Cryptosporidium parvum is a deadly waterborne protozoan parasite that invades the gastrointestinal tract of humans and causes severe to life-threatening gastro enteric disease. Due to the ubiquitous nature of Cryptosporidium parvum in the world’s water, it is necessary to determine the source of an outbreak. Rapid detection and identification of various genotypes of Cryptosporidium are a valuable goal in determining the source of the pathogen in a human epidemic. Exploitation of gene sequences specific to species is a powerful tool detecting pathogens. Molecular beacons are one of these tools for high selectivity and specificity detection of DNA and RNA. Molecular beacon is a single strand of DNA that forms a stem and loop structure, where the stem holds the DNA together and the loop detects a target sequence. This molecular beacon detection is determined by the changes of fluorescent emissions of fluorescent dye linked to the ends of the stem. In this thesis work, a new and novel molecular beacon was designed to detect the specific sequences from the heat shock protein gene of Cryptosporidium parvum that infects humans. This probe is synthesized by the conjugation of pyrene molecules to both ends of the stem which leads to a unique feature of pyrene excimer-monomer switching molecular beacon upon the hybridization of the loop sequence with the target DNA sequence. This thesis systematically investigates the physical binding (e.g., quantum yield) and thermodynamic properties, including enthalpy, entropy, and free energy of this excimer-monomer switching molecular beacon in the presences of complimentary, mismatched, and damaged DNA, respectively, in the three phases: phase one is the molecular beacon in the stem and loop structure, phase two is the molecular beacon hybridized to its target DNA, and phase three is the molecular beacon in a random coil. The effect of magnesium concentration on the binding and thermodynamic properties was also investigated. Finally, as a comparison, a conventional fluorescence resonance energy transfer-based molecular beacon with a fluorophore at the 5’ end and quencher at the 3’ end was used to assess selectivity and sensitivity in detection of DNA-DNA hybridization.

Active nematic elastomers are a class of active materials that possess the elasticity of a rubber, and the orientational symmetry of a liquid crystal. Their constituent elements are typically elongated, cross-linked and active. The cross-linking of the elements leads to an elasticity that prevents the material to ow like a liquid. These elements are active in a sense that they continuously consume and dissipate energy, creating a state that is far-from-equilibrium. Active nematic elastomers may be a good physical model for biological systems such as the metaphase spindle, a complex biological machine that is made of an integrated assembly of microtubules and molecular motors. These motors not only cross-link the microtubules, but also actively slide them against each other, creating a highly dynamic, non-equilibrium state. The metaphase spindle, like other non-equilibrium structures in biology, has important functions to perform. During mitosis, the spindle is responsible for (1) capturing the sister chromatids, (2) bringing all the sister chromatids to the equator of the mother cell, and (3) segregating the daughter chromosome to the opposite poles of the cell. Thus, a fundamental challenge to biological physics is to understand the complex dynamics of the spindle, and similar systems, using the tools of non-equilibrium statistical mechanics. In this Thesis, we develop and explore a phenomenological model for an active nematic elastomer. We formulate the dynamics of this phenomenological model by incorporating the contribution of the active elements to the standard formulation of the hydrodynamic equations of a passive system. In a coarse-grained picture, the activity is taken into account as an extra active stress, proportional to the alignment tensor, added to the momentum equation of an otherwise passive nematic elastomer. Having obtained the equations of motion of an active nematic elastomer, we then investigate the response of the system to an external field by means of examining the structure and the stability of the modes. An active nematic elastomer has eight modes, in which six modes are propagating and two modes are massive. Out of the six propagating modes, two modes are in the longitudinal direction, linked to the density waves, and the other four modes are in the transverse direction, linked to the shear waves. The nature of these propagating modes transitions from dissipative and oscillatory, and vice versa, depending on the length scales. In particular, their stability is largely determined in the hydrodynamic limit, by a competition between the stabilizing effect of the elasticity and the destabilizing effect of the activity. In fact, the activity renormalizes the elastic coefficients down to even a negative value in some cases and thus, rendering the system linearly unstable. This is in contrast to the well-known instability of an active nematic liquid crystal, which is always linearly unstable. We then map out and discuss the stability phase diagram of the active nematic elastomer. Next, we compute and study various equal-time correlation functions of an active nematic elastomer, assuming that the noise spectra are thermal in origin. We find that they can be conveniently arranged into two terms. The first term has the exact mathematical structure of the equal-time correlation functions of a passive nematic elastomer, albeit with certain coefficients renormalized by activity. The second term, which is proportional to the activity, represents the non-equilibrium nature of an active nematic elastomer, and manifestly breaks the Fluctuation-Dissipation Theorem. We also find that (1) the displacement-displacement correlation function decays inversely with the square of the wave number for both the compressible and incompressible nematic elastomer, similar to that of a passive nematic elastomer, with elastic coefficients renormalized by the activity. (2) The density-density correlation function approaches a constant at the long wave-length limit, since the conservation of mass links the density to the rate of changes of the displacement in the longitudinal direction. (3) The director-displacement correlation function is purely imaginary, and thus the director is locked to the displacement with a (π/2) phase-shift. (3) The director-director correlation function approaches a constant value in the long-wavelength limit, instead of decaying inversely with the square of the wave number, like it would for a liquid crystal. This is because of the massive mode stems from the coupling energy, and it indicates that director in the large length scale is locked to a specific angle. These theoretical results are in qualitative agreement with the experimental measurements of the spindle. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection

Calcineurin (CaN), a heterodimeric Ca2+-calmodulin-dependent Ser/Thr phosphatase, regulates diverse pathways, from stress responses in yeast to T-cell activation and cardiac hypertrophy in humans. Calmodulin (CaM), an essential mediator of calcium–dependent signaling pathways, activates CaN in the presence of calcium by binding to an intrinsically disordered region of the enzyme and altering its conformation. My hydrodynamic studies have determined that CaM participates in a 1:1 complex with the CaM-binding domain of βCaN (CaNp, residues 400–423). To explore the molecular mechanism of CaM association with CaN, I have used spectroscopic methods to determine the calcium-dependent and domain–specific interactions of CaM with CaNp. These studies revealed that the affinity of CaM1–148 for CaNp was weak in the absence of calcium, and very high (Kd in the nM to pM range) in the presence of calcium. I have demonstrated that CaNp binding to CaM increases the calcium–binding affinity of each domain of CaM1–148 to a similar degree, thereby retaining the property of sequential calcium binding to the domains, with preference for sites in the C–domain. This allows the N–domain to lag in response to an increase in cellular calcium and perhaps contribute to the regulation of CaN in a manner distinct from that of the C–domain. NMR studies of calcium–saturated CaM1–148 demonstrated that the N–domain of CaM experienced a larger structural perturbation than the C–domain upon binding CaNp. Additional NMR studies revealed that CaNp adopts an anti–parallel orientation when bound to CaM, with the sole aromatic residue of CaNp contacting the N–domain of CaM. This contrasts with many CaM-target complexes in which the sole aromatic residue contacts the C–domain of CaM. Rigorous thermodynamic studies explored how mutations in the calcium-binding sites of mammalian CaM (mCaM) and mutations known to cause disruption of CaM–mediated ion channel regulation in Paramecia (PCaM) affected the allosteric interactions of the domains of CaM in the presence of CaNp. These studies demonstrated separable roles of the domains of CaM in recognition of CaNp. The consequences of a mutation depended upon its location within the complex. Collectively, research presented in this thesis provides insight into the mechanisms whereby the two domains of CaM contribute to recognition of CaN.

