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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

Design and Development of Soft Landing Ion Mobility: A Novel Instrument for Preparative Material Development

Davila, Stephen Juan 08 1900 (has links)
The design and fabrication of a novel soft landing instrument Soft Landing Ion Mobility (SLIM) is described here. Topics covered include history of soft landing, gas phase mobility theory, the design and fabrication of SLIM, as well as applications pertaining to soft landing. Principle applications devised for this instrument involved the gas phase separation and selection of an ionized component from a multicomponent gas phase mixture as combing technique to optimize coatings, catalyst, and a variety of alternative application in the sciences.
2

Study of Novel Ion/surface Interactions Using Soft-landing Ion Mobility

Hoffmann, William Darryle 12 1900 (has links)
Preparative mass spectrometry is a gas-phase ion deposition technique aimed at deposition of monodisperse ion beams on a surface. This is accomplished through the implementation of a soft-landing ion mobility system which allows for high ion flux of conformationally selected ion packets. The soft-landing ion mobility system has been applied to a number of unique chemical problems including the deposition of insulators on graphene, the preparation of reusable surface enhanced Raman spectroscopic substrates, and the deposition of uranium nanoparticles. Soft-landing ion mobility provided a platform for the quick deposition of usable amounts of materials, which is the major objective of preparative mass spectrometry. Soft-landing ion mobility is unique when compared to other preparative mass spectrometric techniques in that the ion packets are conformationally separated, not separated on mass to charge ratio. This provides orthogonal complementary data to traditional mass spectrometric techniques and allows for the study of conformationally monodisperse surfaces. The diversity of problems that have been and continued to be explored with soft-landing ion mobility highlight the utility of the technique as a novel tool for the study of multiple ion/surface interactions.
3

Miniature Mass Spectrometry: Theory, Development and Applications

Fox, James D. 12 1900 (has links)
As mass analyzer technology has continued to improve over the last fifty years, the prospect of field-portable mass spectrometers has garnered interest from many research groups and organizations. Designing a field portable instrument entails more than the scaling down of current commercial systems. Additional considerations such as power consumption, vacuum requirements and ruggedization also play key roles. In this research, two avenues were pursued in the initial development of a portable system. First, micrometer-scale mass analyzers and other electrostatic components were fabricated using silicon on insulator-deep reactive ion etching, and tested. Second, the dimensions of an ion trap were scaled to the millimeter level and fabricated from common metals and commercially available vacuum plastics. This instrument was tested for use in ion isolation and collision induced dissociation for secondary mass spectrometry and confirmatory analyses of unknowns. In addition to portable instrumentation, miniature mass spectrometers show potential for usage in process and reaction monitoring. To this end, a commercial residual gas analyzer was used to monitor plasma deposition and cleaning inside of a chamber designed for laser ablation and soft landing-ion mobility to generate metal-main group clusters. This chamber was also equipped for multiple types of spectral analysis in order to identify and characterize the clusters. Finally, a portion of this research was dedicated to method development in sample collection and analysis for forensic study. A new method for the analysis of illicit chemistries collected via electrostatic lifting is presented. This method incorporates surface-enhanced Raman microscopy as a prescreening tool for nanoextraction and nanospray ionization mass spectrometry.
4

STUDIES OF ION DISSOCIATION KINETICS AND MECHANISMS BY SURFACE-INDUCED DISSOCIATION AND INFRARED MULTI-PHOTON DISSOCIATION/SOFT-LANDING

