Dissertations / Theses on the topic 'Surface activity'

In the last few years, there has been significant progress in the development of a new model for explaining magnetic flux concentrations, by invoking the negative effective magnetic pressure instability (NEMPI) in a highly stratified turbulent plasma. According to this model, the suppression of the turbulent pressure by a large-scale magnetic field leads to a negative contribution of turbulence to the effective magnetic pressure (the sum of non-turbulent and turbulent contributions). For large magnetic Reynolds numbers the negative turbulence contribution is large enough, so that the effective magnetic pressure is negative, which causes a large-scale instability (NEMPI). One of the potential applications of NEMPI is to explain the formation of active regions on the solar surface. On the other hand, the solar dynamo is known to be responsible for generating large-scale magnetic field in the Sun. Therefore, one step toward developing a more realistic model is to study a system where NEMPI is excited from a dynamo-generated magnetic field. In this context, the excitation of NEMPI in spherical geometry was studied here from a mean- field dynamo that generates the background magnetic field. Previous studies have shown that for NEMPI to work, the background field can neither be too weak nor too strong. To satisfy this condition for the dynamo-generated magnetic field, we adopt an “alpha squared dynamo” with an α effect proportional to the cosine of latitude and taking into account alpha quenching. We performed these mean-field simulations (MFS) using the Pencil Code. The results show that dynamo and NEMPI can work at the same time such that they become a coupled system. This coupled system has then been studied separately in more detail in plane geometry where we used both mean-field simulations and direct numerical simulations (DNS). Losada et al. (2013) showed that rotation suppresses NEMPI. However, we now find that for higher Coriolis numbers, the growth rate increase again. This implies that there is another source that provides the excitation of an instability. This mechanism acts at the same time as NEMPI or even after NEMPI was suppressed. One possibility is that for higher Coriolis numbers, an α2 dynamo is activated and causes the observed growth rate. In other words, for large values of the Coriolis numbers we again deal with the coupled system of NEMPI and mean-field dynamo. Both, MFS and DNS confirm this assumption. Using the test-field method, we also calculated the dynamo coefficients for such a system which again gave results consistent with previous studies. There was a small difference though, which is interpreted as being due to the larger scale separation that we have used in our simulations. Another important finding related to NEMPI was the result of Brandenburg et al. (2013), that in the presence of a vertical magnetic field NEMPI results in magnetic flux concentrations of equipartition field strength. This leads to the formation of a magnetic spot. This finding stimulated us to investigate properties of NEMPI for imposed vertical fields in more detail. We used MFS and DNS together with implicit large eddy simulations (ILES) to confirm that an initially uniform weak vertical magnetic field will lead to a circular magnetic spot of equipartition field strength if the plasma is highly stratified and scale separation is large enough. We determined the parameter ranges for NEMPI for a vertical imposed field. Our results show that, as we change the magnitude of the vertical imposed field, the growth rate and geometry of the flux concentrations is unchanged, but their position changes. In particular, by increasing the imposed field strength, the magnetic concentration forms deeper down in the domain.

Lipopolysaccharide (LPS), a major constituent of Gram-negative bacteria, is implicated as the key factor in the development of the Systemic Inflammatory Response Syndrome (SIRS). LPS can arise from an underlying bacteraemia, but given that the majority of patients with SIRS have no detectable bacteraemia, then LPS derived from the gut must be considered. Bacteroides species outnumber the enterobacteria such as E.coli in the gut by approximately 1000-fold. Although Bacteroides LPS is less endotoxic, by simple arithmetic there must be as much biological potential from the LPS of Bacteroides as from E.coli. This thesis re-examines the biological activity of Bacteroides LPS and its possible role in the development of SIRS. LPSs were extracted from seven Bacteroides species by three different techniques: the phenol-water (PW), the phenol-chloroform-petroleum (PCP) and Triton-Mg²⁺. The biological activity of these Bacteroides LPSs was compared to that of an E.coli O18K^- LPS control. In general, Bacteroides LPSs prepared by the PW method were found to have a significantly higher activity in a mouse lethality model, LAL assay, TNF and IL-8 induction assays, than LPS extracted by the PCP or Triton methods. Bacteroides LPS extracted by the PCP method had consistently low activity in all assays. LPS from B.fragilis NCTC 9343 and B.caccae had a consistently higher activity than LPS from B.vulgatus and B.thetaiotaomicron in most assays. Differences in activity between B.fragilis NCTC 9343 LPS grown in different media was seen. The PW method selected for greater amounts of carbohydrate and KDO and the PCP the least. Further information from sub-population studies, Percoll profiles, chemotype on PAGE and chemical analysis failed to account for differences in biological activity between extraction methods and Bacteroides species.

The antibacterial activities of different thin films (TiO2/CuO, Cu/SiO2 and Ag/SiO2) prepared by flame-assisted chemical vapour deposition (FACVD) and atmospheric pressure thermal (APT-FCVD) for TiO2/CuO films, were investigated against standard strains of bacteria used for disinfectant testing and against multi-antibiotic resistant bacteria that have been shown to persist in the hospital environment. These included; MRSA strains (EMRSA15 and two recent clinical isolates MRSA 1595 and MRSA 1669), extended spectrum β-lactamase (ESBL) producing Escherichia coli, a second (ESBL- 2 ) producing Escherichia coli, KPC+ (carbapenemase producing) Klebsiella pneumoniae, Stenotrophomonas maltophilia, Acinetobacter baumannii, Listeria monocytogenes, Salmonella enterica ser typhimurium, and vancomycin resistant Enterococcus faecium (VRE) . The Antimicrobial activity of the above coatings (Cu/SiO2 and Ag/SiO2) was investigated based on the BS ISO 22196:2009 and 2011 Plastics – Measurement of antibacterial activity on plastics and other porous surfaces. The activity of TiO2/CuO films was investigated based on the BS ISO 27447:2009 Test method for antibacterial activity of semiconducting photocatalytic materials. On the TiO2/CuO films, the bacteria were killed by UVA irradiation of the photocatalyst with a >5 log kill within 4-6 h except for the MRSA where a 2.3 log kill was obtained after 6 h increasing to >5 log after 24 h. There was antimicrobial activity in the dark which was enhanced by irradiation with fluorescent light. There was also activity at 5ºC under UVA but activity was lower when fluorescent light was used for illumination. The Cu/SiO2 coating showed a >5 log reduction in viability after 4 h for the disinfectant test strain (E.coli) and for some pathogenic strains include; Acinetobacter baumannii, Klebsiella pneumoniae and Stenotrophomonas maltophilia. However, their activity against the other hospital isolates was slower but still gave a >5 log reduction for extended spectrum β-lactamase producing Escherichia coli and Salmonella enterica typhimurium, and > 2.5 log reduction for vancomycin resistant Enterococcus faecium, Listeria and methicillin resistant Staphylococcus aureus within 24 h. The coating was also active at 5ºC but was slow compared to room temperature. The highest activity of copper /silica films was seen at 35ºC, but bacterial cells were also killed on the control surfaces. The Ag/SiO2 coating was also active against pathogenic bacteria; however the coating was not hard or durable as other coatings used. The activity on natural contamination in an in use test in a toilet facility was also determined for coated ceramic tiles (Cu/SiO2 and Ag/SiO2) and coated steel. The results demonstrated that the tiles were highly active for the first 4 months period and the contamination was reduced by >99.9%. However, tiles lost some of their activity after simulated ageing and washing cycles. The Cu/SiO2 coated ceramic tiles placed in Manchester Royal Infirmary also showed antimicrobial activity and no indicator organisms were detected. The coatings had a good activity against both standard test strains and clinical isolates. The coatings (copper surfaces in particular), may have applications in health care by maintaining a background antimicrobial activity between standard cleaning and disinfection regimes. They may also have applications in other areas where reduction in microbial environmental contamination is important, for example, in the food industry. However, the optimum composition for use needs to be a balance between activity and durability. Keywords: TiO2, CuO, Ag, Antimicrobial; Chemical vapour deposition; Copper; Disinfection surface; Pathogenic bacteria (hospital pathogen).

