Ammonia is one of the most important chemicals for modern civilization as well as a potentially invaluable intermediary component of a future sustainable H2 economy, yet its current production is decidedly unsustainable. Accordingly, researchers are attempting to devise new paradigms for ammonia production, one of which would involve the cyclical reaction of H2 with a nitride compound and the renitridation of that compound with N2 - a thermochemical loop that would allow for ammonia production with renewable inputs and at relatively low pressures. In this paper, researchers identified several ternary and quaternary metal nitrides with the potential to exhibit relatively favorable thermodynamics for both the reduction and nitridation steps of that reaction cycle. These compounds were synthesized via co-precipitation and Pechini synthesis and several were tested under gas flows of 75% H2/Ar at 100-700 C and 75% H2/N2 at 700 C to determine their behavior under these conditions. As suggested by the available literature, Co3Mo3N was found to be a far better candidate for thermochemical looping than Fe3Mo3N or Ni2Mo3N - with higher mass loss and mass regain. Interestingly, quaternary nitrides containing Fe and Co in addition to Mo also demonstrated remarkable reduction and nitridation capability under ambient pressures. Ultimately, this paper demonstrates the feasibility of synthesizing a variety of single phase ternary and quaternary nitrides and the potential that several of these nitrides hold for producing ammonia sustainably via cyclic thermochemistry.

Flavonoids are important biomolecules with a variety of pharmaceutical and agricultural applications. Currently, isolating these compounds is done by plant extraction, however this process is hindered by large land and energy requirements. Previous groups have aimed to overcome these challenges by engineering microbes to produce these important compounds, however this is largely bottlenecked by the lack of intercellular malonyl-CoA availability. To remedy this, the genes matB and matC have been identified as coding for malonyl-CoA synthase and a putative dicarboxylate carrier protein, respectively. Other works have successfully engineered two variants, Streptomyces coelicolor and Rhizobium trifolii, of these genes into Escherichia coli, however this has yet to be accomplished in Gram-positive Corynebacterium glutamicum. Additionally, other groups have neglected to attempt tuning these genes with respect to one another by inserting in front of different inducible promoters. This study has successfully assembled two plasmids containing the Streptomyces coelicolor and Rhizobium trifolii variants of both matB and matC. Preliminary fermentations and GCMS results confirmed that little to none naringenin was produced without the matB-matC module. Additionally, preliminary fermentations revealed that the DelAro1 and DelAro3 strains can be used to reduce metabolism of aromatics like naringenin.

Utilizing DFT calculations, various substitutions on the AlPO-5 zeolite were screened for adsorption of common air molecules. Furthermore, free energy analyses using the Helmholtz free energy equation were performed to determine candidates for selective adsorption of one specific air molecule, and their operating temperature range. Through this study, it was found that Cerium- (92-542 K), Germanium- (69-370 K), Chromium- (35-293 K), and Praseodymium- (0-420 K) substituted AlPO-5 selectively adsorbs to O2 molecules for the given temperature ranges. In addition, Palladium-substituted AlPO-5 selectively adsorbs to CO within 430-755 K.

It is a fact of modern food processing that the majority of products contain one or multiple food additives. Yet, while these additives see great abundance of use, the average consumer has relatively little knowledge about them and, more often than not, a negative opinion of their inclusion. This piece explores the discrepancy between these two realities by delving into the origins, histories of use, health effects, and misconceptions that surround a number of modern food additives, exploring along the way the social changes and regulatory history that brought about the legal landscape of food safety in the United States. Ten author-developed recipes are included at the end to encourage not only a conceptual, but also a practical familiarity with these same food additives.

Lithium ion batteries are quintessential components of modern life. They are used to power smart devices — phones, tablets, laptops, and are rapidly becoming major elements in the automotive industry. Demand projections for lithium are skyrocketing with production struggling to keep up pace. This drive is due mostly to the rapid adoption of electric vehicles; sales of electric vehicles in 2020 are more than double what they were only a year prior. With such staggering growth it is important to understand how lithium is sourced and what that means for the environment. Will production even be capable of meeting the demand as more industries make use of this valuable element? How will the environmental impact of lithium affect growth? This thesis attempts to answer these questions as the world looks to a decade of rapid growth for lithium ion batteries.

Ozone is a highly reactive compound that is harmful at very low concentrations as compared to other pollutants. One method of pollution control is the use of photocatalysis, specifically with titanium dioxide to induce ozone decomposition. An experiment was designed and executed in order to determine the rate of decomposition by coating concrete in 5% by weight titanium dioxide mixed with paint. The experiment was unsuccessful in inducing decomposition but gave important insight into the adsorptive properties of ozone over surfaces, particularly with bare concrete that had an adsorption of 22.51 ± 2.457 ppbv, which was much better than the coated samples. Further studies into the development of photocatalytic paint is needed in order to develop an effective urban ozone pollution control method to be implemented in major cities, particularly in the most polluted such as Los Angeles, California.

