Dissertations / Theses on the topic 'Single mass'
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1
Boyce, Kevin Robert. "Improved single ion cyclotron resonance mass spectroscopy." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/42551.
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Cornell, Eric Allin. "Mass spectroscopy using single ion cyclotron resonance." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/13562.
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Glagolenko, Stanislav Yurievich. "Single-ultrafine-particle mass spectrometer development and application." Thesis, Texas A&M University, 2004. http://hdl.handle.net/1969.1/1083.
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A single-ultrafine-particle mass spectrometer was constructed and deployed for size-resolved ultrafine aerosol composition measurements during the winter of 2002-2003 in College Station, Texas. Three separate experiments were held between December and March with six week intervals. Almost 128,000 mass spectra, corresponding to particles with aerodynamic diameters between 35 and 300 nm, were collected and classified. Fifteen statistically significant classes were identified and are discussed in this paper. Nitrate, potassium, carbon, and silicon/silicon oxide were the most frequently observed ions. Nitrate was present in most of the particles, probably due to the agricultural activity in the vicinity of the sampling site. The nitrate detection frequency was found to be sensitive to the ambient temperature and relative humidity. Another particle class, identified as an amine, exhibited strong relative humidity dependence, appearing only during periods of low relative humidity. There is evidence that some of the detected particles originated from the large urban centers, and were coated with nitrate, sulfate, and organics during transport.
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Wissner-Gross, Zachary Daniel. "Signal variation in single particle aerosol mass spectrometry." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40921.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2007.Includes bibliographical references (p. 33-34).
Rapid and accurate detection of airborne micro-particles is currently an important problem in national security. One approach to such detection, bioaerosol mass spectrometry (BAMS), is currently under development at Lawrence Livermore National Laboratory. BAMS is a type of single particle aerosol mass spectrometry that rapidly records dual-polarity mass spectra of aerosolized micro-particles. However, the accuracy of the BAMS system is limited by various uncertainties, resulting in shot-to-shot variations in the mass spectra. I found that the variations in mass peak areas in BAMS spectra were significantly larger than those predicted by Poisson statistics based on the mean number of detected ions. Furthermore, these variations were surprisingly consistent as a function of peak area among synthetic, organic, and biological samples. For both positive and negative ions, the standard deviation in a peak's area was approximately proportional to the mean value of that area to the 0.9 power. Using the consistency of this data, I also developed a novel method for quantitatively evaluating the similarity between mass spectra using a chi-square factor. Peak area variations in other single particle aerosol mass spectrometers may be similarly analyzed and used to improve methods for rapid particle identification.
by Zachary Daniel Wissner-Gross.
S.B.
5
Lee, Wan-waan, and 李雲鬟. "Studies of single-particle inductively coupled plasma mass spectrometry." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/208541.
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Ho, Koon-sing, and 何觀陞. "Single-cell analysis using inductively coupled plasma mass spectrometry." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hdl.handle.net/10722/196076.
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The technique of single-cell analysis using time-resolved inductively coupled plasma-mass spectrometry has been characterized and optimized. Determination of the metal contents of individual cells provides data on the natural metal contents of the cells and the corresponding distributions in the population. The distribution is a useful indicator of the health and the state of development of the cells. The contents of sorbed metals of individual cells over a duration of time are required to understand the dynamics of metal-cell interactions.
A green alga, Chlorella vulgaris, was used as a model biological cell in this study. The criteria and procedures for proper sampling of the cells into the ICP will be discussed. Ideally, each ICP-MS spike corresponds to one cell, but cell overlapping occurs because the cells enter the ICP randomly. Selection of cell number density and sample uptake rate to minimize spike overlapping will be discussed. A cell counting method based on the frequency of the spikes has been developed.
The distribution of the metal contents of cells was determined by measuring large number of spikes. The minimum number of spikes required was determined by statistical analysis. The spike intensity distribution was correlated with the size distribution of the cells. The peak maximum of the spike intensity distribution was used for the determination of the average metal content of the cells. The use of the peak maximum reduces errors due to spike overlapping in the measurement. Quantitative determination of the metal contents was achieved using standard particles for calibration. Errors in calibration using standard solution nebulization were discussed.
The technique was applied in the study of metal-cell interactions. Sorption of heavy metal ions (as environmental pollutants) by Chlorella vulgaris, and uptake of biometal (as nutrient) and metallodrug (as toxin) by Helicobacter pylori were studied. The technique requires simple sample preparation of removing the culture medium by filtration or centrifugation. The health state of the cells in the presence of toxic metals was related to the change in cell number density. The ratio of the FWHM of the spike intensity distributions of the sorbed metals to the natural metal contents of the cells is identified as a possible indicator of the location of the sorbed metals. The kinetics of metal sorption by the cells can be studied using a single cell culture. The method reduces errors due to uncertainties in cell number density and metal concentration in multiple samples that are required in conventional methods.
The optimal ICP-MS sampling depth of 17 elements, introduced into the ICP by conventional solution nebulization of aqueous standard solutions, has been determined. The elements were selected to represent a wide range of boiling points and ionization potentials. Boiling point of the dried residues and ionization potential of the analyte element were identified as the major factors that determine the optimal sampling position. Since dried sample solution aerosols are effectively nanoparticles, the study provides useful insight on the optimization of the operation conditions and calibration strategies for single-particle analysis using ICP-MS.published_or_final_version
Chemistry
Doctoral
Doctor of Philosophy
7
Lee, Kin-ho, and 李健豪. "Simulation of single-particle inductively coupled plasma-mass spectrometry." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/196478.
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Time-resolved Inductively Coupled Plasma –Mass Spectrometry (ICP-MS) is a versatile tool for the analysis of single particles such as air particles, nanoparticles, and biological cells. In this study, the processes of particle vaporization and analyte atom diffusion and ionization in the ICP were investigated using computer simulation. Gold nanoparticles of particle diameter 10 to 250 nm were used as the model particle. The parameters of the model were optimized with respect to the experimental data. The relative importance of these parameters was investigated. Simulated ICP-MS intensity versus sampling depth for different particle size was calculated.
Two models of particle vaporization, namely heat-transfer-limited and mass-transfer-limited, were adopted to describe the kinetics of vaporization of the gold nanoparticles. The rate of particle vaporization of the limiting model in each 5-µs time step was used in the simulation. The heat-transfer-limited process dominates at lower position of the ICP. The mass-transfer-limited process takes over at sampling depth of 4mm or above where the ICP temperature is higher than 4000K. The simulation assumed that the gold atoms vaporized from the particle in each time step diffuse independently. The number density of the gold atoms was calculated using the Chapman-Enskog diffusion theory for each subsequent time step. The degree of ionization of the gold atoms was estimated using Saha equation and was assumed to be dependent on the plasma temperature only. The simulated ICP-MS intensity at any instant was the sum of the gold ions in the ion plumes from all previous time steps that pass through a 1-mm sampler cone.
