Quantification of the service life extension and environmental benefit of chloride exposed self-healing concrete

Formation of cracks impairs the durability of concrete elements. Corrosion inducing substances, such as chlorides, can enter the matrix through these cracks and cause steel reinforcement corrosion and concrete degradation. Self-repair of concrete cracks is an innovative technique which has been studied extensively during the past decade and which may help to increase the sustainability of concrete. However, the experiments conducted until now did not allow for an assessment of the service life extension possible with self-healing concrete in comparison with traditional (cracked) concrete. In this research, a service life prediction of self-healing concrete was done based on input from chloride diffusion tests. Self-healing of cracks with encapsulated polyurethane precursor formed a partial barrier against immediate ingress of chlorides through the cracks. Application of self-healing concrete was able to reduce the chloride concentration in a cracked zone by 75% or more. As a result, service life of steel reinforced self-healing concrete slabs in marine environments could amount to 60-94 years as opposed to only seven years for ordinary (cracked) concrete. Subsequent life cycle assessment calculations indicated important environmental benefits (56%-75%) for the ten CML-IA (Center of Environmental Science of Leiden University-Impact Assessment) baseline impact indicators which are mainly induced by the achievable service life extension

Effect of Polyurethane Viscosity on Self-Healing Efficiency of Cementitious Materials Exposed to High Temperatures from Sun Radiation

Insulated concrete elements used in building facades, e.g.,sandwich panels, are frequently exposed to sun radiation, which causes high temperatures on the outside. Although the inner and outer cladding are supposed to be independent, a high temperature difference between the outside and the inside of the elements causes thermal bending, which can lead to cracking. These cracks may have an impact on the durability of the outer cladding and are not wanted from an esthetic point of view. A possible solution for this problem is the embedment of encapsulated polyurethane in the concrete matrix in order to repair cracks autonomously. However, healing agents with suitable properties are needed to heal cracks at these conditions. In this research, newly developed polyurethane resins with relatively high viscosity were tested for their healing efficiency at high temperatures. The mechanical properties of the polyurethanes such as bond strength and elasticity were determined. Second, the healing agents were encapsulated and evaluated for their efficiency to heal cracks by capillary absorption tests, strength regain evaluation, and X-ray computed tomography. The new polyurethanes were much more elastic than the commercially available ones and thus more able to withstand opening and closing of cracks due to temperature changes. The water ingress in specimens with healed cracks was found to decrease with increasing viscosity of the polyurethanes. At a temperature of 50 degrees C, the polyurethanes were able to heal cracks so that the water absorption of cracked mortar was reduced to a value that was comparable to the water absorption of uncracked mortar. Also, a strength regain of 100% or more was obtained. Therefore, using self-healing concrete in building facades may have a positive effect on the durability and service life of the construction elements. (c) 2018 American Society of Civil Engineers

Modelling heat and moisture transport in porous materials with CFD for building applications

Paper presented at the 8th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Mauritius, 11-13 July, 2011.Heat and moisture transport in buildings have a large impact on the building envelope durability, the energy consumption in buildings and the indoor climate. Nowadays HAM (Heat, Air and Moisture) models are widely used to simulate and predict the effect of these transport phenomena in detail. Recently these HAM models are being coupled to CFD (Computational Fluid Dynamics) to study the moisture exchange between air and porous materials on a local scale (microclimates). A direct coupling approach between CFD and HAM is applied. The transport equations for heat and moisture in a porous material are directly implemented into an existing CFD package and the transport equations in the air and in the porous material are solved in one iteration by only one solver. In this paper a model for moisture transport in the hygroscopic range and over-hygroscopic range is developed. This way a broad range of problems can be tackled such as drying phenomena and interstitial condensation in building components. The model is verified and validated with data from literature.mp201