The goal of this study was to obtain new information about possibilities to utilize carbon dioxide (CO₂) with photocatalytic activation and reduction by using surface plasmon resonance titanium dioxide based materials decorated with platinum group metals. Carbon dioxide is known to be one of the most common greenhouse gases (GHG) and having a major impact on ongoing global warming. By utilizing CO₂ it is possible to mitigate CO₂ emissions and produce new sustainable fuels. This study included characterization of the prepared palladium (Pd) and platinum (Pt) decorated catalysts and testing their photocatalytic properties in carbon monoxide (CO) oxidation and CO₂ activation reactions under visible light and under irradiation of specific wavelength. In addition to different irradiation also different feed gas combinations were tested in both reactions. Characterization of prepared materials was done with XRD to study the crystalline structure and composition, BET-BJH to get information about the surface area and pore sizes, and TEM for surface structure analyses and distribution of metal decoration. Photocatalytic activity was studied with FT-IR DRIFT analyses with external solar light source and equipped with filters to control the wavelength of irradiation. The results of the characterization showed that preparation of the catalysts was successful. Photocatalytic activity results showed that some of the tested materials are able to oxidise CO and activate CO₂ in the presence of irradiation. Obtained results show that palladium and platinum decorated TiO₂ based materials could possibly be used in surface plasmon enhanced photocatalytic CO₂ reduction successfully
Työn tarkoituksena on selvittää hiilidioksidin (CO₂) hyödyntämisen mahdollisuutta valokatalyyttisellä aktivoinnilla ja pelkistämisellä käyttäen pintaplasmonisesti resonoivia jalometalleja sisältäviä titaanidioksidimateriaaleja. Hiilidioksidin tiedetään olevan yksi yleisimmistä kasvihuonekaasuista ja näin ollen sillä on suuri vaikutus meneillään olevaan ilmaston lämpenemiseen. Hyödyntämällä hiilidioksidia on mahdollista vähentää hiilidioksidipäästöjä ja kehittää uusia kestäviä polttoaineita. Tämä tutkimus sisältää valmistettujen platina- ja palladium-titaanidioksidi-katalyyttien karakterisointia ja niiden valokatalyyttisten ominaisuuksien tutkimista hiilimonoksidin (CO) hapettamisessa ja hiilidioksidin (CO₂) aktivoinnissa näkyvällä valolla ja valituilla valon aallonpituuksilla. Käytettyjen säteilyalueiden lisäksi myös erilaisia syöttökaasun yhdistelmiä tutkittiin molemmissa reaktioissa. Valmistettujen katalyyttien karakterisoinnit tehtiin XRD:llä, jolla saatiin tietoa materiaalien kiderakenteesta ja koostumuksesta, BET/BJH-menetelmällä jolla määritettiin pinta-alat ja huokostilavuudet sekä TEM mikroskopialla, jolla tarkasteltiin pinnan rakenteita ja metallin jakautumista katalyytin pintaan. Valokatalyyttistä aktiivisuutta tutkittiin DRIFT-mittauksin, joissa käytettiin ulkoista valonlähdettä ja erillisiä valosuodattimia, jotta eri aallonpituuksien vaikutusta reaktioon voitiin tutkia tarkemmin. Karakterisointien tulokset osoittivat materiaalien valmistuksen olleen onnistunut. Valokatalyyttisten aktiivisuuskokeiden tutkimustuloksista saatiin selville, että osa palladiumia tai platinaa sisältävistä titaanidioksidimateriaaleista kykeni hapettamaan hiilimonoksidia sekä aktivoimaan hiilidioksidia valosäteilyn avulla. Saadut tutkimustulokset osoittavat, että TiO₂ pohjaisia katalyyttejä platina- ja palladiumlisäyksillä voidaan mahdollisesti käyttää pintaplasmonisella värähtelyllä tehostetussa valokatalyysissä hiilidioksidin pelkistämiseksi

Cystic fibrosis (CF) is a lethal genetic disease that affects 30,000 people in the United States alone. While the disease affects organs throughout the body, it is the lung disease that is the primary cause of morbidity and mortality for people with the disease. CF lung disease is characterized by thick and sticky mucus that obstructs the airways, acute and chronic bacterial infections, and chronic inflammation and remodeling. Thanks to the creation of the CF pig, it is now possible to study the manifestations of CF lung disease at birth. The CF pig develops spontaneous lung disease, similar to that found in humans with CF, making it the ideal model for our studies. One of the critical findings that revealed in studies of the CF pig is that airway surface liquid (ASL) bactericidal activity is impaired in CF at birth, and this activity is pH dependent. Because infants and children with CF tend to suffer greater morbidity from respiratory viruses than non-CF infants and children, we sought to determine if ASL has antiviral activity and if that activity is reduced in newborn CF pigs. We found that pre-incubating either tracheal or nasal ASL from wild-type pigs reduced the infectivity of various recombinant viruses expressing an eGFP or GFP reporter gene. Those viruses include Sendai virus (SeV-eGFP), respiratory syncytial virus (RSV-GFP), the PR8 strain of influenza virus A (PR8-eGFP), and adenovirus (Ad-eGFP), indicating ASL has broad-spectrum antiviral activity. Nasal secretions from newborn CF pigs had strikingly reduced antiviral activity against SeV-eGFP and Ad-eGFP compared to nasal secretions from WT littermates. Unlike what was observed for ASL antibacterial activity, nasal secretion antiviral activity was not affected by pH, nor was it affected by bicarbonate concentration, one of the molecules that drives pH in the airways. However, when we mixed CF and WT nasal secretions at different ratios, we found the antiviral activity to follow a linear trend, with antiviral activity increasing as the percentage of WT nasal secretions increased. This suggests that one or more components of nasal secretions are found less abundantly in CF nasal secretions compared to WT nasal secretions, leading to reduced antiviral activity in CF. The CF pig has facilitated a much greater understanding of the early stages of CF lung disease. This model will allow us to determine what antiviral components are lacking in the CF airways and why they are reduced in CF.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2011.
Cataloged from PDF version of thesis.
Includes bibliographical references.
Hydrophobic polycations have been shown to completely kill bacterial, fungal, and viral pathogens, on-contact. Herein we describe advances with this technology on two fronts: (1) innovation of a polycationic-derivative that simplifies the labor-intensive covalent-immobilization procedure, and (2) elucidation of the current mechanistic understanding of this phenomenon. First, we developed and characterized a novel polycationic polymer capable of crosslinking to cotton via activation with ultraviolet light. The resultant, covalently-immobilized, Nalkyl polyethylenimine (PEI) demonstrates complete bactericidal activity against S. aureus and E. coli (i.e., representative Gram-positive and Gram-negative bacteria, respectively). In addition, by utilizing light to activate the covalent cross-linking, this immobilization procedure is simpler and more versatile than similar chemically-attached bactericidal polycations. Second, we shed light onto how the coating inactivates microbial pathogens. Gramnegative and Gram-positive bacteria exposed to the polycationic coating revealed substantial structural deformation, which allowed for the leakage of their intracellular contents. Characterization of the enzymes leaked into solution from Gram-negative bacteria indicated a disproportionately greater damage done to the outer-membrane than the inner-membrane. In addition, the quantity of proteins leaked into solution showed striking similarity to results obtained from bacteria subjected to lysozyme/EDTA treatment (i.e., a traditional cell lysis technique that degrades the cellular wall). In total, these results suggest that it is this interaction between the polycation and cellular structure (i.e., outer membrane and cell wall) that ultimately compromises bacterial integrity. Expanding our investigation, we studied the effect of the polycationic coating on another membrane-enclosed microbe: the influenza virus. We found that the viral particles adhere to the polycationic coating, which results in a structural deformation, similar to that borne-out by bacteria. As a consequence, viral genomic material is leaked into solution, revealing the viruses' state of inactivation upon adherence to the coating.
by Bryan Boen Hsu.
S.M.

Metallophthalocyanines and metal nanoparticles were successfully synthesized and applied for the electrooxidation of amitrole, nitrite and hydrazine individually or when employed together. The synthesized materials were characterized using the following techniques: predominantly scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), electrochemistry and scanning electrochemical microscopy (SECM). Different electrode modification methods were used to modify the glassy carbon substrates. The methods include adsorption, electrodeposition, electropolymerization and click chemistry. Modifying the glassy carbon substrate with MPc (electropolymerization) followed by metal nanoparticles (electrodeposition) or vice versa, made a hybrid modified surface that had efficient electron transfer. This was confirmed by electrochemical impedance studies with voltammetry measurements having lower detection potentials for the analytes. This work also describes for the first time the micropatterning of the glassy carbon substrate using the SECM tip. The substrate was electrografted with 4-azidobenzenediazonium salt and then the click reaction was performed using ethynylferrocene facilitated by Cu⁺ produced at the SECM tip. The SECM imaging was then used to show the clicked spot.

INTRODUCTION: Hospital acquired infections (HAIs) are the most frequently occurring adverse event in healthcare delivery globally and result in prolonged hospitalization. Implantable devices are commonly affected by these infections due to the formation of biofilms. Gallium (Ga) has been shown to prevent biofilm formation due to its disruption of iron-dependent bacterial growth processes. Defensin, a naturally occurring peptide, has also shown significant antimicrobial qualities. Hence, the synergistic effect of the two strategies is proposed for study in the form of a surface modified antimicrobial polymer to prevent biofilm formation on implantable devices. AIMS AND HYPOTHESES: To develop a surface modification technology, which imparts antimicrobial activity and biocompatibility to the implantable polymer-based devices. More specifically, we aimed to prepare, modify and characterize surface properties of a gallium implanted, defensin immobilized biopolymer and assess its ability to prevent biofilm formation, bacterial adhesion and cytocompatibility. MATERIALS AND METHODS: PLA films were optimized and fabricated, after which they underwent plasma treatment in air or Ga implantation. Samples were characterized using AFM, PFQNM, nano thermal analysis and LCR. Following this, samples had defensin immobilized on their surfaces and this was to be confirmed via Tween-20 wash and subsequent PFQNM analysis. Defensin alone was tested in solution via the Disc Diffusion Assay to assess its capability as an antimicrobial agent. The surfaces then were subjected to a Biofilm formation assay for a period of 14 days after which they were stained and imaged using CLSM. The surfaces were also tested for their ability to invoke an inflammatory response via FBGC formation by M0 phenotype macrophages (through immunofluorescence staining and CLSM) and via measurement of pro-inflammatory cytokine IL-1β (using ELISA) by these same cells. The QBlue assay was used to measure their viability. Finally, the surfaces were assessed for the initial attachment and morphology of myoblasts and for their osteogenic differentiation potential of these cells via the ALP assay which was normalized using total protein content (through the BCA assay). RESULTS AND DISCUSSION: Ga implantation resulted in the increase in carbonization of the surface layer and accordingly, the stiffness of the sample. The increasing fluence of Ga ions also resulted in inconsistencies in ion implantation which could have follow on effects on peptide immobilization due to increased polymer crosslinking. Linker-free immobilization of defensin was confirmed on the Plasma treated and Ga treated surfaces. Both gallium implantation and defensin immobilization independently and synergistically proved to impart antimicrobial activity to the surfaces and the antimicrobial effects of hBD-1 appear to be potentiated by surface immobilization. Defensin immobilization however, appeared to be inconsistent with increasing Ga fluence. IL-1β formation expression increased with decreasing Ga concentration suggesting less inflammation with increasing Ga dose and the increased with introduction of De also. FBGC formation was significantly decreased in all Ga and Ga De treated groups in comparison with PLA. Myoblast morphology appeared to be negatively affected by De on the Ga 14 De and Ga 15 De samples, potentially due to the effects of inconsistent surface stiffness and surface charge. There were no significant changes in ALP production between the PLA control and any other treated sample. CONCLUSION: This novel therapy has the potential to prevent biofilm infection and opens avenues for future research such as in vivo studies, and the viability of using other antimicrobial peptides as linkerfree immobilization has been made possible.

