Final Narrative

https://lib.dr.iastate.edu/carver_narratives/1013/thumbnail.jp

The Electrosphere of Macroscopic "Quark Nuclei": A Source for Diffuse MeV Emissions from Dark Matter

Using a Thomas-Fermi model, we calculate the structure of the electrosphere of the quark antimatter nuggets postulated to comprise much of the dark matter. This provides a single self-consistent density profile from ultrarelativistic densities to the nonrelativistic Boltzmann regime that use to present microscopically justified calculations of several properties of the nuggets, including their net charge, and the ratio of MeV to 511 keV emissions from electron annihilation. We find that the calculated parameters agree with previous phenomenological estimates based on the observational supposition that the nuggets are a source of several unexplained diffuse emissions from the Galaxy. As no phenomenological parameters are required to describe these observations, the calculation provides another nontrivial verification of the dark-matter proposal. The structure of the electrosphere is quite general and will also be valid at the surface of strange-quark stars, should they exist.Comment: 20 Pages, REVTeX4.

Formulation and Processing of Dual Functional Adsorbent/Catalyst Structured Monoliths using an Additively Manufactured Contactor for Direct Capture/Conversion of CO2 with Cogeneration of Ethylene

Utilizing CO2 as a mild oxidant for oxidative dehydrogenation of ethane (ODHE) is an attractive way of recycling this greenhouse contaminant. Typically, CO2 capture and conversion processes are performed in separate beds, however, combining these processes into one bed incurs advantages of lower thermal gradient and reduced energy costs. This study formulated the first generation of structured dual-functional materials (DFMs) by directly 3D printing metal-oxide-CaO/ZSM-5 inks into monolithic contactors. Specifically, we 3D-printed monoliths with V, Ga, Ni, or Ti dopants to perform metal screening and determine which metal generates the best structured DFM for combined CO2 capture and utilization in ODHE. The samples were vigorously characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), N2 physisorption, NH3-temperature programmed desorption (NH3-TPD), H2-temperature programmed reduction (H2-TPR), energy dispersive spectroscopy (EDS), and Pyridine Fourier Transform Infrared Spectroscopy (Py-FTIR). Their CO2 capture/ODHE performances were assessed with CO2 adsorption at 600 °C and ODHE of 25 mL/min 7% C2H6 at 700 °C. The combined adsorption/catalysis experiments indicated that the best performance was observed in V-CaO/ZSM-5 which achieved a staggeringly high CO2 capture (5.4 mmol/g), 65.2% CO2 conversion, 36.5% C2H6 conversion, 98% C2H4 selectivity, and 35.8% C2H4 yield as well as zero thermal cracking after 40 min-on-stream. This performance exceeded that of any previously reported material for combined CO2 capture and ODHE utilization, indicating this novel printing method can generate DFMs with exceptional potential for combined CO2 capture and utilization processes

Drug Delivery On Mg-MOF-74: The Effect Of Drug Solubility On Pharmacokinetics

Biocompatible metal-organic frameworks (MOFs) have emerged as potential nanocarriers for drug delivery applications owing to their tunable physiochemical properties. Specifically, Mg-MOF-74 with soluble metal centers has been shown to promote rapid pharmacokinetics for some drugs. In this work, we studied how the solubility of drug impacts the pharmacokinetic release rate and delivery efficiency by impregnating various amounts of ibuprofen, 5-fluorouracil, and curcumin onto Mg-MOF-74. The characterization of the drug-loaded samples via X-ray diffraction (XRD), N2 physisorption, and Fourier transform infrared (FTIR) confirmed the successful encapsulation of 30, 50, and 80 wt % of the three drugs within the MOF structure. Assessment of the drug delivery performances of the MOF under its various loadings via HPLC tests revealed that the release rate is a direct function of drug solubility and molecular size. Of the three drugs considered under fixed loading condition, the 5-fluorouracil-loaded MOF samples exhibited the highest release rate constants which was attributed to the highest degree of solubility and smallest molecular size of 5-fluorouracil relative to ibuprofen and curcumin. It was also noted that the release kinetics decreases with drug loading, due to a pharmacokinetic shift in release mechanism from singular to binary modes of compound diffusion. The findings of this study highlight the effects of drug\u27s physical and chemical properties on the pharmacokinetic rates from MOF nanocarriers

Integrated Direct Air Capture and Oxidative Dehydrogenation of Propane with CO2 at Isothermal Conditions

