Doctor of Philosophy / Department of Mechanical and Nuclear Engineering / Gurpreet Singh / The inevitable depletion of fossil fuels and related environmental issues has led to exploration of alternative energy sources and storage technologies. Among various energy storage technologies, rechargeable metal-ion batteries (MIB) are at the forefront. One dominant factor affecting the performance of MIB is the choice of electrode material. This thesis reports synthesis of paper like electrodes composed for three representative layered materials (van der Waals sheets) namely reduced graphene oxide (rGO), molybdenum disulfide (MoS₂) and hexagonal boron nitride (BN) and their use as a flexible negative electrode for Li and Na-ion batteries. Additionally, layered or sandwiched structures of vdW sheets with precursor-derived ceramics (PDCs) were explored as high C-rate electrode materials. Electrochemical performance of rGO paper electrodes depended upon its reduction temperature, with maximum Li charge capacity of 325 mAh.g⁻¹ observed for specimen annealed at 900°C. However, a sharp decline in Na charge capacity was noted for rGO annealed above 500 °C. More importantly, annealing of GO in NH₃ at 500 °C showed negligible cyclability for Na-ions while there was improvement in electrode's Li-ion cycling performance. This is due to increased level of ordering in graphene sheets and decreased interlayer spacing with increasing annealing temperatures in Ar or reduction at moderate temperatures in NH₃. Further enhancement in rGO electrodes was achieved by interfacing exfoliated MoS₂ with rGO in 8:2 wt. ratios. Such papers showed good Na cycling ability with charge capacity of approx. 225.mAh.g⁻¹ and coulombic efficiency reaching 99%. Composite paper electrode of rGO and silicon oxycarbide SiOC (a type of PDC) was tested as high power-high energy anode material. Owing to this unique structure, the SiOC/rGO composite electrode exhibited stable Li-ion charge capacity of 543.mAh.g⁻¹ at 2400 mA.g⁻¹ with nearly 100% average cycling efficiency. Further, mechanical characterization of composite papers revealed difference in fracture mechanism between rGO and 60SiOC composite freestanding paper. This work demonstrates the first high power density silicon based PDC/rGO composite with high cyclic stability. Composite paper electrodes of exfoliated MoS₂ sheets and silicon carbonitride (another type of PDC material) were prepared by chemical interfacing of MoS₂ with polysilazane followed by pyrolysis . Microscopic and spectroscopic techniques confirmed ceramization of polymer to ceramic phase on surfaces on MoS₂. The electrode showed classical three-phase behavior characteristics of a conversion reaction. Excellent C-rate performance and Li capacity of 530 mAh.g⁻¹ which is approximately 3 times higher than bulk MoS₂ was observed. Composite papers of BN sheets with SiCN (SiCN/BN) showed improved electrical conductivity, high-temperature oxidation resistance (at 1000 °C), and high electrochemical activity (~517 mAh g⁻¹ at 100 mA g⁻¹) toward Li-ions generally not observed in SiCN or B-doped SiCN. Chemical characterization of the composite suggests increased free-carbon content in the SiCN phase, which may have exceeded the percolation limit, leading to the improved conductivity and Li-reversible capacity. The novel approach to synthesis of van der Waals sheets and its PDC composites along with battery cyclic performance testing offers a starting point to further explore the cyclic performance of other van der Waals sheets functionalized with various other PDC chemistries.

