Graphene - Calling all Chemical Engineers

Since its isolation in 2004, graphene has attracted worldwide attention for its unique electronic properties and its potential in a next generation of nanoelectronic devices. The emerging applications of graphene now extend well beyond electronics to include composite materials, barrier coatings, electrodes, catalyst supports, and theranostics. These applications often rely on the atomically thin, two-dimensional plate-like nature of the material, and in practice are often based on graphene oxide or few-layer graphene, which are low-cost, high production volume members of the larger “graphene material family”. This talk describes research on the assembly of graphene building blocks into advanced materials with applications as transport barriers, encapsulation sacks, and cell delivery vehicles. The talk will highlight the important role that chemical engineers can play in this new field, which involves colloid and surface science, transport phenomena, adsorption, aerosol behavior and complex fluids

Mass Spectrometric Studies on the Primary Products of Fast Pyrolysis of Carbohydrates and the Molecular Structures of Asphaltenes, and the Development of a Rastering Probe for Laser-Induced Acoustic Desorption into an Atmospheric Pressure Chemical Ionization Source

Mass spectrometry (MS) has proven invaluable in the field of mixture analysis and structural elucidation. Tandem mass spectrometry (MS/MS) utilizing collision-activated dissociation (CAD) has become the technique of choice for structural elucidation of unknown analytes in mixtures. When coupled with gas chromatography (GC) or high performance liquid chromatography (HPLC), it allows for trace level analysis of mixture components. In spite of the utility of mass spectrometry in complex mixture analysis, it does have limitations. Traditional GC/MS methods used for the analysis of fast pyrolysis products cannot be used to analyze the primary products, thus limiting the knowledge that can be obtained regarding the true mechanisms of fast pyrolysis, ultimately restricting the level of control over what final products are formed. Analysis of mixtures of hydrocarbons, such as crude oil, is also still a problematic area for mass spectrometry due to the lack of suitable evaporation/ionization methods for the heavier components. Consequently, very little is known about the structures of molecules in asphaltenes, the heaviest fraction of crude oil and one of the most complex mixtures in nature. Elucidating the structures of the compounds present in these mixtures is important for the rational design of methods to prevent the problems the cause. Experiments described in this thesis employed tandem mass spectrometry to achieve a better understanding of the primary products of fast pyrolysis of carbohydrates and structures of molecules in asphaltenes. Chapter 2 briefly describes the instrumentation used for the research presented in this dissertation. Chapter 3 discusses the development of on-line mass spectrometric methods for the determination of the primary products of fast pyrolysis of carbohydrates and their gas- phase reactivity, demonstrating that there are many primary products that cannot be analyzed using traditional methods. Chapter 4 examines the differences in the molecular structures of petroleum and coal asphaltenes. Chapter 5 focuses on changes to asphaltenes\u27 molecular structures when they are subjected to the hydrocracking process, a common practice in crude oil refinement. Chapter 6 compares field deposit asphaltenes, removed from a pipeline, to heptane precipitated asphaltenes from crude oil in a laboratory. Chapter 7 contrasts the effects of using different solvents in atmospheric pressure chemical ionization (APCI) of asphaltenes. Chapters 8 and 9 focus on advances for laser-induced acoustic desorption (LIAD). Chapter 8 discusses improvements LIAD/APCI, including the development of a high-power laser probe for more reproducible evaporation of high-mass compounds into the gas phase, and the development of a rastering assembly that greatly increases the surface area of the LIAD foil that can be sampled. Chapter 9 discusses a novel chamber for preparing sample foils for LIAD by using a drying gas to prepare foils. The new chamber that helps in the production of foils with a more uniform sample layer than previously possible for nonpolar analytes to improve the reproducibility of LIAD

Feeding IC 342: The nuclear spiral of a starburst galaxy

IC 342 is a large nearby (1.8 Mpc, Turner and Hurt, 1991, hereafter T&H) spiral galaxy undergoing a moderate nuclear starburst. T&H have previously mapped the inner arcminute in CO-13(1-0) using the Owens Valley Millimeter Interferometer and found evidence that the nuclear molecular gas takes the form of spiral arms in a density wave pattern. They suggest that radial streaming along the arms may channel gas from the exterior of the galaxy into the nucleus, feeding the starburst. We have mapped the CO-12(1-0) emission of the inner 2 kpc of IC 342 at 2.8 inch resolution using the Owens Valley Radio Observatory (OVRO) Millimeter Interferometer. The greater sensitivity of CO-12 observations has allowed us to trace the spiral pattern out to a total extent of greater than 1 kpc. The CO-12 observations extend considerably the structure observed at CO-13 and offer further evidence that a spiral density wave may extend from the disk into the nucleus of IC 342

Testing and Review of Various Displacement Discontinuity Elements for LEFM Crack Problems