The effects of several simulation parameters on the calculated ICP-MS intensity were investigated. The simulation depth profile of ICP-MS intensity of 100-nm gold nanoparticle was compared to the experimental ICP-MS depth profile. The ICP-MS intensity depends strongly on the ionization temperature of the plasma and the evaporation coefficient of the analyte. The ICP temperature profile, gas velocity, ionization temperature and evaporation coefficient were optimized for the best fit of simulated results to the experimental data.
Simulated calibration curves of gold nanoparticles of nominal diameter of 10 nm to 250 nm are non-linear at any sampling depth. The calibration curve rolls off at high mass due to incomplete vaporization of the larger particles in the ICP. The calibration curve at high sampling depth concaves upward in the low mass range because of significant diffusion loss of the analyte atoms for the small particles.published_or_final_version
Chemistry
Master
Master of Philosophy
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Binder, Thomas, Christian Chmelik, Jörg Kärger, and Douglas M. Ruthven. "Mass-transfer of binary mixtures in DDR single crystals." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-182920.
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Dextras, Philip. "Method for single-cell mass and electrophoretic mobility measurement." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/61235.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Biological Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 137-146).
Analysis of single cells using flow cytometry techniques has created a wealth of knowledge about cellular phenomena that could not be obtained by population average measurements. As these techniques are integrated with others to increase the number of parameters that can be measured on single cells and these measurements are made more quantitative, their ability to discriminate between sub-populations of cells increases. Microfabricated sensors offer unique advantages in this area because their internal geometries can be engineered at a size scale comparable to the cell's, making them naturally well-suited for single-cell measurements. The suspended microchannel resonator (SMR) is a versatile flow cytometry platform which is capable measuring the mass of single cells with femtogram resolution. The net frequency shift of a resonant cantilever as the cell transits the fluid-filled microchannel running through it is proportional to the buoyant mass of the cell. The resonance frequency of the SMR is also highly sensitive to a cell's position along the cantilever's length. This thesis presents a new method which makes use of this property to accurately quantify the electrophoretic mobility (EPM) of cells transiting the SMR while subjected to oscillatory electric fields. Recorded resonance frequency time courses can be analyzed to extract both the buoyant mass and EPM of individual cells. This instrument has been used to simultaneously measure the EPM and buoyant masses of discrete polystyrene microspheres and Escherichia coli bacteria. As it has been applied to microspheres of known density, the integrated measurement makes it possible to compute the absolute mass and surface charge of individual microspheres. It has been shown that integrated single-microsphere mass and surface charge measurement enables differentiation of complex aqueous suspensions which is not possible by either measurement alone.
by Philip Dextras.
Ph.D.
10
Binder, Thomas, Christian Chmelik, Jörg Kärger, and Douglas M. Ruthven. "Mass-transfer of binary mixtures in DDR single crystals." Diffusion fundamentals 20 (2013) 44, S. 1-2, 2013. https://ul.qucosa.de/id/qucosa%3A13614.
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Noel, Jeremy R. "Development and validation of a single mass Lap simulation." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/127896.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, May, 2020Cataloged from the official PDF of thesis.
Includes bibliographical references (page 63).
In this thesis, a single mass model lap time simulation was designed, implemented and validated in MATLAB. The goal of this simulation was to accurately predict the velocity of a formula style open wheeled race car on a given track. The simulation was constructed in MATLAB, and features a function based design that will allow the core algorithm to be used with more sophisticated vehicle models. The code was tested and validated using a combination of contrived and collected map data, and a strong correlation of 0.8067 was shown with 95% confidence bounds of 0.8028, and 0.8105. Finally, this thesis outlines proper testing techniques to obtain the data required to complete the validation process of this simulation.
by Jeremy R. Noel.
S.B.
S.B. Massachusetts Institute of Technology, Department of Mechanical Engineering
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Al-Duri, Bushra Abdul-Aziz Abdul-Karim. "Mass transfer processes in single and multicomponent batch adsorption systems." Thesis, Queen's University Belfast, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.258225.
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Turner-Byfield, Evonne Daelia. "A qualitative comparison of mass grave and single grave decomposition." Thesis, Boston University, 2012. https://hdl.handle.net/2144/12659.
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Thesis (M.S.)--Boston UniversityAnthropological investigation of mass burials is a process that has social and judicial ramifications requiring competent and thorough comprehension of the decompositional transformations occurring between the moment of burial and exhumation. A unique microenvironment is created by the soil and intermingling organisms during the decomposition process which is further altered by the presence of single or multiple bodies within a burial. This thesis was designed to clarify the distinction between mass grave and single grave decomposition rate by identifying the differences between factors affecting decomposition. The study required the experimental interment of five porcine (Sus scrofa Linnaeus) carcasses to simulate single and mass burials of human remains. Two animals were interred in two separate single burials and the remaining animals were placed in one mass burial. They remained buried from June to November 2012, during which time monthly soil samples were extracted and analyzed for nutrient content. Following exhumation, qualitative comparisons of the stages of decomposition and adipocere formation were developed using established scales. The results of this research can be utilized to establish an accurate postmortem interval (PMI) for mass graves and enhance the understanding of the factors affecting mass grave decomposition.
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Stockslager, Max A. "Single-cell mass measurements for drug susceptibility testing in cancer." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/127059.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, May, 2020Cataloged from the official PDF of thesis.
Includes bibliographical references (pages 116-121).
Measuring the size distributions of micron-scale particles is of central importance in the biological sciences and for a wide range of industrial processes. The suspended microchannel resonator (SMR) is a sensor that measures the mass of individual micron-scale particles by detecting a shift in resonance frequency as particles flow through a hollow resonating micro-cantilever beam. While SMRs offer extreme precision for measuring mass, their applications have been limited by low measurement throughput. In the first part of this thesis, I describe several technical advancements aimed at increasing the throughput of SMRs. First, we developed devices containing many SMRs connected fluidically in parallel on the same microfluidic chip. By operating many mass sensors simultaneously, these "parallel SMR arrays" achieve approximately 27-fold higher throughput than previously possible.
To further increase throughput, we developed a computational approach for resolving faster shifts in resonance frequency than previously possible using the resonator-phase-locked-loop coupled feedback systems. We describe in detail the operation and performance limitations of each technique. In the second part of this thesis, I discuss the application of SMRs for drug sensitivity testing in cancer. For most cancers there exists a long, growing list of FDA-approved chemotherapies and targeted agents, but often there is no rational basis to predict which drug will be most effective for a particular patient.. We have shown that in several cancers, tumor cell growth is altered upon ex vivo exposure to cancer therapeutics, and that changes in cell mass can be detected as a functional biomarker for drug sensitivity.
In particular, we show in a retrospective clinical study that cell mass measurements predict the response of glioblastoma multiforme patients to temozolomide, a standard-of-care chemotherapy, and that the SMR drug sensitivity assay predicts the duration that patients survive on therapy better than the gold-standard genetic biomarkers. Looking forward, we envision that functional drug susceptibility testing will be useful for matching patients to effective therapies across a wide variety of cancers.
by Max A. Stockslager.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Mechanical Engineering
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Hamilton, Jason S. "Disease Tissue Imaging and Single Cell Analysis with Mass Spectrometry." Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc984137/.