Yoon, Sung Hwan January 2010 (has links)
This dissertation presents dissociation mechanism and dissociation kinetics studies of gas-phase ions using mass spectrometry (MS). Dissociation of a gas-phase ion is related to its fundamental properties such as composition and structure. However, the detailed processes, internal energy deposition during ion activation as well as the mechanism of dissociation, are not fully known. In the present work, ion structural studies from which mechanisms can be inferred were performed using infrared multiphoton dissociation (IRMPD) spectroscopy, soft-landing, IR spectroscopy, and quantum chemical calculations. Kinetics studies involved instrument modification to add surface-induced dissociation (SID) capability and peak shape analysis. Structural studies were performed to determine dissociation mechanisms. The b₂⁺ ion from AGG is an oxazolone structure as indicated by the IRMPD spectrum and quantum chemical calculations. Protonated 4-ethoxymethylene-2-phenyl-2-oxazolin-5- one is also an oxazolone-type structure, while protonated cyclo-AG is a diketopiperazine structure. Soft-landing experiments were carried out to corroborate IRMPD results. Soft-landed protonated cyclo-AG and protonated 4-ethoxymethylene-2-phenyl-2- oxazolin-5-one underwent neutralization and retained their structures. The soft-landed b₂⁺ ion of AGG showed evidence of ring opening and conversion into a linear structure. The modified matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometers with SID capability were used to study fast dissociation kinetics (sub-microsecond dissociation). Silicon nanoparticle assisted laser desorption/ionization (SPALDI) allows the study of small molecule dissociation kinetics for ions without the matrix interference observed in MALDI. Well characterized systems, such as, N(CH₃)₄⁺, N(CD₃)₄⁺, and substituted benzylpyridinium ions were used to confirm reliability of the peak shape analysis. Obtained dissociation rates, of submicrosecond order, are consistent with the known dissociation theories. Dissociation of fullerenes, C₆₀ and C₇₀, was also investigated with the SID method using a fluorocarbon self-assembled monolayer (FSAM) surface. Fullerene ions produced C(2n)⁺ fragments ion in the kinetic energy range of 150-300 eV. At higher than 400 eV, mass spectra showed additional small fragment ions composed of odd numbers of C units. Energy resolved MS/MS curves support parallel dissociation at high SID energies while peak shape analysis explains sequential dissociation at about 150 eV range. Instrument modification of a MALDI-TOF mass spectrometer with SID capability allowed successful studies of fast unimolecular dissociation kinetics of small ions and fullerenes.
5

Applications of Metallic Clusters and Nanoparticles via Soft Landing Ion Mobility, from Reduced to Ambient Pressures

Aguilar Ayala, Roberto 08 1900 (has links)
Nanoparticles, simple yet groundbreaking objects have led to the discovery of invaluable information due to their physiological, chemical, and physical properties, have become a hot topic in various fields of study including but not limited to chemistry, biology, and physics. In the work presented here, demonstrations of various applications of chemical free nanoparticles are explored, from the determination of a non-invasive method for the study of the exposome via using soft-landing ion mobility (SLIM) deposited nanoparticles as a matrix-assisted laser desorption/ionization (MALDI-MS) matrix replacement, to the direct SLIM-exposure of nanoparticles onto living organisms. While there is plenty of published work in soft-landing at operating pressures of 1 Torr, the work presented here shows how this technology can be operated at the less common ambient pressure. The ease of construction of this instrument allows for various modifications to be performed for a wide array of applications, furthermore the flexibility in metallic sample, operating pressure, and deposition time only open doors to many other future applications. The work presented will also show that our ambient SLIM system is also able to be operated for toxicological studies, as the operation at ambient pressure opens the door to new applications where vacuum conditions are not desired.
6

Överlämning av Byggprojekt : Digitaliseringens inverkan på projektledarens arbete / Construction Project Handover : The digitalisation’s impact on the project manager