Modern medicine is challenged continuously by the increasing prevalence of multi-drug resistant bacteria. Therefore, the development of alternatives to traditional antibiotics is an urgent necessity. Cationic antimicrobial peptides (CAMPs) are components of the innate immune defense system. Histones, generally known as proteins that package and regulate the transcription of DNA, share all of the essential antimicrobial traits of CAMPs, and could be promising alternatives to antibiotics. In this study, I investigated the antimicrobial properties of nucleated-erythrocyte-specific linker histone H5 and its derived peptides. Histone H5 was extracted and purified from chicken erythrocytes using an acid extraction followed by ion exchange chromatography using a step salt gradient; the purity (>95%) was verified by densitometry and proteomics analysis. Purified histone H5 demonstrated potent antimicrobial activity against various Gram-positive and Gram-negative planktonic bacteria, including resistant strains such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE), as well as anti-biofilm activity against Listeria monocytogenes and Pseudomonas aeruginosa. Furthermore, scanning electron microscopy (SEM) revealed significant damage to L. monocytogenes and P. aeruginosa bacterial cell surfaces after histone H5 treatment. The potential for histone toxicity towards mammalian cells was investigated with a hemolytic assay which determined that even at the highest concentration tested (1 mg/mL), histone H5 was non-hemolytic. An in silico analysis determined the predicted antimicrobial domain of histone H5 of which six histone H5-derived peptides with potential antimicrobial activity were identified. These six histone H5-derived peptides were synthesized and tested against bacterial pathogens to determine their antimicrobial properties. Although the H5-derived peptides were identified within the predicted antimicrobial domain of histone H5, they did not possess more potent antimicrobial activity than the full length protein. Overall, this study demonstrates that histone H5 and histone H5-derived peptides could be promising candidates in the development of novel anti-infective therapeutics.

Orientador: Meuris Gurgel Carlos da Silva / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-15T16:01:50Z (GMT). No. of bitstreams: 1 Bertagnolli_Caroline_M.pdf: 6983617 bytes, checksum: 383caf10321743b4b7b79a1b893b1b0d (MD5) Previous issue date: 2010 / Resumo: Argilas bentonitas depois de submetidas a tratamentos químicos aumentam suas potencialidades para maior variedade de uso na remediação ambiental. As argilas organofílicas preparadas a partir de sais quaternários de amônio, que possuam pelo menos uma cadeia com 12 ou mais carbonos, destacam-se como adsorvente para separação de compostos orgânicos da água. Neste trabalho, foram obtidas argilas organofílicas a partir das argilas esmectitas do tipo Verde-Lodo e Bofe provenientes do município de Boa Vista - PB, utilizando os sais quaternários cloreto de cetil piridínio e cloreto de benzalcônio. A argila comercial Spectrogel, fornecida pela empresa Spectrochem também foi estudada para fins de comparação com as amostras produzidas em laboratório. O material obtido foi caracterizado por difração de raios-X, microscopia eletrônica de varredura, espectroscopia de raios-X por energia dispersiva, termogravimetria, calorimetria diferencial de varredura, espectroscopia na região do infravermelho e fisissorção de N2. As argilas modificadas tiveram sua afinidade avaliada em ensaios de capacidade de hidratação em água, sorção e expansão em derivados do petróleo, no caso, gasolina, óleo diesel, óleo lubrificante e querosene. Para o conjunto argila/derivado do petróleo que apresentou melhor comportamento e para amostra comercial, foram realizadas cinéticas de remoção e ensaios em banho finito a temperatura ambiente, para avaliar a separação deste poluente presente em meio aquoso. Os resultados da caracterização indicam a efetivação do processo de organofilização e as mudanças ocorridas na estrutura física e química das argilas. Os ensaios de capacidade de hidratação mostraram a falta de afinidade da argila modificada pela água, enquanto os ensaios de sorção e expansão confirmam o caráter organofílico, evidenciando o potencial de uso das argilas modificadas como alternativa aos tratamentos existentes para remoção de compostos orgânicos de água / Abstract: Bentonite clays organically modified with quaternary ammonium salt, whose features enable the interaction with organic compounds, have great potential use for environmental remediation such as adsorption of organic compounds from wastewater. In this work, organophilic clays 'Verde-Lodo' and 'Bofe' bentonite from the State of Paraíba (Brazil) were organofilizated by intercalation of two different quaternary salts. The surfactants used were cetyl-pyridinium chloride and benzalkonium chloride. The commercial clay Spectrogel, provided by Spectrochem, was also studied for comparison with samples produced in laboratory. The obtained material had been characterized by use of X-ray diffraction, scanning electron microscopy, energy dispersive X-ray techniques, termogravimetric analysis, differential scanning calorimetry, Fourier transform infrared spectroscopy and N2 adsorption-desorption. The organophilic character was evaluated by swelling capacity test in water. The clay likeness for petroleum derived: gasoline, diesel oil, lubricant oil and kerosene oil were defined by sorption and swelling tests. The clay/petroleum derived that showed the best performance and commercial clay were performed kinetic removal and bath sorption, to evaluate the separation of this pollutant in water. The hydrophobic and organophilic character were observed by swelling capacity test in water, sorption and swelling tests. The potential for removal of petroleum derived from wastewaters was verified, it was showing potential use for environmental remediation / Mestrado / Engenharia de Processos / Mestre em Engenharia Química