Collection of reprints from journal articles / Includes bibliographies / 1 v. (various pagings) : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (D. Sc.)--University of Adelaide, 1987

Bibliography: leaves 273-287. / xviii, 289 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The aim of this thesis is to develop a new method for the conceptual design of heat exchanger networks. The initial designs can be optimized using conventional non-linear optimization techniques in the subset of the problem's initial dimensionality. / Thesis (Ph.D.)--University of Adelaide, Dept. of Chemical Engineering, 1994

Les carbonitrures de vanadium et de niobium permettent de contrôler la taille de grain lors des traitements en phase austénitique. Une optimisation du traitement thermique nécessite de connaître l'évolution de l'état de précipitation, mais peu de données sont disponibles à présent sur le sujet. Cette étude porte sur le suivi des cinétiques de réversion des carbures de vanadium et de niobium dans l'austénite, sur deux alliages modèles de haute pureté FeCV et FeCVNb, et sur une nuance industrielle destinée à la fabrication d'aciers à ressorts. L'étude expérimentale combine plusieurs techniques expérimentales : la structure et la composition chimique des précipités sont déterminées par microscopie électronique en transmission et techniques associées (analyse EDX, imagerie HAADF), la distribution de taille des particules est mesurée par microscopie électronique à balayage (grâce à un détecteur d'électrons transmis), et la fraction volumique des précipités est suivie par dosage chimique des éléments précipités. Dans le but de prédire l'évolution de l'état de précipitation au cours du traitement d'austénitisation, un modèle de précipitation-réversion est développé. Ce modèle permet de décrire (i) l'existence d'un précipité binaire en prenant en compte l'écart à la stœchiométrie, (ii) la coexistence de deux précipités binaires indépendants, (iii) l'évolution d'une seule famille de précipités ternaires mixtes à composition chimique variable (VxNb1-xC). Ces différentes approches ont été validées sur les alliages modèles, puis appliquées aux cas de la nuance industrielle.

A miniature reciprocating expander is being developed as part of a larger program to develop a heat actuated heat pump for portable applications. By utilizing the higher energy density of liquid hydrocarbon fuels relative to batteries, a heat actuated heat pump would be able to provide cooling for much longer than motor driven units of equal weight. A prototype expander has been constructed and demonstrated to produce up to 22 W of shaft power at 2500 rpm using 60 psig, room temperature nitrogen as the input. Assuming adiabatic conditions, the expander appears to operate at up to 80% isentropic efficiency. However, when heat inflow to the expander is accounted for, the resulting polytropic efficiency is about 10% lower. In addition to experimental results, models of expander performance with different loss mechanisms are presented. These mechanisms include over- and under-expansion, in-cylinder heat transfer, clearance volume, friction, and valve pressure drop. / Graduation date: 2005

Ice formed from seawater, called sea ice, is both an important actor in and a sensitive indicator of climate change. Covering 7% of the World Ocean, sea ice damps the atmosphere-ocean exchanges of heat, radiation and momentum in polar regions. It also affects the oceanic circulation at a global scale. Recent satellite and submarine observations systems indicate a sharp decrease in the extent and volume of Arctic sea ice over the last 30 years. In addition, climate models project drastic sea ice reductions for the next century, in both hemispheres, with potentially large consequences on climate and ecosystems. Contrary to what is commonly believed, sea ice retains about 25% of the oceanic salt when it forms. As salt cannot lock in the ice crystalline lattice, it accumulates in liquid inclusions of salty water (brine). Under a temperature change, the inclusions freeze or melt and release or absorb huge amounts of latent heat. This affects heat transfer through and storage in sea ice, which may affect the mass balance of sea ice at a global scale. This is the central hypothesis of this work. In order to address this problem, the author develops two sea ice models and assesses their ability to simulate the recent evolution of the sea ice mass balance. Then, the physics of brine uptake and drainage are included in the models and sea ice desalination is investigated. Finally, the impact of sea ice salinity variations on the global sea ice mass balance is studied. The roles of sea ice thermal properties, of ice-ocean salt / fresh water fluxes and of oceanic feedbacks are evaluated. The new salinity module improves the simulation of ice and ocean characteristics compared to observations. Including salinity variations increases ice growth, reduces vertical mixing in the ocean and the ocean-to-ice heat flux. In conclusion, salinity variations should be included in future sea ice models used for climate projections.

Laszlo Tisza. / "February 26, 1960." "Reprinted from Annals of Physics, volume 13, no.1, April 1961." / Bibliography: p. 90-92. / Army Signal Corps Contract No. DA36-039 sc-78108. Dept. of the Army Project No. 3-99-20-001 Project 3-99-00-000. U.S. Air Force Contract AF49(638)-95.

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