Källbrink, Marcus, Månsson, Jacob January 2018 (has links)
Med den höga utvecklingstakt som teknik och digitala system för närvarande har, öppnas möjligheter till en omfattande utveckling och förändring av fastighetsbranschen. För fastighetsförvaltare innebär det att de olika processerna kan effektiviseras och optimering av arbetsprocesser, ofta genom utökat användande av digitala fastighetssystem och hjälpmedel, kan göras. Detta resulterar i att arbetsprocesser förändras, både i förvaltningsskedet och dessförinnan, genom produktionen av fastigheten. För att undersöka dessa förändringar i branschen har detta arbete genom ett antal intervjuer och en litteraturstudie, undersökt hur informationen som finns i byggprojekt och projektledarens roll ska hanteras och vilken inverkan digitaliseringen har vid överlämning från byggskede till förvaltning.  Resultaten visar att de förvaltande företagen bör involveras i stor utsträckning i tidiga skeden av projektet. Detta involverande bör ske i projekteringen, men likaså bör de bjudas in till byggmöten, för att dels kunna komma med information och dels erhålla information från övriga parter.  Likaså är det viktigt att projektorganisationen, inklusive förvaltaren tidigt inleder arbete med att sortera information som primär eller sekundär inför förvaltningsskedet. Där den primära utgör information kring den dagliga driften och underhållet, denna hålls aktuell och uppdaterad av förvaltningen. Den sekundära informationen är sådan som kan vara bra att ha om särskilda situationer uppstår, men inte behöver hållas uppdaterad då den endast syftar till att användas vid dessa särskilda händelser. För att underlätta indelningen av informationen är det inte enbart kompetensen om de olika perspektiven som krävs, utan även förståelse för varandras arbete och behov mellan de olika parter involverade i projektet. För en effektiv överlämning är det viktigt att den mottagande organisationen är beredd att ta emot den digitala information som levereras genom någon typ av digitalt verktyg, exempelvis fastighetssystem och dylika verktyg för förvaltning och övervakning av fastigheter. Dessa system kan både minska kostnader, underlätta underhållsplaner, effektivisera den allmänna förvaltningen och öka hållbarheten vid förvaltning och underhåll av fastigheten.  Det är slutligen viktigt att projektet inte avslutas för hastigt, så information och erfarenheter som erhållits förloras utan att dokumenteras, således är det av stor vikt att erfarenhetsåterföringen får stor prioritet över lag. / With the high rate of development in tech and digital systems of today, new possibilities appear for large changes, and evolution within the real estate sector. This results in potentials to enhance and optimise the work processes of the facility managers. Generally, this can be achieved through further implementation of CMMS, and other digital aids. The development will result in a need to change of routines among the workers in facility management, as well as during the construction and design stage of the project. To investigate these changes and the development in real estate, several interviews and a literature review on the subject has been performed. Through these, a more thorough study of how the information in construction projects is managed, how the role of the project manager is affected, and lastly what impact the digitalisation has on the handover from construction phase to facility management.  The results show how the facility managing companies should be involved in the early stages of the project. Preferably their involvement should start in the design stage, and continue during the project, to provide valuable input and receive information from involved parties. It is also important that the project organization, including the facility management, start work on separating information into primary and secondary information aimed at the management stage. Where the primary information consists of operation and maintenance information to be kept up to date by the facility management. The secondary information can be stored in an archive ready to be used in case something unexpected happens but does not need to be updated like the primary. To aid the separation of the information it is not only expertise about the diverse perspectives that is important but also an understanding of each individual way of working and the different needs between the many different parties involved.  For a smooth and efficient handover, it is essential that the receiving organisation is prepared to receive the digital information being delivered through some sort of digital tool, like MMS or similar systems for facilitating and monitoring properties. These systems may both lower costs and ease maintenance planning, streamline the general facility management and improve the sustainability in operation and maintenance of properties.  Finally, it is important that the project does not end too abruptly, so that information and experiences acquired gets lost without being documented. It is consequently of great importance that experience feedback is given a significant priority in every project.
7