Master of Science / Department of Mechanical and Nuclear Engineering / Gurpreet Singh / Polymer-derived ceramics (PDCs) such as silicon oxycarbide (SiOC) have shown promise as an electrode material for rechargeable Li-ion batteries (LIBs) owing to the synergy between its disordered carbon phase and hybrid bonds of silicon with oxygen and carbon. In addition to their unique structure, PDCs are known for their high surface area (~822.7 m² g⁻¹), which makes them potential candidates for supercapacitor applications. However, low electrical conductivity, voltage hysteresis, and first cycle lithium irreversibility have hindered their introduction into commercial devices. One approach to improving charge storage capacity is by interfacing the preceramic polymer with boron or aluminium prior pyrolysis. Recent research has shown that chemical interfacing with elemental boron, bulk boron powders and even exfoliated sheets of boron nitride leads to enhancements in thermal and electronic properties of the ceramic. This thesis reports the synthesis of a new type of PDC composite comprising of SiOC embedded with boron nitride nanotubes (BNNTs). This was achieved through the introduction of BNNT in SiOC pre-ceramic polymer at varying wt.% loading (0.25, 0.5 and 2.0 wt.%) followed by thermolysis at high temperature. Electron microscopy and a range of spectroscopy techniques were employed to confirm the polymer-to-ceramic transformation and presence of disordered carbon phase. Transmission electron microscopy confirmed the tubular morphology of BNNT in the composite. To test the material for electrochemical applications, the powders were then made into free-standing paper-like electrodes with reduced graphene oxide (rGO) acting as support material. The synthesized free-standing electrodes were characterized and tested as electrochemical energy storage materials for LIBs and symmetric supercapacitor applications. Among the SiOC-BNNT composite paper tested as anode materials for LIBs, the 0.25 wt.% BNNT composite paper demonstrated the highest first cycle lithiation capacity corresponding to 812 mAh g⁻¹ (at a current density of 100 mA g⁻¹) with a stable charge capacity of 238 mAh g⁻¹ when asymmetrically cycled after 25 cycles. On the contrary, the 0.5 wt.% BNNT composite paper demonstrated the highest specific capacitance corresponding to 78.93 F g⁻¹ at a current density of 1 A g⁻¹ and a cyclic retention of 86% after 185 cycles. This study shows that the free carbon content of SiOC-BNNT ceramic composite can be rationally modified by varying the wt.% of BNNT. As such, the paper composite can be used as an electrode material for electrochemical energy storage.

