Development of 3D printed networks in self-healing concrete

This paper presents a new form of biomimetic cementitious material, which employs 3D-printed tetrahedral mini-vascular networks (MVNs) to store and deliver healing agents to damage sites within cementitious matrices. The MVNs are required to not only protect the healing agent for a sufficient period of time but also survive the mixing process, release the healing agent when the cementitious matrix is damaged, and have minimal impact on the physical and mechanical properties of the host cementitious matrix. A systematic study is described which fulfilled these design requirements and determined the most appropriate form and material for the MVNs. A subsequent series of experiments showed that MVNs filled with sodium silicate, embedded in concrete specimens, are able to respond effectively to damage, behave as a perfusable vascular system and thus act as healing agent reservoirs that are available for multiple damage-healing events. It was also proved that healing agents encapsulated within these MVNs can be transported to cracked zones in concrete elements under capillary driving action, and produce a recovery of strength, stiffness and fracture energy

3D-printed mini-vascular networks for self-healing lime-based mortars

Climate change is exposing our built heritage to greater and more extreme hazards. Historic masonry repair technologies must evolve in response to these, promoting a new, long-term resilient preservation strategy. Drawing inspiration from the study of mini-vascular networks to develop self-healing in concrete structures, this work proposes the use of biomimetic mini-mini vascular networks (m-MVNs) for repairing cracks in lime-based mortars. The m-MVNs are 3D printed units formed by interconnected channels capable of storing and protecting healing agents that are released when threshold damage is exceeded. In the case where patching is required for restoration of historic masonry wall, m-MVNs are designed to fit completely within the mortar joint. Initial results demonstrated that m-MVNs printed from clear PLA, have a promising design capable of storing healing agents without leaking or premature curing. Future experiments will investigate the appropriateness of this design of m-MVNs to enclose suspensions of bacteria and deliver them to cracks

Ecovilas : aprendizagens, espiritualidade e ecologia

Fil: Comunello, Luciele Nardi. Pontifícia Universidade Católica do Rio Grande do Sul. Programa de Pós-Graduação em Educação; Brasil.Fil: Moura Carvalho, Isabel Cristina de. Pontifícia Universidade Católica do Rio Grande do Sul. Programa de Pós-Graduação em Educação; Brasil.Este trabalho está inserido em um projeto mais amplo que investiga a ambientalização de práticas educativas e religiosas, articulando elementos culturais, éticos e políticos imbricados nas epistemologias que fundamentam propostas de Educação Ambiental. Neste recorte abordamos práticas ecologicamente orientadas e seu entrelaçamento com a experiência de uma espiritualidade imanente, em uma Ecovila, sublinhando sua potencialidade para a compreensão da participação do mundo material na construção de sentidos em um mundo mais-quehumano. Ecovilas se apresentam como fenômeno emergente e, segundo a Rede Global de Ecovilas, propõem o combate ‘à degradação dos ambientes sociais, ecológicos e espirituais’. Os resultados apresentados provém de observação participante e entrevistas em uma Ecovila no Sul do Brasil. As informações coletadas conduziram a um diálogo com o campo da espiritualidade New Age e com as questões que são cerne da abordagem dos Novos Materialismos, além da Fenomenologia, ao problematizarem as fronteiras entre natureza-cultura. Rituais, práticas de saúde, cura e autoconhecimento, como o Temazcal, entre outras experiências vividas nesta comunidade, parecem reposicionar a relação humano-ambiente, trazendo luz aos fluxos de vida dos materiais.This paper is part of a wider research project that investigates environmentalization of religious and educational practices, intertwining cultural, ethical and political elements entangled in epistemologies that support Environmental Education. With this framework, we address ecological practices intertwined with experiences of an immanent spirituality, in an Ecovillage, stressing their potencial to comprehend materials participation on meaning production in a more-than-human world. Ecovillages are a presentification of an emergent phenomenon and, according to the Global Ecovillage Network, they propose to struggle against “the degradation of social, ecological and spiritual environments”. The presented results come from an ethnographic experience –with participant observation and interviews– in an Ecovillage in South of Brazil. The obtained information led us to a dialogue with the field of New Age, spirituality and with topics that are central in the New Materialisms approach, in addition to Phenomenology, since they address the problems on frontiers between nature-culture. Rituals, health, healing and selfknowledge practices, as Temazcal, among other experiences lived by the community, seem to replace the relation human-environment, bringing light to life flow of materials

Influence of healing agents and concrete environment on PLA 3D printed mini-vascular networks for self-healing concrete structures

The aim of this study is to investigate the effect of alkaline environment and healing agents on 3D-printed Poly Lactic Acid (PLA) mini vascular networks (MVNs) for self-healing concrete structures. PLA is an interesting thermoplastic polymer for 3D printing MVNs, due to its good mechanical property and its sustainability. Studies conducted recently on single channel MVNs also known as TETs, and dual channel MVNs, or d-TETs, have indicated that they can effectively store either a single or two-component healing agents to promote the self-healing process in concrete structures. Solubility tests and Differential Scanning Calorimetry (DSC) analysis were conducted in this study to assess the degradation of PLA polymer resulting from various factors, including the printing process, embedment of MVNs in concrete matrices, and prolonged contact with healing agents such as sodium silicate and nanolime solutions