Post-operative atrial fibrillation: a maze of mechanisms

Post-operative atrial fibrillation (POAF) is one of the most frequent complications of cardiac surgery and an important predictor of patient morbidity as well as of prolonged hospitalization. It significantly increases costs for hospitalization. Insights into the pathophysiological factors causing POAF have been provided by both experimental and clinical investigations and show that POAF is ‘multi-factorial’. Facilitating factors in the mechanism of the arrhythmia can be classified as acute factors caused by the surgical intervention and chronic factors related to structural heart disease and ageing of the heart. Furthermore, some proarrhythmic mechanisms specifically occur in the setting of POAF. For example, inflammation and beta-adrenergic activation have been shown to play a prominent role in POAF, while these mechanisms are less important in non-surgical AF. More recently, it has been shown that atrial fibrosis and the presence of an electrophysiological substrate capable of maintaining AF also promote the arrhythmia, indicating that POAF has some proarrhythmic mechanisms in common with other forms of AF. The clinical setting of POAF offers numerous opportunities to study its mechanisms. During cardiac surgery, biopsies can be taken and detailed electrophysiological measurements can be performed. Furthermore, the specific time course of POAF, with the delayed onset and the transient character of the arrhythmia, also provides important insight into its mechanisms

Whole-chromosome hitchhiking driven by a male-killing endosymbiont.

Neo-sex chromosomes are found in many taxa, but the forces driving their emergence and spread are poorly understood. The female-specific neo-W chromosome of the African monarch (or queen) butterfly Danaus chrysippus presents an intriguing case study because it is restricted to a single 'contact zone' population, involves a putative colour patterning supergene, and co-occurs with infection by the male-killing endosymbiont Spiroplasma. We investigated the origin and evolution of this system using whole genome sequencing. We first identify the 'BC supergene', a broad region of suppressed recombination across nearly half a chromosome, which links two colour patterning loci. Association analysis suggests that the genes yellow and arrow in this region control the forewing colour pattern differences between D. chrysippus subspecies. We then show that the same chromosome has recently formed a neo-W that has spread through the contact zone within approximately 2,200 years. We also assembled the genome of the male-killing Spiroplasma, and find that it shows perfect genealogical congruence with the neo-W, suggesting that the neo-W has hitchhiked to high frequency as the male-killer has spread through the population. The complete absence of female crossing-over in the Lepidoptera causes whole-chromosome hitchhiking of a single neo-W haplotype, carrying a single allele of the BC supergene and dragging multiple non-synonymous mutations to high frequency. This has created a population of infected females that all carry the same recessive colour patterning allele, making the phenotypes of each successive generation highly dependent on uninfected male immigrants. Our findings show how hitchhiking can occur between the physically unlinked genomes of host and endosymbiont, with dramatic consequences

The European Reference Genome Atlas: piloting a decentralised approach to equitable biodiversity genomics.

ABSTRACT: A global genome database of all of Earth’s species diversity could be a treasure trove of scientific discoveries. However, regardless of the major advances in genome sequencing technologies, only a tiny fraction of species have genomic information available. To contribute to a more complete planetary genomic database, scientists and institutions across the world have united under the Earth BioGenome Project (EBP), which plans to sequence and assemble high-quality reference genomes for all ∼1.5 million recognized eukaryotic species through a stepwise phased approach. As the initiative transitions into Phase II, where 150,000 species are to be sequenced in just four years, worldwide participation in the project will be fundamental to success. As the European node of the EBP, the European Reference Genome Atlas (ERGA) seeks to implement a new decentralised, accessible, equitable and inclusive model for producing high-quality reference genomes, which will inform EBP as it scales. To embark on this mission, ERGA launched a Pilot Project to establish a network across Europe to develop and test the first infrastructure of its kind for the coordinated and distributed reference genome production on 98 European eukaryotic species from sample providers across 33 European countries. Here we outline the process and challenges faced during the development of a pilot infrastructure for the production of reference genome resources, and explore the effectiveness of this approach in terms of high-quality reference genome production, considering also equity and inclusion. The outcomes and lessons learned during this pilot provide a solid foundation for ERGA while offering key learnings to other transnational and national genomic resource projects.info:eu-repo/semantics/publishedVersio

Intramyocardial paravalvular abscess after aortic valve replacement

Myocardial abscess is a rare but life-threatening disease with various clinical presentations. We describe the case of a paravalvular abscess distending intramurally 7 years post surgery for aortic valve replacement. Early detection and urgent surgical intervention is essential for this otherwise fatal disease entity