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Cells have been found to have an inherent heterogeneity that has led to an increase in the development of single-cell analysis methods to characterize the extent of heterogeneity that can be found in seemingly identical cells. With an understanding of normal cellular variability, the identification of disease induced cellular changes, known as biomarkers, may become more apparent and readily detectable. Biomarker discovery in single-cells is challenging and needs to focus on molecules that are abundant in cells. Lipids are widely abundant in cells and play active roles in cellular signaling, energy metabolism, and are the main component of cellular membranes. The regulation of lipid metabolism is often disrupted or lost during disease progression, especially in cancer, making them ideal candidates as biomarkers. Challenges exist in the analysis of lipids beyond those of single-cell analysis. Lipid extraction solvents must be compatible with the lipid or lipids of interest. Many lipids are isobaric making mass spectrometry analysis difficult without separations. Single-cell extractions using nanomanipulation coupled to mass spectrometry has shown to be an excellent method for lipid analysis of tissues and cell cultures. Extraction solvents are tunable for specific lipid classes, nanomanipulation prevents damage to neighboring cells, and lipid separations are possible through phase dispersion. The most important aspect of single-cell analysis is that it uncovers the extent of cellular heterogeneity that exists among cellular populations that remains undetected during averaged sampling.
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Woodard, Aaron Jacob, and Aaron Jacob Woodard. "Bayesian Estimation of a Single Mass Concentration Within an Asteroid." Thesis, The University of Arizona, 2017. http://hdl.handle.net/10150/625702.
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Orbit determination has long relied on the use of the Kalman filter, or specifically the extended Kalman filter, as a means of accurately navigating spacecraft. With the advent of cheaper, more powerful computers more accurate techniques such as the particle filter have been utilized. These Bayesian types of filters have in more recent years found their way to other applications. Dr. Furfaro and B. Gaudet have demonstrated the ability of the particle filter to accurately estimate the angular velocity, homogenous density, and rotation angle of a non-uniformly rotating ellipsoid shaped asteroid. This paper extends that work by utilizing a particle filter to accurately estimate the angular velocity and homogenous density of an ellipsoidal asteroid while simultaneously determining the location and mass of a mass concentration modeled as a point mass embedded within the asteroid. This work shows that by taking measurements in several locations around the asteroid, the asteroid's rotation state and mass distribution can be discerned.
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Trevitt, Adam John. "Ion trap studies of single microparticles : optical resonances and mass spectrometry /." Connect to thesis, 2006. http://eprints.unimelb.edu.au/archive/00003039.
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Ball, Rachel Jennifer. "A mass spectrometry based hybridisation assay for single nucleotide polymorphism analysis." Thesis, University of Southampton, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417404.
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Fry-Bouriaux, Louis. "Towards the mass fabrication of single electron transistors for biosensing applications." Thesis, University of Leeds, 2017. http://etheses.whiterose.ac.uk/18870/.
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The development of ultra sensitive charge sensing devices such as single-electron transistors (SETs) for next-generation biomedical applications has received considerable attention in the past few years. In this thesis, a potential approach for the mass-fabrication of metallic SETs for ultra-sensitive biosensing applications --- an important prerequisit for early diagnosis of many serious diseases --- is investigated. Using the orthodox theory of Coulomb blockade it is shown that it is possible to engineer an SET system that can satisfy the requirements for a highly sensitive charge sensor operating at room temperature while using metallic electrodes rather than semiconductor structures. In this configuration, the SET design and fabrication process is simplified greatly by lifting the dependence of the system on the confinement energy of electrons in the quantum dots (QDs), as is the case in semiconductor SETs. In return, this makes the tunnel junction properties and the geometrical arrangement of the islands and electrodes far more critical in determining the maximum operating temperature of the device. Here, the geometrical requirements for such a sensitive device are studied theoretically whilst the tunnel junction properties are studied experimentally and then theoretically to provide a thorough assessment of the abilities of the proposed SET system. Atomic-layer deposition (ALD) has proven to be a highly reliable technique for depositing uniform thickness and reproducible thin metal-oxide films and particularly the Al2O3 ALD process is known to be `ideal' with highly reproducible properties. Here, a systematic study of the electronic properties of ALD deposited Al2O3 thin films in MIM structures was performed to assess the ALD techniques applicability to the mass fabrication of quantum tunneling junctions for metallic SET structures. The two most crucial material parameters relevant to the design of metallic SET tunnel barriers are studied in detail; the dielectric constant of the film that determines the junction capacitance, and the properties of the potential barrier that mediates electron tunneling. Photolithographic techniques were used to create electrodes with a wide range of characteristic lengths as to provide a wide range of impedances. Measurements and subsequent analysis show that a high consistency can be attained over large surface areas in the film properties, and that electrode coverage is very effective, showing promise for mass-fabrication applications. Further analysis of the measurements shows that small static distortions in the barrier can affect the symmetry of MIM diode IV characteristics operating in the direct tunneling regime and that under certain circumstances the effect of surface states can be observed in the tunneling conductance.
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Zawadowicz, Maria Anna. "Understanding the chemistry of atmospheric particles using single particle mass spectrometry." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/113793.
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Thesis: Ph. D. in Atmospheric Chemistry, Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 197-219).
This thesis explores ways in which single particle mass spectrometry can be extended, whether through hardware improvements, or through the use of advanced data processing techniques to provide new kinds of aerosol chemistry measurements. Most of this work has been carried out using the Particle Analysis by Laser Mass Spectrometry (PALMS) instrument, an aircraft deployable mass spectrometer that uses intense (~10 9 Wcm -2 ) UV laser pulses to vaporize and ionize single particles and measures their mass spectra using a time-of-flight mass spectrometer. Near-term and long-term hardware improvements as well as advanced data analysis techniques are explored in order to extract new chemical information from the thus obtained single particle mass spectra. Hardware improvements to PALMS are explored, such as the use of a high-powered femtosecond laser to obtain single particle mass spectra and a new high resolution compact mass analyzer. Also, a new commercial mass spectrometer LAAPToF is characterized and compared to PALMS. In addition to hardware improvements, novel data analysis techniques for analysis of single particle mass spectra were developed as a part of this work. In particular, a new method to identify biologically-derived particles is presented and used to derive vertical profiles of bioaerosol from near-surface to the upper troposphere.
by Maria Anna Zawadowicz.
Ph. D. in Atmospheric Chemistry
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Barma, Rajan. "Studies in mass transfer from single gas bubbles in gas liquid systems." Thesis, Teesside University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283232.
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Christopoulos, Costa (Costa D. ). "A machine-learning approach to aerosol classification for single-particle mass spectrometry." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/115038.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 21-26).