Mechanical response and predictive modelling of vascular self-healing cementitious materials using novel healing agents

Self-healing systems represent an effective means of increasing the resilience of cementitious structures, extending service life and reducing cement production. This is achieved through the mitigation of cracking related durability problems. The success of a self-healing system is critically dependent on the selection of an appropriate healing agent, which depends upon the specific application, as well as a number of criteria including crack filling ability and the degree of mechanical healing required. In the present study, we develop modified formulations of a cyanoacrylate-based adhesive, suitable for use in a vascular self-healing cementitious material. The aim is to develop an ‘ideal’ healing agent for the self-healing system that has an extended shelf life and maximises load recovery. To this end, modified cyanoacrylates are tailored using a combination of predictive modelling and physical testing. The physical tests investigate both the mechanical, flow and chemical properties of the different healing agent formulations, including tensile strength, viscosity and curing. The predictive modelling employs a coupled chemo-mechanical model that is used to guide the physical testing programme through the prediction of the performance of different formulations. The results of the investigation show that a tailored formulation of a cyanoacrylate based healing agent increases the load recovery by 48% relative to the best performing original formulation. In addition, it is shown that the numerical model is able to predict the load response of new formulations with good accuracy

Role of Human Organic Cation Transporter 1 (hOCT1) Polymorphisms in Lamivudine (3TC) Uptake and Drug-Drug Interactions

Lamivudine (3TC), a drug used in the treatment of HIV infection, needs to cross the plasma membrane to exert its therapeutic action. Human Organic cation transporter 1 (hOCT1), encoded by the SLC22A1 gene, is the transporter responsible for its uptake into target cells. As SLC22A1 is a highly polymorphic gene, the aim of this study was to determine how SNPs in the OCT1-encoding gene affected 3TC internalization and its interaction with other co-administered drugs. HEK293 cells stably transfected with either the wild type form or the polymorphic variants of hOCT1 were used to perform kinetic and drug-drug interaction studies. Protein co-immunoprecipitation was used to assess the impact of selected polymorphic cysteines on the oligomerization of the transporter. Results showed that 3TC transport efficiency was reduced in all polymorphic variants tested (R61C, C88R, S189L, M420del, and G465R). This was not caused by lack of oligomerization in case of variants located at the transporter extracellular loop (R61C and C88R). Drug-drug interaction measurements showed that co-administered drugs [abacavir (ABC), zidovudine (AZT), emtricitabine (FTC), tenofovir diproxil fumarate (TDF), efavirenz (EFV) and raltegravir (RAL)], differently inhibited 3TC uptake depending upon the polymorphic variant analyzed. These data highlight the need for accurate analysis of drug transporter polymorphic variants of clinical relevance, because polymorphisms can impact on substrate (3TC) translocation but even more importantly they can differentially affect drug-drug interactions at the transporter level

Characterisation of innovative mortar formulations for the restoration of Roman mosaics

This contribution is focused on the study of the workability and mechanical properties of innovative mortars previously developed for preservation of ancient mosaics. The new formulations are based on the study of the Vitruvian recipe for Roman mortars, respecting the compatibility criteria with the original material. Different additives in different concentrations have been added to the previous formulations with the aim of studying their role in improving the durability, physicochemical, and rheological properties of the consolidating formulations. Preliminary slump tests were carried out to evaluate the effect of the additives on the workability of designed limebased mortars. The achieved results highlighted the benefits of the use of plant-derived gel and inorganic nanoparticles in mortar mixtures, when added in suitable concentration. Considering these results, the best mortars formulations have been selected to examine in depth their mechanical properties

O desenvolvimento de um modelo matemático para a previsão da aprovação da disciplina de cálculo 1 utilizando regressão logística/ The development of a mathematical model for the forecast on approval in calculus 1 using logistic regression

Este estudo visa identificar quais fatores são significativos na aprovação dos calouros dos cursos de engenharia da Universidade Federal do Pará (UFPA) na disciplina de Cálculo 1, a qual possui um dos maiores índices de reprovação dentro das universidades. Utilizando o software IBM SPSS Statistics, pode-se criar um banco de dados de variáveis dicotômicas e com isso fazer a regressão logística que, por meio dela, obteve-se uma função que possui como entrada as variáveis categóricas e como saída a probabilidade de passar ou não em Calculo 1. Para tanto, entrevistou-se 281 discentes que já cursaram a disciplina, respondendo à 13 perguntas (variáveis categóricas) cada. Observou-se com este estudo que existem questões (variáveis de entrada) que são mais significativas que outras e concluiu-se que a aprovação em Cálculo 1 está fortemente relacionada ao interesse e gosto pelo estudo da matemática desde a fase pré-universidade dos alunos.