Abstract This thesis studies the long-term evolution of the photospheric magnetic field using surface flux transport simulations. The photospheric magnetic field and magnetic activity are tightly connected to space weather, and affect the whole heliosphere including the Earth. However, due to a lack of reliable observations our understanding of the long-term evolution of the photospheric magnetic field is still poor. Surface flux transport models, which are capable of simulating the evolution of the whole surface field from observations of solar activity, can be used to study the field in times when direct observations are not available. In this thesis we validate our surface flux transport model, optimize its parameters and test its sensitivity to uncertainties in parameter values and input data. We find a need to extend the model with a decay term to properly model the deep and long minimum between solar cycles 23 and 24, and simulate the photospheric magnetic field of cycles 21–24 using magnetographic observations as input. We also study consequences of hemispherically asymmetric activity, and show that activity in one hemisphere is enough to maintain polar fields in both hemispheres through cross-equatorial flow of magnetic flux. We develop a new method to reconstruct active regions from calcium K line and sunspot polarity observations. We show that this reconstruction is able to accurately capture the correct axial dipole moment of active regions. We study the axial dipole moments of observed active regions and find that a significant fraction of them have a sign opposite to the sign expected from Hale’s and Joy’s laws, proving that the new reconstruction method has an advantage over existing methods that rely on Hale’s and Joy’s laws to define polarities. We show one example of a long simulation covering solar cycles 15–21, demonstrating that using the active region reconstruction and surface flux transport model presented in this thesis it is possible to simulate the large-scale evolution of the photospheric magnetic field over the past century
Original papers The original publications are not included in the electronic version of the dissertation. Virtanen, I. O. I., Virtanen, I. I., Pevtsov, A. A., Yeates, A., & Mursula, K. (2017). Reconstructing solar magnetic fields from historical observations. II. Testing the surface flux transport model. Astronomy & Astrophysics, 604, A8. https://doi.org/10.1051/0004-6361/201730415 http://jultika.oulu.fi/Record/nbnfi-fe2017103050356 Virtanen, I. O. I., Virtanen, I. I., Pevtsov, A. A., & Mursula, K. (2018). Reconstructing solar magnetic fields from historical observations. III. Activity in one hemisphere is sufficient to cause polar field reversals in both hemispheres. Astronomy & Astrophysics, 616, A134. https://doi.org/10.1051/0004-6361/201732323 http://jultika.oulu.fi/Record/nbnfi-fe201902205813 Virtanen, I. O. I., Virtanen, I. I., Pevtsov, A. A., Bertello, L., Yeates, A., & Mursula, K. (2019). Reconstructing solar magnetic fields from historical observations. IV. Testing the reconstruction method. Astronomy & Astrophysics, 627, A11. https://doi.org/10.1051/0004-6361/201935606 http://jultika.oulu.fi/Record/nbnfi-fe2019091828628 Virtanen, I. O. I., Virtanen, I. I., Pevtsov, A. A., & Mursula, K. (2019) Axial dipole moment of solar active regions in cycles 21-24. Manuscript

This research focused on the characterization of organosilicone surfactants and their effects on sulfonylurea herbicide activity. The project included efficacy tests, rainfastness studies in the greenhouse, radiotracer studies on herbicide uptake, fluorescent dye studies on surface deposition, and various measurements of physico-chemical properties. In measuring physico-chemical properties, a logistic dose response relationship was found between adjuvant concentration and contact angle on parafilm. An AsymSigR relationship existed between adjuvant concentration and surface tension for all the adjuvants. The organosilicones, Silwet L-77, Silwet 408, and Sylgard 309, and Kinetic (a blend of an organosilicone with a nonionic surfactant) gave equilibrium surface tension values around 20 dyne/cm and showed great spreading ability on the foliage of velvetleaf. With the conventional adjuvants, Agri-Dex, methylated soybean oil, Rigo oil concentration, and X-77, and Dyne-Amic (a blend of an organosilicone with a crop oil concentrate), surface tension was rarely below 28 dyne/cm and spreading ability was limited on velvetleaf. In addition, the organosilicone surfactant and Kinetic also lowered dynamic surface tension, which may improve droplet retention on leaf surfaces. The differences in physico-chemical properties between Kinetic and Dyne-Amic confirmed that carefully electing a co-adjuvant for an organosilicone blend is critical to avoid antagonism with trisiloxane molecules and retain the unique physico-chemical properties of organosilicone in the blends. Studies involving structurally-related organosilicones showed that the end structure in the trisiloxane hydrophilic group has little or no effect on surface tension, contact angle, spread pattern, herbicide uptake and translocation, and efficacy of primisulfuron on velvetleaf. It may be suggested that there is not a strict requirement to purify the end structure during the synthesis process, which is time consuming and expensive. When 14C-primisulfuron was combined with organosilicones or the blends, the uptake of 14C at 1 or 2 h after herbicide application was significantly higher than when combined with conventional adjuvants in velvetleaf. In the greenhouse, organosilicone surfactants greatly increased the rainfastness of primisulfuron in velvetleaf. The effect was immediate and dramatic, even when simulated rainfall was applied 0.25 h after treatment. In addition, herbicide efficacy on marginally susceptible weed species, velvetleaf and barnyardgrass, was significantly increased. A very complicated relationship exists between herbicides and adjuvants. The enhancement effects of adjuvants are often herbicide specific, weed species specific, and even environment specific. No one type of adjuvant functions well in all circumstances. Therefore, there is a need to understand the properties and functions of each class of adjuvants and locate the 'right' niche for each individual adjuvant.
Ph. D.

EEG has been used to explore the electrical activity of the brain for manydecades. During that time, different components of the EEG signal have been iso-lated, characterized, and associated with a variety of brain activities. However, nowidely accepted model characterizing the spatio-temporal structure of the full-brainEEG signal exists to date.Modeling the spatio-temporal nature of the EEG signal is a daunting task. Thespatial component of EEG is defined by the locations of recording electrodes (rang-ing between 2 to 256 in number) placed on the scalp, while its temporal componentis defined by the electrical potentials the electrodes detect. The EEG signal is gen-erated by the composite electrical activity of large neuron assemblies in the brain.These neuronal units often perform independent tasks, giving the EEG signal ahighly dynamic and non-linear character. These characteristics make the raw EEGsignal challenging to work with. Thus, most research focuses on extracting andisolating targeted spatial and temporal components of interest. While componentisolation strategies like independent component analysis are useful, their effective-ness is limited by noise contamination and poor reproducibility. These drawbacks tofeature extraction could be improved significantly if they were informed by a globalspatio-temporal model of EEG data.The aim of this thesis is to introduce a novel data-surface reconstruction (DSR)technique for EEG which can model the integrated spatio-temporal structure of EEGdata. To produce physically intuitive results, we utilize a hyper-coordinate transfor-mation which integrates both spatial and temporal information of the EEG signalinto a unified coordinate system. We then apply a non-uniform rational B spline(NURBS) fitting technique which minimizes the point distance from the computedsurface to each element of the transformed data. To validate the effectiveness of thisproposed method, we conduct an evaluation using a 5-state classification problem;with 1 baseline and 4 meditation states comparing the classification accuracy usingthe raw EEG data versus the surface reconstructed data in the broadband rangeand the alpha, beta, delta, gamma and higher gamma frequencies. Results demon-strate that the fitted data consistently outperforms the raw data in the broadbandspectrum and all frequency spectrums.