Compositional analysis of atmospheric and laboratory aerosols is often conducted via single-particle mass spectrometry (SPMS), an in situ and real-time analytical technique that produces mass spectra on a single particle basis. In this study, machine learning classification algorithms are created using a dataset of SPMS spectra to automatically differentiate particles on the basis of chemistry and size. While clustering methods have been used to group aerosols into broad categories based on similarity, these models do not incorporate known aerosols labels and are not explicitly formulated for classification. Furthermore, traditional methods often rely on a smaller set of well-known, important variables whereas the proposed method is more general and flexible, allowing researchers to automatically quantify and select important variables from any aerosol subset. In this work, machine learning algorithms build a predictive model from a training set in which the aerosol type associated with each mass spectrum is known. Several such classification models were created to differentiate aerosol types in four broad categories: fertile soils, mineral/metallic particles, biological, and all other aerosols using -40 common positive and negative spectral features. For this broad categorization, machine learning resulted in a classification accuracy of -93%. More complex models were developed to classify aerosols into specific categories which resulted in a classification accuracy of -87%. The trained model was then applied to a 'blind' mixture of aerosols with model agreement on the presence of secondary organic aerosol, coated and uncoated mineral dust and fertile soil. Additionally, the model is used to characterize an ambient atmospheric dataset collected from the free troposphere.
by Costa Christopoulos.
S.B.
23
Dobner, Sarah-Jane. "“Huggables”, “furry lovers” and “weapons of mass destruction” - Entanglements of older, British singletons with (non-sexual) touch." Thesis, Linköpings universitet, Tema Genus, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-150093.
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In a cultural web of myth, sexualisation and prejudice, how do older, British singletons gain access to health-giving, non-sexual touch? This study takes interview material from five single women and three single men (all cisgender, white, heterosexual, British, between 37-76 years) and interlaces it with autoethnographic commentary, poems and artworks to explore negotiations around touch. Drawing on Haraway and Barad’s theoretical concept of “entanglements” (2008; 2007), cross-disciplinary connections are woven across feminist new materialism and social sciences, the body and discourse, the conscious and subconscious. Findings, which are partial, provisional, messy and complex (Haraway 1988), include powerful narratives of shame, denial and cauterisation of touch-needs. These co-exist with corporeal tales of the richness and variety of touch-opportunities, the tactile importance of cats and a “turn” by the oldest, female participants away from a romantic, heterosexual partner towards bonding with the landscape.
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Lui, Kwok-on, and 呂國安. "Single particle analysis by time-resolved ICP-MS measurement." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B46582630.
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Bowman, Amanda. "Lipidomic Analysis of Single Cells and Organelles Using Nanomanipulation Coupled to Mass Spectrometry." Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc849662/.
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The capability to characterize disease states by way of determining novel biomarkers has led to a high demand of single cell and organelle analytical methodologies due to the unexpected heterogeneity present in cells of the same type. Lipids are of particular interest in the search for biomarkers due to their active roles in cellular metabolism and energy storage. Analyzing localized lipid chemistry from individual cells and organelles is challenging however, due to low analyte volume, limited discriminate instrumentation, and common requirements of separation procedures and expenditure of cell sample. Using nanomanipulation in combination with mass spectrometry, individual cells and organelles can be extracted from tissues and cultures in vitro to determine if heterogeneity at the cellular level is present. The discriminate extraction of a single cell or organelle allows the remainder of cell culture or tissue to remain intact, while the high sensitivity and chemical specificity of mass spectrometry provides structural information for limited volumes without the need for chromatographic separation. Mass analysis of lipids extracted from individual cells can be carried out in multiple mass spectrometry platforms through direct-inject mass spectrometry using nanoelectrospray-ionization and through matrix-assisted laser/desorption ionization.
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Chan, Ka-lok, and 陳嘉樂. "Single droplet generation by dripping-mode electrospray for ICP-MS measurement." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/202348.
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Stoker, Emily B. "Comparative Studies on Scale-Up Methods of Single-Use Bioreactors." DigitalCommons@USU, 2011. https://digitalcommons.usu.edu/etd/889.
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This study was performed to increase knowledge of oxygen mass transfer (kLa) and mixing times in the scale-up of disposable bioreactors.Results of oxygen mass transfer studies showed kLa to increase with increasing agitation and aeration rates. By maintaining a scale-up constant such as gassed power to volume or shear, an almost constant kLa was achieved during scale-up from 50 to 2000 L. Using the scale-up constant Pg/V resulted in statistically higher kLa values at greater reactor volumes. Mixing times were revealed to be significantly affected by agitation, but not by the aeration rates tested. No pattern was recognized in the mixing time data over an increase in volume.
Commonly used methods for predicting kLa upon scale-up were compared to experimental data. New coefficients were determined to fit the historic models to the parameters of this study, namely the unique geometry and low agitation and aeration rates used in the single-use systems. Each of the resulting four models was found to have average error rates from 16-23%. Although the error rates are not statistically different, the Moresi and Patete model was determined to be most conceptually accurate. The Moresi and Patete model found kLa to be more dependent on aeration than on the power input. This finding was consistent with the results of the experimental studies.
The results of this study were for aeration rates (0.02-0.04 vvm) and agitation rates (Pg/V range of 2-20 W/m3) that are commonly used in single-use bioreactor systems.
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Finch, Jeffrey William. "Selective mass spectrometry by single-photon ionization from a molecular hydrogen laser source." Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/185895.
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A molecular hydrogen laser, with an output of 7.8 eV photons in the vacuum ultraviolet, is evaluated as a selective source for photoionization mass spectrometry. Types of compounds ionized by the laser include a variety of amines, nitrogen heterocycles, drugs of abuse, pharmaceuticals, and polynuclear aromatic hydrocarbons (PAHS). The laser is coupled to a time-of-flight mass analyzer, which allows a spectrum to be recorded with each laser pulse. The laser is a "soft" ionization source and mass spectra of nearly all of the compounds studied yield single ion peaks due to the parent molecule with no fragments. This results in simplified mass spectra with a one-to-one correspondence of photoactive molecules with molecular ion peaks. Since the photoionization threshold of the laser is relatively low, selectivity of the photoactive species is high in the presence of a complex sample matrix. The performance of the laser source is improved with a few changes in the original design. In addition, the previous method of recording mass spectra with a photographic emulsion is replaced with a digital oscilloscope, which averages spectra over many laser pulses. As a result, a true assessment of the technique's sensitivity is finally achieved. The time-of-flight mass spectrometer is modified with a new microchannel plate ion detector and preamplifier. As a result, detection limits for PAH's improve by nearly three orders of magnitude, from the 100 ng range to the 100 pg range. Selectivity of the laser photoionization source in complex mixture analysis is demonstrated with the ability to detect PAH's in a drinking water sample at concentrations below 100 parts-per-trillion, using a simple solid-phase extraction technique. Application of the technique for rapid screening of drugs of abuse in urine is demonstrated where solid-phase extraction columns are utilized for sample pretreatment. Urine samples spiked with drugs such as cocaine, codeine, morphine, phencyclidine, and methadone, yield photoionization mass spectra consisting of parent molecular ions for the drugs with a few noninterfering ion signals from the matrix. The technique is evaluated and compared to other drug screening techniques such as enzyme-multiplied immunoassay.
