Thesis (B.S.) Magna Cum Laude --Butler University, 2009. / Includes bibliographical references (leaf 29).

There is an increased interest in the Conductive Bridge Random Access Memory (CBRAM) and Resistive Random Access Memory (RRAM) because of their excellent scaling potential, low power consumption, high switching speed, good retention and endurance properties. Although, various mechanisms have been proposed to explain the switching behavior in CBRAM devices, i.e. metal ion migration and subsequent formation and rupture of conductive filament, formation of conductive path via oxygen ion transport etc, there are still many aspects of these mechanisms that are little understood or are being disputed. This work probes the details of the switching mechanisms on a new level and asks questions like: 1) How is the formation of nanofilament affected by various degrees of Cu diffusion stopping power of the inert electrode? To answer this question, resistive switches with very thin Cu layers covering the Pt electrode were fabricated and analyzed. 2) How does a limited source of active ions impact the formation and rupture of nanofilaments? To answer this question, new samples with limited Cu supply were fabricated and analyzed. 3) What is the mechanism of nanofilament formation in Pt/TaOx/Pt resistive switches where the active copper electrode is removed and replaced by inert Pt electrode. 4) What are the most suitable conditions (material structure of the device and operation conditions) to set and reset multi nanofilaments? This work summarizes the current status of analysis of the data obtained while attempting to explain interesting phenomena like volatile switching and multiple filament formation experienced by modifying the switch structures. / Master of Science

No description available.

No description available.

No description available.

Thesis (M.Pharm.)--University of the Witwatersrand, Faculty of Health Sciences, 2013. / Essential oils are not only used singularly but have been used in combination for many years. There is, however, very little scientific evidence to support the claims made for combined antimicrobial efficacy. With this in mind, a study was designed to investigate the antimicrobial activity of Lavender (Lavandula angustifolia) essential oil, in combination with other essential oils with antimicrobial relevance. The micro-dilution minimum inhibitory concentration (MIC) assay was undertaken, whereby the fractional inhibitory concentration (ƩFIC) was calculated for 54 oil combinations. When lavender oil was assayed in 1:1 ratios with other oils, synergistic (23.5%), additive (52.5%), non-interactive (23.5%) and antagonistic (0.5%) interactions were observed. Four 1:1 combinations were synergistic against Candida albicans and Staphylococcus aureus (Lavandula angustifolia in combination with Daucus carota (ΣFIC 0.50 and 0.50); Juniperus virginiana (ΣFIC 0.50 and 0.50); Cinnamomum zeylanicum (ΣFIC 0.40 and 0.50) and Citrus sinensis (ΣFIC 0.42 and 0.38)). In order to understand the antimicrobial potential of these synergistic essential oil combinations, further antimicrobial analysis was undertaken whereby the oils were placed in varying ratios. Two of the four combinations (Lavandula angustifolia in combination with either Cinnamomum zeylanicum or Citrus sinensis), were identified as the most promising, demonstrating synergy at varying ratios, and thus the major chemical constituents of the essential oils were investigated further. The major chemical constituents identified in Lavandula angustifolia (GC-MS) were linalyl acetate (36.7%), linalool (31.4%) and terpinen-4-ol (14.9%). The GC-MS profiles for all other oils in the study were also confirmed. The major chemical constituents of the most promising essential oil combinations were investigated in equal and varying ratios to determine the effect of chemistry on antimicrobial outcome. When one of the major essential oil constituents (linalyl acetate) of Lavandula angustifolia was combined with limonene found in Citrus sinensis, synergistic interactions were noted for all nine combinations against C. albicans; including the ratio at which the two major constituents would be mixed should the two oils be combined. Lavandula angustifolia essential oil was placed in combination with four conventional antimicrobial agents (ciprofloxacin, chloramphenicol, fusidic acid and nystatin) to determine which of these agents in combination with Lavandula angustifolia would demonstrate the best antimicrobial effect. Synergy was determined for Lavandula angustifolia in combination with ciprofloxacin against S. aureus (ΣFIC of 0.49) and Lavandula angustifolia in combination with chloramphenicol against P. aeruginosa (ΣFIC of 0.29). No antagonism was noted for the combinations investigated. When placed in variable ratios it was identified that Lavandula angustifolia provided the pivotal role in the synergistic interactions observed against C. albicans and S. aureus, with ratios higher in Lavandula angustifolia essential oil concentration showing considerably better antimicrobial effects. In order to determine the antimicrobial effects of Lavandula angustifolia in triple essential oil combinations, the method of MODDE® Design of Experiments was employed. The Design of Experiments (MODDE 9.1®) software identified that Lavandula angustifolia (from the combination of Lavandula angustifolia: Citrus sinensis: Cedrus atlantica) and Thymus vulgaris (from the combination of Lavandula angustifolia: Daucus carota: Thymus vulgaris) were the essential oils with the greater antimicrobial effect in the combinations analysed. Lavender remains one of the most sought after essential oils. This comprehensive study on the antimicrobial effects of Lavender (Lavandula angustifolia) combinations demonstrates promising in vitro effects and lends some credibility for combined use in aromatherapy for the treatment of infections

Thesis (M. Phil.)--University of Hong Kong, 2007. / Also available online.

Thesis (M. Phil.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.

In recent years, the fundamental researches on nanocrystals have been received increasing attentions for the novel applications, especially the nonvolatile memory technology. Adoption of nanocrystals technology could solve the serious limitation suffered by the conventional nonvolatile memory, flash, while scaling down. Once the thin tunneling oxide of flash device has been created a leaky path, all the stored charge in the floating gate will be lost after numerous counts of data reading and writing. Hence, the thinning of tunneling oxide will become one of important keys to the scaling limitation. Furthermore, if the tunneling oxide can not be thinned any more, both the operation voltage and speed of memory can not be improved. These drawbacks will restrict the development of nonvolatile memory. Replacement of floating gate structure with nanocrystals could effectively avoid the data losing due to the leaky path in the thin tunneling oxide. All stored charges can¡¦t be lost through the few leaky paths since the charges are stored in distributed nanocrystals. The charges stored nearby the leaky path will be lost, but others are still kept in the distributed and independent nanocrystals. The advantages of metal nanocrystals has have higher density of states around Fermi level, stronger coupling with conduction channel, wide range of available work functions and smaller energy perturbation due to carrier confinement. So metal nanocrystals can reduce operate voltage, and increase write/erase speed and endurance. In this thesis, we will study of cobalt and cobalt-silicide as the memory storage element. The nanocrystals were formed by high temperature oxidation or metal rapid thermal annealing with all kinds of conditions. And we analyze the effect of electron storage at metal nanocrystals by means of material and electrical analysis.

Thesis (M.S. in molecular plant sciences)--Washington State University, December 2009. / Title from PDF title page (viewed on Jan. 8, 2010). "Program in Molecular Plant Sciences." Includes bibliographical references (p. 61-68).