Corneal degenerative diseases and opacity are leading causes of corneal impairment and blindness worldwide. Like many epithelial tissues, the constant renewal of transparent corneal epithelial cells is essential for a lifelong healthy cornea and optimal vision. The limbus (the boundary between the cornea and the conjunctiva) is believed to be the site that harbours adult stem cells responsible for corneal maintenance and repair after injury, referred to as limbal epithelial stem cells (LESCs). In the basal limbal epithelium, an active LESC subset divides to yield progenitor cells that migrate centripetally into the corneal epithelium for cell renewal. This asymmetric division however, is assumed to be regulated by a balance between cell renewal and loss of cells from the corneal surface. The search for specific LESC molecular markers has been difficult and to date there are few if any candidate markers that unambiguously identify LESCs but not their immediate progeny. Consequently, LESC clonality, activity and proliferative dynamics have remained poorly understood. In addition, the nature of the regulatory molecular pathways involved during LESC activity is still an open key question. In this research project, we identified stem cells on the ocular surface of the eye, assayed their activity and demonstrated quantitively for the first time how the cornea responds to damage. The retention of DNA labelling reagents in control and wounded corneas was combined with clonal analyses of cell division and migration using mice mosaic for reporter LacZ expression. Corneal transplant in LacZ reporter transgenic mice showed migration of LacZ-positive cells into the donor corneal button, with long-term disruption of patterns of migration. Corneal epithelial scrape wounds at the periphery also showed long– term disruption. Label retention suggested a small but statistically significant proliferation response of LESCs to injury, but this was attenuated or absent in aging mice and Pax6 mutants. The Hippo signalling pathway has been shown to have promising results in regulating stem cell activity and proliferation in many organs, however, its effect on LESC proliferation is unknown. Here, we investigated the regulatory role of the Hippo−YAP signalling pathway during cell proliferation, and determined whether the label retention assay in a uniform population of dividing cells is a real indicator of slow-cycling cells in vivo. Cell-cycling kinetics, Abstract v proliferation rate, and label retention were determined in a spontaneous human corneal epithelial (HCE-S) cell line, using double-labelling IdU and EdU thymidine analogues. During homeostasis, HCE-S cells underwent approximately one cell cycle per day, however, cells in which YAP-dependent signalling was activated by 17-Allylamino-17-demethoxygeldanamycin (17-AAG), an inhibitor of heat shock protein 90 (Hsp90), showed slower proliferation rate and longer cell-cycle time. In vitro label-retention assay in confluent cultures estimated number of ~3-4 cell cycles needed to dilute out the label from slow-cycling cells in vivo. The data are suggestive that the Hippo pathway has a potential regulatory role in proliferative corneal epithelium, and that label-retention assay is a real indicator of slow-cycling cells. Furthermore, this research observed the proliferative dynamics of conjunctival stem cells. Clonal analysis of patterns of cell growth in the conjunctiva were analysed following tamoxifen-induction of LacZ transgene activity. The long−term presence of coherent patches of LacZ-positive cells suggested the presence of long-lived conjunctival stem cells but that the turnover time for the bulbar conjunctival epithelium may be more than 16 weeks. The key results of this research are that the limbus is the niche for stem cells, that there is a unidirectional migration of cells from the limbus to the corneal epithelium during homeostasis, but this is disrupted, perhaps permanently, by wounding. We find only a mild response of limbal epithelial stem cells to acute corneal injury, which is reduced to no response with age and is dependent on genetic background.

Transglutaminase-2 (TG2) is a Ca2+-dependent crosslinking enzyme involved in the post-translational modification of proteins via the formation of Nε(γ-glutamyl)lysine isodipeptides. TG2 is externalised in the extracellular matrix (ECM) through an unconventional and not fully understood pathway. Under normal conditions, TG2 modulates cell adhesion, proliferation and tissue repair. Under continuous cell insult higher expression and elevated extracellular trafficking of TG2 contribute to the pathogenesis of tissue scarring. TG2 is known to have affinity for heparin, and in a previous study cell-surface heparan sulphate (HS) has been implicated in extracellular TG2 mediated RGD-independent cell adhesion, a non-enzymatic process independent from the α5β1 integrin-binding to the RGD domain on FN (Verderio et al., 2003). Hence HS proteoglycan (HSPG) could act as cell surface co-receptor for FNbound TG2 or contribute to the regulation of extracellular TG2 activity in cell adhesion and tissue repair. The aims of this study were: 1) to study the role of externalised TG2 in cell adhesion in primary fibroblasts. 2) to investigate the role of HSPG syndecan-4 (Sdc-4), a crucial component of focal adhesions in TG2-mediated cell-adhesion. 3) to characterise the interaction between TG2 and HSPG, in particular Sdc-4, and to investigate how this interaction can influence TG2 biological functions in vitro. 4) to examine the role of Sdc-4 as a regulator of pro-fibrotic TG2 activity in experimental model of kidney fibrosis (UUO). The results obtained have shown that: 1) externalised TG2 plays an important role in mediating early events of cell adhesion in primary fibroblasts. 2) FN-bound TG2 relies on the presence of Sdc-4 for its role in RGD-independent cell adhesion. 3) TG2 has a high affinity for HS (Kd ~ 20 nM) and it is associated with Sdc-4 at the cell surface in primary fibroblasts. 4) TG2 crosslinking activity at the cell surface relies on the presence of the HS chains of Sdc- 4 and other HS proteoglycans. HS-binding does not have a direct role in TG2 activity regulation, but the presence of intact Sdc-4 is essential for TG2 localisation at the cell surface. 5) Sdc-4 is protective against the development of UUO and it regulates the release and activity of the pro-fibrotic factor TG2 in UUO, suggesting a possible co-operative role of TG2 and Sdc-4 in the development of kidney fibrosis. In conclusion, HSPG, and in particular Sdc-4 emerged to have a crucial role in the cellsurface trafficking and regulation of TG2 biological activities both in vitro and in vivo.

The purpose of this study was to compare core muscle activity during resistance exercises performed on stable ground versus an unstable surface and to examine whether lifting at different relative intensities affects core muscle activity levels. Twelve trained men performed four different movements including the deadlift, back squat, military press, and curl. Surface electromyography (EMG) was utilized to assess the activity of the rectus abdominis, external oblique, transversus abdominis, and erector spinae muscles. Participants performed each movement under three separate conditions including standing on stable ground with 50% of their one repetition maximum (1-RM), standing on a BOSU balance trainer with 50% of their 1-RM and, standing on stable ground with 75% of their 1-RM. The following muscles exhibited greater activity during the 75% 1-RM condition than all other conditions: the transversus abdominis (TA) and external oblique (EO) muscles during the deadlift; the rectus abdominis (RA) during the squat; the TA, RA, and EO during the press, and TA and erector spinae (ES) during the curl. The ES muscle during the press movement and EO during the squat movement were more active during the BOSU 50% 1-RM condition than the stable 50% 1-RM condition. Healthy individuals might consider performing the military press, curl, squat and deadlift movements with higher intensity resistances while standing on stable ground to incur higher widespread muscle activity of the core region.

