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In this master thesis work calcination parameters' impact on the resulting quicklimes slaking reactivity is investigated. This is done by calcination of three different sedimentary limestones in an N2 atmosphere according to a design of experiment matrix. The limestones are from Wolica Poland, Slite Sweden and Jutjärn Sweden. The temperatures and residence times are varied between 1000ºC, 1050ºC, and 1100ºC for 5 min, 27.5 min, and 60 min. There were seven experiments per limestone sample. The calcination experiments were conducted in an electrical muffle furnace.When the limestone samples were calcined, the resulting quicklimes slaking reactivity was tested according to standard SS-EN 459-2:2010 Building lime - Part 2: Test methods. Four different parameters were used to determine the slaking reactivity, these were the maximum temperature, how much the temperature increases under the initial 30 s, the time it takes for the temperature to reach 60ºC, and the time for the slaking to become 80% finished.From the slaking reactivity experiments, the calcination parameters to produce the most reactive quicklime for the limestone from Wolica and Jutjärn are 1000ºC for 60 min, and for the limestone from Slite 1100ºC for 5 min. For all three limestones the least reactive quicklime was received by calcining at 1100ºC for 60 min. The most and least reactive quicklimes were analyzed in SEM, where it could be seen that the least reactive quicklime samples were coarser compared to the most reactive samples. Depending on what slaking reactivity parameter is of interest, the calcination settings should be different and can be an indication for operation parameters for industrial kilns. The statistical analysis on the experimental model showed that the experiment had a poor statistical fit for most of the experiment. This could be due to that the model possibly was too simple to describe the calcination parameters complex impact on the slaking reactivity.

Continuous efforts have been directed towards controlled calcium carbonate biomineral synthesis in recent years. Compared to their inorganic counterparts, biominerals are more tensile in industrial applications, biocompatible with scientific designs, and sustainable for the environment. Most current approaches for synthetic biomineral production rely heavily on sophisticated engineering techniques to constrain the physical property of their crystals, which limits the adaptability of these products. Here, we proposed a novel approach to synthesize calcium carbonate biominerals by reproducing skeletogenesis of the sea urchin larva in vitro using common cellular and molecular methods. Skeleton formation in Lytechinus variegatus sea urchin embryos is a highly coordinated event, where ectodermal cells in different domains express distinct patterning cues that are received by adjacent primary mesenchyme cells (PMCs), which in turn secrete the skeleton. Our group and others have identified a range of skeletal patterning cues, and based on our current understanding of the mechanism, we envisioned a synthetic ectoderm culture using defined ectodermal lineages that, when combined with PMCs, will direct the synthetic production of skeletal structures. Here we have developed a detailed protocol for establishing such as ectoderm culture and have begun initial experiments towards this goal. Future deployment of this protocol will provide invaluable insights into the mechanism of skeletal patterning in sea urchins, as well as an unprecedented system for customized synthetic calcium carbonate biomineral production. Finally, improving our mechanistic understanding of skeletal patterning in echinoderms has the potential to shed light on analogous biomineralization processes in other species as well. / 2024-10-03T00:00:00Z

Groundwater quality in karst systems is difficult to monitor because the extreme heterogeneity within the recharge area and complex subsurface flow network makes flowpaths and travel rates difficult to predict. Understanding how flowpaths vary during storm events is important because water transmitted through conduit flowpaths can travel fast, may come from long distances, and has little filtration of contaminants. The hypothesis tested in this project is that ion ratios in spring discharge will show the timing of changes from diffuse to quick flow depending on storm intensity and antecedent conditions and provide more detail than total ion conductivity. Cedar Run Spring is located in the Cumberland Valley of south-central Pennsylvania. The valley is part of the larger Great Valley Section and is composed of Cambro-Ordovician aged carbonate units, collectively known as the Cumberland Valley Sequence. Initial background monitoring with data loggers and monthly samples indicated that Cedar Run Spring had a conduit component within the flow network. An automated stormwater sampler was installed at the spring and collected twenty-four water samples for major-ion analysis. Storm-intensity conditions ranged from high to low for the four storm events collected. In addition, the antecedent conditions varied from wet to dry. The Mg/Ca ratio characterizes the flowpath through which the water moves. A higher ratio indicates more diffuse flow because slower flow paths are needed to dissolve dolomite (which contains Mg), while a lower ratio indicates more conduit flow because calcite (Ca dominant) dissolves more readily. Hysteresis loops of conductivity versus discharge rotated counterclockwise because conductivity decreased on the rising limb of storm response, followed by an increase on the falling limb for all but the winter storm, which was influenced by road salt. In contrast, hysteresis loops for Mg/Ca versus discharge rotated in a clockwise direction for all but one of the storm events because of an increase in Mg/Ca that indicated a flush of older matrix water. The storm event that did not display in initial increase in Mg/Ca was apparently flushed by a recent previous storm event. Mg/Ca hysteresis for the storm events that were diffuse displayed several sharp increases and decrease in addition to several smaller hysteresis loops in response to multiple slugs of recharge water. These variations were not indicated in overall conductivity. High intensity events displayed a quick switch in flowpaths, as indicated by the increase in Mg/Ca early on the rising limb, and a single hysteresis loop. The rapid change in Mg/Ca suggested that during storm events water was able to enter the karst system through sinkholes, then activated flowpaths with older matrix water. Mg/Ca proved to be better at tracking the variability in flowpaths during storm events than the overall conductivity, because Mg/Ca is directly related to water-rock interactions. / Geology