Chemistry Commons^™

Probing Proximal Intramolecular Hydrogen Bonding Interactions On A Norbornane Scaffold, Carly A. Rock, Dakota B. Green, Martin J. Flores, Jeremy M. Carr, Thufail M. Ismail, Gregory S. Tschumper

Chemistry Faculty Research & Creative Works

A systematic computational study was conducted on 12 unique 2,6-disubstituted norbornane derivatives to assess the ability of various acceptor groups (A = F, Cl, Br, OH, OCH3, SH, SCH3, NHCH3, N(CH3)2, PH2, PHCH3, and P(CH3)2) to engage in intramolecular hydrogen bonding with a proximal OH donor. 32 unique minima have been characterized with M06-2X and df-MP2 geometry optimizations as well as PNO-LCCSD(T)-F12 single point energy computations. Conformations with the OH donor oriented toward the acceptor to form an OH···A contact (+HB) consistently had lower electronic energies (by approximately 2 to 8 kcal mol^–1) than their counterparts with the …

Computational Characterization Of A Recently Identified Disinfection Byproduct In Drinking Water: The Chloronitramide Anion And Its Monohydrate Complex, Thufail M. Ismail, Max R. Tucker, Gregory S. Tschumper

Chemistry Faculty Research & Creative Works

The chloronitramide anion (ClNNO₂⁻) was recently identified as disinfection byproduct in drinking water, and various quantum chemistry methods (CCSD(T), MP2, B3LYP, ωB97XD, and M06-2X) are employed in this study to characterize this negatively charged species and its monohydrate complex. Both vertical and adiabatic quantities indicate the excess electron is bound by 3–4 eV. Four ClNNO₂⁻ monohydrate minima were identified, each exhibiting double ionic hydrogen bonding. The computed ClNNO₂⁻⋯H₂O interaction approaches 15 kcal/mol, and it induces pronounced vibrational frequency shifts in both fragments. Natural bond orbital analysis shows a redistribution of …

Electric Dipole Forbidden, Quadrupole Allowed Transitions In The Pure Rotational Spectrum Of Cyclopropylchloromethyldifluorosilane, Alexander R. Davies, Abanob G. Hanna, Alma Lutas, Gamil A. Guirgis, S. A. Cooke, Garry S. Grubbs

Chemistry Faculty Research & Creative Works

In a recent publication, some electric dipole forbidden, quadrupole allowed ΔJ = +2 and x-type transitions were observed in the chirped-pulse Fourier transform microwave spectrum of two conformations of cyclopropylchloromethyldifluorosilane. Many of these transitions arise from a handful of mixed states and mechanisms are proposed through which these transitions become weakly allowed. Observations of electric dipole forbidden, quadrupole allowed transitions in rotational spectra are unusual for molecules which contain a chlorine nucleus owing to the small quadrupole moment of ³⁵Cl and ³⁷Cl; thus, we believe we are the first to observe x-type transitions arising from perturbations caused by …

Leveraging Molecular Mechanisms Of Desorption To Enhance Pfas Bioavailability In Contaminated Soils, Husam Kafeenah, Margaret D. Taiwo, Patrica Ivy Agorsor, Michael O. Eze

Chemistry Faculty Research & Creative Works

Per- and polyfluoroalkyl substances (PFAS) are known for their strong binding properties to soil matrices owing to their amphiphilic properties. While most studies focus on the search for novel PFAS bio degraders, our knowledge of sustainable biomolecules that could drive PFAS desorption and make them more bioavailable is limited. This study investigated the effectiveness of rhamnolipids and organic acids in desorbing PFAS compounds from contaminated soil. Rhamnolipids (25 mg/L) significantly enhanced the release of PFAS compounds from soil, achieving up to 90 % desorption. Acetic acid provided 60–90 % desorption efficiency for most of the PFAS studied, except for PFDA …

Hybrid Data-Driven Cement-Stabilized Soil Design: An Integration Of Machine Learning, Multi-Objective Optimization, And Life Cycle Assessment, Chikezie Chimere Onyekwena, Yunli Li, Ikenna J. Okeke, Ubani Obinna Uzodimma, Monday Uchenna Okoronkwo, Wenping Wu

