Calcium aluminate cement (CAC) is a rapid hardening cementitious material often used in niche concrete repairs where high early-age strength and robust durability are required. This research project characterized the implications of the additions of various mineral and chemical admixtures to plain CAC to mitigate strength reductions associated with conversion, an inevitable strength reduction associated with the densification of metastable hydrates (CAH10 and C2AH8) to stable hydrates (C3AH6 and AH3). The effect of these admixtures on early-age strength development, volume change, and the correlation to macro-scale performance were reported in this dissertation. Various mixtures of CAC were investigated including: pure CAC, binary blends of CAC with fly ash (Class C) or CaCO3, and ternary blends of CAC with slag and silica fume. Characterization of the influence of these admixtures on hydration was completed using x-ray diffraction, isothermal calorimetry, and chemical shrinkage. Investigations on the implications of early-age volume change were conducted for autogenous deformation. In addition to laboratory testing, the final phase of the project was to correlate and elucidate the data generated in the laboratory to real-world field performance. Field trials were conducted to evaluate and monitor the behavior of CAC systems and investigate the link between laboratory generated research and actual large scale behavior. / text

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Portland cement hydration is an exothermic process. The heat evolved during the hydration process is especially important in mass concrete, and hot and cold weather concreting. Heat of hydration is affected by several factors like chemical composition of cement, fineness of cement and ambient temperature. The major aim of this thesis is to investigate the effect of cement composition and fineness, amount and composition of the fine portion (&lt / 45 &micro / m) of natural pozzolan-incorporated cement on hydration heat. For this purpose, a portland cement and pozzolan-incorporated blended cements containing different amounts of natural pozzolan (trass) were used. The heat of hydration was measured using isothermal calorimetry. The values of heat of hydration for mixtures with different finenesses containing different amounts of added pozzolan were determined. The results obtained were used to find a correlation between the fineness, composition of cement and heat of hydration. According to this study, pozzolan incorporation in small amounts accelerates hydration. A similar effect was obtained for higher pozzolan amounts. Finer cements react faster and result in higher amounts of early heat evolved compared to coarser cements. In addition, it was found that the sum of the heat of hydration values of fine and coarse portion of cements was less than the total heat of hydration of blended cements. Moreover, a satisfactory correlation could not be established between results of isothermal calorimetry, and adiabatic calorimetry, setting time, and strength.

abstract: Alkali-activated aluminosilicates, commonly known as "geopolymers", are being increasingly studied as a potential replacement for Portland cement. These binders use an alkaline activator, typically alkali silicates, alkali hydroxides or a combination of both along with a silica-and-alumina rich material, such as fly ash or slag, to form a final product with properties comparable to or better than those of ordinary Portland cement. The kinetics of alkali activation is highly dependent on the chemical composition of the binder material and the activator concentration. The influence of binder composition (slag, fly ash or both), different levels of alkalinity, expressed using the ratios of Na2O-to-binders (n) and activator SiO2-to-Na2O ratios (Ms), on the early age behavior in sodium silicate solution (waterglass) activated fly ash-slag blended systems is discussed in this thesis. Optimal binder composition and the n values are selected based on the setting times. Higher activator alkalinity (n value) is required when the amount of slag in the fly ash-slag blended mixtures is reduced. Isothermal calorimetry is performed to evaluate the early age hydration process and to understand the reaction kinetics of the alkali activated systems. The differences in the calorimetric signatures between waterglass activated slag and fly ash-slag blends facilitate an understanding of the impact of the binder composition on the reaction rates. Kinetic modeling is used to quantify the differences in reaction kinetics using the Exponential as well as the Knudsen method. The influence of temperature on the reaction kinetics of activated slag and fly ash-slag blends based on the hydration parameters are discussed. Very high compressive strengths can be obtained both at early ages as well as later ages (more than 70 MPa) with waterglass activated slag mortars. Compressive strength decreases with the increase in the fly ash content. A qualitative evidence of leaching is presented through the electrical conductivity changes in the saturating solution. The impact of leaching and the strength loss is found to be generally higher for the mixtures made using a higher activator Ms and a higher n value. Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR) is used to obtain information about the reaction products. / Dissertation/Thesis / M.S. Civil Engineering 2012