Thesis (MSc)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: Biofouling is the attachment and biofilm formation that leads to negative repercussions such as persistent post-harvest infections, infections obtained from medical implants and continual surface contamination of food processing plants. Much of the problem lies with the resistance that develops against conventional treatments due to the formation of mature biofilms. Thus the focus has shifted from the removal of biofilms to the prevention of initial attachment of organisms. This entails the use of antimicrobial surfaces that either have an inherent antimicrobial activity, e.g. certain metals, or surfaces that are modified by the attachment of antimicrobial agents. The attachment of antimicrobial agents can either be through covalent bonding or adsorption, depending on the intended use of the surface as well as the mode of action of the antimicrobial agent. Antimicrobial peptides (AMPs) are ubiquitous in nature, tend to have a broad spectrum of activity, are very stable and have been shown to maintain activity when covalently bound to solid surfaces. Tyrocidines (Trcs), antimicrobial peptides produced by Bacillus aneurinolyticus, are cyclodecapeptides with a broad spectrum of activity against Grampositive bacteria, fungi, yeasts and the human malaria parasite, Plasmodium falciparum. The aim of this study was to determine the antimicrobial activity of surfaces treated with a tyrocidine extract, under which conditions the activity remained stable and to look into possible applications of these peptide-treated surfaces. The study focussed on different solid surfaces namely mixed cellulose, polyvinylidene fluoride, polycarbonate, cellulose acetate, cellulose (paper)(CL) and high density cellulose packing material (HDC), as a pilot study to assess the antimicrobial activity of Trc and gramicidin S (GS) treated solid surfaces. Peptide desorption and subsequent analysis by mass spectrometry was used to confirm the presence and integrity of the Trcs adsorbed. Scanning electron microscopy was utilised to show that the adsorbed peptides did not affect the structural integrity of the treated filters. However, it was shown that the adsorbed peptides changed the hydrophobic/hydrophilic character by means of a wettability assay. A cell viability assay and erythrocyte assay were developed from existing methodologies to determine the biological activity of the AMP-functionalised polymeric material. Seven of the AMP treated solid surfaces showed antimicrobial activity when challenged with >105 Micrococcus luteus cells/cm2. Although the polycarbonate filter lost antimicrobial activity at the high cell concentrations, it was shown to have potent antimicrobial activity at lower cell concentrations. Complete inhibition of M. luteus growth was observed for both the gramicidin S and tyrocidine extract treated high density cellulose and cellulose filters. Stability tests showed that the tyrocidines remained adsorbed to cellulose filters and biologically active when exposed multiple water washes, water washes at different temperatures (25°C - 100°C) and pH changes (pH 1-12). The antimicrobial activity was only affected after exposure to the water wash of pH 13 which is possible due to susceptibility of the CL filters to high pH solvents. A preliminary study on the effect of Trcs treated CL filters on the sterilization, germination and effect on tomato seedlings was conducted. It was found that Trcs had no effect on the germination and did not fully sterilise the seeds or environment against fungi. However, it was observed that 5 μg/mL Trcs treated filters promoted root length opposed to the toxic effect seen with filters treated with higher Trc concentrations. It is hypothesised that Trcs prefer to bind to hydrophilic surfaces exposing the hydrophobic residues and the cationic residue of the peptide to interact with the bacterial membrane to elicit its antimicrobial response. The exposed residues contain some of the hydrophobic residues and the cationic Orn9/Lys9, which are crucial to the antimicrobial activity of the peptides. Hydrophobic interaction is particularly important for the haemolytic activity which is currently the only viable method of detection of the adsorbed Trcs. Trcs also have a preference for adsorption onto cellulose and cellulose analogues which points to possible application in protective food wrapping and wood surface protection. Trcs maintains its antimicrobial activity regardless of adsorption to solid surfaces. It can therefore be concluded that Trcs treated solid surfaces hold great potential in preventing the initial bacterial colonization and subsequent biofilm formation. Antimicrobial peptide enriched solid surfaces can thus be developed and tailored to a specific application such as filters, catheters and packaging materials.
AFRIKAANSE OPSOMMING: Biovervuiling is die aanhegting en vorming van biofilms met negatiewe gevolge soos aanhoudende na-oes infeksies, infeksies op mediese inplantings en voortdurende oppervlak besoedeling van voedselverwerkings fabrieke. Die probleem lê grotendeels by die weerstand wat ontwikkel word teen konvensionele behandelings as gevolg van die vorming van volwasse biofilms. Die fokus het gevolglik verskuif vanaf die verwydering van biofilms na die voorkoming van aanvanklike aanhegting van organismes aan oppervlaktes. Dit behels die gebruik van antimikrobiese oppervlaktes wat of 'n inherente antimikrobiese aktiwiteit het, bv. sekere metale óf oppervlaktes wat aangepas is deur die aanhegting van antimikrobiese middels. Die aanhegting van antimikrobiese agente kan of deur kovalente binding óf adsorpsie plaasvind, afhangende van die beoogde gebruik van die oppervlak, sowel as die metode van werking van die antimikrobiese agent. Antimikrobiese peptiede (AMPe) is alomteenwoordig in die natuur, is geneig om 'n breë spektrum van aktiwiteit te hê, is baie stabiel en het getoon dat aktiwiteit in stand gehou word wanneer dit kovalent gebind word op soliede oppervlaktes. Tirosidiene (Trcs), antimikrobiese peptiede wat deur Bacillus aneurinolyticus geproduseer word, is siklodekapeptiede met 'n breë spektrum van aktiwiteit teen Gram-positiewe bakterieë, swamme, giste en die menslike malaria parasiet Plasmodium falciparum. Die doel van hierdie studie was om die antimikrobiese aktiwiteit te bepaal van oppervlaktes wat met 'n tirosidien ekstrak behandel is, te bepaal onder watter omstandighede die aktiwiteit stabiel bly en om te soek na moontlike toepassings van hierdie peptied-behandelde oppervlaktes. Die studie het gefokus op verskillende soliede oppervlaktes naamlik gemengde sellulose, polyvinylidene fluoried, polikarbonaat, sellulose asetaat, sellulose (papier)(CL) en 'n hoë digtheid sellulose verpakkings materiaal (HDC), as 'n loodsstudie om die antimikrobiese aktiwiteit van die Trcs en gramisidien S (GS) behandelde soliede oppervlaktes te ondersoek. Peptied-desorpsie en daaropvolgende ontleding deur massaspektroskopie is gebruik om die teenwoordigheid en integriteit van die geadsorbeerde Trcs te bevestig. Skandering elektronmikroskopie is gebruik om aan te toon dat die geadsorbeerde peptiede geen invloed op die strukturele integriteit van die behandelde filters het nie. Daar is egter getoon dat die geadsorbeerde peptiede die hidrofobiese / hidrofiliese karakter verander. „n Lewensvatbaarheid selgebaseerde toets en eritrosiet toets is ontwikkel uit bestaande metodes om die biologiese aktiwiteit van die AMP-gefunktionaliseerde polimeriese materiaal te bepaal. Sewe van die AMP behandel soliede oppervlaktes het antimikrobiese aktiwiteit getoon wanneer dit met > 105 Micrococcus luteus selle/cm2 gedaag is. Hoewel die polikarbonaat filter antimikrobiese aktiwiteit met hoë sel konsentrasies verloor het, is dit getoon dat dit wel uitgeproke antimikrobiese aktiwiteit het teen laer konsentrasies selle. Volledige inhibisie van M. luteus groei is waargeneem vir beide die hoë digtheid sellulose en sellulose filters wat met GS en tirosidien ekstrak behandel is. Stabiliteit toetse het getoon dat die tirosidiene geadsorbeer en biologies aktief op sellulose filters bly nadat dit blootgestel is aan verskeie water was-stappe, waterwasse by verskillende temperature (25 °C -100 °C) en pH veranderinge (pH 1-12). Die antimikrobiese aktiwiteit was net beïnvloed ná blootstelling aan die water met 'n pH 13, wat moontlik is te danke aan die vatbaarheid van die CL filters by hoë pH oplosmiddels is. 'n Voorlopige studie is gedoen om die uitwerking van Trcs behandelde CL filters op die sterilisasie, ontkieming en tamatiesaailinge te bepaal. Daar is gevind dat Trcs geen effek op die ontkieming het nie, maar dat dit nie volledig die sade en omgewing steriliseer vir fungiese groei nie. Daar is egter waargeneem dat 5 μg/mL Trcs behandelde filters wortel lengte van die saailinge bevorder teenoor die giftige uitwerking soos waargeneem vir die filters wat met hoër konsentrasies Trcs behandel is. Dit word gepostuleer dat Trcs verkies om aan hidrofiliese oppervlaktes te bind wat die van die hidrofobiese aminosure en die kationiese residu van die peptied blootstel om aan die bakteriële membraan te bind om gevolglik antimikrobiese reaksie te ontlok. Die blootgestelde deel bevat sommige van die hidrofobiese residue en positiewe Orn9/Lys9 wat noodsaaklik vir die antimikrobiese aktiwiteit van die peptiede. Die hidrofobiese interaksies is veral belangrik vir die hemolitiese aktiwiteit wat tans die enigste bruikbare metode van opsporing van die geadsorbeerde Trcs is. Trcs het ook 'n tendens vir adsorpsie op sellulose en sellulose analoë wat dui op die moontlike toepassing in beskermende voedselverpakking en die beskerming van houtoppervlaktes. Trcs handhaaf hul antimikrobiese aktiwiteit, ongeag van adsorpsie aan soliede oppervlaktes. Dit kan dus afgelei word dat Trcs-behandelde soliede oppervlaktes die potensiaal het om die aanvanklike kolonisasie van bakterië te voorkom en die daaropvolgende biofilm vorming. Antimikrobiese peptied verrykde soliede oppervlaktes kan dus ontwikkel en aangepas word vir gebruik in spesifieke toepassing soos in filters, kateters en verpakkingsmateriaal.

Depuis plusieurs années, une nouvelle génération de matériaux appelés “matériaux intelligents” et définis par leur capacité d’adaptation à leur environnement, est intensément développée. Des systèmes sensibles à différents stimuli tels que le pH, la lumière, ou encore une force mécanique, impliquée dans un grand nombre de processus naturels, comme l’adhésion et la prolifération cellulaire, ont été rapportés. Ce travail de thèse a ainsi été dédié au développement de matériaux mécano-sensibles. Plus précisément de matériaux transformant une contrainte mécanique en un signal chimique, en mimant le processus physique utilisé par la nature, à savoir des changements conformationnels de protéines. Nous avons donc cherché à atteindre ce but en greffant covalemment des protéines ou des enzymes sur un substrat élastomère. Etirer le substrat devant induire des modifications de structure des protéines, conduisant ainsi à des modulations de leurs propriétés
Since many years, a new generation of materials called « smart materials » and defined by their capacity to adapt to their environment is intensively developed. Systems sensitive to different stimuli such as pH, light or ionic strength have been reported. One of these stimuli can also be a mechanical force which is involved in many reactions in nature such as, cells adhesion and proliferation, tissues growing or even plants developments. The aim of my thesis was dedicated to the elaboration of mechano-responsive materials. More precisely, materials that transform a stretching constraint into a chemical signal by mimicking the physical processes used by nature, namely protein conformational changes. We planned to achieve this goal by covalently grafting proteins or enzymes onto a stretchable substrate or incorporating them into cross-linked polymer networks. Stretching these materials should induce protein conformational changes leading to modifications of their properties

Les bactéries lactiques, en particulier Lactococcus lactis sont utilisées en industrie agroalimentaire. Ces bactéries sont connues pour avoir une activité réductrice, désignant leur aptitude à abaisser le potentiel redox (Eh) d’un milieu. Le génome de L. lactis MG1363 code plusieurs protéines possédant un motif CXXC potentiellement liées à une activité redox. Pour comprendre le rôle des protéines de surface riches en cystéines, deux approches ont été utilisées. Par l’approche bioinformatique, notre intérêt s'est porté sur deux protéines de surface de fonctions inconnues et à motif CX2CX10CX2C : Llmg_0524 et Llmg_0526. Leurs gènes forment un opéron induit temporairement en début de croissance. Dans les deux protéines, le motif chélate un ion de zinc par les résidus cystéines, formant un complexe très stable. Nos données suggèrent que cet opéron contribue à l'intégrité de la paroi cellulaire et que le zinc participe à la stabilité des protéines. L'identification des protéines à thiols exofaciaux par une approche biochimique indique la présente d’AhpF à la surface de L. lactis. La délétion du gène ahpF entraîne une forte sensibilité du mutant au cumène hydroperoxyde, mais aucune au peroxyde d'hydrogène. Le cumène hydroperoxyde provoque une modification de la proportion en acide gras chez le mutant ahpF, le mécanisme de cyclopropanation contribue à sa survie en réponse à un stress oxydatif. La compréhension des fonctions impliquées dans l'activité réductrice des lactocoques permettra une meilleure maîtrise du Eh dans la fabrication des produits fermentés et un meilleur contrôle des flores pathogènes et d’altérations. Le projet Food-Redox a été financé par l'ANR
Lactic acid bacteria, particularly Lactococcus lactis are used in dairy industry. These bacteria are known to have a reducing activity, indicating their ability to lower the redox potential (Eh) of a medium. L. lactis MG1363 genome encodes several proteins with a CXXC motif, potentially linked with a redox activity. To understand the role of proteins rich in cysteine located at the surface of L. lactis, two approaches were used, one bioinformatics and biochemical another. For bioinformatic approach, interest was focused on two proteins of unknown function and CX2CX10CX2C motif: Llmg_0524 and Llmg_0526. Their corresponding genes form an operon temporarily induces in early growth phase. In these two proteins, the pattern chelate a zinc ion via its cysteine residues. The zinc-cysteine complexe is very stable, it suggests a probable role in protein stability. Data suggest that this operon contributes to the cell wall integrity. The identification of exofacial thiol proteins by a biochemical approach indicates that AhpF is present at the surface of L. lactis. The ahpF gene deletion causes a strong sensitivity to the cumene hydroperoxide, but no sensibility for hydrogen peroxide. In the mutant ahpF incubation with cumene hydroperoxide modified fatty acid proportion, cyclopropanation mechanism thus contributes to the survival in response to oxidative stress. Understanding the lactococci functions involved in the reduction activity allows a better control of redox potentiel in the fermented food production and thus a better control of foodbornes microorganisms in these products. Food-Redox project is financially supported by the French National Research Agency

