Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (leaves 201-237).

An ion scattering surface analysis system using TOF energy-analysis of the scattered ions was improved with a duoplasmatron ion source and new data-handling electronics. The new source gave greater beam current and stability. The new electronics were: a timing filter amplifier and constant fraction discriminator. Much work was done on alignment of the sample in the beam and reduction of the spot size. To add to the flexibility of the beam guidance system a new pair of steering plates was added. Some of the test spectra are presented to show the operation of the system. Relevant material on various aspects of the system are presented in the appendices. / None / Master of Engineering (ME)

Infants and young children with tracheostomies need better respiratory monitors. Mucus in the tracheostomy tube presents a serious choking hazard.  Current devices indirectly detect respiration, often yielding false or delayed alarms.  A compact ultrasonic time-of-flight (TOF) airflow sensor capable of attaching directly to the tracheostomy tube has been developed to address this need.  The ultrasonic flow sensing principle, also known as transit time ultrasound, is a robust method that correlates the timing of acoustic signals to velocity measurement.  The compact prototype developed here can non-invasively measure all airflow into and out of a patient, so that breath interruption can easily be detected. This paper concerns technical design of the sensor, including the transducers, analog/digital electronics, and embedded systems hardware/software integration.   Inside the sensor's flow chamber, two piezoelectric transducers sequentially transmit and receive ping-like acoustic pulses propagating upstream and downstream of flow.  A microcontroller orchestrates measurement cycles, which consist of the transmission, reception, and signal processing of each acoustic pulse.  The velocity and direction of airflow influence transit time of the acoustic signals.  Combining TOF measurements with the known geometry of the flow chamber, average air velocity and volumetric flow rate can be calculated.  These principles have all been demonstrated successfully by the prototype sensor developed in this research. / Master of Science

I dagens samhälle används internet för kommunikation mellan människor runtom i världen. Det första videosamtalet gjordes runt år 1940 och det är dags fören utveckling, där 3D är något som skulle kunna göra videomöten mer verkliga.För att möjliggöra detta så konstruerades ett system som skulle kunna ta in datafrån olika time-of-flight- och färgkameror och en ljudenhet. Denna data ska sedankomprimeras och sändas över internet för att kunna spelas upp på någonannans 3D-skärm. För att samtalet inte ska kännas fördröjt måste samtliga delartillsammans ske inom realtid. De utvecklingsmetoder som har använts är parprogrammeringoch en variant utav testdriven utveckling. Systemet har utvärderatsutifrån tidmätningar, bildkvalitet och datastorlek för att hitta en bra balansmellan tid och kvalitet. Systemet konstruerades med fem delar: insamling avbilder och ljud, bilduppskalning, komprimering och avkomprimering, internetöverföringsamt rendering. Resultatet visade att de delar som berörs av datastorlekoch bildkvalitet kunde uppnå en bra balans mellan tid och kvalitet. Dockkunde inte alla mål uppnås då vissa delar tog upp mer tid än realtidsmålet samtatt alla delar inte han konstrueras. Eftersom systemet byggdes upp modulärt såkan de delar som inte uppnådde målen förbättras eller bytas ut. Utifrån resultatetkunde sedan lösningsförslag ges för att förbättra resultaten för en eventuell vidareutveckling. / In todays society internet is used for communication between each other aroundthe world. The first video call was made around the year 1940 and it is time fora development, where 3D is something that can make video calls more real. Tomake this possible a system was constructed that would be able to get data fromdifferent time-of-flight cameras and color cameras and audio devices. That datashould later on be compressed and transmitted over internet to be able to play iton someone else’s 3D-display. To prevent the feeling of delay in the call, allparts together must happen in real time. The development methods that havebeen used is pair programming and a variation of test-driven development. Thesystem has been evaluated by time messurements, image quality and data sizeto find a good balance between time and quality. The system was constructedby five parts: capturing of images and audio, image upscaling, compression anddecompression, network streaming and also rendering. The result showed thatthe parts affected by data size and image quality could achieve a good balancebetween time and quality. However, all goals could not be achieved becausesome parts where too slow for the real time goal to be achieved and also someparts could not be constructed in time. Since the system was built up modularlythe parts that did not achieve the goals can be improved or replaced. Based onthe results, solution proposals was made to improve the results for a possiblefurther development.

In MALDI, for laser fluences below the saturation point the ion yield per shot follows a cubic dependence on the irradiated area, leading to a conclusion that smaller spots produce overall less ions and therefore are less viable. However, Qiao et al. showed that by decreasing the laser spot size it is possible to raise the saturation point, and thus increase the ion yield per unit area, also known as sensitivity. Here we explore laser spots below 10 micrometer diameter to determine whether they offer any practical advantage. We show that sensitivity is greater for a flat-top 3-4 micrometer spot than for a 10 micrometer spot. The sensitivity is greater for a Gaussian-like 3-5 micrometer spot than for flat-top 5-25 micrometer spots. We also report for the first time sensitivity versus theoretical fluence profile for a Gaussian-like beam focused to a spot of 3-5 micrometer.