Heat of hydration is a property of Portland cement and a direct result of the chemical reaction between cement and water. The amount of heat released is dependent upon the cement mineralogical composition, curing temperature, water to cement ratio, and cement fineness. High temperature resulting from heat of hydration (thereon referred to as HOH) of cement can affect the hydration process, and consequently the kinetics of development of the mechanical properties of concrete. One of the main reasons triggering the interest in HOH of cement is its implication in thermal cracking of concrete. The high temperature gradient between the inner core and the outer surface of a concrete element is known to result in large tensile stresses that may exceed tensile strength, thus leading to early–age thermal cracking in mass concrete. This dissertation initially addresses accurately predicting the heat of HOH of Portland cement at seven days based on the heat flow data collected from isothermal calorimetry for a time interval of 0-84 h. This approach drastically reduces the time required to identify the seven day HOH of Portland cement. The second part of this study focuses on cement fineness and its critical role on the heat generated by Portland cement during hydration. Using a matrix of four commercially available Portland cements, representing a wide range of mineralogical composition, and subjecting each of the as-received cements to several grinding increments, a linear relationship was established between cement fineness and heat of hydration. The effect of cement fineness and mineralogical composition on HOH of Portland cement was then related through a mathematical expression to predict the HOH of Portland cement based on its mineralogical composition and fineness. Three expressions were proposed for the 1, 3 and 7 day HOH. The findings indicate that the equations developed, based on cement main phase composition and fineness, can be used to identify cements with high heat of HOH that may cause thermal cracking in mass concrete elements. Also, the equations can be used to correlate the HOH with the other properties of Portland cement for quality control and prediction of chemical and physical properties of manufactured Portland cement and concrete. Restrained shrinkage experiments results on mortar specimens prepared with cements of variable phase composition and fineness indicate that interaction of C3A and sulfate source is the prime phenomenon followed by cement fineness as the second main factor influencing concrete cracking. In order to minimize this effect, the third part of this study focused on studying alternatives that can lower the heat generated by concrete on hydration through the incorporation of nanomaterials; namely, graphene nanoparticles. The results indicate that incorporation of graphene a as replacement for Portland cement improves thermal diffusivity and electrical conductivity of the cement paste. Consequently, the use of graphene can trigger improvement of the thermal conductivity of concrete elements thus reducing the cracking potential of concrete. Measurements of HOH of graphene-cement paste, at w/c=0.5, using isothermal conduction calorimetry, indicate that incorporation of graphene up to 10% increases the length of the induction period while reduces the magnitude of the alite main hydration peak due to the filler effect. Furthermore, increasing the w/c ratio from 0.5 to 0.6 and graphene content from 1 % to 10% (as a partial replacement of cement) increases the 7 day HOH of Portland cement by 50 J/g. Isothermal conduction calorimetry heat flow curves show that incorporation of graphene particles up to 10% does not have significant effect on interaction of aluminates and sulfates sources since the time of occurrence of the C3A sulfate depletion peak is not affected by graphene substitution up to 10%. Full factorial statistical design and analysis conducted on compressive strength data of mortar specimens prepared at two w/c ratios, using cements of different finenesses and graphene content indicates that the quantity of graphene and the physical interaction due to variable w/c, graphene and cement fineness, have the smallest P-value among all the samples, representing the most significant impact on compressive strength of mortar samples. It appears that in graphene cement paste composites, addition of 1% graphene results in 21% reduction of Young’s modulus. Increasing the graphene content from 1% to 5% and/or 10% does not show significant effect on Young’s modulus. Similar trends can be observed in the hardness of graphene cement paste samples. In conclusion, partial replacement of Portland cement with graphene nanoparticles in concrete mixtures is a good alternative to lower the cracking potential in mass concrete elements.

