58 research outputs found
Tubal factor infertility and perinatal risk after assisted reproductive technology
No full textLetter to the EditorEsme I. Kamphuis, Frederik J. R. Hermans, Ben Willem J. Mo
Improving identification and treatment of women with increased risk of preterm birth
No full textPreterm birth is one of the major global health problems. It is globally defined as birth before 37 weeks of gestation. Annually 15 million babies are born preterm worldwide, with an incidence rate varying between five and fifteen percent. Preterm birth and its associated complications are held responsible for 1 million deaths annually amongst children under the age of 5 years. Sequelae of preterm birth affect childhood and adolescents’ health in term of neuro-developmental disorders, behavioural disorders and chronic diseases. Preterm birth not only influences the children but also has an impact on parents and society, and it is associated with healthcare costs up to billions. Prevention of preterm birth is one of the main tasks for obstetricians and researchers working in the obstetrical field. Keystones for adequate prevention of preterm birth are effective identification (prediction and diagnosing) and treatment of women with an increased risk of preterm birth. Due to the heterogeneity of preterm birth there are several caveats concerning the identification and treatment of women with an increased risk of preterm birth. Thus we need further improvement of both to improve the prevention of preterm birth. The objective of this thesis was to improve the prevention of preterm birth by reaching back to the keystones; identification and treatment of women at risk of preterm birth. The aims of the studies incorporated in this thesis are twofold. Part 1, addresses several research questions to improve the identification of women at risk of preterm birth; Part 2 addresses several research questions to improve treatment of women with an increased risk of preterm birth
Biogeochemical impact of cable bacteria on coastal Black Sea sediment
No full textCable bacteria can strongly alter sediment biogeochemistry. Here, we used laboratory incubations to determine the potential impact of their activity on the cycling of iron (Fe), phosphorus (P) and sulfur (S). Microsensor depth profiles of oxygen, sulfide and pH in combination with electric potential profiling and fluorescence in situ hybridisation (FISH) analyses showed a rapid development (5 d) of cable bacteria, followed by a long period of activity (200 d). During most of the experiment, the current density correlated linearly with the oxygen demand. Sediment oxygen uptake was attributed to the activity of cable bacteria and the oxidation of reduced products from the anaerobic degradation of organic matter, such as ammonium. Pore water sulfide was low (5 uM) throughout the experiment. Sulfate reduction acted as the main source of sulfide for cable bacteria. Pore water Fe2C reached levels of up to 1.7mM during the incubations, due to the dissolution of FeS (30 %) and siderite, an Fe carbonate mineral (70 %). Following the upward diffusion of Fe2C, a surface enrichment of Fe oxides formed. Hence, besides FeS, siderite may act as a major source of Fe for Fe oxides in coastal surface sediments where cable bacteria are active. Using uXRF, we show that the enrichments in Fe oxides induced by cable bacteria are located in a thin subsurface layer of 0.3 mm. We show that similar subsurface layers enriched in Fe and P are also observed at field sites where cable bacteria were recently active and little bioturbation occurs. This suggests that such subsurface Fe oxide layers, which are not always visible to the naked eye, could potentially be a marker for recent activity of cable bacteria.BT/Environmental Biotechnolog
The charge transport mechanism in cable bacteria
No full textIn this dissertation, the charge transport mechanism in the conductive fibres of cable bacteria is investigated. In Chapter 1, the research field of bacterial electricity is introduced. Three kinds of bacterial nanowires are discussed: Shewenella nanowires, Geobacter nanowires and the conductive fibres fromcable bacteria. Even though the three types of protein wires are all conductive, the cable bacteria’s protein wires stand out because their activation energy of conductance is much lower than that of the other nanowires and because they transport electrons over centimeter instead of micrometer distances. These differences suggest they have a distinct charge transport mechanism. To put different transport mechanisms in more context, metallic conduction, semiconduction, and hopping conduction are treated side by side and emphasis is placed on the temperature dependence of conductivity....BT/Environmental Biotechnolog
Het aromatiseren (BTX) van IC5-crude" ex nafta kraker DOW Chemicals
No full textDocument(en) uit de collectie Chemische ProcestechnologieDelftChemTechApplied Science
A Cross-System Comparison of Dark Carbon Fixation in Coastal Sediments
No full textDark carbon fixation (DCF) by chemoautotrophic microorganisms can sustain food webs in the seafloor by local production of organic matter independent of photosynthesis. The process has received considerable attention in deep sea systems, such as hydrothermal vents, but the regulation, depth distribution, and global importance of coastal sedimentary DCF have not been systematically investigated. Here we surveyed eight coastal sediments by means of stable isotope probing (13C-DIC) combined with bacterial biomarkers (phospholipid-derived fatty acids) and compiled additional rates from literature into a global database. DCF rates in coastal sediments range from 0.07 to 36.30 mmol C m−2 day−1, and there is a linear relation between DCF and water depth. The CO2 fixation ratio (DCF/CO2 respired) also shows a trend with water depth, decreasing from 0.09 in nearshore environments to 0.04 in continental shelf sediments. Five types of depth distributions of chemoautotrophic activity are identified based on the mode of pore water transport (advective, bioturbated, and diffusive) and the dominant pathway of microbial sulfur oxidation. Extrapolated to the global coastal ocean, we estimate a DCF rate of 0.04 to 0.06 Pg C year−1, which is less than previous estimates based on indirect measurements (0.15 Pg C year−1), but remains substantially higher than the global DCF rate at deep sea hydrothermal vents (0.001–0.002 Pg C year−1).BT/Environmental Biotechnolog
