Physiology of the polyextremophile Natranaerobaculum magadiense

Concrete is a strong, durable and cheap material. Its main problem is cracking, inducing to major problems like sulphate and chloride attacks, carbonation and decalcification. Repairing concrete can be very costly. The solution is the Self Healing Concrete. A sustainable, reliable, economical, in long term, and stable concept. Based on an aerobic spore-forming bacteria introduced in concrete and whenever there was a crack and water came in, the bacteria would start precipitating CaCO3. Concrete can be found also in oil wells. Due to high temperatures and pressures, suffers a lot of stresses and tensions. In Aarhus University, researchers decided to apply the Self Healing Cement in this anaerobic environment. A proper bacteria needed to be found to handle such conditions. Natranaerobaculum magadiense (N. magadiense) was the bacteria to be studied. The project is centred on the precipitation of CaCO3 induced by N. magadiense. The main goal of this work was to study the physiology of N. magadiense at different conditions. It was investigated its behaviour in terms of extreme conditions, since it is a polyextremophile. The project tests involved a reduction of carbonate (HCO –3 ) from the optimum media, that conflict with microbial CaCO3 precipitation. N. magadiense’s behaviour when the pH was changed. A carbon source replacement to measure the CO2=CO 2–3 production and extreme conditions were applied and the results were evaluated. We proved that N. magadiense cannot grow without carbonates. It was not found a good replacement carbon source. [HCO –3 ] cannot be reduced a lot, and [NaCl] cannot be a replacement compound, since [Cl– ] inhibited the cells, and it is not recommended to change the pH. The iron reduction process is more noticeable at lower temperatures and the fermentative process is at higher temperatures. In conclusion, N. magadiense is a good candidate to be used in the oil industry but more research is needed to move to its application

Concurrent Carbon Capture and Biocementation through the Carbonic Anhydrase (CA) Activity of Microorganisms -a Review and Outlook, Environmental Processes

Biocementation, i.e., the production of biomimetic cement through the metabolic activity of microorganisms, offers exciting new prospects for various civil and environmental engineering applications. This paper presents a systematic literature review on a biocementation pathway, which uses the carbonic anhydrase (CA) activity of microorganisms that sequester CO2 to produce biocement. The aim is the future development of this technique for civil and (geo-)environmental engineering applications towards CO2-neutral or negative processes. After screening 248 potentially relevant peer-reviewed journal papers published between 2002 and 2023, 38 publications studying CA-biocementation were considered in the review. Some of these studies used pure CA enzyme rather than bacteria-produced CA. Of these studies, 7 used biocementation for self-healing concrete, 6 for CO2 sequestration, 10 for geotechnical applications, and 15 for (geo-)environmental applications. A total of 34 bacterial strains were studied, and optimal conditions for their growth and enzymatic activity were identified. The review concluded that the topic is little researched; more studies are required both in the laboratory and field (particularly long-term field experiments, which are totally lacking). No studies on the numerical modelling of CA-biocementation and the required kinetic parameters were found. The paper thus consulted the more widely researched field of CO2 sequestration using the CA-pathway, to identify other microorganisms recommended for further research and reaction kinetic parameters for numerical modelling. Finally, challenges to be addressed and future research needs were discussed

Concurrent Carbon Capture and Biocementation through the Carbonic Anhydrase (CA) activity of microorganisms ‑ a review and outlook

Biocementation, i.e., the production of biomimetic cement through the metabolic activity of microorganisms, offers exciting new prospects for various civil and environmental engineering applications. This paper presents a systematic literature review on a biocementation pathway, which uses the carbonic anhydrase (CA) activity of microorganisms that sequester CO2 to produce biocement. The aim is the future development of this technique for civil and (geo-)environmental engineering applications towards CO2-neutral or negative processes. After screening 248 potentially relevant peer-reviewed journal papers published between 2002 and 2023, 38 publications studying CA-biocementation were considered in the review. Some of these studies used pure CA enzyme rather than bacteria-produced CA. Of these studies, 7 used biocementation for self-healing concrete, 6 for CO2 sequestration, 10 for geotechnical applications, and 15 for (geo-)environmental applications. A total of 34 bacterial strains were studied, and optimal conditions for their growth and enzymatic activity were identified. The review concluded that the topic is little researched; more studies are required both in the laboratory and field (particularly long-term field experiments, which are totally lacking). No studies on the numerical modelling of CA-biocementation and the required kinetic parameters were found. The paper thus consulted the more widely researched field of CO2 sequestration using the CA-pathway, to identify other microorganisms recommended for further research and reaction kinetic parameters for numerical modelling. Finally, challenges to be addressed and future research needs were discussed

Advancements in bacteria based self-healing concrete and the promise of modelling

In the last two decades self-healing of concrete through microbial based carbonate precipitation has emerged as a promising technology for making concrete structures more resilient and sustainable. Currently, progress in the field is achieved mainly through physical experiments, but their duration and cost are barriers to innovation and keep the number of large scale applications still very limited. Modelling and simulation of the phenomena underlying microbial based healing of concrete may provide a key to complement the experimental efforts, but their development is still in its infancy. In this review, we briefly present the field, introduce some key aspects emerged from the experiments, present the main ongoing developments in modelling and simulation of mineral and microbial systems, and discuss how their synergy may be accomplished to speed up progress in the near future

