Chemistry Commons^™

Phytoplankton Responses To Changing Irradiance And Carbon Fertilization, Alison Siersma

Graduate Theses and Dissertations (2019 - present)

Phytoplankton play a crucial role in marine ecosystems due to their innate ability to fix carbon. As atmospheric CO2 levels continue to rise from fossil fuel combustion, the resulting increase in dissolved CO2 and the concurrent decrease in ocean pH are likely to impact the phytoplankton community. The response of phytoplankton to elevated CO2 can vary significantly among species and environmental conditions (e.g. light, temperature, nutrient availability). To address these variations, an experiment was conducted using a controlled photobioreactor system, maintaining high and low light, constant temperature, nutrient levels, and two pCO2 concentrations. This study focused on two regionally relevant …

Uranium(Vi) & Thorium(Iv) Speciation In Organic Media Containing Organophosphorus & Diglycolamide Extractants, Joel Castillo

UNLV Theses, Dissertations, Professional Papers, and Capstones

Developing sustainable green energy systems is a continually growing concern as the world is faced with urgent issues of climate change and global warming. Nuclear energy provides one of the most efficient solutions to supplying power to the electrical grid without causing more carbon pollution. There are nearly a hundred thousand metric tons of used nuclear fuel (UNF) stored on-site at decommissioned nuclear power plants for an indefinite period of time. Achieving a finalized closed fuel cycle is a crucial part in developing the nuclear energy necessary for combating the issues of pollution and greener energy. Understanding actinide speciation especially …

Development Of Uranium Fluoride Microstructures, Harry Jang

UNLV Theses, Dissertations, Professional Papers, and Capstones

Uranium microstructured materials with controlled size and shape have found applications in several branches of the nuclear industry including as targets for medical isotopes production, fuels for nuclear reactors, standards for analytical measurements, and energy sources for space exploration. Morphological studies of actinide materials are also highly relevant to nuclear forensics-related work. Other potential applications include information storage, catalysis, sensors, and luminescent devices. Most studies on uranium microstructured materials have focused on binary oxides, nitrides, carbides, and fluorides, with the spherical shape being the dominant morphology. Prior to the work reported in this dissertation, aside from UF4 microspheres (ms) and …

Nuclear Fuel Cycle Chemistry: A Density Functional Study, Eduardo Montoya

UNLV Theses, Dissertations, Professional Papers, and Capstones

The nuclear fuel cycle aptly describes the life cycle of nuclear fuel sources such as uranium. From its early forms in naturally bearing ores, to its high-temperature sintering into a fuel pellet, the chemistry uranium experiences throughout the fuel cycle is diverse, driving many experimental efforts towards understanding its chemistry to both improve nuclear technologies and advance the safety and handling of nuclear materials. Computing techniques and methodologies can be used to supplement experimental research and are readily available to researchers interested in utilizing computing-based data to support experimental findings. Density functional theory (DFT) is commonly practiced, reliably predicting the …

Aars Online: A Collaborative Database On The Structure, Function, And Evolution Of The Aminoacyl-Trna Synthetases, Jordan Douglas, Haissi Cui, John J. Perona, Oscar Vargas-Rodriguez, Henna Tyynismaa, Claudia Alvarez Carreno, Jiqiang Ling, Lluis Ribas De Pouplana, Xiang-Lei Yang, Multiple Additional Authors

Chemistry Faculty Publications and Presentations

The aminoacyl-tRNA synthetases (aaRS) are a large group of enzymes that implement the genetic code in all known biological systems. They attach amino acids to their cognate tRNAs, moonlight in various translational and non-translational activities beyond aminoacylation, and are linked to many genetic disorders. The aaRS have a subtle ontology characterized by structural and functional idiosyncrasies that vary from organism to organism, and protein to protein. Across the tree of life, the 22 coded amino acids are handled by 16 evolutionary families of Class I aaRS and 21 families of Class II aaRS. We introduce AARS Online, an interactive Wikipedia-like …

Synthesis Of Chemical Fuels And Feedstocks From Co2 For Extraterrestrial Applications, Samuel Keith Conlin