Assessment of Acculturation: Issues and Overview of Measures
No full textPublicly available acculturation measures are systematically reviewed based on three criteria: scale descriptors (name of the scale, authors, year, target group, age group, subscales, and number of items), psychometric properties (reliabilities) and conceptual and theoretical structure (acculturation conditions, acculturation orientations, acculturation outcomes, acculturation attitudes, acculturation behaviors, conceptual model and life domains). Majority of the reviewed acculturation measures are short, single-scale instruments that are directed to specific target groups. Additionally, they mainly assess behavioral acculturation outcomes than acculturation conditions and orientations. Regarding the psychometric properties; most measures have an adequate internal consistency; yet cross-cultural validity of the instruments have not been reported. Guidelines for choosing or developing acculturation instruments are provided in the chapter
The impact of street canyon morphology and traffic volume on NO<sub>2</sub> values in the street canyons of Antwerp
No full textAir pollution remains a major environmental and health concern in urban environments, especially in street canyons that show increased pollution levels due to a lack of natural ventilation. Previous studies have investigated the relationship between street canyon morphology and in-canyon pollution levels. However, these studies are typically limited to the scale of a single street canyon and city-wide assessments on this matter are scarce. In 2018, NO2 concentrations were measured in 321 street canyons in the city of Antwerp (Belgium) as part of the large-scale citizen-science project “CurieuzeNeuzen”. In our research, this data was used to study the correlation between morphological indices (e.g. aspect ratio (AR), lateral aspect ratio (LAR), presence of trees) and the traffic volumes on a city-wide scale. The maximum hourly traffic volume (TVmax) and AR correlated significantly with the measured NO2 values, making them useful indicators for air quality in street canyons. For street canyons with AR > 0.65, a TVmax of 300 vehicles/hour was found as a threshold value to guarantee acceptable air quality. No significant correlations were found for the other parameters. Finally, a number of typical street canyon types were defined, which can be of fundamental interest for further research and spatial policy making.BT/Environmental Biotechnolog
Validation and optimization of the ATMO-Street air quality model chain by means of a large-scale citizen-science dataset
No full textDetailed validation of air quality models is essential, but remains challenging, due to a lack of suitable high-resolution measurement datasets. This is particularly true for pollutants with short-scale spatial variations, such as nitrogen dioxide (NO2). While street-level air quality model chains can predict concentration gradients at high spatial resolution, measurement campaigns lack the coverage and spatial density required to validate these gradients. Citizen science offers a tool to collect large-scale datasets, but it remains unclear to what extent such data can truly increase model performance. Here we use the passive sampler dataset collected within the large-scale citizen science campaign CurieuzeNeuzen to assess the integrated ATMO-Street street-level air quality model chain. The extensiveness of the dataset (20.000 sampling locations across the densely populated region Flanders, ∼1.5 data points per km2) allowed an in-depth model validation and optimization. We illustrate generic techniques and methods to assess and improve street-level air quality models, and show that considerable model improvement can be achieved, in particular with respect to the correct representation of the small-scale spatial variability of the NO2-concentrations. After model optimization, the model skill of the ATMO-Street chain significantly increased, passing the FAIRMODE model quality threshold, and thus substantiating its suitability for policy support. More generally, our results reveal how a “deep validation” based on extensive spatial data can substantially improve model performance, thus demonstrating how air quality modelling can benefit from one-off large-scale monitoring campaigns.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.BT/Environmental Biotechnolog
A model analysis of centimeter-long electron transport in cable bacteria
No full textThe recent discovery of cable bacteria has greatly expanded the known length scale of biological electron transport, as these multi-cellular bacteria are capable of mediating electrical currents across centimeter-scale distances. To enable such long-range conduction, cable bacteria embed a network of regularly spaced, parallel protein fibers in their cell envelope. These fibers exhibit extraordinary electrical properties for a biological material, including an electrical conductivity that can exceed 100 S cm −1. Traditionally, long-range electron transport through proteins is described as a multi-step hopping process, in which the individual hopping steps are described by Marcus electron transport theory. Here, we investigate to what extent such a classical hopping model can explain the conductance data recorded for individual cable bacterium filaments. To this end, the conductive fiber network in cable bacteria is modelled as a set of parallel one-dimensional hopping chains. Comparison of model simulated and experimental current(I)/voltage(V) curves, reveals that the charge transport is field-driven rather than concentration-driven, and there is no significant injection barrier between electrodes and filaments. However, the observed high conductivity levels (>100 S cm −1) can only be reproduced, if we include much longer hopping distances (a > 10 nm) and lower reorganisation energies (λ < 0.2 eV) than conventionally used in electron relay models of protein structures. Overall, our model analysis suggests that the conduction mechanism in cable bacteria is markedly distinct from other known forms of long-range biological electron transport, such as in multi-heme cytochromes.BT/Environmental BiotechnologyQN/Blanter GroupQN/van der Zant La
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