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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Synthesis of MOFs for Low Valent, Low Coordinate Metal Stabilization and Catalysis

Rabon, Allison Marie January 2021 (has links)
No description available.
62

Exploring the concept of boundaries in a training group encounter

Viljoen, Greyling January 2013 (has links)
The concept of boundaries in group theory gained prominence in the 70s and 80s mainly as a construct to describe significant group events. A contributing factor was when general systems theory, in which boundaries are central, was applied to living systems. Boundaries continued to be used predominantly to refer to structural aspects of a group, such as time structuring, membership, role, subgroupings, and task, and, to a lesser extent, as an abstract construct to refer to group processes and dynamics. In group practice, the use of boundaries as a guide and instrument to gauge group dynamics has been limited. In general, boundaries are not used to assess group events in order to determine a course of action or intervention. The first part of the research explores the concept of boundaries in three theoretical frameworks. The second part of the research explores the application of boundaries as a construct central to the understanding of group dynamics in an experiential time-limited training group. It also examines ways in which this can lead to enhanced group practice. The focus was on boundaries as psychological dimensions in the group space. In the exploration of boundaries in existing theoretical frameworks, an important link between boundaries and trauma, which inevitably involves a breach and violation of boundaries, was highlighted. A novel qualitative content analysis method was designed to reveal boundary changes systematically and to show how boundaries were redefined over a period of time. A unique feature of this computer assisted (Atlas.ti) method is that boundary shifts are quantitatively tracked, allowing further qualitative exploration. This method was applied in a case study of a training group, so demonstrating the applicability of the method to the study of small groups. Results of the case study revealed the impact that events prior the group had on group boundary development, in particular emotional linking in the group. Shifts in psychological boundaries were clearly visible in the quantitative analysis of boundaries in focus, across boundaries, indicated by transactions across boundaries. South Africa, as is the case in other societies in transition, is characterised by continuous breaches and violations of boundaries. By viewing group interactions through a boundary lens, group leaders can understand the complexity of group dynamics better. With this understanding, facilitators and leaders of groups can deliberately influence psychological boundaries. In so doing they can create opportunities for individual transitions and societal transformation. / Thesis (PhD)--University of Pretoria, 2013. / gm2014 / Psychology / Unrestricted
63

Models of Domination in Graphs

Haynes, Teresa W., Hedetniemi, Stephen T., Henning, Michael A. 01 January 2020 (has links)
A set S of vertices in a graph G is a dominating set if every vertex not in S is adjacent to at least one vertex in S. In this chapter, we present logical models called frameworks, each of which gives a different perspective of dominating sets.
64

Design and Fabrication of Metal-Organic Framework Membranes for Gas Separations

Zhou, Sheng 03 1900 (has links)
Industrial productions need the separation processes, but they are quite energyintensive, which occupy about half of the total energy consumption. Membranetechnology based on a non-thermal route is expected to reduce the associated energy duties by ~90%, but effective membrane materials capable of precisely isolating targeted species from complex mixtures are highly needed. Metal-organic frameworks (MOFs), possessing the tuneable pore size and geometry, are regarded as the promising platform for molecular separations and membrane design. This dissertation illustrates the rational design and the guided fabrication for various MOF membranes. Respectively, different gas separation applications were addressed by using these membranes, such as light hydrocarbon separations, carbon dioxide (CO2) captures and natural gas purifications. A versatile strategy for membrane fabrication is developed based on the electrochemical method. Following this, a family of face-centered cubic (fcu) MOF membranes were obtained, which possess different ligands and different clusters, namely rare-earth hexanuclear or zirconium hexanuclear clusters. Two MOF membranes based on fumarate (fum) linker, Zr-fum-fcu-MOF and Y-fum-fcu-MOF, showed efficient separation for the propylene/propane binary mixture, as well as the butane/isobutane equimolar mixtures, respectively. Further aperture editing applied to Zr-fum-fcu-MOF via mixed-linker approach permits the introduction of shape irregularity to the parent trefoil-shaped apertures, inducing an ideal shape-mismatch with tetrahedral CH4 molecules and blocking their transportation while affecting linear molecules slightly such as nitrogen (N2) and CO2. The resultant Zr-fum67-mesaconate (mes)33-MOF membranes exhibit great promise for natural gas purification, including efficient nitrogen rejection and simultaneous removal of CO2 and N2 from natural gas. In addition, a unique CO2-recognition membrane based on a fluorinated MOF (KAUST-7) is constructed for multipurpose CO2 capture, including CO2/H2, CO2/N2 and CO2/CH4 separation. The specific affinity to CO2 coupling with the molecular sieving capability of KAUST-7 enables the membrane to be nearly only permeable to CO2, excluding both smaller H2 molecule and larger N2 or CH4 molecules. Moreover, in order to be closer to the real applications, the defective Zr-fum-fcu- MOF nanoparticles based mixed-matrix membranes are constructed for natural gas purification under practical conditions
65