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McKay, Adam Robert Crawford. "A mass spectrometry study of noncovalent interactions : from single proteins to intact ribosomes." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612967.
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Tennyson, Donna. "Lessons learned from Hurricane Sandy survivors| A qualitative intrinsic single-case study." Thesis, University of Phoenix, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10108360.
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The goal of this qualitative single-case study was to investigate the problem with more than 50% of Americans admitting they are not prepared for natural disasters before they occur. The sample for this study was 24 purposively selected Hurricane Sandy survivors in New York and New Jersey who were 25 years of age or older. Data was collected through ten open-ended interview questions presented during telephone interviews. This study was guided by the theoretical framework of normative risk management decision making. Thematic analysis was used to code and analyze the data collected. This study was focused on answering two broad research questions related to why more than 50% of Americans are not prepared for natural disasters before they occur and the factors that prevent them from preparing. The major recommendations for future research and practice were related to the lack of a distinction between individuals who perceive they are prepared (who are deemed unprepared according to regulatory guidelines) and the possibility they are included with the more than 50% of Americans who are not prepared although they require modification of preparedness behavior while individuals who are not prepared require adoption of preparedness behavior. The other recommendations describe the factors that prevent individuals from preparing as lack of notification and signaling communications that indicate a natural disaster is imminent and expected to be severe; and individual disbelief in the validity of the communications. This study contributes to filling the gap in the literature related to the lived experience with natural disasters.
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Odeneye, Michael Adetunji. "Infrared photodissociation of gas phase ions : single photon and multiphoton events." Thesis, University of Sussex, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311414.
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Piehowski, Paul D. Ewing Andrew Graham. "Investigating lipid heterogeneity in single cells using time-of-flight secondary ion mass spectrometry." [University Park, Pa.] : Pennsylvania State University, 2009. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-4585/index.html.
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Garthe, Daniel. "Fluiddynamics and mass transfer of single particles and swarms of particles in extraction Columns." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=980324718.
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Goodwin, Richard J. A. "Microsampling and on-line separation techniques for mass spectrometry : analysis of single fungal cells." Thesis, University of Edinburgh, 2006. http://hdl.handle.net/1842/12042.
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My research during this interdisciplinary investigation was to primarily focus on the development of novel single cell sampling and analysis methods. Using micromanipulation, microsampling and mass spectroscopic analysis techniques to determine the concentration of biologically relevant molecules quantitatively from living fungal cells, as well as to study the uptake of externally applied compounds. Evaluation of a range of on-line separation techniques, including Capillary Liquid Chromatography (CapLC), nanoLC and capillary electrophoresis (CE) was made for suitability to be coupled to a range of mass spectrometers for the analysis of fungal cytoplasm. Techniques for microsampling at the single cell level from the model organism, Neurospora crassa, and transfer of the sample from under the microscope for analysis by mass spectrometry, following on-line separation, were developed. Capillary electrophoresis electrospray mass spectrometry (CE-ESI-MS) was used to measure intra cellular concentrations of trehalose, quantitatively, with mechanisms developed for detection of external contamination of the samples taken from viable, actively growing cells of Neurospora crassa, by the use of laser induced fluorescence (LIF). The measured concentration for intra-cellular disaccharide was determined to be 1.3mM by the methods developed and described during this thesis. In addition, topical applications of fungicide were made, with intra-cellular measurements taken by single cell analysis. Following application of 14.8μM azoxystrobin, the fungicide under investigation at saturation concentration in water, intra-cellular concentrations were measured at 9.9μM after 5 minutes.
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Managh, Amy J. "Single-cell tracking of therapeutic cells using Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry." Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/16723.
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Cellular therapy is emerging as a clinically viable strategy in the field of solid organ transplantation, where it is expected to reduce the dependency on conventional immunosuppression. This has produced a demand for highly sensitive methods to monitor the persistence and tissue distribution of administered cells in vivo. However, tracking cells presents significant challenges. In many cases transplanted cells are autologous with the immune system of the transplant recipient, and hence are invisible to typical methods of detection. To enable their differentiation, the cells must be labelled with a suitable, non-toxic and long lifetime label, prior to their administration to patients. In addition, administered cells represent only a small fraction of the recipient's endogenous cells, which necessitates the use of an extremely sensitive detection method. Laser ablation – inductively coupled plasma – mass spectrometry (LA-ICP-MS) is an exquisitely sensitive analytical technique, capable of imaging trace elements in complex samples, at high spatial resolution.
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Reinard, Melissa S. "Characterization of individual fine and ultrafine particles with a real-time single particle mass spectrometer." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 178 p, 2009. http://proquest.umi.com/pqdweb?did=1654492151&sid=4&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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October, Firzana. "Proteomic and SNP analysis of the Cadherin 10 type-II (CDH10) gene, in the South African autistic population." University of the Western Cape, 2013. http://hdl.handle.net/11394/4826.
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>Magister Scientiae - MScAutism or autism spectrum disorder (ASD) is a very diverse neurological disorder that manifests specifically in children and infants between the ages of two to three years of age. An individual suffering is deemed as autistic and individuals suffering would be classed under the banner of ASD. It is observed that sufferers have impairment in their social and interactive skills. It has both genetic and environmental factors that contribute to its diversity and although the primary cause of autism is still unclear, scientist are investigating both factors. In this study we aimed to investigate the molecular genetics of autism in the South African (SA) population. This was done in two parts, a genetic association study and afunctional genomics (proteomic study). An association study of the 2 single nucleotide polymorphisms (SNPs) of the Cadherin 10 type II gene (CDH10) (rs4307059 and rs4327572) was investigated in the SA healthy and autistic population. The proteomic approach was used to determine the differential expression of genes of the healthy population and compared to the autistic population of African descent. In both parts of the project, objectives were achieved. The SNPs were successfully genotyped however no association was determined for autism in the SA population. The urine protein profiles with 1 dimensional (1D) and 2dimensional (2D) Sodium Dodecyl Sulfate-Poly Acrylamide Gel Electrophoresis (SDSPAGE)generated in this study has revealed the following proteins, Uromodulin, Vitelline membrane outer layer protein homologue, kinninogen-1, Alpha-1-Antitrypsin, Ig Kappa chain region C, and CD59 glycoprotein that require further investigation. The results indicated that six of the identified proteins were expressed in both groups but were found to be either quantitatively or statistically significant. However, a statistically significant difference was observed in the expression of one protein (Uromodulin) which was observed to be expressed in the healthy group but absent in the experimental group. However further investigation is required validation of these findings.
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Sun, Xiaobo. "Forensic Applications of Gas Chromatography/Mass Spectrometry, High Performance Liquid Chromatography--Mass Spectrometry and Desorption Electrospray Ionization Mass Spectrometry with Chemometric Analysis." Ohio University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1329517616.
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Cheng, Guilong. "Unraveling Macro-Molecular Machinery by Mass Spectrometry: from Single Proteins to Non-Covalent Protein Complexes." Diss., The University of Arizona, 2007. http://hdl.handle.net/10150/195466.