Graduate Theses and Dissertations

The reduction of CO₂ into products for either the storage of renewable electricity or to act as a source of renewable feedstock for industry, is not economically feasible given the current costs of renewable energy. Significant amounts of work have gone into attempting to optimize both electrochemical and nonthermal plasma-based CO₂ reduction systems in an attempt to reduce side reactions and improve energy efficiency in order to meet cost feasibility targets. These techniques can also be adapted for In-Situ Resource Utilization (ISRU) contexts, which are far less sensitive to the cost of renewable energy yet have more strenuous …

Machine Learning Optimized Depolymerization Of Pet (Polyethylene Terephthalate) Via Glycolysis, Mehwash Aamir

Theses and Dissertations

Over 90% of the approximately 1 million PET bottles sold every minute end up in landfills or oceans, where they can persist for centuries. Plastic pollution urgently needs sustainable management and recycling solutions to mitigate the environmental impact of PET waste. From all techniques to recycle plastic waste, catalytic glycolysis stands out for its rapid reaction time, high monomer yields, lower costs, and enhanced durability.

In this work glycolysis of PET was evaluated under microwave conditions using 1,5,7-Triazabicyclo [4.4.0] dec5-ene (TBD) and 1,8-Diazabicyclo [5.4.0] undec-7-ene (DBU) as catalysts, being DBU as the best catalyst for further analysis. The effect of …

Cellulose–Starch Composite Aerogels As Thermal Superinsulating Materials, Safoura Ahmadzadeh, Angelina Sagardui, David Huitink, Jingyi Chen, Ali Ubeyitogullari

Chemistry & Biochemistry Faculty Publications and Presentations

The demand for sustainable packaging materials is rapidly increasing due to growing environmental concerns over the impact of plastic waste. In this study, biodegradable, porous, lightweight, and high-surface-area microcrystalline cellulose–starch (MCC-S) hybrid aerogels were synthesized via supercritical carbon dioxide (SC–CO₂) drying. The samples were generated using five different MCC-S weight ratios and characterized for their morphology, crystallinity, and structural and thermal properties. When MCC and S were used together, aerogels with superior properties were obtained compared to those made from each component individually. Specifically, the 1:2 MCC-S aerogel exhibited the highest porosity (97%), the lowest density (0.058 g/cm …

The Disordered Negatively Charged C-Terminus Of The Large Hect E3 Ubiquitin Ligase Herc2 Provides Structural And Thermal Stability To The Hect C-Lobe, Kelly L. Waters, Kayla J. Rich, Noah D. Schwaegerle, Tianyi Yang, Shuanghong Huo, Donald E. Spratt

Chemistry

Homologous to the C-terminus of E6AP (HECT) and RCC1-like domain (RLD)-containing protein 2 (HERC2) is a large, 528 kDa E3 ubiquitin ligase that is associated with cancer, oculocutaneous albanism type 2, Prader-Willi syndrome, and other neurological diseases. HERC2 has been found to contribute to double-stranded DNA break repairs, tumor suppression, maintaining centrosome architecture, and ubiquitylation. The C-terminal portion of the HECT domain (C-lobe) of HERC2 is responsible for transferring ubiquitin to a substrate but the precise function of the other eight domains in HERC2 are unknown. Interestingly, HERC2 contains a unique and negatively charged C-terminal …

Selective Hydroxyl Functionalization Using Novel Bifunctional Macrocyclic Catalysts And Sufex-Based Methodologies, Austin Seilkop

All Dissertations

The research behind this dissertation explores innovative strategies for the functionalization of alcohols. Alcohols are abundant in biologically relevant molecules and pharmaceutical drugs, so designing new methods for modifying them has gained significant interest over the years. The first and second chapters of this dissertation focus on the selective functionalization of a particular class of alcohols, amino alcohols, a well-represented functional handle in biomolecules. The hydroxyl functionalization of amino alcohols often demands multiple synthetic steps. We developed a new class of macrocyclic catalysts to enable precise and efficient transformations of amino alcohols, advancing the scope and efficiency of amino alcohol …

Hydrothermal Synthesis, Characterisation, And Magnetic Study Of First-Row Transition Metal Molybdates And First-Row Transition Metal Vanadates, Mahsa Foroughian Foroughian

All Dissertations

Growing high-quality single crystals of transitional metal oxides have been of interest over the last two centuries because of the many applications of these transparent materials in various industries, such as optics, magnetism, semiconductors, and batteries. During this period, a variety of crystal growth techniques have been utilized, each offering unique advantages and disadvantages to the solid-state community.