Loading and Delivery of Biologics Using Biocompatible Nano-carriers, BioMOFs

Alahmed, Othman 28 June 2022 (has links)
Biologics such as DNA and protein have immense biomedical applications, especially in diagnosis and therapy. However, many barriers hinder these applications, including biologics transport and liability in biological systems. Therefore, biocompatible and stable nanocarriers with high Biologics loading efficiency can provide a platform for advances in biologics applications. Metal-organic frameworks (MOFs) have gained significant interest within the biomedical field, mainly because of their building block versatility, porosity, stability, and chemical and biological functionality. Currently, increasing research is dedicated to improving MOFs biocompatibility, stability, and functionality for drug delivery. Using biomolecules as organic linkers could improve biocompatibility, physiological condition stability, and biological functionality. The main goal of this dissertation is to investigate the applicability of biomolecule-based Metal-organic frameworks (BioMOFs) as nanocarriers to achieve cellular delivery of active biologics. Herein, we analyzed adenine and saccharate metal−organic frameworks (BioMOF) in terms of biocompatibility, loading capability, protection, and cellular delivery of biologics. Our findings suggest that the usage of biomolecules as an organic linker generates BioMOFs with reduced cytotoxicity compared with the widely used MOFs such as Zinc Imidazole framework-8 (ZIF-8). In addition, the base-pairing functionality of coordinated adenine of KAUST-BioMOFs (KBMs) is preserved and can be used to load ssDNA. Both KAUST-BioMOFs (KBMs) and Zinc adenineated framework (ZAF) load, protect, and deliver functional ssDNA to cells. In addition, we showed the possibility of in situ encapsulation of active lysozyme in zinc saccharate (Zn-Sac) with modified synthesis procedures.
66

Patterns of influence in management decision making. Analysis of decision processes in four types of Brazilian organizations.

Rodrigues, Indiana P. F. January 1987 (has links)
The distribution of influence in organizational decisions is analysed in relation to institutional frameworks and characteristics inherent to decision topics. Distribution of influence is defined as the concentration of participants in decision process and their specific capability to influence decision outcomes. This definition encompasses two dimensions which are: participation in the decision processes and effective influence upon the decision outcomes. Institutional frameworks are distinguished according to the loci of their genesis and existence, that are: the focal organization the task-environment and the larger social context. Six characteristics inherent to decision topics are identified as related to variables defined as properties of decision. The analysis is carried out at two distinct stages. At the first stage, it examines the relationships of the institutional frameworks - existing at the organization and the task environment level - and of the properties of decisions with the distribution of influence in decision processes. At the second stage, the patterns of influence that emerged out of the first stage of analysis are analysed in terms of cultural traits prevailing in Brazilian society. The results point to variation in the distribution of influence in decision processes associated with factors of the taskenvironment, of the context of the organizations and characteristics inherent to decision topics. But they do not provide a wholly satisfactory explanation of such variation. A more general pattern of influence in management decisionmahing, characterized by low level of participation and high centre of influence in decision processes, appears as the dominant profile of the distribution of influence in Brazilian organizations. Interpreted in the light of the Brazilian social context, this pattern of influence in management decision making shows pervasive cultural traits, identified in the macro social system. Comparing the patterns of influence in management decisionmaking in Brazil and Britain, similarities and differences come to light. The comparative analysis corroborates the argument that patterns of influence in management decision making are bound to contingent as much as to institutional factors. / Conselho Nacional de Desenvolvimento Cientifico e Tecnologico CNPq - and from the Universidade Federal de Minas Gerais - UFMG
67

Cleaner Futures: Covalent Organic Frameworks for Sustainable Degradation of Lignocellulosic Materials