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2016.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references.
The intermittent nature of renewable energy sources requires a clean, scalable means of converting and storing energy. Water electrolysis can sustainably achieve this goal by storing energy in the bonds of oxygen and hydrogen molecules. The efficiency of this storage-conversion process is largely determined by the kinetic overpotential required for the oxygen evolution and reduction reactions (OER and ORR), respectively. This thesis focuses on transition metal oxides as alternative oxygen catalysts to costly and scarce noble metals. In order to develop descriptors to improve catalytic activity, thus reducing material cost for commercial technologies, this work studies fundamental processes that occur on model catalyst systems. Electrochemical studies of epitaxial oxide thin films establish the intrinsic activity of oxide catalysts in a way that cannot be realized with polydisperse nanoparticle systems. This thesis has isolated the activity of the catalyst on a true surface-area basis, enabling an accurate comparison of catalyst chemistries, and also revealed how different terminations and structures affect the kinetics. These studies of epitaxial thin films are among the first to probe phenomena that are not straightforward to isolate in nanoparticles, such as the role of oxide band structure, interfacial charge transfer (the "ligand" effect), strain, and crystallographic orientation. In addition, these well-defined surfaces allow spectroscopic examinations of their chemical speciation in an aqueous environment by using ambient pressure X-ray photoelectron spectroscopy. By quantifying the formation of hydroxyl groups, we compare the relative affinity of different surfaces for this key reaction intermediate in oxygen electrocatalysis. The strength of interaction with hydroxyls correlates inversely with activity, illustrating detrimental effects of strong water interactions at the catalyst surface. This fundamental insight brings molecular understanding to the wetting of oxide surfaces, as well as the role of hydrogen bonding in catalysis. Furthermore, understanding of the mechanisms of oxygen electrocatalysis guides the rational design of high-surface-area oxide catalysts for technical application.
by Kelsey A. Stoerzinger.
Ph. D.

[EN] The behavior of the heart is governed by electrical currents generated in the myocardium, and therefore, the study of the cardiac electrical activity is essential for the diagnosis of cardiac diseases. The forward problem of the electrocardiography (FP) entails the calculation of the torso potentials from the electrical activity of the heart and the 3D body model, while the inverse problem (IP) resolution allows the noninvasive reconstruction of the electrical activity of the heart from surface potentials. The IP is of great importance in clinical applications since it allows estimating the electrical activity of the myocardium with only noninvasive recordings. However, IP resolution is still a big challenge in electrocardiography since it is ill-posed, very unstable and has multiple solutions. In this thesis different algorithms and strategies based on the IP resolution were developed and applied in the noninvasive diagnosis of ventricular and atrial arrhythmias and evaluated with mathematical cellular models and clinical data bases. The thesis focuses on the IP resolution for the noninvasive reconstruction of the myocardial electrical activity for different diseases and propagation patterns, implementing a novel system for complex propagation patterns. The obtained results and propagation patterns were evaluated and classified with the corresponding optimal resolution strategy that minimizes the error and increases the stability of the system, proving its advantages and disadvantages depending on the different diseases and their activation pattern. A novel iterative method was implemented for the IP dipolar resolution optimized for representing simple propagation patterns, achieving a high stability and robustness against noise by constraining the solution to a limited number of dipoles. However, propagation patterns not representable by few dipoles need to be computed with the IP in terms of epicardial solutions which provide a more detailed estimation of the myocardial activity. IP resolution in the voltage and phase domains showed a good accuracy for simple and organized propagation patterns. This method allowed the noninvasive diagnosis of the Brugada syndrome or the location of ectopic focus in atrial arrhythmias by performing a parametric analysis of the electrograms morphology or the activation map reconstruction. However, mathematical and patient results presented in this thesis proved that, for complex propagation patterns like atrial fibrillation (AF), inverse solutions in the voltage and phase domains are over-smoothed and over-optimistic, simplifying the complex AF activity, leading to non-physiological results that do not match with the complex intracardiac electrograms recorded in AF patients. In this thesis, we proposed a novel technique for the noninvasive identification and location of high dominant frequency AF sources, based on the assumption that in many cases atrial drivers present the highest activation rate with an intermittent propagation to the rest of the tissue that activates at a slower rate. Although, voltage and phase inverse solutions for AF complex propagation patterns were over smoothed and inaccurate, the noninvasive estimation of frequency maps was significantly more accurate, allowing the identification of the AF frequency gradient and location of high frequency sources. This technique may help in planning ablation procedures, avoiding unnecessary interseptal punctures for right-to-left frequency gradients cases and facilitating the targeting of the AF drivers, reducing risk and time of the clinical procedure.
[ES] El comportamiento del corazón se rige por corrientes eléctricas generadas en el miocardio y, por lo tanto, el estudio de su actividad eléctrica es esencial para el diagnóstico de enfermedades cardíacas. El problema directo (PD) de la electrocardiografía implica el cálculo de los potenciales del torso a partir de la actividad eléctrica del corazón y el modelo 3D del cuerpo, mientras que la resolución del problema inverso (PI) permite la reconstrucción no invasiva de la actividad eléctrica del corazón a partir de los potenciales de superficie, cobrando una gran importancia en la práctica clínica. Sin embargo, sigue siendo un gran desafío para la electrocardiografía ya que está mal planteado, es muy inestable y tiene múltiples soluciones. A lo largo de esta tesis se han desarrollado diferentes estrategias para la resolución del PI, aplicándolas en el diagnóstico no invasivo de arritmias ventriculares y auriculares, verificándolas mediante modelos celulares matemáticos y bases de datos clínicas. La tesis se centra en la resolución del PI para la reconstrucción no invasiva de la actividad eléctrica del miocardio para diferentes enfermedades cardiacas con diferentes patrones de propagación, implementando un novedoso sistema para patrones de propagación complejos. Además, se han validado los resultados obtenidos y se han clasificado los diferentes patrones de propagación con la estrategia de resolución del PI óptima que minimice el error y aumente la estabilidad del sistema. Un nuevo método iterativo fue implementado para la resolución del PI para fuentes dipolares, siendo óptimo para representar patrones de propagación simples, logrando una alta estabilidad e inmunidad al ruido al restringir la solución a un número limitado de dipolos. Sin embargo, los patrones de propagación que no pueden ser representados por un número limitado de dipolos deben calcularse mediante la resolución del PI en términos de potenciales epicárdicos, proporcionando una estimación más detallada de la actividad del miocardio. La resolución del PI en el dominio de la tensión y fase mostró ser muy preciso para patrones de propagación simples y organizados. Este método permite el diagnóstico no invasivo del síndrome de Brugada o la ubicación de focos ectópicos en arritmias auriculares mediante un análisis paramétrico de la morfología de los electrogramas o la reconstrucción de los mapas de activación. Sin embargo, los resultados matemáticos y clínicos presentados en esta tesis demostraron que, para patrones de propagación complejos como la fibrilación auricular (FA), los resultados obtenidos mediante la resolución del PI en el dominio de la tensión y fase son demasiado suaves y optimistas, simplificando enormemente la complejidad de la FA, llevando a resultados no fisiológicos que no coinciden con la actividad compleja de los electrogramas intracardiacos registrados en pacientes con FA. En esta tesis, se ha propuesto una novedosa técnica para la identificación y localización no invasiva de fuentes con una frecuencia dominante alta, basado en la suposición de que en muchos casos las fuentes eléctricas que generan y mantienen la FA presentan una tasa de activación más alta, con una propagación intermitente hacia el resto del tejido auricular cuya frecuencia de activación es más lenta. Aunque las soluciones en el dominio de la tensión y fase para patrones de propagación complejos fueron más suaves y menos precisas, la estimación no invasiva de los mapas de frecuencia fue significativamente más precisa, permitiendo la identificación del gradiente de frecuencia y ubicación de las fuentes de FA de alta frecuencia. Esta técnica puede ser de gran ayuda en la planificación de los procedimientos de ablación, evitando punciones interseptales innecesarias para casos con un gradiente de frecuencia de derecha a izquierda y facilitando la localización de las fuentes de alta frecuencia
[CAT] El comportament del cor es regeix per corrents elèctrics generades en el miocardi i, per tant, l'estudi de la seua activitat elèctrica és essencial per al diagnòstic de malalties cardíaques. El problema directe (PD) de l'electrocardiografia implica el càlcul dels potencials del tors a partir de l'activitat elèctrica del cor i el model 3D del cos, mentre que la resolució del problema invers (PI) permet la reconstrucció no invasiva de l'activitat elèctrica del cor a partir de els potencials de superfície. La resolució del PI de l'electrocardiografia té una gran importància en la pràctica clínica atès que fa possible una estimació de l'activitat elèctrica del miocardi únicament a partir de registres no invasius. No obstant això, la resolució del PI segueix sent un gran desafiament per a la electrocardiografia ja que està mal plantejat, és molt inestable i té múltiples solucions. Al llarg d'aquesta tesi s'han desenvolupat diferents estratègies basades en la resolució PI, aplicant-les en el diagnòstic no invasiu d'arítmies ventriculars i auriculars, verificant mitjançant models cel·lulars matemàtics i bases de dades clíniques. La tesi se centra en la resolució del PI per a la reconstrucció no invasiva de l'activitat elèctrica del miocardi per a diferents malalties cardíaques amb diferents patrons de propagació, implementant un nou sistema per a patrons de propagació complexos. A més se han validat els resultats obtinguts i se han classificat els diferents patrons de propagació amb l'estratègia de resolució del PI òptima que minimitze l'error i augmente l'estabilitat del sistema. Un nou mètode iteratiu va ser implementat per a la resolució del PI per fonts dipolars, sent òptim per representar patrons de propagació simples, aconseguint una alta estabilitat i immunitat al soroll en restringir la solució a un nombre limitat de dipols. No obstant això, els patrons de propagació que no poden ser representats per un nombre limitat de dipols s'han de calcular mitjançant la resolució del PI en termes de potencials epicàrdics, proporcionant una estimació més detallada de l'activitat del miocardi. La resolució del PI en el domini de la tensió i fase va mostrar ser molt precís per a patrons de propagació simples i organitzats. Aquest mètode permet el diagnòstic no invasiu de la síndrome de Brugada o la ubicació de focus ectòpics en arítmies auriculars mitjançant una anàlisi paramètric de la morfologia dels electrogrames o la reconstrucció dels mapes d'activació. No obstant això, els resultats matemàtics i clínics presentats en aquesta tesi van demostrar que, per patrons de propagació complexos com la fibril·lació auricular (FA), els resultats obtinguts mitjançant la resolució del PI en el domini de la tensió i fase són massa suaus i optimistes, simplificant enormement la complexitat de la FA, obtenint resultats no fisiològics que no coincideixen amb l'activitat complexa dels electrogrames intracardiacos registrats en pacients amb FA. En aquesta tesi, s'ha proposat una nova tècnica per a la identificació i localització no invasiva de fonts amb una freqüència dominant alta, basat en la suposició que en molts casos les fonts elèctriques que generen i mantenen la FA presenten una taxa d'activació més alta, amb una propagació intermitent cap a la resta del teixit auricular on la freqüència d'activació és més lenta. Encara que, les solucions en el domini de la tensió i fase per patrons de propagació complexos van ser més suaus i menys precises, l'estimació no invasiva dels mapes de freqüència va ser significativament més precisa, permetent la identificació del gradient de freqüència i ubicació de les fonts de FA d'alta freqüència. Aquesta tècnica pot ser de gran ajuda en la planificació dels procediments d'ablació, evitant puncions interseptales innecessaris per a casos amb un gradient de freqüència de dreta a esquerra i facilitant la
Pedrón Torrecilla, J. (2015). Non-invasive Reconstruction of the Myocardial Electrical Activity from Body Surface Potential Recordings [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/58268
TESIS