Traditionally, metal oxides such as molybdates and vanadates are produced using high-temperature techniques (700 to 1200 °C). These methods can cause oxygen to be expelled, resulting in the creation of lattice defects and lower-valence metal ions and complicate precise measurements of physical …

Recyclable Composites Prepared From Animal Coproducts And Industrial Waste Sulfur, Perla Y. Sauceda-Oloño

All Dissertations

Pursuing sustainable and environmentally friendly materials has become a significant objective in materials science, particularly flame retardants and construction materials. This dissertation explores the development and evaluation of novel composites and high sulfur-content materials (HSMs) as potential alternatives to conventional, environmentally harmful materials.

Chapter one reviews recent advancements in environmentally benign flame-retardant additives, highlighting the potential of bio-derived phenols, polysaccharide derivatives, and greener phosphorus sources. The review discusses how green additives can enhance the flame retardancy, thermal stability, and smoke suppression properties of various polymers while addressing the challenges and future directions in the field.

Chapter two investigates the production …

Lessons Learned From Establishing And Running A Mössbauer Laboratory In Industry, Paulo De Souza

Research outputs 2022 to 2026

Mössbauer spectroscopy offers unique capabilities for primary industry sectors such as mining, mineral processing, and steelmaking, as well as in environmental services and advanced manufacturing. However, there are three key limiting factors: the time required to record a single spectrum, the challenges of managing an additional radioactive source on company premises, and the lack of personnel skilled in analysing Mössbauer spectra and understanding its operation. More commonly used techniques such as XRD, SEM, or XRF have technical staff who can interpret data with support from standard libraries and user-friendly software packages. In contrast, Mössbauer spectroscopists, who often hold degrees in …

Insights From Diverse Environments: Investigating The Fate And Transport Of Semivolatile Organic Contaminants In Alpine, Arctic, And Arid Regions, Jeffrey Perala-Dewey

All Graduate Theses and Dissertations, Fall 2023 to Present

This dissertation investigates the fate and transport of pollutants through four field-based studies in a diverse array of environments. These pollutants travel through the atmosphere and end up in places far from their original sources. In this work I explore how chemical properties of the pollutants and the environmental processes that are present change the way the pollutants travel through the environment. In the first study, pollutants from car engines were quantified in the vegetation along transects in three alpine valleys. Using these measurements, I investigated how the chemical properties of the pollutants impacted their interplay with wind systems in …

Microwave-Assisted Green Synthesis Of Spiroindolinopyranopyrazoles, Esther Owusu

Theses and Dissertations

Green Chemistry, usually known as sustainable chemistry, is widely implemented worldwide to safeguard human health and the environment. Recent investigations in organic synthesis and chemical transformation have demonstrated that green chemistry techniques are significantly reducing both chemical waste and reaction time. In order to fulfill this ecological requirement, it is crucial to lessen the utilization of perilous solvents and noxious chemicals, while also creating innovative reaction methods that decrease the production of trash. The implementation of such methodologies can greatly enhance the field of green chemistry. A more environmentally friendly synthetic method was utilized to generate spiro chemicals and their …

Novel, Ultra-Fast Electrochemical Sensors For The Enhanced Detection Of Neurotransmitters And Toxic Heavy Metals In Aqueous Solutions, Noel Manring

Theses and Dissertations

Neurodegenerative diseases (NDDs) are a growing global health concern, affecting millions of people worldwide. NDDs arise from the progressive loss of neuronal cell function, ultimately leading to cell death. Abnormal levels of neurotransmitters, the chemical messengers in the brain, have also been linked to NDDs. Despite various treatments and medications aimed at alleviating physical and mental symptoms, there is currently no cure or means to halt disease progression. While the exact pathogenesis of NDDs remain poorly understood, cognitive decline is largely attributed to brain volume reduction, particularly in the hippocampus. Clinical studies suggest that environmental factors, such as exposure to …

Synthesis Of Photocleavable Molecules For Neurological Applications, Nishal Madujith Egodawaththa Arachchilage Don

Theses and Dissertations

In recent biomedical research, the precise control of molecular dynamics through light activation has emerged as a powerful tool, particularly in the field of neurobiology. This approach involves the use of photocleavable cages or photoprotective groups (PPGs) that are chemically tethered to biologically active molecules such as neurotransmitters or calcium chelators. These cages remain inert until exposed to specific wavelengths of light, typically in the visible range, triggering the release of the active compound with high spatiotemporal precision.