Developing routes of utilizing CO2 emissions is important for long-term environmental preservation, as storing such emissions underground will eventually become unsustainable. One way of utilizing CO2 emissions is as a light-oxidant feedstock for oxidative dehydrogenation of propane (ODHP) to propylene. However, the adsorption and reaction steps typically occur at widely different temperatures, meaning that the thermal gradients – and by extension process energy requirements – are often unreasonably high. In recent years, dual-functional materials (DFMs) – i.e., materials comprised of a high temperature adsorbent phase alongside a heterogeneous catalyst – have been employed for combined CO2 adsorption and utilization over one material within a single bed using a reduced thermal gradient. However, these materials have never been formed into practical contactors and have never been applied to ODHP applications. Therefore, in this study we manufactured the first-generation of DFM adsorbent/catalyst monoliths, comprised of CaO (adsorbent) and M@ZSM-5 (M = V-, Ga-, Ti-, or Ni-oxide) heterogeneous catalysts, using our novel direct metal-oxide 3D printing technique. The monoliths were vigorously characterized using N2 physisorption, C3H8-DRIFTS, NH3-TPD, Py-FTIR, H2-TPR, XRD, XPS, and elemental mapping and were assessed for CO2 capture/ODHP utilization at 600–700 ºC. The adsorption/catalysis experiments revealed that these materials can perform both processes effectively at 600 ºC, with reduced propylene yield at higher temperature, which eliminated the need for a thermal gradient between the adsorption and catalysis steps. Between the various samples, the Ti-doped monolith generated the best balance of CO2 conversion (76%) and propylene selectivity (39%), due to the high dispersion of TiO2, favorable redox properties and controlled acidity of the dopant. However, it was also found that varying the metal dopant could be used to control the heuristics of CO2/C3H8 conversion, C3H6 selectivity, and C3H6 yield, meaning that the manufacturing process outlined herein represents a promising way of tuning the chemical properties of structured DFM adsorbent/catalyst materials. More importantly, this study establishes a promising proof-of-concept for 3D printing as a facile means of structuring these exciting composite materials and expands DFMs to the previously unexplored application of ODHP

Binderless zeolite monoliths production with sacrificial biopolymers

3D printing has emerged as an attractive way of formulating structured adsorbents, as it imparts lower manufacturing costs compared to hydraulic extrusion while also allowing for unprecedented geometric control. However, binderless structures have not been fabricated by 3D printing, as ink formulation has previously required clay binders which cannot be easily removed. In this study, we report the development of a facile approach to shape engineer binderless zeolites. 3D-printed inks comprised of 13X, 5A, ZSM-5, and experimental South African zeolites were prepared using gelatin and pectin as binding agents along with dropwise addition of various solvents. After printing, the dried monoliths were calcined to remove the biopolymers and form 100% pure zeolite structures. From N2 physisorption and CO2 adsorption measurements at 0 °C, all monoliths showed narrowing below 1 nm from their powders, which was attributed to pore malformation caused by intraparticle bridging during calcination

Enhanced Cas12a editing in mammalian cells and zebrafish

Type V CRISPR-Cas12a systems provide an alternate nuclease platform to Cas9, with potential advantages for specific genome editing applications. Here we describe improvements to the Cas12a system that facilitate efficient targeted mutagenesis in mammalian cells and zebrafish embryos. We show that engineered variants of Cas12a with two different nuclear localization sequences (NLS) on the C terminus provide increased editing efficiency in mammalian cells. Additionally, we find that pre-crRNAs comprising a full-length direct repeat (full-DR-crRNA) sequence with specific stem-loop G-C base substitutions exhibit increased editing efficiencies compared with the standard mature crRNA framework. Finally, we demonstrate in zebrafish embryos that the improved LbCas12a and FnoCas12a nucleases in combination with these modified crRNAs display high mutagenesis efficiencies and low toxicity when delivered as ribonucleoprotein complexes at high concentration. Together, these results define a set of enhanced Cas12a components with broad utility in vertebrate systems

Targeting Tumour-Initiating Cells with TRAIL Based Combination Therapy Ensures Complete and Lasting Eradication of Multiple Myeloma Tumours In Vivo

Multiple myeloma (MM) remains an incurable disease despite improvements to available treatments and efforts to identify new drug targets. Consequently new approaches are urgently required. We have investigated the potential of native tumour necrosis factor-related apoptosis-inducing ligand (TRAIL), in combination with doxorubicin, to induce apoptotic cell death in phenotypically distinct populations of myeloma cells in vitro and in vivo. The cytotoxic potential of TRAIL alone, and in combination with DOX, was assessed in vitro in purified CD138+ and CD138− cells from the MM cell lines and samples from patients with MM. Mouse xenografts obtained by implanting CD138− MM cells were used to assess the efficacy of TRAIL, alone and in combination with DOX, in vivo. CD138− cells were shown to be more resistant to the cytotoxic activity of TRAIL than CD138+ cells and have reduced expression of TRAIL death receptors. This resistance results in preferential killing of CD 138+ cells during exposure of MM culture to TRAIL. Furthermore, prolonged exposure results in the appearance of TRAIL-resistant CD138− cells. However, when TRAIL is combined with doxorubicin, this results in complete eradication of MM cells in vivo. Most importantly, this treatment successfully eliminates CD138− cells implicated in tumour initiation and growth maintenance. These findings may explain the failure of current therapies and offer a promising new approach in the quest to cure MM and disseminated cancers