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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.
1

Synthesis and Characterization of Cross-Conjugated Macrocycles and Exploratory Study of their Organometallic Chemistry

Gholami, Mojtaba 11 1900 (has links)
This thesis covers the synthesis, characterization and physical studies of cross-conjugated macrocycles, expanded radialenes, as well as their related derivatives. The main synthetic protocol that is used throughout this thesis is based on the Pd-mediated Sonogashira cross coupling reaction of a desilylated iso-polydiacetylene with a dibromoolefin. To initiate the synthesis, a series of [3], [4], and [5]expanded radialenes was synthesized, characterized, and studied by UV-vis spectroscopy, electrochemistry, and solid-state analysis. The results confirm the macrocycles are achievable in reasonable yields and suitable for further physical studies without any concerns for their stability in the solid or solution phase. At the same time, the use of tetrabromoethene in analogous Sonogashira cross coupling reactions afforded bisexpanded radialenes and radiaannulenes that exhibited interesting physical properties according to UV-vis spectroscopy and cyclic voltammetric analysis. This thesis also covers some interesting results, in particular, for [3]expanded radialenes that undergo cycloaddition reactions. As well, physical studies of the target radialenes show that as the macrocycles become more strained, they exhibit more unique and unexpected electronic and optical properties. Having the first series of the radialenes in hand, the synthetic plan shifted towards the synthesis of functional expanded radialenes, which were produced in good to very good yields. In particular, the existence of a [4]expanded radialene carrying triisopropylsilylethynyl groups as exocyclic substituents provided an opportunity for derivatization of the expanded radialene framework. The general protocol for radialene synthesis was also applied using tetrabromides of anthracenylidene and pentacenylidene in Sonogashira reactions. These efforts afforded structurally unique bisexpanded radialene and radiaannulene products. Because of their shape and structure, radialenes have potential for use in organometallic chemistry or as ligands in inorganic chemistry. Exploratory studies have been focused on [3] and [4]expanded radialenes. By all accounts, [3]radialenes reacted more easily with selected precursors such Pt(PPh3)4 and Co2(CO)8. Throughout this thesis, all the major radialene frameworks are established in terms of solid-state structures by X-ray crystallography. Finally, electrochemical analyses show that the new series radialenes reported in this work are generally reduced at higher potentials when compared to the previous generation of expanded radialenes based on butadiynyl building blocks.
2

Synthesis and Characterization of Cross-Conjugated Macrocycles and Exploratory Study of their Organometallic Chemistry

Gholami, Mojtaba Unknown Date
No description available.
3

El cantico espiritual y su deuda con el cantar de los cantares

Inciarte, Monique Dascha. January 2001 (has links)
Thesis (M.A.)--University of California, Santa Cruz, 2001. / Typescript. Includes bibliographical references (leaves 78-80).
4

Expanding the Scope of Coupling Partners in Catalytic Cross-Coupling Reactions

Hua, Xi Ye January 2016 (has links)
Carbon-carbon (C-C) bond formation is among the most important processes in organic chemistry. Transition metal catalyzed C-C bond formation is an active research area that shows great potential due to high selectivity and relatively mild conditions. In Chapter 1, a new reaction for direct acylation of aryl halides is discussed. Specifically, the catalytic reaction between aryl halides/pseudohalides and aldehydes is explored. The choice of ligand, base, solvent, temperature, catalyst and substrates are important factors for optimizing this catalytic reaction. The various combinations of all these factors have, therefore, been examined by high-throughput screening (HTS) in order to develop the new C-C coupling reaction. In Chapter 2, a new methodology is reported in order to expand the scope of the Kumada-Corriu cross-coupling reaction. The strategy to achieve this goal is mechanistically based, matching oxidative addition rates with the rate of syringe pump addition of the Grignard to minimize the exposure of sensitive groups to the aggressive nucleophile. Aryl chlorides containing esters, amides, nitriles, pyrazines, carbamates, ketones, and other sensitive functionalities are all demonstrated to undergo chemoselective cross-coupling with this technique. The mechanistic reason for the effectiveness of this strategy is uncovered by continuous-infusion ESI-MS studies.
5

Sprache mit Potenzial : XML als Grundlage des Cross-Media-Publishing /

Jackenkroll, Melanie. January 2006 (has links)
Fachhochsch., Diplomarbeit, u.d.T.: Jackenkroll, Melanie: Nutzen vom XML für die Herstellung verschiedener medialer Varianten von Informationsmitteln--Zugl.: Köln, 2002.
6

Cross-cultural management in international construction projects : Case study of China Machinery Industry Construction Group Inc.

