUSION: Both the in vitro and human studies suggested lower percutaneous absorption of BPS compared with BPA, but a lower biotransformation efficiency of BPS should also be considered in its evaluation as a BPA substitute.
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| 8. |
- Liu, Jiaying, et al.
(författare)
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Exposure and dietary sources of bisphenol A (BPA) and BPA-alternatives among mothers in the APrON cohort study
- 2018
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Ingår i: Environment International. - : Elsevier BV. - 0160-4120 .- 1873-6750. ; 119, s. 319-326
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Tidskriftsartikel (refereegranskat)abstract
- Diet is regarded as the main source of bisphenol A (BPA) exposure, but comparatively little is known about dietary sources of BPA-alternatives. Here we measured exposure of BPA and BPA-alternatives among pregnant women in Canada, estimated their 24-h intakes and examined the importance of various dietary sources. Free and total BPA, bisphenol S (BPS) and bisphenol F (BPF) were measured in 467 second trimester maternal urine samples, and in 455 paired samples collected M three months postpartum. Linear regression was used to evaluate associations between urinary concentrations of bisphenols and 24-h dietary recall data. The geometric means of total BPA in second trimester and postpartum urine (1.2 and 0.95 ng/mL, respectively) were 5-7 times higher than corresponding total BPS (0.16 and 0.17 ng/mL). The detection frequency of BPF was only 9% (i.e. > 1.0 ng/mL). However, M both time points 95th percentiles of total BPF (7.3 and 4.2 ng/mL, respectively) were similar to total BPA (8.2 and 5.0 ng/mL). Free BPS and BPF were detected in < 2% of samples, but were detectable when total BPS or BPF concentrations were highest, always M < 1% of the total concentration. The tolerable daily intake for total BPA (i.e. 18 nmol/kg BW/d) was not exceeded, but for BPS the estimated 24-h intake was as high as 14 nmol/kg BW/d (95th percentile: 0.12 nmol/kg BW/d), and for BPF was even higher among the highest centile of exposure (maximum and 95th percentile: 30, 0.81 nmol/kg BW/d). Canned food consumption was associated with higher total BPA, but was not associated with BPS. For BPF, mustard consumption may be an important exposure source, particularly among the highest exposed. Relatively high exposure to BPS and BPF in a minority of pregnant women highlights the need to better understand the associated health risks and exposure sources of BPA-alternatives.
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| 9. |
- Liu, Jiaying, et al.
(författare)
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Interaction of prenatal bisphenols, maternal nutrients, and toxic metal exposures on neurodevelopment of 2-year-olds in the APrON cohort
- 2021
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Ingår i: Environment International. - : Elsevier BV. - 0160-4120 .- 1873-6750. ; 155
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Tidskriftsartikel (refereegranskat)abstract
- Background: Epidemiological studies suggest that Bisphenol-A (BPA) is a developmental neurotoxicant, but the modifying effects of maternal nutrient status or neurotoxicant metal co-exposures have not been reported. Bisphenol-S (BPS) is being used as a BPA-alternative, but few epidemiological studies have evaluated its effects.Objectives: To examine if prenatal maternal BPA or BPS exposure are associated with children's neurodevelopment at two years of age while adjusting for effect-measure modification by sex, maternal nutrients, and co-exposure to neurotoxic metals.Methods: Total BPA and BPS concentrations were analyzed in spot maternal urine from the second trimester; metals and maternal nutrient status were analyzed in blood. Child neurodevelopment was evaluated with the Bayley Scales of Infant Development-III (Bayley-III) at age 2 (394 maternal-child pairs) and linear regression was used to investigate associations.Results: Among nutrients and neurotoxic metals, selenium (Se) and cadmium (Cd) were the most significant predictors of Bayley-III scale scores. Higher maternal Cd was significantly correlated with poorer motor performance (p < 0.01), and higher levels of maternal Se were significantly associated with poorer performance on the cognitive, motor, and adaptive behavior scales (p < 0.05). While maternal Cd did not modify relationships between bisphenol exposures and Bayley-III scores, both maternal Se and child sex were significant effectmeasure modifiers. Associations between BPA exposure and social emotional scores were negative for boys (p = 0.056) but positive for girls (p = 0.046). Higher exposure to bisphenols was associated with lower motor scores among children with lower levels of maternal Se.Conclusion: Higher maternal Cd was associated with poorer motor development, but it was not an effect-measure modifier of bisphenols' effects on motor development. Maternal Se may be protective against adverse effects of bisphenols, and additional nutrient-bisphenol interaction studies examining sex-specific effects of BPA and BPS on child development are warranted.
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| 10. |
- Liu, Jiaying, et al.
(författare)
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Prolonged Exposure to Bisphenol A from Single Dermal Contact Events
- 2017
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 51:17, s. 9940-9949
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Tidskriftsartikel (refereegranskat)abstract
- Bisphenol A (BPA) is an endocrine disruptor frequently detected in human biofluids. Dermal absorption of BPA from thermal paper receipts occurs but BPA pharmacokinetics following dermal exposure is not understood. To compare the pharmacokinetics of dermal and dietary BPA exposure, six male participants handled simulated receipts containing relevant levels of BPA (isotope-labeled BPA-d(16)) for 5 min, followed by hand-washing 2 h later. Urine (0-48 h) and serum (0-7.5 h) were monitored for free and total BPA-d16. One week later, participants returned for a dietary administration with monitoring as above. One participant repeated the dermal administration with extended monitoring of urine (9 days) and serum (2 days). After dietary exposure, urine total BPA-d16 peaked within 5 h and quickly cleared within 24 h. After dermal exposure, cumulative excretion increased linearly for 2 days, and half the participants still had detectable urinary total BPA-d(16) after 1 week. The participant repeating the dermal exposure had detectable BPA-d(16) in urine for 9 days, showed linear cumulative excretion over 5 days, and had detectable free BPA-d(16) in serum. Proportions of free BPA-d(16) in urine following dermal exposure (0.71%-8.3% of total BPA-d(16)) were generally higher than following the dietary exposure (0.29%-1.4%). Compared to dietary BPA exposure, dermal absorption of BPA leads to prolonged exposure and may lead to higher proportions of unconjugated BPA in systemic circulation.
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