MAX phases are layered hexagonal early transition metal carbides, sometimes nitrides, where M is an early transition metal, A is an A group element, most prominently groups 13 or 14, and X is either carbon or nitrogen.1 They are gaining a lot of attention because of their unusual properties. Particularly, their hardness, chemical stability at room temperature, and high melting points. These properties provide a material that is viable for a wide range of demanding applications.2,3 MAX phases display a combination of both ceramic and metallic characteristics. Furthermore, they also serve as a precursor for two-dimensional MXenes.4,5<br/>Generally, bulk synthesis of MAX phases is done through traditional solid state synthesis techniques. For example, three solid state synthesis techniques include solid state method, hot pressing and arc melting and annealing. During solid state method, the powder precursors are preheated between 350 and 400°C, allowing for decomposition of starting reagents and removal of volatile products leaving only the oxides. At this point the germination phase has completed, and the crystal growth phase begins. Under the effect of a concentration gradient and very high temperatures, cations migrate, forming well-ordered layers. Slow cooling rates are used in order to ensure crystallinity of the product.6 The second method, hot pressing, involves the mixing of powder precursors thoroughly and then cold pressed into a green body – a ceramic body powder pre-sintering. They are then heated under vacuum and often high pressure in order to form the product. Two variants of hot-pressing exits: reactive hot pressing, where the pressure during the reaction will vary throughout the reaction, and isostatic hot pressing, where the pressure is held constant throughout the entire reaction.7 Another solid-state technique is arc melting and annealing. During arc melting, alternating current is applied to the electrode inside an inert reactor, which is arranged as to generate an arc discharge. The heat produced by arcing causes rapid melting of the samples.8 While these methods are most common, they are not always viable due to the specialized equipment required in order to achieve the high temperature and pressure conditions. Furthermore, these specific techniques don’t allow for high control over particle size and morphology. <br/>Because of this, alternative, non-conventional synthesis techniques have been developed involving more readily available tube furnaces and microwaves, which lack the extreme pressures instead opting for ambient conditions.9 Sol-gel techniques have been developed by the group of Christina Birkel, and have successfully produced MAX phases through calcination of homogeneous citric acid-based gel-precursors. Some advantages of using these gel-precursors include shorter diffusion paths, and faster mass transport, thus, resulting in lower reaction temperatures and shorter reaction times. Ultimately, this allows for control over particle morphology and size.10<br/>The focus of this work is to discover optimal synthesis conditions to create spherical Cr2GaC. Spherical MAX phases have been briefly explored in existing literature using polymer-based hollow microsphere templates.10 These polymer microspheres have been used to synthesize spherical metal oxides. This is achieved by heating the metal oxide precursors which adhere to the spheres, then by thermal treatment, the template is then removed.11 <br/>Two different microsphere templates will be explored to study the advantages and disadvantages of different size distributions and surface conditions of the spheres. Furthermore, reaction temperature, reaction time, citric acid equivalents, and gel to microsphere ratio will be altered to determine optimal synthesis parameters for depositing Cr2GaC onto spherical templates. Cr2GaC serves as a model compound because it has been successfully synthesized through sol-gel chemistry in the past.10 This phase will be prepared through non-conventional sol-gel chemistry, with various heating profiles, both furnace and microwave, and will be characterized through X-ray diffraction (XRD), and Rietveld refinement. Further, the morphology and atomic composition will be analyzed through scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS).

A survey was created to help gain some insight on the opinions of homeowners across the <br/>Phoenix Metro Area. This survey consisted of 7 questions relating to personal experiences and <br/>the homeowners’ opinions or concerns. The results of the survey showed that there are a few <br/>concerns surrounding solar energy with an emphasis on the cost of maintenance of panels and <br/>the payback period where the homeowners would see a return on their investment. Most of the <br/>homeowners answered that they do not use solar energy but have thought about using it for their <br/>main source of energy before. The homeowners in the survey also thought that solar energy was <br/>overall too expensive and that it would take a long time before they would see any payoff or <br/>savings from the solar panels. It was found that the payback period for panels is around 7 years <br/>and that depending on the size of the solar system installed or on the model used, solar panels <br/>cost much less than many people think. This was found by researching non-biased resources <br/>from government websites and from local energy companies’ websites. To combat the concerns <br/>found from the survey, an infographic was created to help inform the public about solar energy <br/>and allow the homeowners to make decisions that are well informed and not based on <br/>misinformation. The infographic included information related to the survey by explaining the <br/>survey and explaining topics that were of concern to the homeowners who took the survey. In <br/>addition, the infographic displayed information about solar energy and that the decision to use <br/>solar is ultimately up to the audience.