Lan, Pui Ching 05 1900 (has links)
As countries pledge their commitment to a net-zero future, much of the previously forgotten climate change research were revitalized by efforts from both governmental and private sectors. In particular, the utilization of lignocellulosic materials saw a special spotlight in research interest for its abundance and its carbon removal capability during photosynthesis. The initial effort in mimicking enzymatic active sites of β-glucosidase will be explored. The crystalline covalent organic frameworks (COFs) allowed for the introduction of a variety of noncovalent interactions, which enhanced the adsorption and the catalytic activity against cellobiose and its glycosidic bonds. The physical processes associated with this reaction, such as the kinetics, equilibrium, and activation energies, will be closely examined and compared with existing standard materials and comparable advanced catalysts. In addition, several variants of COFs were synthesized to explore the effect of various noncovalent interactions with cellobiose. A radical-bearing COF was synthesized and characterized. The stability of this radical was examined by electron paramagnetic resonance spectroscopy (EPR) and its oxidative capability tested with model lignin and alcoholic compounds. The reaction products are monitored and identified using gas chromatography-mass spectroscopy (GC-MS). An oxidative coupling of phenol was explored, and its initial results are presented in chapter 5.
68

Unraveling the Photocatalytic Behavior of Metal-Organic Frameworks: Structure-Performance Correlations

Kolobov, Nikita 08 1900 (has links)
With the increasing demand for energy consumption and the limitations of traditional carbon-based energy sources, the importance of renewable energy generation is undeniable. Among the various methods for generating and storing energy, green hydrogen production through photocatalytic water splitting has gained significant interest. However, despite numerous studies dedicated to finding the perfect material, achieving large-scale industrial applications is still a distant goal. Metal-Organic Frameworks (MOFs) have emerged as a particularly intriguing option due to their exceptional tunability and versatility. Nevertheless, there remains a substantial gap in our understanding of their performance and fundamental aspects. In this study, we focus on Ti-based MOFs, which have shown great promise owing to the redox properties of titanium. We introduce a novel Ti-oxo chain pyrene MOF called ACM- 1, which exhibits remarkable activity in both the hydrogen evolution reaction (HER) and organic transformations. This outstanding performance can be attributed to the high mobility of photogenerated electrons and the strong localization of holes within the material. To further enhance the photocatalytic activity of ACM-1, we employ defect engineering techniques, specifically fluorination of the metal-oxo units. The introduction of fluorine effectively reduces the band gap of the material, leading to improved light absorption capabilities and a significant boost in photocatalytic performance. Additionally, we synthesize a new MOF named ICGM-1, which shares isochemical characteristics with the well-studied MIL-125-NH2. Despite the identical NH2-bdc linker, ICGM-1 differs in terms of its Ti-sbu composition, providing a unique opportunity to investigate the influence of node geometry on photocatalytic activity. Our study reveals that the rod-type geometry is unfavorable due to lower electron charge mobility, highlighting the importance of node architecture in designing efficient photocatalysts. Finally, we report the synthesis of two new Zr-based MOFs, ACM-10 and ACM-11, based on the redox-active TTFT linker. Through Ti grafting, we demonstrate the potential of ACM-10 for HER, further expanding the range of viable MOF photocatalysts.
69

Formation of Functionalized Supramolecular Metallo-organic Oligomers with Cucurbituril

Del Valle, Ian M. January 2015 (has links)
No description available.
70

A Physical Education Curriculum Plan For Malawi

Tembo, Mark Jimu 25 April 2002 (has links)
This document is about a plan to develop physical education curriculum in Malawi. Despite its official recognition, the subject is often regarded as a low entity on the school curriculum. Several factors contribute to this status, chief among them is: lack of well-prepared teachers; equipment and materials; negative attitude by certain key individuals in the society. This document is the first attempt to develop a broad and balanced physical education curriculum in Malawi. In this document, two curriculum frameworks have been provided. One such curriculum frameworks is for the primary school (elementary) grades 1-8 and the other, the secondary (high) school 1-4. These frameworks are detailed with teaching and learning topics in physical education in such a way that every school child will have an opportunity to participate for enjoyment, knowledge and skill acquisition for personal and national benefit. This study is drawn upon the US and UK models where programs such as Saber-Tooth, Catch, Spark and Sport-England have been very successful. The assumption of this plan, comprehensive as it may be, is the essence of collective effort of the people of Malawi to implement the ideas it contains. / Ph. D.

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