The purpose of this study was to compare trunk muscle activity during common Pilates exercises performed at different angles of support. Nineteen college aged students volunteered as participants and performed 2 exercises (modified teaser and high plank) on three different surface inclinations. Muscle activity of the abdominals and back extensors on the right side of the body were recorded using surface electrodes and were expressed as a percent of the individual muscles maximum contraction (MVIC) recorded during data collection. These values were compared using 1-way repeated measures ANOVAs. During the high plank, the altered surface inclination changed the abdominal activity. During the modified teaser differences were seen between all muscles when comparing activity on the incline surface to the decline surface. The results of this study suggest that trunk muscle activity can be altered by modifying the surface angle.

La modification du TiO₂ P25 par un ou deux métaux a connu un intérêt considérable ces dernières années, car ils constituent des catalyseurs et photocatalyseurs très actifs à la fois sous lumière UV et visible. Des nanostructures à un ou deux métaux, comme Au, Ag, Ag@CuO et CuO déposés sur le TiO₂ P25 ont la capacité d’absorber la lumière visible sur un large domaine de longueurs d’onde. Le TiO₂ modifié par des nanoparticules métalliques (comme, Cu, Au ou Ag) absorbe la lumière visible grâce à la résonance de plasmon de surface localisée (LSPR) des métaux. Dans le cas d’une hétérojonction de semi-conducteurs, la lumière visible est absorbée grâce à l’énergie du gap plus faible du second semi-conducteur (par rapport à celle du TiO₂ P25). La modification par une ou deux nanoparticules métallique induit une plus grande activité photocaralytique sous lumière visible par rapport au TiO₂ P25 pur, par transfert d’électrons vers la bande de conduction du P25. De plus sous lumière UV, la vitesse de capture d’électrons photo-excités peut être améliorée, ce qui inhibe les processus de recombinaison et permet de stocker ces électrons photo-excités.Cette thèse présente une synthèse des récentes avancées dans la préparation de TiO₂ modifié en surface par un ou deux métaux et ses applications environnementales. Des nanoparticules d’or ont été synthétisées par une méthode chimique à partir de chlorure de tetrakis(hydroxymethyl) phosphonium (THPC), des nanoparticules de Ag, Ag@CuO et CuO ont été synthétisées sur TiO₂ par radiolyse. L’effet de nombreux paramètres (comme la taille et la forme des particules ou la quantité de métal déposé) sur l’activité photocatalytique (oxydation du phénol, du 2-propanol et de l’acide acétique et génération d’hydrogène) a été étudié. La dynamique de porteurs de charge a été étudiée par conductivité microonde résolue en temps (TRMC)
The modification of TiO₂-P25 with one or two metal-based nanoparticles, have attracted considerable attention in recent years, as a new class of highly active catalysts and photocatalysts under both UV and visible light irradiation. One or two-metal-based structures, such as Au, Ag, Ag@CuO and CuO deposited on TiO₂-P25 have the ability to absorb visible light in a wide spectral range. Surface modified TiO₂ with metal nanoparticles (such as Cu, Au, Ag) absorb visible light due to the localized surface plasmon resonance (LSPR). In the case of semiconductor heterojunctions, they absorb visible light due to the narrow band gap of the second semiconductor, lower than TiO₂-P25. The modification with one or two metal-based nanoparticles induces a higher activity under visible light compared to pure TiO₂-P25, due to the transfer of electrons to the conduction band of TiO₂-P25. On the other hand, under UV irradiation, the speed of trapping photoexcited electrons can be improved, and inhibit the recombination process and have the capability of the storage of photoexcited electrons.This thesis presents recent advances in the preparation and environmental application of the surface modification of TiO₂-P25 with one or two-metal-based nanoparticles: The Au-NPs were synthesized by chemical method using tetrakis(hydroxymethyl) phosphonium chloride (THPC), and the nanoparticles of Ag, Ag@CuO and CuO-NPs were synthesized by gamma irradiation. Moreover, the effects of various parameters (such as particle size, shape of the nanoparticles and amount of metals) on the photocatalytic activity (phenol, 2-propanol and acetic acid oxidation, as well as hydrogen generation) were also studied. The charge carrier dynamics was studied by time resolve microwave conductivity (TRMC)

Self-assembly of polysaccharide derivatives at liquid/solid interfaces was studied by surface plasmon resonance spectroscopy (SPR) and quartz crystal microbalance with dissipation monitoring (QCM-D). Carboxymethyl cellulose (CMC) adsorption onto cellulose surfaces from aqueous solutions was enhanced by electrolytes, especially by divalent cations. A combination of SPR and QCM-D results showed that CMC formed highly hydrated layers on cellulose surfaces (90 to 95% water by mass). Voigt-based viscoelastic modeling of the QCM-D data was consistent with the existence of highly hydrated CMC layers with relatively low shear viscosities of ~ 10-3 Nâ ¢sâ ¢m-2 and elastic shear moduli of ~ 105 Nâ ¢m-2. Adsorption of pullulan 3-methoxycinnamates (P3MC) and pullulan 4-chlorocinnamates (P4CC) with different degrees of cinnamate substitution (DSCinn) onto cellulose, cellulose acetate propionate (CAP), poly(L-lactic acid) (PLLA), and methyl-terminated self-assembled monolayer (SAM-CH3) surfaces was also studied by SPR and QCM-D. Hydrophobic cinnamate groups promoted the adsorption of pullulan onto all surfaces and the adsorption onto hydrophobic surfaces was significantly greater than onto hydrophilic surfaces. SPR and QCM-D results showed that P3MC and P4CC also formed highly hydrated layers (70 to 90% water by mass) with low shear viscosities and elastic shear moduli. Finally, cellulose adsorption and activity on pullulan cinnamate (PC) and cellulose blend films were studied via QCM-D and in situ atomic force microscopy (AFM). The hydrophobicity of PC surfaces was controlled by adjusting the degree of cinnamate substitution per anhydroglucose unit (DSCinn). It was found that cellulase showed weak adsorption onto low DSCinn PC surfaces, whereas cellulase adsorbed strongly onto high DSCinn PC surfaces, a clear indication of the role surface hydrophobicity played on enzyme adsorption. Moreover, cellulase catalyzed hydrolysis of cellulose/PC and cellulose/polystyrene (PS) blend surfaces was studied. The QCM-D results showed that the cellulase hydrolysis rate on cellulose in cellulose/PC blend surfaces decreased with increasing DSCinn. AFM images revealed smooth surfaces for cellulose/PC (DSCinn = 0.3) blend surfaces and laterally phase separated morphologies for cellulose/PC (DSCinn â ¥ 0.7) blend surfaces. The combination of QCM-D and AFM measurements indicated that cellulase catalyzed hydrolysis was strongly affected by surface morphology. The cellulase hydrolysis activity on cellulose in cellulose/PS blend surfaces was similar with cellulose/PC blend surfaces (DSCinn â ¥ 0.7). These studies showed self-assembly of macromolecules could be a promising strategy to modify material surfaces and provided further fundamental understanding of adsorption phenomena and bioactivity of macromolecules at liquid/solid interfaces.
Ph. D.