For neurotransmitter systems, such as glutamate (Glu), which plays a critical role in synaptic transmission and memory formation, researchers have developed novel …

The Application Of High-Resolution Mass Spectrometry For The Analysis Of Biopolymers, Metabolites, And Biologically Relevant Small Molecules, Christ Duc Tran

Graduate Doctoral Dissertations

High-resolution mass spectrometry (HRMS), as its name suggests, possesses high resolving power that enables the separation of ions with very close mass values. This is particularly beneficial for analyzing complex samples where numerous compounds may have similar masses, as it helps prevent signal overlaps and ensures an accurate spectral analysis. The current work explores the diverse applications of high-resolution mass spectrometry in oligonucleotide research, organic synthesis and medicinal chemistry. Oligonucleotide research: Chapters 2-5 present the research results from studies that employed ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC-HRMS) to understand the pharmacokinetics of RNA interference (RNAi) therapeutics. The …

Rate Coefficients For Rotational State-To-State Transitions In H2O + H2 Collisions As Predicted By Mixed Quantum–Classical Theory, Carolin Joy, Dulat Bostan, Bikramaditya Mandal, Dmitri Babikov

Chemistry Faculty Research and Publications

Aims. A new dataset of collisional rate coefficients for transitions between the rotational states of H₂O collided with H₂ background gas is developed. The goal is to expand over the other existing datasets in terms of the rotational states of water (200 states are included here) and the rotational states of hydrogen (10 states). All four symmetries of ortho- and para-water combined with ortho- and para-hydrogen are considered.

Methods. The mixed quantum–classical theory of inelastic scattering implemented in the code MQCT was employed. A detailed comparison with previous datasets was conducted to ensure that this …

Methyl Jasmonate Advances Fruit Ripening, Colour Development, And Improves Antioxidant Quality Of ‘Yoho’ And ‘Jiro’ Persimmon, Mahmood Ul Hasan, Zora Singh, Hafiz Muhammad Shoaib Shah, Andrew Woodward, Eben Afrifa-Yamoah

Research outputs 2022 to 2026

Methyl jasmonate (MJ) has potential to regulate fruit ripening and quality. ‘Yoho’ and ‘Jiro’ persimmons were sprayed with MJ (0, 2, 4, and 6 mM), four weeks before anticipated harvest to evaluate its effects on fruit colour and bioactive compounds. Preharvest MJ application significantly improved fruit colour with increased a*, b*, chroma, and colour index. The MJ 6 mM application had significantly enhanced soluble solids content (SSC), reduced total chlorophyll content in peel and pulp, and soluble and total tannins in persimmons. MJ treatments exhibited higher contents of total phenolics, flavonoids, carotenoids, and antioxidant activities. Additionally, MJ treatments enhanced the …

Enhanced Light Absorption For Solid-State Brown Carbon From Wildfires Due To Organic And Water Coatings, Zezhen Cheng, Manish Shrivastava, Amna Ijaz, Daniel Veghte, Gregory W. Vandergrift, Kuo-Pin Tseng, Nurun Nahar Lata, Will Kew, Kaitlyn Suski, Johannes Weis, Gourihar Kulkarni, Larry K. Berg, Jerome D. Fast, Libor Kovarik, Lynn Mazzoleni, Alla Zelenyuk, Swarup China

Michigan Tech Publications

Wildfires emit solid-state strongly absorptive brown carbon (solid S-BrC, commonly known as tar ball), critical to Earth's radiation budget and climate, but their highly variable light absorption properties are typically not accounted for in climate models. Here, we show that from a Pacific Northwest wildfire, over 90% of particles are solid S-BrC with a mean refractive index of 1.49 + 0.056i at 550 nm. Model sensitivity studies show refractive index variation can cause a ~200% difference in regional absorption aerosol optical depth. We show that ~50% of solid S-BrC particles from this sample uptake water above 97% relative humidity. We …

Single-Entity Collisional Electrochemistry At The Micro- And/Or Nano-Interface Between Two Immiscible Electrolyte Solutions, Li-Fang Yang, Jun-Jie Chen, Ling-Yu Chen, Si-Qi Jin, Tao-Xiong Fang, Si-Jia He, Liang-Jun Shen, Xin-Jian Huang, Xiao-Hang Sun, Hai-Qiang Deng