This dissertation describes the results of time-of-flight spectroscopic examination of H⁺ ions resulting from electron bombardment of the hydrogen halide molecules HF, HCl, HBr, and HI. The time-of-flight spectra of the H⁺ fragments and their corresponding H⁺ fragment kinetic energy spectra are used to study the dissociative processes that yield H⁺ fragments for electron bombardment energies in the 15 eV to 51 eV range. The H⁺ fragments are produced in an interaction region defined by a pulsed electron beam colliding with the target gas. By keeping the gas pressure sufficiently low to guarantee that the fragment path length to the ion detector is much less than the mean-free path length in the gas, the fragments' velocities can be considered a sample of fragment velocities produced by the electron beam and hydrogen halide gas in the interaction region. The geometry of the interaction region primarily detected fragments produced at 90° to the electron beam axis. The electron gun used was designed to allow computer control of the electron bombardment energy. The computer also controlled a programmable multichannel analyzer that allowed the data to be acquired in a fashion that permitted normalization of the H⁺ TOF spectra taken at different electron bombardment energies. This normalization procedure allowed the use of ionization efficiency curves in detection of the thresholds of H⁺ production channels for HCl and HBr. For HF and HI the thresholds of H⁺ production channels had to be determined by visual examination of the TOF spectra. The electronic structure of the hydrogen halide molecules has been a popular topic of study over the years. Since this work represents the first TOF study of electronic excitation processes that lead to dissociation resulting in H⁺ fragments from the hydrogen halides, it should prove to be a significant contribution toward an understanding of the highly excited electronic states of these molecules and their molecular ions. The interpretation of the results obtained indicated that both configuration interactions between adiabatic electronic states that lead to predissociation-type processes and inner valence shell excitations were probably the primary contributors to the H⁺ fragment production.

The focus of this dissertation is the introduction of surface-induced dissociation (SID) into a commercially available quadrupole time-of-flight mass spectrometer as an alternative ion fragmentation method. The performance of the SID device was characterized and its applications were demonstrated by dissociating peptides, proteins, inorganic salt clusters and non-covalent protein complexes. The SID setup allowed direct comparison of SID with conventional collision-induced dissociation (CID) on the same instrument, taking advantage of the characteristics of Q-TOF instrumentation, including extended mass range, high sensitivity and resolution. With the SID setup installed, no significant reduction of the ion transmission was evident. SID fragmentation patterns of peptides are, in general, similar to CID, with slight differences in the relative intensities of immonium ions, backbone cleavage b- versus y- type ions, and y- versus y-NH3 ions. This suggests enhanced accessibility to high energy/secondary fragmentation channels with SID. SID studies on cesium iodide clusters (CsI) also revealed that SID deposits more internal energy.The utility of mass spectrometric methods to probe the gas phase cyclization process was studied with [D-Ala2]-Leucine Enkephalin amide. This peptide showed prominent formation of the [M-NH3]+ ion which is believed to be the linear b5 ion with a C-terminal oxazolone structure. Other fragments in the spectra indicate that the linear b5 ion undergoes cyclization, subsequent ring opening and further dissociation to rearranged fragments that cannot be explained by the initial sequence. The similarities between the cyclic and b5-ion from the linear peptide indicated the formation of a heterogeneous ion population and this is further supported by gas-phase H/D exchange experiments. An ion funnel interface to improve ion transmission at high pressures was tested in a custom built quadrupole-surface-quadrupole instrument. The ion transmission efficiency for selected bio-molecules such as YGGFLR, insulin chain-B, ubiquitin and cytochrome c showed to approach almost 90%, with the funnel interface installed. The ion transmission efficiency was effected by several factors including: the size of the analyte, the DC gradient, the RF frequency, and the RF amplitude. The higher fragmentation efficiencies for SID in the presence of the funnel interface indicated higher internal energy deposition for the funnel interface.