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Presented in this dissertation are studies of protein dynamics and protein/protein interactions using solution phase hydrogen/deuterium exchange in combination with mass spectrometry (HXMS). In addition, gas phase fragmentation behaviors of deuterated peptides are investigated, with the purpose of increasing resolution of the HXMS. In the area of single protein dynamics, two protein systems are studied. Studies on the cytochrome c2 from Rhodobacter capsulatus indicate its domain stability to be similar to that of the horse heart cytochrome c. Further comparison of the exchange kinetics of the cytochrome c2 in its reduced and oxidized state reveals that the so-called hinge region is destabilized upon oxidation. We also applied a similar approach to investigate the conformational changes of photoactive yellow protein when it is transiently converted from the resting state to the signaling state. The central β-sheet of the protein is shown to be destabilized upon photoisomerization of the double bond in the chromophore. Another equally important question when it comes to understanding how proteins work is the interactions between proteins. To this end, two protein complexes are subjected to studies by solution phase hydrogen deuterium exchange and mass spectrometry. In the case of LexA/RecA interaction, both proteins show decreases in their extents of exchange upon complex formation. The potential binding site in LexA was further mapped to the same region that the protein uses to cleave itself upon interacting with RecA. In the sHSP/MDH system, hydrogen/deuterium exchange experiments revealed regions within sHSP-bound MDH that were significantly protected against exchange under heat denaturing condition, indicative of a partially unfolded state. Hydrogen/deuterium exchange therefore provides a way of probing low resolution protein structure within protein complexes that have a high level of heterogeneity. Finally, the feasibility of increasing resolution of HXMS by gas phase peptide fragmentation is investigated by using a peptide with three prolines near the C-terminus. Our data show that deuterium migration indeed occurs during the collision activated dissociation process. Caution is required when interpreting the MS/MS spectra as a way of pinpointing the exact deuterium distribution within peptides.
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Pratt, Kerri Anne. "New insights into single-particle mixing state using aircraft aerosol time-of-flight mass spectrometry." Diss., [La Jolla] : University of California, San Diego, 2009. http://wwwlib.umi.com/cr/ucsd/fullcit?p3372559.
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Thesis (Ph. D.)--University of California, San Diego, 2009.Title from first page of PDF file (viewed Oct. 7, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.
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Szwec, Stuart V. "Transfer reaction studies of medium mass nuclei-single-particle occupancies and neutrinoless double beta decay." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/transfer-reaction-studies-of-medium-mass-nuclei--singleparticle-occupancies-and-neutrinoless-double-beta-decay(6120c9fe-c85d-42fd-908f-e07e07cccd50).html.
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Two separate investigations are presented, both linked by a common interest in the occupancy of the valence neutron orbitals and their relation to nuclear structure studies. A study of the change in neutron occupancy in the 0Î1⁄22Î2 decay of 136 Xe â 136 Ba has been performed. The neutron occupancies of 136 Ba have been probed us- ing the (p,d) and ( 3 He,α) neutron-removal reactions and the (d,p) and (α, 3 He) neutron-addition reactions, performed at the Institut Physique Nucl Ìeaire, Orsay. The same reactions have been performed on 134 Ba as an additional consistency check. Spectroscopic factors were extracted through a DWBA analysis and the valence orbital occupancies were extracted using the Macfarlane and French sum rules. The change in neutron occupancy that occurs during 0Î1⁄22Î2 decay was then determined and compared to those calculated by using the interacting shell model and the interacting boson model. The comparison showed that while the various models were able to qualitatively describe the change in occupancy, quantitatively there are significant differences between the models. These are the same models that are used to determine the nuclear matrix elements used in determining the rate of 0Î1⁄22Î2 decay. An additional systematic study of the valence neutron occupancies on the seven even stable tin isotopes is presented. The occupancies were probed in two sets of experiments. The first measurement used the low Q-value (p,d) and (d,p) reactions performed at the Maier-Leibnitz-Laboratory, Munich, to extract spec- troscopic information for low-j orbitals. The second measurement used the high Q-value ( 3 He,α) and (α, 3 He) reactions at the Institut Physique Nucl Ìeaire, Orsay to extract spectroscopic information for high-j states. Absolute cross sections were determined and the amount transferred angular momenta was identified by comparison of angular distributions to those calculated using a DWBA analysis. The spectroscopic factors were used in conjunction with the Macfarlane-French sum rules to determine the valence neutron occupancies. These measurements not only qualitatively test the robustness of sum rules in transfer reactions but also provide information about the neutron occupancy of 116 Sn and 124 Sn, two nu- clei of relevance to 0Î1⁄22Î2 decay. The measured occupancies of these two isotopes were compared to those obtained from recent theoretical calculations.
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Doebber, Ian Ross. "Investigation of Concrete Wall Systems for Reducing Heating and Cooling Requirements in Single Family Residences." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/35499.
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The single family housing sector currently accounts for approximately 15% (US DOE 2002) of the total national energy consumption with the majority of the energy use associated with the HVAC system to provide comfort for the residents. In response to recent concern over the unpredictability of the energy supply and the pollution associated with its consumption, new methods are constantly being developed to improve the energy efficiency of homes. A variety of concrete wall systems including Multi-functional Precast Panel (MPP) systems and Insulating Concrete Form (ICF) systems have been proposed to not only improve the building envelope thermal performance but other important residential characteristics such as durability and disaster and fire resistance. MPPs consist of Precast Concrete Panels (PCPs) that incorporate structural elements, interior and exterior finishes, insulation, and even heating/cooling systems into a single manufactured building panel. The ICF system is a cast-in-place concrete panel system that does not offer the level of integration found in the MPP system but has become increasingly accepted in the building construction industry. This research evaluates the thermal performance benefits of concrete wall systems in detached, single family home applications. The thermal performance benefits of two MPP systems and an ICF system are analyzed within the context of a representative or prototypical home in the U.S. and are compared to two wood frame systems; one representing a typical configuration and the other an energy efficient configuration. A whole wall approach is used to incorporate the two and three dimensional conduction and transient characteristics of the entire wall assembly, including the clear wall and wall detail regions, into a whole building simulation of the prototypical house. The prototypical house heating and cooling energy consumption associated with each wall system is determined for six representative climates throughout the U.S. to evaluate the effect of various ambient conditions on the relative energy savings. For each wall system, the effect of thermal bridging on overall R value, the effect of thermal capacitance, and the role of infiltration on energy use are investigated.
The results of the research include a comparison of the prototypical house energy savings associated with each of the wall systems; an assessment of the relative importance of the increased insulation, thermal mass, and improved air tightness on the overall energy load; and a comparison of the cost of ownership for the various wall systems. The results indicate that properly designed concrete wall systems can reduce annual heating and cooling costs. In addition, the results show that the most significant impacts of improved wall systems are, from greatest to least: infiltration reduction, improved insulation configuration, and thermal capacitance. Finally, the results show that while there are energy savings associated with concrete wall systems, economic justification of these systems must also rely on the other attractive features of concrete systems such as greater durability and disaster resistance.