Journal of Electrochemistry

Single-entity collisional electrochemistry (SECE) is a branch of single-entity electrochemistry. It can directly characterize entities/particles with single particle resolution through random collisions between particles and electrodes in a solution, and obtain rich physicochemical information, thus becoming one of the frontiers of electroanalytical chemistry in the past two decades. Interestingly, the (micro/nanoscale) sensing electrodes have evolved from a polarizable liquid/ liquid (mercury/liquid) interface to a solid/liquid interface and then to a liquid/liquid interface (i.e., an interface between two immiscible electrolyte solutions, ITIES), as if they have completed a cycle (but in fact they have not). ITIES has become the latest sensing …

Precision Delivery Using Nanopipette For Single-Cell Studies, He Zhang, Maksudur Rahman, Yang Tao, Joseph W Sampson, Hang Ren

Journal of Electrochemistry

Nanopipette based scanning probe technique is a versatile tool in non-contact imaging in biology. In addition to the topographic imaging, its capability of localized delivery of bio-active molecules is emerging. In this mini review, we introduce the applications of nanopipette in single-cell researches with a focus on localized delivery. The working principles of three delivery modes including resistive pulse, pressure-driven flow, and electroosmotic flow-driven delivery are summarized and compared. Their applications in single-cell researches are reviewed. The current technical challenges in scanning ion conductance microscopy-based delivery, and their growing influence in medicine and pharmacologic researches are also discussed.

Preface To Special Issue On Single-Entity Electroanalysis, Fei Li, Yi-Lun Ying, Yi-Ge Zhou

Journal of Electrochemistry

No abstract provided.

Author Spotlight, Li-Fang Yang, Joseph W. Sampson, Xiao-Hang Sun, Hai-Qiang Deng, He Zhang, Md Maksudur Rahman, Yang Tao, Hang Ren

Journal of Electrochemistry

No abstract provided.

Aqueous Supercapacitors With Wide Operative Voltage Window And Long Cycling Life Enabled By Electrolyte Hybridization Effect, Shi-Hua Ma, Qi Yin, Jin-Ping Zhao

Journal of Electrochemistry

Developing supercapacitors (SCs) with long cycling life and wide operative voltage window is a significant topic in the field of aqueous electrolytes. Although the design of water in salt (WIS) electrolytes has pushed the development of aqueous electrolytes to a new height, the WIS electrolytes with an operative voltage window of up to 2.5 V is still very scarce. Herein, in order to enrich the type of aqueous electrolyte with high operative voltage, tetramethylammonium trifluoromethanesulfonate (TMAOTf) based WIS electrolyte was used as a model to construct WIS based hybrid electrolyte with acetonitrile (ACN) co-solvent and LiTFSI co-solute. In view of …

Journal Of Electrochemistry, The Flagship Journal Of Chinese Chemical Society Electrochemical Committee, Made A Public Appearance At The 22nd National Electrochemical Congress, Editorial Office Of J.Electrochem.

Journal of Electrochemistry

No abstract provided.

The Award Ceremony Of The 2nd Xiamen University Short Video Abstract Contest For Science And Technology Journal Papers Came To A Successful Conclusion, Editorial Office Of J.Electrochem.

Journal of Electrochemistry

No abstract provided.

The 9th National Conference Of Solid State Battery Successfully Held In Xiamen, Fujian, Zheng-Liang Gong

Journal of Electrochemistry

No abstract provided.

Cyclization Of Diols Using Ferrocenium Cations & Other Iron-Based Catalysts, Cody D. Amann, Fnu Khushboo, Sai Anvesh Bezawada, Eike B. Bauer

Undergraduate Research Symposium

Our research involves the study and improvement of iron-based catalysts. The Bauer group has recently found that the ferrocenium cation, along with other iron-based compounds, are catalytically active in the cyclization of various diols to obtain five-membered tetrahydrofuran derivatives. My research involved comparing the effect of 2 different counter-anions of the ferrocenium cation along with 2 other iron-based catalysts that were previously synthesized in the Bauer lab for their catalytic activity in the title reaction. Cyclization test reactions were performed by reacting three different types of diols with each of four different iron catalysts. The three diols used were 4-methyl-1-phenyl-1,4-pentanediol …