Feasibility of Hybrid Thermoplastic Composite-Concrete Load Bearing System

Thermoplastic composites have many advantages over thermoset composites such as being recyclable, rapidly manufacturable, and more impact resistant. The goal of this thesis is to assess the feasibility of using thermoplastic composites in structural applications through literature review, mechanical testing, design of a load-bearing hybrid composite-concrete structures, and the implementation of thermoplastic composites for tensile reinforcement of concrete. The study had four objectives covering the stated goal. Conduct a literature review to direct thermoplastic material selection Characterize thermoplastic material mechanical properties using standardized mechanical testing Design a hybrid composite-reinforced concrete beam, and Develop thermoplastic shear connectors to develop composite action between thermoplastic reinforcement and concrete Initially, thermoplastics that can be reinforced with E-glass fibers to be used as a structural part were investigated. Materials were selected for experimental characterization after extensive literature review based on performance, cost and manufacturing methods. Two industry accepted processes were selected for use in fabrication: vacuum infusion, a longstanding and highly accepted process traditionally used for the manufacturing of thermoset composites; and thermoforming, a fast production process that takes advantage of many properties of thermoplastic materials. Next, properties of these materials required for structural applications were quantified through mechanical testing. These properties include the modulus of elasticity, Poisson’s ratio and the ultimate strength in tension, compression and shear in principal material directions. Having a complete list of material properties is necessary in composite design. A design for a load-bearing composite-concrete beam was developed. In conventional construction, steel reinforcing bars are used to carry the tension in a concrete beam, but steel is susceptible to corrosion. These hybrid composite-concrete structures rely on the transfer of forces (composite action) between the thermoplastic composite, which acts as reinforcement, and the concrete section of the beam. The composite action is necessary for the composite reinforcement to develop tension through shear flow at the interface. The initial design to demonstrate the use of thermoplastic composites in this manner is the fabrication of a simple prismatic beam with the bottom-face reinforced with the composite. This provides a simple structure to demonstrate the feasibility of this technology for use in structural applications. Finally, the ability of the shear connectors developed to produce composite action in the proposed beam was experimentally assessed. Hybrid composite-concrete specimens were tested in compression to assess the feasibility of shear connectors (studs) to carry the shear flow at the interface between the thermoplastic reinforcement and concrete. Conclusions and recommendations are presented in Chapter 5. Recommendations for future work include the implementation of small-scale short-beam tests in four-point bending to further assess the degree of composite action being generated in the structure. Recommendations for future research on more effectively achieving composite action in hybrid thermoplastic composite-concrete members is also addressed

A possible new approach in the prediction of late gestational hypertension: The role of the fetal aortic intima-media thickness

The aim was to determine the predictive role of combined screening for late-onset gestational hypertension by fetal ultrasound measurements, third trimester uterine arteries (UtAs) Doppler imaging, and maternal history. This prospective study on singleton pregnancies was conducted at the tertiary center of Maternal and Fetal Medicine of the University of Padua during the period between January 2012 and December 2014. Ultrasound examination (fetal biometry, fetal wellbeing, maternal Doppler study, fetal abdominal aorta intima-media thickness [aIMT], and fetal kidney volumes), clinical data (mother age, prepregnancy body mass index [BMI], and parity), and pregnancy outcomes were collected. The P value <0.05 was defined significant considering a 2-sided alternative hypothesis. The distribution normality of variables were assessed using Kolmogorov-Smirnoff test. Data were presented by mean (±standard deviation), median and interquartile range, or percentage and absolute values. We considered data from 1381 ultrasound examinations at 29 to 32 weeks’ gestation, and in 73 cases late gestational hypertension developed after 34 weeks’ gestation. The final multivariate model found that fetal aIMT as well as fetal umbilical artery pulsatility index (PI), maternal age, maternal prepregnacy BMI, parity, and mean PI of maternal UtAs, assessed at ultrasound examination of 29 to 32 weeks’ gestation, were significant and independent predictors for the development of gestational hypertension after 34 weeks’ gestation. The area under the curve of the model was 81.07% (95% confidence interval, 75.83%-86.32%). A nomogram was developed starting from multivariate logistic regression coefficients. Late-gestational hypertension could be independently predicted by fetal aIMT assessment at 29 to 32 weeks’ gestation, ultrasound Doppler waveforms, and maternal clinical parameters. Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc

Urban Voids After the Pandemic. A New Chance for Greenway

Our proposal deals with the meaning of urban voids in the post-COVID-19 period to suggest new understandings of how urban green corridors can positively affect design for healthier and more sustainable cities. According to Secchi (1986), planning through the void involves a profound revision of the way we think about the city, reversing the points of interest, proposing as polarities the spaces that do not usually emerge. The void thus becomes an opportunity, a chance to improve the structure of our urban landscape (Lopez-Pineiro, 2020). A city is a powerful place, always in motion and transformation. It has an artificial spirit full of surprises and vague limits. It is the scene of remarkable transformations that in their wildness are partially ungovernable by the designers themselves. The desire to control them leaves a series of abandoned and unfinished spaces, “holes” that live from their discontinuity with the surroundings (Labriola, 2021). During a period of crisis, like the one that we are still living with COVID-19 (Fabris et al, 2020), it is common to re-think our cities to create better places for the community. After the long period of forced distance that we lived, an evolution of public space is recommended. During the pandemic, the emptiness of our cities permitted Nature to re-appropriate its spaces. Following this trend and thinking about a new kind of public space where Nature and its inside processes are the protagonists, it is possible to intervene in our cities. The porosity of the urban fabric in towns without humans, blocked at home by the never-ending lockdowns, became a new green corridor that revealed the presence of wildlife (both fauna and flora) as part of a forgotten urban layer that turned visible again. The preservation of this new asset should be possible. The spaces to allow this change can be the abandoned and empty areas present in the contemporary city’s sick body that we can finally heal. The so-called wastelands, voids, or terrain vague, have a significant value independent from the environment in which they are inserted, showing a relationship with the contemporary city extraneous to its rhythms. For this reason, they are the perfect place for experimentation in terms of greenways, a possible starting point to re-think how green can be part of the urban texture and how to conceive public and open spaces after the nowadays crisis. The paper considers the Metropolitan City of Milan as a remarkable case study to understand the pivotal role played by urban voids in the formation of greenways and their capacity of reshaping the environmental, aesthetic and healthy dimensions of urban landscapes

Softness Matters: Effects of Compression on the Behavior of Adsorbed Microgels at Interfaces

Deformable colloids and macromolecules adsorb at interfaces, as they decrease the interfacial energy between the two media. The deformability, or softness, of these particles plays a pivotal role in the properties of the interface. In this study, we employ a comprehensive \emph{in situ} approach, combining neutron reflectometry with molecular dynamics simulations, to thoroughly examine the profound influence of softness on the structure of microgel Langmuir monolayers under compression. Lateral compression of both hard and soft microgel particle monolayers induces substantial structural alterations, leading to an amplified protrusion of the microgels into the aqueous phase. However, a critical distinction emerges: hard microgels are pushed away from the interface, in stark contrast to the soft ones, which remain steadfastly anchored to it. Concurrently, on the air-exposed side of the monolayer, lateral compression induces a flattening of the surface of the hard monolayer. This phenomenon is not observed for the soft particles as the monolayer is already extremely flat even in the absence of compression. These findings significantly advance our understanding of the pivotal role of softness on both the equilibrium phase behavior of the monolayer and its effect when soft colloids are used as stabilizers of responsive interfaces and emulsions

Exploiting anisotropic particle shape to electrostatically assemble colloidal molecules with high yield and purity

Biological and Soft Matter Physic

Prevention of congenital malformations and other adverse pregnancy outcomes with 4.0 mg of folic acid : community-based randomized clinical trial in Italy and the Netherlands

Background: In 2010 a Cochrane review confirmed that folic acid (FA) supplementation prevents the first- and second-time occurrence of neural tube defects (NTDs). At present some evidence from observational studies supports the hypothesis that FA supplementation can reduce the risk of all congenital malformations (CMs) or the risk of a specific and selected group of them, namely cardiac defects and oral clefts. Furthermore, the effects on the prevention of prematurity, foetal growth retardation and pre-eclampsia are unclear.Although the most common recommendation is to take 0.4 mg/day, the problem of the most appropriate dose of FA is still open.The aim of this project is to assess the effect a higher dose of peri-conceptional FA supplementation on reducing the occurrence of all CMs. Other aims include the promotion of pre-conceptional counselling, comparing rates of selected CMs, miscarriage, pre-eclampsia, preterm birth, small for gestational age, abruptio placentae.Methods/Design: This project is a joint effort by research groups in Italy and the Netherlands. Women of childbearing age, who intend to become pregnant within 12 months are eligible for the studies. Women are randomly assigned to receive 4 mg of FA (treatment in study) or 0.4 mg of FA (referent treatment) daily. Information on pregnancy outcomes are derived from women-and-physician information.We foresee to analyze the data considering all the adverse outcomes of pregnancy taken together in a global end point (e.g.: CMs, miscarriage, pre-eclampsia, preterm birth, small for gestational age). A total of about 1,000 pregnancies need to be evaluated to detect an absolute reduction of the frequency of 8%. Since the sample size needed for studying outcomes separately is large, this project also promotes an international prospective meta-analysis.Discussion: The rationale of these randomized clinical trials (RCTs) is the hypothesis that a higher intake of FA is related to a higher risk reduction of NTDs, other CMs and other adverse pregnancy outcomes. Our hope is that these trials will act as catalysers, and lead to other large RCTs studying the effects of this supplementation on CMs and other infant and maternal outcomes.Trial registration: Italian trial: ClinicalTrials.gov Identifier: NCT01244347.Dutch trial: Dutch Trial Register ID: NTR3161