Chemical and Biochemical Engineering Faculty Research & Creative Works

Soil stabilization is crucial in geotechnical engineering, yet conventional methods are often time-consuming, resource-intensive, and environmentally unsustainable. Despite growing interest in Machine Learning (ML) and optimization tools for mix design, few studies integrate these methods with decision-making techniques and environmental assessment to support practical implementation. This study proposes a hybrid data-driven framework for predicting strength, optimizing mix compositions, and evaluating environmental impacts via life cycle assessment of cement-stabilized soft soils. Six ML models were evaluated, and the top-performing eXtreme Gradient Boosting (XGB) model was further improved using the Grey Wolf Optimizer (GWO). The optimized XGB-GWO model, integrated with a polynomial …

Performance And Mechanistic Insights Into Cement Systems Modified With Wastewater-Recovered Struvite, Ugochukwu Ewuzie, Rupack R. Halder, Abdulkareem O. Yusuf, Abiodun A. Saka, Godwin I. Ogbuehi, Titus C. Egbosiuba, Damilola A. Daramola, Monday Uchenna Okoronkwo

Chemical and Biochemical Engineering Faculty Research & Creative Works

Struvite, the stable hydration product and primary strength phase in magnesium ammonium phosphate cement (MAPC), derived from wastewater treatment, has recently been utilized as a sustainable additive to Portland cement (PC). However, its impacts on cement hydration kinetics, pore refinement, rheology, and the mechanisms underlying these processes have not been comprehensively studied. This study developed Portland cement-struvite (PCS) systems by replacing PC with 3–20 % struvite (ST wt.%: PCS3–PCS20) and evaluated these processes using isothermal calorimetry, 3D micro-computed tomography (μXCT), time-dependent rheometry, X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR), and the Krstulović-Dabić (K-D) model. The FTIR/XRD confirmed the coexistence …

Heterogeneous Catalysis Of Large Biomolecules: Insights From Platinum Particle Size In Nad+Regeneration, Jianwei Li, Samuel Robertshaw, Shouying Huang, Shelley D. Minteer, Xiaodong Wang

Chemistry Faculty Research & Creative Works

Nicotinamide adenine dinucleotide (NAD⁺) cofactor regeneration is essential for enabling dehydrogenase-promoted biosynthesis for value-added chemicals. Heterogeneous catalytic cofactor regeneration, using supported metal catalysts, is an emerging approach and has shown great promise. However, mechanistic insight remains largely unexplored. In this work, a series of silica-supported platinum (Pt) catalysts have been prepared for NAD⁺ cofactor regeneration, to understand the roles of Pt particle size and structure. A turnover frequency (TOF) 'volcano plot' was obtained for Pt clusters in the range of 2.2–7.1 nm, with the maximum TOF (136 h⁻¹) observed at 5.6 nm. Selective Pt site …

Ultrasonic Extraction-Based Analysis Of Persistent Organic Pollutants In Blubber From False Killer Whales, Michael O. Eze, Eva Borras, Mitchell M. Mccartney, Don R. Bergfelt, Kristi L. West, Sarah E. Hooper, Cristina E. Davis

Chemistry Faculty Research & Creative Works

In view of the toxic effects of persistent organic pollutants (POPs), fast and effective assessment of their concentrations in marine mammals is important for understanding individual and population-level health impacts. This study developed an ultrasonic-based method that is less time-consuming, uses minimal solvent, and thus is more sustainable than the gold standard Soxhlet method for accurate analysis of organochlorine pesticides (OCs), polychlorinated biphenyls (PCBs), and benzene hexachlorides (BHC) in false killer whale blubber. This method was developed by comparing concentrations of POPs obtained using the traditional Soxhlet and novel ultrasonic extraction methods using blubber from false killer whales (n = …

Synergistic V2ctₓ Mxene–Pani Hybrid With Expanded Interlayers For Ultrastable And High-Rate Pseudocapacitive Energy Storage, Amideddin Nouralishahi, Maryam Sharifi Paroushi, Mansour Razavi, Amarachi Clare Nnachor, Harish Singh, Manashi Nath