The numerical modeling of hydraulic fractures in unconventional reservoirs presents significant challenges for field applications. There remains a need for accurate models that field personnel can use, yet remains consistent to the underlying physics of the problem [1]. For numerical simulations, several authors have considered a number of issues: the coupling between fracture mechanics and fluid dynamics in the fracture [2], fracture interaction [3-5], proppant transport [6], and others [7-9]. However, the available literature within the oil and gas industry often ignores the importance of the crack tip in modeling applications developed for engineering design. The importance of accurate modeling of the stress induced near the crack tip is likely critical in complex geological reservoirs where multiple propagating crack tips are interacting with natural fractures. This study investigates the influence of various boundary element numerical techniques on the accuracy of the calculated stress intensity factor near the crack tip and on the fracture profile, in general. The work described here is a part of a long-term project in the development of more accurate and efficient numerical simulations for field engineering applications

A LumberJack Sunflower, Blooming from Undergraduate Research

It was one year ago in spring 2017 when I did not understand how to write research, let alone be confident in it. In the fall 2016 semester, I was part of a class project that worked to provide donations to families affected by flooding in Louisiana. In the following spring 2017 semester, I worked to present my own findings and practice from that project towards a research paper. From that paper I earned the opportunity to be part of an Undergraduate Research Conference. In the timespan of one year from that conference to spring 2018, I worked harder in research and presentations. Going further in research provided me many opportunities to grow professionally. The university I am attending seeks to transform its students with research and learning experiences. This paper seeks to speak about how research and learned experiences as envisioned by the author’s university can turn students into better versions of themselves, by providing examples of learned experiences from the author as an undergraduate student

Is a local bar a good place to find a companion? The near infrared morphology of Maffei 2

Maffei 2 is one of the closest large spiral galaxies lying just beyond the Local Group. It would probably be one of the most heavily studied galaxies in the sky were it not for the approximately 5 magnitudes of visual extinction resulting from its position behind the Galactic plane. It is the site of a burst of nuclear star formation indicated by strong infrared and radii continuum emission. Interferometric maps of CO-12 and CO-13 emission indicate that star formation is associated with a barlike structure consisting of arms of molecular gas that extend from within approximately 50 pc of the dynamical center out to a radius of at least 500 pc. HI maps have shown the galaxy to have an angular extent of approximately 15 feet and a neutral gas mass typical of a large spiral galaxy

Mineralogy and provenance of the TiO₂ - ilmenite heavy mineral sand deposit of Nataka

The Nataka heavy mineral sand deposit occurs along the northeast Mozambique coastline. It comprises a regional Pleistocene elliptical structure extending from Somalia, passing through Kenya, Tanzania, Madagascar and Mozambique, to Richards Bay in South Africa. The deposit consists of fine- to medium- grained, unconsolidated red sediments, hosting heavy minerals. The deposit mineral assemblage is made up of non-valuable phases comprising mostly magnetite, hematite, chromite, monazite, and the valuable phases dominated by ilmenite (50.91 wt. %), with additional zircon and rutile (9.96 and 3.52 wt. % respectively). The total heavy minerals comprise about 5% volume, of which 2 % are valuable heavy minerals making up about 445 Mt (million tonnes) probable resources. This study focuses on the mineralogical characterization of ilmenite from the Nataka deposit, alongside with sediment provenance. Mineralogical and chemical characterisation of ilmenite undertaken on 32 samples from 16 selected drill holes using a combination of QEMSCAN and EPMA revealed that the ilmenite has undergone different stages of alteration, at distinct environment conditions, yielding products spanning from hydrated ilmenite to leucoxene. The alteration dominantly involved groundwater, which was oxidizing and acidic, hence the predominance of ilmenite-pseudorutile alteration. Long exposure to direct sunshine has been hypothesized as a different process that might have favoured the direct alteration of ilmenite to leucoxene and of pseudorutile to leucoxene, on a smaller scale. The major impurities in the ilmenite are Al and Si, which are enriched in the advanced ilmenite alteration products (leucoxene), where they fill pores and cracks. Chromium impurities occur as discrete grains of chrome spinel. The compositional variety of magnetite, Cr-spinel, tourmaline, zircon and rutile indicate major contribution from granitoid terranes, subjected to granulite metamorphic facies (750 to 1000 :C), and minor contribution from mafic plutonic intrusions. The granitoid field as a sediment source area if analysed in conjunction with zircon ages (1100 – 900 Ma, 900 – 700 Ma, and 650 – 500 Ma), and zircon δ¹⁸O (7.07 ‰) is consistent with preferential sourcing from the proximal Mesoproterozoic Nampula Complex, with some contribution from igneous plutonic rocks from Xixano, Lalamo and Montepuez Complexes