Li Yiu-Ching. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (p. 123-132). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

The Centers for Disease Control and Prevention deemed the increase in overdose fatalities, due to the use of opioids, an “opioid epidemic” in the United States. Heroin, fentanyl, and other synthetic opioids are commonly abused and are contributing to the opioid epidemic. In 2016, the Drug Enforcement Administration temporarily placed three fentanyl analogs (beta-hydroxythiofentanyl, butyryl fentanyl, and furanyl fentanyl) under Schedule I due to their imminent threat to public health. These drugs elicit analgesic effects similar to heroin making them desirable drugs to abuse. Novel fentanyl analogs and designer opioids are expected to become more prominent in forensic casework in the near future as the opioid epidemic continues. These drugs can be seen in forensic seized drug and urine casework samples either alone or mixed with other drugs of abuse. It is therefore necessary to have an efficient methodology to identify these new compounds. Currently, gas chromatography-mass spectrometry (GC/MS) is used to identify drugs of abuse and is considered the “gold standard” in forensic casework. However, analysis times can often range from 15 to 60 minutes in length. Another drawback is the need for spectral library matching, which requires analytical reference materials for identification. Therefore, the identification of novel fentanyl analogs and designer drugs is limited until a reference material becomes available. In this study, direct sample analysis time-of-flight mass spectrometry (DSA-TOFMS) was evaluated to provide rapid identification of fentanyl and other synthetic opioids in seized drug and urine casework samples. DSA is a direct ambient ionization source, which requires no chromatography and minimal sample preparation. TOFMS is a high resolution mass spectrometer that uses collision-induced dissociation (CID) to produce precursor ion and characteristic fragmentation ions, which provide additional structural and molecular formula information, allowing for the identification of compounds without a reference material. The analytes explored in this study include: heroin, 6-monoacetylmorphine (6-MAM), morphine, fentanyl, norfentanyl, 4-anilino-N-phenethylpiperidine (4-ANPP), acetyl fentanyl, beta-hydroxythiofentanyl, butyryl fentanyl, furanyl fentanyl, valeryl fentanyl, AH-7921, U-47700, buprenorphine, norbuprenorphine, desomorphine, MT-45, W-15, and W-18. Direct sample analysis time-of flight mass spectrometry (DSA-TOFMS) is a novel instrumentation that could be utilized in the forensic sciences field to qualitatively identify illicit substances in casework samples. In this study, 19 compounds of interest containing heroin, fentanyl, fentanyl analogs, and other synthetic opioids were evaluated using DSA-TOFMS. DSA-TOFMS abbreviated the workload of the analysis and was utilized to provide precursor ion and characteristic fragmentation ions within an analysis time of 20 seconds. Certified reference standards were used to optimize instrumentation settings, to determine precursor ions and characteristic fragmentation ions, and to determine the limit of detection of the instrument. A carryover study determined there were no persisting ions present when entering the capillary inlet between runs. A repeatability study revealed the DSA-TOFMS repeated results within the acceptable criteria range of above 500 counts and within 10ppm error 93% (10ppm) and 83% (1ppm). Forensic seized drug casework samples were evaluated with DSA-TOFMS and qualitatively identified. Out of the 64 samples, 89% were qualitatively identified as heroin, 4% were qualitatively identified as fentanyl, 1% was qualitatively identified as heroin and fentanyl, 3% were qualitatively identified as acetyl fentanyl, and 3% were qualitatively identified as furanyl fentanyl. The casework samples containing furanyl fentanyl were considered “true unknown unknown samples,” as the Maine Health and Environmental Testing Laboratory gas chromatography-mass spectrometry library did not have a spectrum to use for the identification of these samples. Forensic urine casework samples were evaluated with DSA-TOFMS. Samples previously confirmed to contain compounds of interest were prepared using minimal sample preparation technique (filtered using 0.45 microns syringe filters and diluted (1:10) with LC/MS grade water). Analysis displayed the limitations of DSA-TOFMS as only twelve of the forty compounds of interest were present and only three of the twelve were within the acceptable criteria range. DSA-TOFMS is a fast and reliable technique with minimal sample preparation for forensic seized drug samples. However, the concentration in complex matrixes, such as urine and blood, were unable to be qualitatively identified using this sample preparation method by DSA-TOFMS.

<p>Buildings, maps and objects et cetera, can be modeled using a computer or reconstructed in 3D by data from different kinds of cameras or laser scanners. This thesis concerns the latter. The recent improvements of Time-of-Flight cameras have brought a number of new interesting research areas to the surface. Registration of several ToF camera point clouds is such an area.</p><p>A literature study has been made to summarize the research done in the area over the last two decades. The most popular method for registering point clouds, namely the Iterative Closest Point (ICP), has been studied. In addition to this, an error relaxation algorithm was implemented to minimize the accumulated error of the sequential pairwise ICP.</p><p>A few different real-world test scenarios and one scenario with synthetic data were constructed. These data sets were registered with varying outcome. The obtained camera poses from the sequential ICP were improved by loop closing and error relaxation.</p><p>The results illustrate the importance of having good initial guesses on the relative transformations to obtain a correct model. Furthermore the strengths and weaknesses of the sequential ICP and the utilized error relaxation method are shown.</p>