Calcineurin (CaN) plays an important role in T-cell activation, cardiac system development, and nervous system function. Previous studies have suggested that the regulatory domain (RD) of CaN binds Calmodulin (CaM) towards the N-terminal end of CaN. Calcium-loaded CaM activates the serine/threonine phosphatase activity of CaN by binding to the regulatory domain, although the mechanistic details of this interaction remain unclear. It is thought that CaM binding at the RD displaces the auto inhibitory domain (AID) from the active site of CaN, which activates phosphatase activity. In the absence of calcium-loaded CaM, the RD is at least partially disordered, and binding of CaM induces folding in the RD. Previous studies have shown that an ?-helical structure forms in the N-terminal half of the RD, but organization may occur in the C-terminal region as well. Here, we are presenting a model for the structural transition of the full length RD as it binds to CaM. Using nuclear magnetic resonance (NMR) spectroscopy, we have successfully assigned >85% of the 15N, 13C?, 13C? and HN chemical shifts of the unbound, regulatory domain of CaN. Secondary chemical shifts support a model where the RD is highly disordered. Our study of the CaM and CaN interaction supports the formation of a distal helix in the region between the AID and calmodulin-binding region. Heat capacity changes upon binding predict that 43 residues fold when CaM binds to CaN, consistent with the formation of this distal helix. Paramagnetic relaxation enhancement (PRE) studies of this interaction suggest a potential binding mode where the distal helix binds to CaM near residues I10-A11. Mutagenesis in the distal helix disrupts PREs, further supporting this hypothesis. Together, these data suggest that the interactions between CaM and the distal helix of CaN can be important in regulation of phosphatase activity.

Protein bars have become a popular option among consumers to increase protein content in their diets. Since there is a large market for protein bars, many factors must be considered when creating a protein bar that both satisfies consumers and has a long shelf-life. Hardening and textural changes in protein bars are some of the most common modes of shelf-life failure in this product category. When the typical product creation timeline from formulation to launch can be as short as 3-6 months and with added pressure from executives to quickly launch another new product afterwards, product development scientists simply do not have time to test the full shelf life of their product before release. For this reason, it is imperative that rapid methods for detecting bar hardness and predicting shelf life of bar formulations are developed. The objective of this research is to utilize calorimetric techniques to rapidly detect and identify bar hardening reactions. Six different protein bar formulations were studied, with each containing a combination of either whey protein isolate (WPI), milk protein isolate (MPI), or partially hydrolyzed whey protein isolate (HWPI), reducing-sugar, non-reducing sugar, and vegetable shortening. All bars were stored at 45°C and ambient humidity for 21 d. Isothermal microcalorimetry (IMC) was used to evaluate bar hardening-related reactions and was compared to objective and subjective hardness measurements. Hardness, color, water activity, moisture content, and sensory evaluation were measured at d 1, 7, 14, and 21. The results of this study indicate that isothermal calorimetry may be used to narrow down bar hardening reactions and points to Maillard browning as a main driver of hardening. These techniques may be used to predict bar shelf life, if Maillard browning is used as the basis for hardening. Furthermore, this research highlights the importance of ingredient selection during bar formulation to minimize hardening.