Mathematical prediction of the compressive strength of bacterial concrete using gene expression programming

The impact of microbial calcium carbonate on concrete strength has been extensively evaluated in the literature. However, there is no predicted equation for the compressive strength of concrete incorporating ureolytic bacteria. Therefore, in the present study, 69 experimental tests were taken into account to introduce a new predicted mathematical formula for compressive strength of bacterial concrete with different concentrations of calcium nitrate tetrahydrate, urea, yeast extract, bacterial cells and time using Gene Expression Programming (GEP) modelling. Based on the results, statistical indicators (MAE, RAE, RMSE, RRSE, R and R2) proved the capability of the GEP 2 model to predict compressive strength in which minimum error and high correlation were achieved. Moreover, both predicted and actual results indicated that compressive strength decreased with the increase in nutrient concentration. In contrast, the compressive strength increased with increased bacterial cells concentration. It could be concluded that GEP2 were found to be reliable and accurate compared to that of the experimental results

Development of an electrical resistance-based corrosion monitoring system for offshore applications.

La imagen de la página 62 está sujeta a confidencialidad por la autora. 124 p.El objetivo principal de la tesis es el desarrollo de un sistema de monitorización remota de la corrosión para estructuras off-shore (eólica y oil & gas). Mediante este sistema se pretende medir en forma remota la velocidad de corrosión de estructuras expuestas a un medio altamente agresivo como el marino, y así conocer en tiempo real el estado de salud de las estructuras en servicio, permitiendo reducir costes de mantenimiento y reparación, etc. Las condiciones de trabajo de las estructuras offshore representan diversos retos científico-tecnológicos: El ambiente corrosivo y los fenómenos combinados de corrosión-fatiga, corrosión bajo tensión, tribocorrosión, los esfuerzos mecánicos debido al viento, olas, bloques de hielo flotante, la fragilización por hidrógeno, el biofouling en la parte sumergida, son algunos de ellos. Si bien se han llevado a cabo múltiples trabajos en el diseño de materiales y componentes offshore con el objetivo principal de incrementar la vida útil de los mismos, las condiciones extremas de trabajo a la que están sometidos estos materiales siguen representando un desafío que necesita de nuevos desarrollos.En la presente tesis se recogen sendos estados del arte relacionados con las diversas estructuras marinas susceptibles de ser monitorizadas por este sistema, los fenómenos de corrosión y como afectan a los materiales de interés, y estrategias sobre la protección frente a la corrosión y la monitorización de la misma. Paralelamente, se hace hincapié en el efecto de las bacterias sulfatoreductoras en la aleación de acero al carbono HSLA de grado R5 escogido en el presente proyecto. Se detalla la caracterización del acero HSLA empleado, su comportamiento frente a la corrosión comparado con otras aleaciones, una caracterización metalográfica completa que avala el uso del presente material en líneas de fondeo.Finalmente, se detalla de manera cronológica el desarrollo del sensor de corrosión basado en la técnica de la resistencia eléctrica, así como la caracterización de fenómenos parásitos asociados a las medidas de baja y ultra-baja resistencia sobre el que se basa el funcionamiento del sensor

Ono: an open platform for social robotics

In recent times, the focal point of research in robotics has shifted from industrial ro- bots toward robots that interact with humans in an intuitive and safe manner. This evolution has resulted in the subfield of social robotics, which pertains to robots that function in a human environment and that can communicate with humans in an int- uitive way, e.g. with facial expressions. Social robots have the potential to impact many different aspects of our lives, but one particularly promising application is the use of robots in therapy, such as the treatment of children with autism. Unfortunately, many of the existing social robots are neither suited for practical use in therapy nor for large scale studies, mainly because they are expensive, one-of-a-kind robots that are hard to modify to suit a specific need. We created Ono, a social robotics platform, to tackle these issues. Ono is composed entirely from off-the-shelf components and cheap materials, and can be built at a local FabLab at the fraction of the cost of other robots. Ono is also entirely open source and the modular design further encourages modification and reuse of parts of the platform

A Review on Cementitious Self-Healing and the Potential of Phase-Field Methods for Modeling Crack-Closing and Fracture Recovery

Improving the durability and sustainability of concrete structures has been driving the enormous number of research papers on self-healing mechanisms that have been published in the past decades. The vast developments of computer science significantly contributed to this and enhanced the various possibilities numerical simulations can offer to predict the entire service life, with emphasis on crack development and cementitious self-healing. The aim of this paper is to review the currently available literature on numerical methods for cementitious self-healing and fracture development using Phase-Field (PF) methods. The PF method is a computational method that has been frequently used for modeling and predicting the evolution of meso- and microstructural morphology of cementitious materials. It uses a set of conservative and non-conservative field variables to describe the phase evolutions. Unlike traditional sharp interface models, these field variables are continuous in the interfacial region, which is typical for PF methods. The present study first summarizes the various principles of self-healing mechanisms for cementitious materials, followed by the application of PF methods for simulating microscopic phase transformations. Then, a review on the various PF approaches for precipitation reaction and fracture mechanisms is reported, where the final section addresses potential key issues that may be considered in future developments of self-healing models. This also includes unified, combined and coupled multi-field models, which allow a comprehensive simulation of self-healing processes in cementitious material