Preparative Mass Spectrometry: Instrumentation and Applications

Pei Su (9762467) 12 December 2020 (has links)
<p>Ion soft landing is a preparative mass spectrometry technique that enables intact deposition of polyatomic ions onto surfaces. The ability to select ions with well-defined mass, charge, and kinetic energy, along with precise control over size, shape, and position of the ion beam in the deposition process distinguishes ion soft landing from traditional synthetic and surface preparation approaches. A wide range of projectile ions including molecular ions, non-covalent complexes, clusters, and ionic fragments generated in the gas phase have been used in soft-landing studies to address both the fundamental questions related to ion-surface interactions and enable applications of hyperthermal beams.</p> <p>Since the first soft landing instrument was implemented by Cooks and co-workers in 1977, significant advances have been achieved in preparative mass spectrometry instrumentation. Current instrument development efforts are focused on obtaining high ion currents, increasing the experimental throughput, and developing capabilities for layer-by-layer deposition. In chapter 2 and 3, two novel instrumentation approaches are introduced, which improve the ion flux and experimental throughput of ion soft landing research. In particular, soft landing of ions of both polarities enables the bottom-up construction of ionic materials. Meanwhile, a rotating wall mass analyzer substantially increases the mass range of mass-selective deposition and disperses multiple species on the same surface thereby increasing the experimental throughput. These instrumentation developments open up the opportunities to explore research topics in the field of catalysis, energy storage and production, biology, and quantum sciences.</p> <p>In chapter 4, I describe a novel <i>in situ</i> spectroelectrochemistry approach for studying structural changes of electroactive species during electrochemical processes. In these experiments, ion soft landing is used to prepare well-defined ions at electrochemical interfaces. In addition, understanding of the gas-phase properties of cluster ions is important for their application in ion soft landing research. Ions can be prepared in the proper physical and chemical state via gas-phase chemistry approaches, and the favorable properties and reactivities of ions can thereby be harnessed using ion soft landing. In chapter 5 and 6, gas phase properties of host-guest complexes of cyclodextrins and polyoxometalates and molybdenum halide clusters are discussed.</p>
8

Toxicological and Biochemical Changes Induced by Sub-Acute Exposure of Biological Organisms to Silver Nanoparticles Using Soft-Landing Ion Mobility Instrument

Nayek, Subhayu 12 1900 (has links)
In this study, we have developed a novel way of generating and exposing biological organisms (both prokaryotic and eukaryotic) to silver nanoparticles (AgNPs) and studying the biochemical changes induced by these particles. We analyzed the various organs of Wistar rats for localization and quantification of these particles using mass spectrometric and molecular biological techniques. Highest levels of AgNP was found in the lung tissue in addition to being present in the liver and kidneys. Analysis of the of the blood plasma from AgNP exposed rats revealed elevated levels of glutathione-disulfide, which is indicative of reactive oxygen species (ROS) generation, which was further validated using ROS specific immunofluorescence staining of liver tissue. Quantification of blood lactate levels of the AgNP exposed rats showed increased lactate levels, which is indicative of anaerobic respiration and may result from AgNP-induced oxidative stress. Further analysis of bone marrow cells from AgNP exposed rats showed a higher number of micronuclei formation in developing erythrocytes and bone marrow cytotoxicity. Finally, analysis of the genes involved in the renin-angiotensin system (RAS) and inflammatory response revealed upregulation in transcript levels of many of these important genes in the liver tissue. Taken together, our study provides an initial road map for the identification of different signaling pathways that are altered by the AgNP exposure and contributes to a comprehensive understanding of the mechanism involved in silver nanoparticle-induced toxicity.
9

Soft Landing of Size Selected Nanoparticles Produced by Magnetron Sputtering / Soft Landing von durch Magnetronsputtern erzeugten größenselektierten Nanopartikeln

Larson, Christopher 23 November 2012 (has links)
No description available.
10

A Study of Silver: an Alternative Maldi Matrix for Low Weight Compounds and Mass Spectrometry Imaging

Walton, Barbara Lynn 05 1900 (has links)
Soft-landing ion mobility has applicability in a variety of areas. The ability to produce material and collect a sufficient amount for further analysis and applications is the key goal of this technique. Soft-landing ion mobility has provided a way to deposit material in a controllable fashion, and can be tailored to specific applications. Changing the conditions at which soft-landing ion mobility occurs effects the characteristics of the resulting particles (size, distribution/coverage on the surface). Longer deposition times generated more material on the surface; however, higher pressures increased material loss due to diffusion. Larger particles were landed when using higher pressures, and increased laser energy at ablation. The utilization of this technique for the deposition of silver clusters has provided a solvent free matrix application technique for MALDI-MS. The low kinetic energy of incident ions along with the solvent free nature of soft-landing ion mobility lead to a technique capable of imaging sensitive samples and low mass analysis. The lack of significant interference as seen by traditional organic matrices is avoided with the use of metallic particles, providing a major enhancement in the ability to analyze low mass compounds by MALDI.

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