Liu, Yuan, You, Li January 2014 (has links)
ABSTRACT Title: Cross-cultural management in international construction projects: Case study of China Machinery Industry Construction Group Inc. Level: Final assignment for Master Degree in Business Administration Author: Yuan Liu, You Li Supervisor: Aihie Osarenkhoe Examinor: Maria Fregidon-Malama Date: 2014.04.18 Aim : This study presents the characteristic and current status of the international construction projects, and figure out which barriers caused by cross-cultural differences the multinational corporations and enterprise would face, as well as the solutions for these barriers. Method: This study was carried out by using a qualitative and quantitative research method. We gathered relevant information by conducting questionnaire to Chinese employees working in Congo, Rep and interviews which include four managers of China Machinery Industry Construction Group Inc (CMICGI). By comparing the literature review and finding, we find barriers caused by cross cultural differences and relevant solutions. Result & Conclusions : Through the literature review associating with the analysis of the questionnaire and interview, we find out that there are nine barriers in the project, the reason why they appeared and how them influence the projects. We also find solutions to solve the barriers. Suggestions for future research: This study restricted to geographical and time, it only included one company and one country. More cases can be concluded in future research. Contributions for the study: The study results show how barrier case of cross-cultural different impact in international construction project. We also - 3 - contribute the evaluation for each barrier. Cultural differences between multinational trading are frequently neglected by firms but have a significant impact. Our research can help more companies to find some problems which they usually ignored. KEYWORDS — Cross-cultural management, Barriers, Cross-cultural difference, International construction projects, Identification, Evaluation
7

Optical Cross-Connect Switch Architectures for Hierarchical Optical Path Networks

SATO, Ken-ichi, HASEGAWA, Hiroshi, KAKEHASHI, Shoji 01 October 2008 (has links)
No description available.
8

Experimental electron scattering from atomic and molecular hydrogen, helium, neon, argon and krypton /

Bohm, Robert Roman. January 1973 (has links) (PDF)
Thesis (Ph.D.) -- University of Adelaide, Dept. of Physics, 1974.
9

Design, fabrication, and characterization of nano-scale cross-point hafnium oxide-based resistive random access memory

Ellis, Noah 27 May 2016 (has links)
Non-volatile memory (NVM) is a form of computer memory in which the logical value (1 or 0) of a bit is retained when the computer is in its’ powered off state. Flash memory is a major form of NVM found in many computer-based technologies today, from portable solid state drives to numerous types of electronic devices. The popularity of flash memory is due in part to the successful development and commercialization of the floating gate transistor. However, as the floating gate transistor reaches its’ limits of performance and scalability, viable alternatives are being aggressively researched and developed. One such alternative is a memristor-based memory application often referred to as ReRAM or RRAM (Resistive Random Access Memory). A memristor (memory resistor) is a passive circuit element that exhibits programmable resistance when subjected to appropriate current levels. A high resistance state in the memristor corresponds to a logical ‘0’, while the low resistance state corresponds to a logical ‘1’. One memristive system currently being actively investigated is the metal/metal oxide/metal material stack in which the metal layers serve as contact electrodes for the memristor with the metal oxide providing the variable resistance functionality. Application of an appropriate potential difference across the electrodes creates oxygen vacancies throughout the thickness of the metal oxide layer, resulting in the formation of filaments of metal ions which span the metal oxide, allowing for electronic conduction through the stack. Creation and disruption of the filaments correspond to low and high resistance states in the memristor, respectively. For some time now, HfO2 has been researched and developed to serve as a high-k material for use in high performance CMOS MOSFETs. As it happens, HfO2-based RRAM devices have proven themselves as viable candidates for NVM as well, demonstrating high switching speed (< 10 ns), large OFF/ON ratio (> 100), good endurance (> 106 cycles), long lifetime, and multi-bit storage capabilities. HfO2-based RRAM is also highly scalable, having been fabricated in cells as small as 10 x 10 nm2 while still maintaining good performance. Previous work examining switching properties of micron scale HfO2-based RRAM has been performed by the Vogel group. However, a viable process for fabrication of nano-scale RRAM is required in order to continue these studies. In this work, a fabrication process for nano-scale cross-point TiN/ HfO2/TiN RRAM devices will be developed and described. Materials processing challenges will be addressed. The switching performance of devices fabricated by this process will be compared to the performance of similar devices from the literature in order to confirm process viability.
10

En studie kring cross-shopping, lojalitet och värdeskapande : Examensarbete

Kaspersson, Julia, Olsson, Isabella January 2016 (has links)
Vi har gjort en kvalitativ uppsats för att undersöka vilka drivkrafter och värden som påverkar konsumenters beteende avseende cross-shopping inom livsmedelshandeln. Vår avsikt var att få insikt i hur företag kan möta konsumenters preferenser för att påverka deras lojalitet.  Vår slutsats blir att det finns samband mellan värde och lojalitet och att butiker har stora möjligheter att påverka detta genom sina värdeförslag och butikskoncept. Värde kan upplevas i exempelvis butikslayout, märkning av varor och personalens bemötande. Vi har observerat att konsumenter kan cross-shoppa och samtidigt vara lojala.

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