Master of Science
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Pica, Giuseppe. "Donor electron states for silicon quantum computing : from single spins to scaled architectures." Thesis, University of St Andrews, 2015. http://hdl.handle.net/10023/7816.
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This PhD work took place in the framework of theoretical research aimed at implementation of quantum computing schemes and algorithms in solid state devices. The electron and nuclear spins of dopant atoms implanted in silicon crystals, that already lie at the core of commercial diodes and the photovoltaic industry, are able to store quantum information longer than anything else in the solid state. Controlled manipulations of silicon qubits depend on the ability to tune the nanoscopic donor electron state: we provide a complete theoretical picture that includes, within the insightful and analytic framework of effective mass theory, the effects of the non-trivial silicon conduction band and the different lattice distortions caused by the implantation of the donor species. Calibration of the multi-valley bulk theory to account for binding energies and electron-nuclear hyperfine couplings allows improved estimates of the exchange splittings between two neighbouring donors, that provide the simplest handle for tuning two-qubit operations. Further refinements to our approach lead to exceptional agreement with experimental measurements of Stark effects, where an external electric field is used to enable local single qubit manipulations within global driving fields: we set reliable thresholds on such gating speeds across all group V donors. Finally, we propose a scalable scheme for silicon quantum computing that relies on the coherent transfer of information from Si:Bi donors, that are established as excellent memory qubits, to surface quantum dots that are easier to manipulate, within a topological surface code which enables outstanding tolerance to errors. Analysis of the optimal working regimes and inclusion of the leading sources of decoherence allow us to set out a robust design of the basic building block of future realizations.
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Morrison, Erin R. "Can We Re-use “Single-Use” Solid Phase Extraction Cartridges?" Scholar Commons, 2017. http://scholarcommons.usf.edu/etd/7065.
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Organic and inorganic compounds are present as contaminants in varying concentrations throughout our water cycle. Examples of these contaminants include the endocrine disrupting compounds (EDCs) bisphenol-A (BPA) and 17β-estradiol (E2) from plastics and pharmaceutical use. It can be necessary to obtain the concentration of these compounds within the water cycle for analysis by interested parties such as research groups, regulatory agencies, and private organizations. These concentrations, however, can be too dilute within the initial sample for analysis. Therefore it is necessary to concentrate the compound of interest (analyte) prior to analysis. One such way to do this is by way of Solid Phase Extraction (SPE).
SPE uses a small cartridge which contains chromatographic packing material to chemically extract analytes from a water sample onto a solid phase. To increase concentration, these analytes are then transferred (eluted) to a substantially smaller volume of organic solvent for eventual analyses. These commercially available cartridges are relatively inexpensive, approximately $5 each. However, these cartridges are labeled as single use. In large-scale analyses, this can quickly add up to a sizable percentage of the analysis budget. Additionally, sizable waste volumes can be generated from these analyses in the form of non-degradable polypropylene plastic. If these cartridges can be re-used, material costs as well as waste volumes can be substantially reduced. However, little is known regarding how the quality of analysis degrades with cartridge re-use. The objective of this project is to evaluate the number of times SPE cartridges can be reused without compromising the results of the subsequent analyses.
Based on a review of prior literature, I identified and developed protocols for extracting analytes (BPA and E2) from water via SPE, then analyzing them with gas chromatography and mass spectrometry (GC-MS). These protocols have been developed to mimic those employed by research labs, industry, and other entities for which the results of this study would be most applicable. The only deviation is the re-use of the cartridge rather than disposal and replacement. One type of commercially available SPE cartridge (Oasis HLB, Waters Inc., Milford, MA) was used and two water types were tested. The water was spiked with fixed concentrations of BPA and E2, and then analyzed by way of SPE/GC-MS. For both water types, I performed multiple SPE runs on 10 cartridges each. I tracked the history of GC-MS peak areas, which indicate apparent analyte concentration. Peak area data were analyzed as a function of the number of analyses performed (run number), and evaluated for statistically significant changes as well as overall trends. Statistically significant change and/or trends would indicate that the cartridge had exceeded the maximum allowable number of re-uses and would thereby identify the number of times the “single-use” cartridge can reliably be re-used.
Peak area history for 20 SPE runs per cartridge for pure water samples and 10 SPE runs for wastewater effluent showed no statistically significant changes or trends on peak area. This indicates that cartridges can be re-used at least 10 times without compromising the integrity of water sample analysis for the EDCs considered in this study.
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Hanna, Sarah Jane. "Development and characterization of a single particle mass spectrometer with soft photoionization for organic aerosol studies." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/11882.
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Aerosol particles, which are ubiquitous in the Earth’s atmosphere, can be 20-90% organic carbon by mass. These organic aerosols are thought to play an important role in climate, human health, and the chemistry of the atmosphere. Their composition, however, can be extremely complex, presenting a significant challenge to standard analytical techniques. Over the past several decades aerosol mass spectrometry has become an important tool for determining organic aerosol chemical composition.
This thesis describes the development and characterization of a new aerosol mass spectrometer designed for analysis of individual organic aerosol particles.
A unique vacuum UV source and custom monochromator, fully tunable from 7.4 to 10.2 eV (168 to 122 nm), was developed and characterized using gas phase analytes. The VUV source was coupled to a single particle mass spectrometer which uses a tunable CO₂ laser for particle vaporization and an ion trap for mass analysis.
Initial aerosol experiments were carried out using caffeine particles. The appearance energy of caffeine molecular ions from the vaporized particle was measured by scanning the VUV photon energy. The impact of increasing vaporization energy was also studied.
Following the caffeine experiments, a detailed study of oleic acid and 2,4-dihydroxybenzoic acid (DHB) aerosols was undertaken. The appearance energies of both the molecular and fragment ions were measured and the impact of ionization wavelength was determined. In addition, the results were compared to those from similar studies done with time-of-flight mass analyzers, allowing observation of the impact of long ion storage times on the mass spectra.
The final part of this thesis compares the IR laser vaporization of small, solid caffeine and DHB aerosols with larger, liquid oleic acid particles. The translational energy of the vaporized aerosol plume was followed by changing the delay between the vaporization and ionization events. The extent of fragmentation was monitored and was found to be dependent on both vaporization energy and ionization delay time. Both translational energy and the degree of fragmentation were seen to change with particle type, an effect which has important implications for pulsed laser desorption in aerosol mass spectrometry.
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Sorenson, Kristan L. "Comparative Studies on Oxygen Mass Transfer for the Design and Development of a Single-Use Fermentor." DigitalCommons@USU, 2010. https://digitalcommons.usu.edu/etd/738.
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Accurate experimental oxygen mass transfer coefficient, a measure of how quickly oxygen travels from a gas bubble to the bulk liquid, is important for comparing performance and for evaluating the oxygen transfer capability of a fermentor. Delays in probe response and changing gas volumes upon start-up of gassing affect the accuracy of oxygen transfer measurements. To mitigate these inaccuracies, a standard correction procedure for oxygen mass transfer data was established for highly oxygenated, well-mixed fermentation systems. Probe response time correction was generated by applying a second-order response model to dissolved oxygen probes and shown to be effective within 4%. By using a derived model for transient volume rise, the effect of changing gas volume at start-up was shown to cause very minimal error (1-2%) in kLa.
