Light-driven conversion of CO2 to chemicals provides a sustainable alternative to fossil fuels, but homogeneous systems are typically limited by cross reactivity between different redox half... Show moreLight-driven conversion of CO2 to chemicals provides a sustainable alternative to fossil fuels, but homogeneous systems are typically limited by cross reactivity between different redox half reactions and inefficient charge separation. Herein, we present the bioinspired development of amphiphilic photosensitizer and catalyst pairs that self-assemble in lipid membranes to overcome some of these limitations and enable photocatalytic CO2 reduction in liposomes using precious metal-free catalysts. Using sodium ascorbate as a sacrificial electron source, a membrane-anchored alkylated cobalt porphyrin demonstrates higher catalytic CO production (1456 vs 312 turnovers) and selectivity (77 vs 11%) compared to its water-soluble nonalkylated counterpart. Time-resolved and steady-state spectroscopy revealed that self-assembly facilitates this performance enhancement by enabling a charge-separation state lifetime increase of up to two orders of magnitude in the dye while allowing for a ninefold faster electron transfer to the catalyst. Spectroelectrochemistry and density functional theory calculations of the alkylated Co porphyrin catalyst support a four-electron-charging mechanism that activates the catalyst prior to catalysis, together with key catalytic intermediates. Our molecular liposome system therefore benefits from membrane immobilization and provides a versatile and efficient platform for photocatalysis. Show less
The ovary is perhaps the most dynamic organ in the human body, only rivaled by the uterus. The molecular mechanisms that regulate follicular growth and regression, ensuring ovarian tissue... Show moreThe ovary is perhaps the most dynamic organ in the human body, only rivaled by the uterus. The molecular mechanisms that regulate follicular growth and regression, ensuring ovarian tissue homeostasis, remain elusive. We have performed single-cell RNA-sequencing using human adult ovaries to provide a map of the molecular signature of growing and regressing follicular populations. We have identified different types of granulosa and theca cells and detected local production of components of the complement system by (atretic) theca cells and stromal cells. We also have detected a mixture of adaptive and innate immune cells, as well as several types of endothelial and smooth muscle cells to aid the remodeling process. Our results highlight the relevance of mapping whole adult organs at the single-cell level and reflect ongoing efforts to map the human body. The association between complement system and follicular remodeling may provide key insights in reproductive biology and (in)fertility. Show less
McMaster, K.L.; Van den Broek, P.W.; Espin, C.A.; Pinto, V.; Janda, B.; Lam, E.; ... ; Van Boekel, M. 2014
The purpose of this study was to translate cognitive models of reading comprehension to educational practice to develop an intervention that is theoretically sound, effective, and feasible for... Show moreThe purpose of this study was to translate cognitive models of reading comprehension to educational practice to develop an intervention that is theoretically sound, effective, and feasible for classroom use. Specifically, the effects of questioning type (Causal versus General) and timing (Online versus Offline) on struggling readers' comprehension were compared. Sixty-two fourth-graders identified as struggling comprehenders were placed in groups of 3-5 students; groups were assigned randomly to Causal or General questioning conditions. All groups received both Online and Offline questioning in counterbalanced order. Tutors delivered intervention for 20-30 min, 3 times per week, for 18 sessions. Dependent measures included students' recall and oral reading of narrative text. Theoretical, empirical, and practical perspectives were triangulated to select the combination of question type and timing that appeared most promising. Findings are discussed with particular emphasis on challenges associated with translating cognitive theory to practice in classroom-based settings. Show less
Beltman, J.J.; Akker, T. van den; Lam, E.; Moens, M.; Kazima, J.; Massaquoi, M.; Roosmalen, J. van 2011
Objective To evaluate progress made at district level in Malawi towards reaching the 5th Millennium Development Goal, the reduction of maternal mortality. Methods In 2006, community-based maternal... Show moreObjective To evaluate progress made at district level in Malawi towards reaching the 5th Millennium Development Goal, the reduction of maternal mortality. Methods In 2006, community-based maternal mortality in Thyolo, Malawi was calculated by applying the 'sisterhood method', a survey that relies on participants responding to basic questions about maternal mortality in their families. Results were compared with a 1989 sisterhood study in the same district. Information on facility-based maternal mortality in 2005 was extracted from district hospital records. Results The community-based maternal mortality ratio (MMR) was calculated as 558 per 100 000 live births (95% CI 260 to 820). A comparison with the MMR from the 1989 survey (409 per 100 000 live births) shows that maternal mortality had not declined. The hospital-based MMR was 994 per 100 000 live births in 2005. Conclusion Maternal mortality in this district has not reduced and may actually have increased. The threat of failure to achieve Millennium Development Goal 5 increases the moral obligation to improve access to quality health care. Show less
