A Review of the Compressive Strength Predictor Variables of Geopolymer Concrete

Having a prediction model for the geopolymer concrete (GPC) compressive strength gives Engineers an edge in project quality and cost control. Compressive strength of geopolymer concrete is dependent on various components that formed the concrete, and the curing regime. This paper is the outcome of a review of various variables (components and relationships) that influence the compressive strength of (GPC). The variables identified from the literature are; Concentration (Molarity) of the Hydroxide solution, Alkaline Liquid/Geopolymer Solids (Liquid/Binder) ratio, Sodium silicate to Sodium hydroxide ratio (SS/SH), curing time, curing temperature, Water/Geopolymer Solids ratio, age, fineness of the binder (pozzolan), rest period, admixtures and aggregates. A careful examination of the influence of each variable on compressive strength revealed that Hydroxide concentration, SS/SH, curing temperature, Alkaline Liquid/Geopolymer Solid ratio and Water/Geopolymer Solid ratio are the major determinants of GPC compressive strength

A microphysiological model of the bronchial airways reveals the interplay of mechanical and biochemical signals in bronchospasm

In asthma, the contraction of the airway smooth muscle and the subsequent decrease in airflow involve a poorly understood set of mechanical and biochemical events. Organ-level and molecular-scale models of the airway are frequently based on purely mechanical or biochemical considerations and do not account for physiological mechanochemical couplings. Here, we present a microphysiological model of the airway that allows for the quantitative analysis of the interactions between mechanical and biochemical signals triggered by compressive stress on epithelial cells. We show that a mechanical stimulus mimicking a bronchospastic challenge triggers the marked contraction and delayed relaxation of airway smooth muscle, and that this is mediated by the discordant expression of cyclooxygenase genes in epithelial cells and regulated by the mechanosensor and transcriptional co-activator Yes-associated protein. A mathematical model of the intercellular feedback interactions recapitulates aspects of obstructive disease of the airways, which include pathognomonic features of severe difficult-to-treat asthma. The microphysiological model could be used to investigate the mechanisms of asthma pathogenesis and to develop therapeutic strategies that disrupt the positive feedback loop that leads to persistent airway constriction

The More You Talk, the Worse It Is

Prior works have established the association between students’ perceptions of school discipline and both behavioral and academic outcomes. The interplay between disciplinary fairness and students’ perceptions of their rights, however, warrants further investigation. In an effort to better understand the development of students’ perceptions of school disciplinary climates amid variation in school legal environments, we identified students’ perceptions of their due process rights based on 5,490 student surveys and 86 in-depth interviews in New York, North Carolina, and California high schools. We then examine the link between students’ perceptions of their due process rights, their past experiences with school discipline, and their perceptions of school disciplinary fairness. While quantitative results reveal a negative relationship between students’ perceptions of their rights and perceptions of disciplinary fairness, our qualitative data bolster this finding and deepen our understanding of students’ perceptions, illustrating students’ complex, varied, and often vague understandings of their due process rights when faced with disciplinary sanctions. As prior work has underscored the critical relationship between students’ perceptions of their schooling experiences and educational outcomes, uncovering this negative relationship is an important step toward understanding how variation in perceptions of rights may have consequences for students’ educational outcomes