The unsteady-state method of kLa determination was used to compare design aspects of a hypothetical fermentor, including gas sparging devices and locations, baffle geometries and quantities, and impeller configurations. It was shown that locating the sparging device in the center of the tank, directly below the drive shaft and bottom impeller, is optimal for oxygen mass transfer. Sparger type was shown to have little effect on oxygen mass transfer values, although an open-pipe sparger was shown to provide slightly more oxygen mass transfer than a ring sparger. The use of rounded baffles in place of traditional rectangular baffles resulted in a 67-80% decrease in oxygen mass transfer coefficient. A comparison of three and four traditional baffles showed that three baffles produced a higher oxygen mass transfer than four. Correlation of baffle ratio and oxygen mass transfer coefficient indicated that the optimum baffle ratio is approximately one. Radial impellers were observed to provide better mixing, and thus higher oxygen mass transfer coefficients than axial impellers. In seven of ten comparisons, an impeller quantity ratio of 1.33 instead of 1.00 provided significant improvement in kLa. Additionally, only two of ten comparisons showed a difference between traditional Rushton turbine impellers and Smith turbine impellers, indicating that the difference in oxygen mass transfer capability of the two is negligible.
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Angevine, Christopher. "CHARACTERIZATION OF INDIVIDUAL CHARGED Au25(SG)18 CLUSTERS AND THEIR ENHANCEMENT OF SINGLE MOLECULE MASS SPECTROMETRY." VCU Scholars Compass, 2014. http://scholarscompass.vcu.edu/etd/613.
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Metallic quantum clusters are stable structures that can exhibit many useful magnetic, chemical, and optical properties. Developing clusters for specific applications requires accurate methods for characterizing their physical and chemical properties. Most cluster characterization methods are ensemble-based measurements that can only measure the average values of the cluster properties. Single cluster measurements improve upon this by yielding information about the distribution of cluster parameters. This investigation describes the initial results on a new approach to detecting and characterizing individual gold nanoclusters (Au25(SG)18) in an aqueous solution with nanopore-based resistive pulse sensing. We also present a new application where the clusters are shown to increase the mean residence time of polyethylene glycol (PEG) molecules within an alpha hemolysin (αHL) nanopore. The effect appears over a range of PEG sizes and ionic strengths. This increases the resolution of the peaks in the single molecule mass spectrometry (SMMS) current blockade distribution and suggests a means for reducing the ionic strength of the nanopore solute in the SMMS protocol.
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Al-Jimaz, A. S. "The hydrodynamic behaviour and mass transfer characteristics of single droplets in a pulsed sieve plate column." Thesis, Aston University, 1992. http://publications.aston.ac.uk/9791/.
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The literature relating to the performance of pulsed sieve plate liquid-liquid extraction columns and the relevant hydrodynamic phenomenon have been surveyed. Hydrodynamic behaviour and mass transfer characteristics of droplets in turbulent and non-turbulent conditions have also been reviewed. Hydrodynamic behaviour, i.e. terminal and characteristic velocity of droplets, droplet size and droplet breakup process, and mass transfer characteristics of single droplets (de0.6 cm) were investigated under pulsed (mixer-settler & transitional regimes) and non-pulsed conditions in a 5.0 cm diameter, 100 cm high, pulsed sieve plate column with three different sieve plate types and variable plate spacing. The system used was toluene (displaced) - acetone - distilled water. Existing photographic techniques for following and recording the droplet behaviour, and for observing the parameters of the pulse and the pulse shape were further developed and improved. A unique illumination technique was developed by which a moving droplet could be photographed using cine or video photography with good contrast without using any dye. Droplet size from a given nozzle and droplet velocity for a given droplet diameter are reduced under pulsing condition, and it was noted that this effect is enhanced in the presence of sieve plate. The droplet breakup processes are well explained by reference to an impact-breakup mechanism. New correlations to predict droplet diameter based on this mechanism are given below. vskip 1.0cm or in dimensionless groups as follows:- (We)_crit= 3.12 - 1.79 (Eo)_crit A correlation based on the isotropic turbulence theory was developed to calculate droplet diameter in the emulsion regime. vskip 1.0cm Experimental results show that in the mixer-settler and transitional regimes, pulsing parameters had little effect on the overall dispersed phase mass transfer coefficient during the droplet formation and unhindered travel periods.
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Chen, Yanfeng. "Analysis of Biological Molecules Using Stimulated Desorption Photoionization Mass Spectrometry." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14620.
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Surface-assisted laser desorption/ionization mass spectrometry (SALDI MS) is a novel technique for direct analysis of organic and biological molecules. Amino acids, dipeptides, and organoselenium compounds were successfully detected by SALDI on carbon and silicon surfaces. Surface effects, solvent effects, temperature effects and pH effects were studied. A possible mechanism of SALDI is proposed based on observed results.
In general, stimulated desorption results in neutral yields that are much larger than ion yields. Thus, we have exploited and further developed laser desorption single photon ionization mass spectrometry (LD/SPI MS) as a means of examining biomolecules. The experimental results clearly demonstrate that LD/SPI MS is a very useful and fast analysis method with uniform selectivity and high sensitivity.
Selenium (Se) is an essential ultra-trace element in the human body. In efforts to obtain more useful information of selenium metabolites in human urine, mass determination of unknown organoselenium compounds in biological matrices using SALDI MS was investigated. In another approach, several selenium metabolites in human urine were successfully detected by LD/SPI MS. A HPLC-MS/MS method was also developed for a quantitative case study of selenium metabolites in human urine after ingestion of selenomethionine.
Low-energy electrons (LEE, 3-20 eV) have been shown to induce single and double strand breaks (SSB and DSB) in plasmid DNA. To understand the genotoxic effects due to secondary species of high-energy radiation, we investigate the role of transient negative ions and the specificity in LEE-DNA damage by examining the neutral product yields using low electron stimulated dissociation SPI MS. The neutral yields as a function of incident electron energy are also correlated with the SSBs and DSBs measured using post-irradiation gel electrophoresis. The results provide further insight concerning the mechanisms of LEE-induced damage to DNA.
Overall, this research provided an in-depth understanding of non-thermal surface processes and the development of new mass spectrometric techniques for the analysis of biomolecules.
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Fujita, Naotaka. "Noninvasive longitudinal quantification of β-cell mass with [111In]-labeled exendin-4." Doctoral thesis, Kyoto University, 2020. http://hdl.handle.net/2433/245834.
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京都大学0048
新制・課程博士
博士(医学)
甲第22149号
医博第4540号
新制||医||1039(附属図書館)
京都大学大学院医学研究科医学専攻
(主査)教授 川口 義弥, 教授 上本 伸二, 教授 富樫 かおり
学位規則第4条第1項該当
Doctor of Medical Science
Kyoto University
DFAM