Thesis advisor: Udayan Mohanty
The high surface area and atomic-level tunability offered by nanoparticles has defined their promise as heterogeneous catalysts. While initial studies began with nanoparticles of a single metal assuming thermodynamic shapes, modern work has focused on using nanoparticle composition and geometry to optimize nanocatalysts for a wide variety of reactions. Further optimization of these refined nanocatalysts remains difficult, however, as the factors that determine catalytic activity are intertwined and a fundamental understanding of each remains elusive. In this work, precise synthetic methods are used to tune a number of factors, including composition, strain, metal-to-metal charge transfer, atomic order, and surface faceting, and understand their impact on catalysis. The first chapter focuses on current achievements and challenges in the synthesis of intermetallic nanocatalysts, which offer long-range order that allows for total control of surface structure. A particular focus is given to the impact of the synthetic approach on the activity of the resulting nanoparticles. In the second chapter, multilayered Pd-(Ni-Pt)x nanoparticles serve as a controlled arena for the study of metallic mixing and order formation on the nanoscale. The third chapter controls the shell thickness of Au@PdPt core-alloyed shell nanoparticles on a nanometer scale to isolate strain at the nanoparticle surface. In the fourth chapter, the synthetic approaches of chapters two and three are applied to catalysis. In totality, the work presented here represents a brick in the foundation of understanding and exploiting structure-function relationships on the nanoscale, with an eye toward the rational design of tailored nanocatalysts
Thesis (PhD) — Boston College, 2020
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry

Kyoto University (京都大学)
0048
新制・課程博士
博士(人間・環境学)
甲第11661号
人博第267号
新制||人||67(附属図書館)
16||158(吉田南総合図書館)
23304
UT51-2005-D410
京都大学大学院人間･環境学研究科文化･地域環境学専攻
(主査)教授 森谷 敏夫, 教授 田口 貞善, 助教授 小田 伸午
学位規則第4条第1項該当

Nanoshells (NS) and nanoparticles (NP) are tunable plasmonic particles that can be precisely engineered for specific applications including surface enhanced spectroscopies. A new, general method for the synthesis of core-shell and solid nanoparticles has been developed and is presented. Based on the CO reduction of Au3+, this new process yields the highest quality gold nanoshells synthesized to date. The constraints on precursor lifetime have been relaxed and post-synthesis purification has been eliminated. Nonresonant surface enhanced Raman optical activity (SEROA) has been investigated using biomolecular analytes deposited on Au nanoshell or nanoparticle substrates. The first, and currently the only, near-infrared (780 nm) excited scattered circular polarization Raman optical activity spectrometer (NIROAS) has been constructed. Surface enhanced Raman optical activity spectroscopy has been validated by the collection of symmetrical, surface enhanced, signed circular polarization intensity difference spectra from several test molecules including, (S)- and (R)-tryptophan, and (SS)- and (RR)-phenylalanine-cysteine.

碩士
國立臺灣科技大學
高分子系
95
In this study, a series of gelatin derivatives is prepared by the reaction of gelatin with polyoxyethylenated stearyl ether and dextrin. The structures of these products were conformed by the measurement of FT-IR, 1H-NMR and EA analyses. The fundamental properties containing foaming, surface tension, wetting, emulsion, and fluorescence properties and application for scouring, bleaching and nylon dyeing of surfactants have been evaluated. From the results, the good properties including surface tension, foaming and wetting properties were found. The surface tension increase with the increase of polyoxyethylene length in structure. The emulsified oil particles were found almost independent of the time changes. Zeta potential decrease with the increase of polyoxyethylene length of surfactants. In application, it presents good effect on cotton scouring bleaching, and in nylon-acid dyes system, they present a retarding effect.

Sunspots and active regions are two of the many manifestations of the solar magnetic field. This field plays an important role in causing phenomena such as coronal mass ejections, flares, and coronal heating. Therefore, it is important to study the origin of sunspots and active regions and determine the underlying mechanism which creates them. It is believed that flux tubes rising from the bottom of the convection zone can create sunspots. However, there are still unanswered questions about this model. In particular, flux tubes are expected to expand as they rise, hence their strength weakens and some sort of reamplification mechanism must complement this model to match the observational properties of sunspots. To compensate for the absence of such an amplification mechanism, the field strength of the flux tubes, when at the bot- tom of the convection zone, must be far stronger than present dynamo models can explain. In the last few years, there has been significant progress toward a new model of magnetic field concentrations based on the negative effective mag- netic pressure instability (NEMPI) in a highly stratified turbulent plasma. NEMPI is a large-scale instability caused by a negative contribution to the total mean-field pressure due to the suppression of the total turbulent pressure by a large-scale magnetic field. In this thesis, I study for the first time NEMPI in the presence of a dynamo-generated magnetic field in both spherical and Carte- sian geometries. The results of mean-field simulations in spherical geometry show that NEMPI and the dynamo instability can act together at the same time such that we deal with a coupled system involving both NEMPI and dynamo effects simultaneously. I also consider a particular two-layer model which was previously found to lead to the formation of bipolar magnetic structures with super-equipartition strength in the presence of a dynamo-generated field. In this model, the turbulence is forced in the entire domain, but the forcing is made helical in the lower part of the domain, and non-helical in the upper part. The study of such a system in spherical geometry showed that, when the stratification is strong enough, intense bipolar regions form and, as time passes, they expand, merge and create giant structures. To understand the underlying mechanism of the formation of such intense, long-lived bipolar structures with a sharp boundary, we performed a systematic numerical study of this model in plane parallel geometry by varying the magnetic Reynolds number, the scale separation ratio, and Coriolis number. Finally, I investigate the formation of the current sheet between bipolar regions and reconnection of oppositely orientated magnetic field lines and demonstrate that for large Lundquist numbers, S, the reconnection rate is nearly independent of S – in agreement with recent studies in identical settings.

碩士
國立臺灣科技大學
纖維及高分子工程系
89
ABSTRACT In this study, higher fatty alcohols are directly reacted with glucose to synthesize alkyl glucosides in the presence of p-toluene sulfonic acid as a catalyst, and phosphorus oxychloride is applied at low temperature to modify alkyl glucosides by the reaction via chloroform as a solvent. Then sodium hydroxide solution is used to adjust the pH value of the products to 8. Therefore the synthesized compounds called glucose derivatives are a novel series of anionic surfactants with multi-anionic groups in the structure. The structure of the glucose derivatives was confirmed by 1H-NMR, FTIR, and elemental analysis respectively. From the results of the experiments, these glucose derivatives can display excellent surface-active properties including low foaming , better pH buffer capacity than water, reducing surface tension, promoting wetting power, improving the dyeing ability in direct dye-cotton dyeing system, etc. Key word : surfactant、surface activity、glucose

碩士
國立臺灣科技大學
高分子工程系
93
Absract In this study, a series of gelatin-alcohol surfactants was prepared by the reaction of gelatin, a hydrolyzate of collagen, with alcohols containing methanol, pentanol, decanol, dodecanol, and octadecanol. The structure of these surfactants was confirmed by FT-IR, 1H-NMR and elemental analysis. The experimental results showed that these surfactants exhibited excellent surface-active properties　including reducing surface tension, foaming, contact angle, streaming current reading, pH buffer capacity, dispersing power, chelating ability for calciumion, scouring and bleaching in cotton, interactions between the dye and the surfactants, and promotion and migration property in nylon Key word：gelatin、surface、surface tension、wetting power.

碩士
國立臺灣科技大學
高分子工程系
93
In this study, a series of casein derivative surfactants was prepared by the reaction of casein with carboxylic acids containing decanoic acid ,lauric acid, myristic acid, stearic acid and oleic acid. The structure of these casein derivative surfactants was verified by the FTIR ,1H-NMR, Elemental Analysis .The experimental results indicated that these surfactants were possess of excellent surface-active properties containing surface tension ,wetting power , foaming ,streaming current reading , pH buffer capacity , dispersiny power ,chelating ability for calciumion , scouring and bleaching in cotton , nylon dyeing and dyeing properties in nylon fabiers.

碩士
國立臺灣科技大學
高分子工程系
92
In this study，Gelatin hydrolyzate was prepared by alkaline hydrolysis with gelatin.Then a series of gelatin derivative surfactants have been synthesized by the reaction of succinic anhydride、(2-Nonen-1-yl)succinic anhydride 、(2-Dodecen-1-yl)succinic anhydride and Gelatin hydrolyzate. There are amino acids containing in the structure of gelatin derivative surfactants and gentle to skin. 1H-NMR、FT-IR and element analysis have been used to confirm structure of these compounds.These surfactants have been found to exhibit excellent surface active properties including reducing surface tension、foaming、wetting power、pH buffer capacity,etc.