This thesis broadly addresses the issue of materials sustainability in the production of Portland cement concrete. Two methods are presented, both aimed at achieving more sustainable concrete through the use of waste and recycled materials. The first method involves utilizing reclaimed asphalt pavement (RAP) as an aggregate in structural concrete, and the second method involves utilizing waste quarry fines as partial replacement of Portland cement in concrete mixes. Many efforts have been made in recent years to justify the use of RAP aggregates in concrete. All previous efforts appear to unanimously report a reduction in concrete performance with varying proportions of RAP usage. The poor performance of RAP aggregates in concrete is attributed mainly to a larger, more porous interfacial transition zone (ITZ) and to the cohesive failure of the asphalt. It is hypothesized that the detrimental impact on the ITZ is attributable to organic compounds leached from the asphalt in the high pH pore solution. This study proves the presence of organic compounds in the pore solution and demonstrates that there is an apparent retardation of cement hydration. This study also attempted to pretreat the RAP in a sodium hydroxide (NaOH) solution to pre-leach the organic compounds. The pretreatment demonstrated that organic compounds were leached and that NaOH modified the asphalt surface chemistry. However, only a marginal improvement in compressive strength was observed by completing the pretreatment. Replacement of Portland cement by filler products is a practice aimed at reducing the carbon footprint of concrete, such as is common with Type IL Portland limestone cement. This study investigates the impact of replacing cement with seven different quarry fines materials. The quarry fines were used to replace cement at 5% to 20% by volume in either cement paste or mortar samples that were then analyzed for various physicochemical properties. It was found that all the quarry fines had detrimental impact on the hydration kinetics of cement pastes. The inclusion of quarry fines was also found to cause varying degrees of reduction in mortar compressive strength. While further analyses of the quarry fines are required, quarry fines 2, 5 and 7 did display encouraging signs to suggest the potential for use as a filler material in blended cements. / Master of Science / This thesis broadly addresses the issue of sustainability in the cement and concrete industry. Sustainability is a significant problem for the cement and concrete industry due to the large amount of carbon emissions produced in the manufacturing process of Portland cement. One method to reduce the carbon footprint of concrete is to use recycled aggregates, and reclaimed asphalt pavement (RAP) is investigated in this thesis as a recycled aggregate option. Previous studies have shown that the use of RAP in concrete results in poor mechanical performance when compared to conventional concrete. In this thesis, the RAP was pretreated by soaking it in sodium hydroxide (NaOH) to see if any improvement is noted. It was determined that the pretreatment resulted in marginal improvements in concrete performance. Another method to reduce the carbon footprint of concrete is through the use of substitutions of Portland cement. In this thesis, quarry fines from around Virginia were investigated for potential as substitutive material. Quarry fines are a by-product from quarrying operations and are often considered a waste material because they have limited applications. This study analyzed the performance of cementitious materials prepared with various substitutive percentages of quarry fines and found that, in general, the inclusion of quarry fines resulted in a decrease of mechanical performance. In total, seven quarry fines were tested and only two showed potential for use as a substitution in Portland cement concrete. These two investigations are essential in reaching the goal of reducing the carbon footprint of the cement and concrete industry.

There is a high demand for quadruplex-specific compounds that not only bind preferentially to quadruplex DNA over duplex DNA, but also bind to one quadruplex motif over other motifs. Quadruplex structures are recognized as common occurrences in cancer cells, and if a compound could stabilize this structure, it may serve as an effective anti-cancer treatment with minimal side effects. In this study, cyanine dyes’ interactions with DNA were analyzed with fluorescence titrations, UV-Vis thermal studies, circular dichroism titrations, and surface plasmon resonance (SPR) analysis. With these techniques, binding affinity, DNA stabilization, and conformational shifts were analyzed to determine if cyanine dyes could act as quadruplex-specific binding compounds for possible cancer treatments.

Many processes in living systems occur through transient interactions among proteins. Those interactions are often weak and are driven by small changes in free energy. Due to the short-living nature of these interactions, our knowledge about driving forces, dynamics and structures of these types of protein-protein heterocomplexes are though limited. This is especially important for cellular copper (Cu) trafficking: Copper ions are essential for all eukaryotes and most bacteria. As a cofactor in many enzymes, copper is especially vital in respiration or detoxification. Since the same features that make copper useful also make it toxic, it needs to be controlled tightly. Additionally, in the reducing environment of the cytosol, Cu is present as insoluble Cu(I). To circumvent both toxicity and solubility issues, a system has evolved where copper is comforted by certain copper binding proteins, so-called Cu-chaperones. They transiently interact with each other to distribute the Cu atoms in a cell. In humans, one of them is Atox1. It binds copper with a binding site containing two thiol residues and transfers it to other binding sites, mostly those of a copper pump, ATP7B (also known as Wilsons disease protein). My work was aimed at understanding copper-mediated protein-protein interactions on a molecular and mechanistic level. Which amino acids interact with the metal? Which forces drive the transfer from one protein to the other? Using biophysical and biochemical methods such as chromatography and calorimetry on wild type and point-mutated proteins in vitro, we found that the copper is transferred via a dynamic intermediate complex that keeps the system flexible while shielding the copper against other interactions. Although similar transfer interactions can be observed in other organisms, and many conclusions in the copper field are drawn from bacterial and yeast analogs, we believe that it is important to investigate human proteins, too. Not only is their regulation different, but also only in humans we find the diseases linked to the proteins: Copper level regulation diseases are to be named first, but atypical copper levels have also been linked to tumors and amyloid dispositions. In summary, my observations and conclusions are of basic research character and can be of importance for both general copper and human medicinal research.