Objectives: In this pilot study, our intention was to ascertain what formulation of a carbohydrate-derived fulvic acid (CHD-FA) topical applicator was optimal for patients to use during a larger study where the efficacy of fulvic acid (CHD-FA) in treating moderate acne vulgaris will be investigated. Methods: 15 individuals with inflammatory acne with an acne grade of III or lower were asked to volunteer for the study. They were split into 3 groups. Each group was asked to use a different formulation (a cream base, gel base and wet applicator formulation) each week. After each week, the individuals returned to fill out a questionnaire evaluating the formulation they used that week. They were also examined by the clinician for any possible side effects, and given the next formulation to use for the following week. The trial was 3 weeks long, and after using all 3 formulations the individuals were asked to fill out a final questionnaire evaluating all 3 formulations. The clinician was also asked to fill out a questionnaire giving his/her opinion on the formulations. Results: The results did not give conclusive evidence of one particular formulation being favored above all the others. All the formulations performed more or less equally as well. According to the final questionnaire, 6 out of the 15 individuals were most satisfied with the wet applicator, 4 out of 15 preferred the cream base and 5 out of 15 preferred the gel base. 5 out of 15 individuals were least satisfied with the wet applicator, 3 out of 15 with the cream base, and 7 out of 15 were least satisfied with the gel. While there was no conclusive indication for one particular formulation, there were some common complaints or observations by individuals about each formulation. Most individuals said the wet applicator had an initial burning sensation to the skin upon application, but it disappeared a few seconds after application. Many individuals said they felt the cream base was oily and made the skin appear oily after application. The gel base was said to smell the worst, along with the wet applicator, while the cream smelt the least. A few individuals complained that the gel left a residue on the skin. Conclusion: While the study did not give a clear indication of one particular formulation that was preferred by individuals, it did produce interesting results that can be used to make some of the formulations more favourable. In the main trial, further investigation will be done to optimize the formulation. / Dissertation (MSc)--University of Pretoria, 2010. / Pharmacology / unrestricted

We develop a theory of unbounded derived categories of quasi-coherent sheaves on algebraic stacks. In particular, we show that these categories are compactly generated by perfect complexes for stacks that either have finite stabilizers or are local quotient stacks. We also extend Toën and Antieau–Gepner’s results on derived Azumaya algebras and compact generation of sheaves on linear categories from derived schemes to derived Deligne–Mumford stacks. These are all consequences of our main theorem: compact generation of a presheaf of triangulated categories on an algebraic stack is local for the quasi-finite flat topology.

This thesis describes the synthesis, characterization and magnetic investigation of homometallic lanthanide complexes based on two different o-vanillin-derived Schiff base ligands: H2ovph and H2ovgrd. The studies were performed using single crystal X-ray diffractometry, Powder XRD and SQUID magnetometry. Chapter 2 focuses on dinuclear systems 1-8 coordinated to the ligand H2ovph and presents their structural and magnetic properties, mainly with respect to their intramolecular interactions. Chapter 3 describes two hexanuclear systems, 9 (DyIII) and 10 (GdIII), with trigonal prism-assembled core structures. A structural comparison to other similar complexes in the literature is performed. A series of dinuclear complexes, 11-15, based on the ligand H2ovgrd are described in Chapter 4, focusing on the synthetic strategy, crystal structures and magnetism. The presence of the lanthanide contraction is evident in this system of complexes and is consistent with the intrinsic lanthanide contraction property.

