Thermal Emission of Strontium Products for Scalar Diagnostics in Internal Combustion Engines

Developments in optical diagnostics for combustion systems have been essential to the recent improvements in efficiency and abatement of emissions that internal combustion engines have undergone recently. Great emphasis has been placed in the measurement of quantities with high temporal and spatial resolution, which has enabled the understanding of key physical and chemical processes, but there remains a need for obtaining spatially integrated measurements to understand how local events affect the overall behavior of the gases in a turbulent combustion chamber. Strontium offers a potential avenue to provide these measurements. When present in combustion it produces strontium monohydroxide, which spontaneously emits radiation in several bands of the visible spectrum, and thus enables the determination of temperature independently of species concentration through the Boltzmann distribution. Further, chemical equilibrium calculations can relate equivalence ratio to the relative concentration strontium and strontium monohydroxide, which could also be measured optically. The potential of this technique was explored in this work. An optical engine was operated under different conditions with a strontium-containing fuel and spectral measurements of the radiation emitted from the chamber were performed. The temperature in the cylinder was predicted by a one-dimensional thermodynamic model that used a two-zone model for flame propagation. The relative spectrally resolved emission intensity of atomic strontium and strontium monohydroxide was measured using a spectrometer coupled with camera, and the collected signals were related to the conditions in the chamber. From the results the mathematical formulation for the relationship of spectral intensity with temperature was found to be adequate, and important insights for the application of the diagnostic in imaging experiments were obtained. A universally applicable calibration was not attained due to experimental limitations, however, but the key barriers to overcome were identified.PHDMechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/153368/1/ivantib_1.pd

A microfabricated rapid desalting device for integration with electrospraying tip

Electrospray Ionization (ESI) is a technique that permits the soft ionization of large proteins and biomolecules without fragmenting them, which allows them to be characterized via Mass Spectrometry (MS). It has the potential of permitting the identification of transient intermediate products in biological processes in situ, which would provide great insight to researchers in the growing fields of proteomics and metabolomics. However, this application presents a technical challenge in that most relevant biochemistry occurs in aqueous solutions with high salt content, which makes successful identification of analytes by ESI-MS difficult. This thesis presents the design, fabrication, and characterization of a microfabricated dialysis module that could alleviate this issue by desalting samples inline between sampling and electrospraying interfaces. Its small volume (~10 nL) minimizes sample transit time and, thus, optimizes ESI-MS analysis temporal resolution. A preliminary analytical model of dialysis elucidates the key performance parameters and sets the guidelines for consideration in its design. The device is then microfabricated in a cleanroom environment using techniques that have been well established by the microelectronics industry such as E-beam evaporation and Reactive Ion Etching. The system efficiency is demonstrated experimentally by assessing its salt removal effectiveness as a function of sample residence time. Mass spectrometry analyses of proteins in solutions with high salt content further corroborate its performance.M.S

Microfabricated Ultrarapid Desalting Device for Nanoelectrospray Ionization Mass Spectrometry

Salt removal is a prerequisite for electrospray ionization mass spectrometry (ESI-MS) analysis of biological samples. Rapid desalting and a low volume connection to an electrospray tip are required for time-resolved measurements. We have developed a microfabricated desalting device that meets both requirements, thus providing the foundational technology piece for transient ESI-MS measurements of complex biological liquid specimens. In the microfabricated device, the sample flows in a channel separated from a higher flow rate, salt-free counter solution by a monolithically integrated nanoporous alumina membrane, which can support pressure differences between the flow channels of over 600 kPa. Salt is removed by exploiting the large difference in diffusivities between salts and the typical ESI-MS target bioanalytes, e.g., peptides and proteins. We demonstrate the capability to remove 95% of salt from a sample solution in ∼1 s while retaining sufficiently high concentration of a relatively low molecular weight protein, cytochrome-c, for ESI-MS detection