archives@tulane.edu / Human adipose-derived stem cells (ASCs) efficiently modulate the inflammatory microenvironment, making them ideal for the treatment of inflammatory, autoimmune, and neurodegenerative diseases like multiple sclerosis (MS). Clinical translation of ASC therapies has been limited, making strategies to improve ASC post-transplant immunosuppressive capabilities especially important. Autophagy, a stress-induced degradative pathway, plays a crucial role in the paracrine signaling of ASCs, which drives their therapeutic action. Therefore, I investigated the modulatory effect of autophagy preconditioning in ASC physiology and therapeutic potential using the autophagy inducer Rapamycin (Rapa-ASCs) or the inhibitor 3-methyladenine (3MA-ASCs). Following 4 and 24-hour preconditioning, ASC stemness and immunomodulatory capacity were examined. Results demonstrate that neither Rapa nor 3-MA altered morphology or surface marker expression, indicating preservation of stemness. RT-qPCR analysis revealed that 4-hour preconditioning with Rapa-ASCs and 3MA-ASCs alone upregulated transcription of cyclooxygenase-2 (COX2), but not secretion of its downstream effector molecule prostaglandin E2 (PGE2). Following stimulation with interferon-gamma (IFNγ) to mimic a pathological microenvironment, both 4-hour Rapa-ASCs and 3MA-ASCs upregulated COX2 transcription and PGE2 secretion. 4-hour Rapa-ASCs also upregulated expression of the cytokines transforming growth factor beta (TGF-β) and interleukin-6 (IL-6). As each of these molecules have demonstrated therapeutic effects in the experimental autoimmune encephalomyelitis (EAE) mouse model of MS, I hypothesized that 4-hour Rapamycin preconditioning may bestow the greatest improvement to ASC immunomodulatory potential in EAE. To test this, EAE mice were treated at peak disease severity with control ASCs (EAE-ASCs), Rapa-preconditioned ASCs (EAE-Rapa-ASCs), or a vehicle control (EAE). Results revealed that EAE-ASCs enhanced rotarod locomotor activity, improved clinical disease scores, and elevated intact myelin in the spinal cord compared to both EAE and EAE-Rapa-ASC animals. This correlated with augmented CD4+ T helper (Th) and T regulatory (Treg) cells in the spinal cord, and significantly increased interleukin-10 (IL-10) transcripts. Conversely, EAE-Rapa-ASC mice showed no clinical or motor function improvement, reduced myelin levels, and significantly less Th and Treg cells in the spinal cord. These findings suggest that short-term Rapamycin preconditioning diminishes the therapeutic efficacy of ASCs when applied to late-stage EAE and highlights the importance of investigating novel therapeutic strategies in vivo in physiologically relevant disease models. / 1 / Rachel Wise

In this thesis, we capitalize on the two-dimensional (2D) nature of MXenes by using them as precursors for the synthesis of 2D functional material. MXenes are easily intercalated with monovalent cations K, Na, Li due to their expanded d-spacing after etching. Based on these ideas, we have developed new synthesis processes of texture functional materials using MXenes as precursors. We have successfully synthesized two-dimensional Nb2C MXene based high aspect ratio ferroelectric potassium niobate (KNbO3) and well-oriented photoluminescent rare earth doped lithium niobate (LiNbO3:Pr3+) crystals, which have great potential in opto-electronics applications. In addition, this thesis demonstrates that poly(vinylidene fluoride) (PVDF)-based percolative composites using two-dimensional (2D) MXene nanosheets as fillers exhibit significantly enhanced dielectric permittivity. Furthermore, we fabricated MXene/in-plane aligned PVDF photo-thermo-mechanical solar tracking actuator for energy harvesting applications.

Sepsis-induced immunosuppression increases the risk of chronic infection and reduces survival. Myeloid-derived suppressor cells (MDSCs) expand in the bone marrow and spleen during murine polymicrobial sepsis, contributing to immunosuppression. A better understanding of molecular controls of MDSC production is needed to identify treatment targets. We previously reported that miR-21 and miR-181b couple with transcription factor NFI-A to induce MDSCs during murine sepsis. Here, we expand upon these observations by showing that conditional deletion of the Nfia gene in the myeloid lineage precludes MDSC development. NFI-A-deficient Gr1+CD11b+ myeloid cells are not immunosuppressive and differentiate normally into macrophages and dendritic cells. In contrast, ectopically expressed NFI-A prevents differentiation of these immature Gr1+CD11b+ cells, while converting them into MDSCs. In addition, NFI-A-deficient Gr1+CD11b+ cells decreased, and cells transfected with NFI-A increase expression of miR-21 and miR181b. Our results support a myeloid cell loop in which NFI-A and miR-21 and miR-181b sustain Gr1+CD11b+ MDSC-dependent immunosuppression during sepsis.