Chemistry Faculty Research & Creative Works

Recently, MXene-conducting polymer hybrids have emerged as promising electrode materials for sustainable energy storage applications, owing to their impressive electrochemical properties. Herein, we report the synthesis of vanadium carbide MXene nanoparticles (V2CT_x-MXene) using innovative Spark Plasma Sintering (SPS) technology followed by exfoliation steps. The V2CT_x nanoparticles were incorporated with PANI (MXene-PANI) by electrochemical polymerization of aniline monomers in the presence of V2CT_x nanolayers, to be used as a highly efficient material for charge storage application. PANI nanofibers form a conductive and porous architecture, which intercalates the V2CT_x nanoflakes. The resulting structure increases the interlayer spacing …

Enhanced Superconductivity And Vortex Dynamics In Quasi-1d Tas2 Nanowires, Mathew Pollard, Visakha Ho, Clarissa Wisner, Eric W. Bohannan, Yew San Hor

Chemistry Faculty Research & Creative Works

We report the synthesis of high-quality 2H-TaS₂ nanowires via a controlled two-step conversion process from TaS₃ precursors, achieving robust superconductivity with a transition temperature T c ≈ 3.6K, which is significantly higher than bulk 2H-TaS₂ (T c ≈ 0.8K). Structural and compositional analyses confirm phase purity and preserved one-dimensional morphology, while magneto transport measurements reveal an enhanced upper critical field μ 0 H c2 (2K)≈5 T, far exceeding the bulk value (_μ0H_c2 (0)≈1.17T), attributed to dimensional confinement and suppression of charge-density wave order. Magnetic characterization demonstrates complex vortex dynamics, including flux jumps and a …

Effect Of Ionic Strength On Gelation Time And Strength Of Amps-Based Polymer Gels, Maryam Sharifi Paroushi, Xuyang Tian, Baojun Bai, Thomas P. Schuman, Yin Zhang, Mingzhen Wei

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Polymer gel treatment has been widely applied for improving sweep efficiency and controlling excessive water and gas production. Their performance depends on gelation time and final gel strength. In most studies, brine salinity is used to describe the effect of formation water on gel behavior. However, changing salinity also changes ionic strength and ion composition at the same time. Because of this coupling, it is difficult to identify the mechanisms controlling gelation, which has led to inconsistent trends in the literature. Increasing salinity has been reported to either slow or accelerate gelation and to weaken or strengthen gels depending on …

Scalable Transfer Of Dna Origami–Directed Nanoparticle Arrays Onto Functional Surfaces Using Thermal Release Tape, Yuwei Zhang, Chikadibia Genevieve Edward, Ethan Keuhn, Shelley D. Minteer, Risheng Wang

Chemistry Faculty Research & Creative Works

Precise integration of DNA origami nanostructures onto functional substrates is essential for advancing electronics, photonics, and biosensing. However, most surface-assembly methods are highly sensitive to substrate type, limiting their broader applications. Here, we introduce a thermal release tape (TRT)-assisted transfer method that enables efficient, large-area printing of DNA origami-guided gold nanoparticle (AuNP-DNA origami) arrays from mica onto diverse surfaces. The method relies on differential adhesion: AuNP-DNA origami arrays form strong electrostatic and hydrogen-bonding interactions with 3-aminopropyltriethoxysilane (APTES)-functionalized receiver substrates, while the TRT adhesive weakens upon heating to 120°C, allowing release from the tape. Using this approach, well-ordered AuNP-DNA origami arrays …

Evaluation Of A Novel Re-Crosslinkable Preformed Particle Gel For Conformance Control In Ultra-High Temperature Reservoirs, Yanbo Liu, Tao Song, Caleb Kwasi Darko, Thomas P. Schuman, Mingzhen Wei, Baojun Bai

Chemistry Faculty Research & Creative Works

Preferential fluid flow remains a major challenge in subsurface energy production and gas storage operations, resulting in excessive water production in mature oil fields, reduced heat extraction in geothermal reservoirs, and low sweep and storage efficiency in CO₂-EOR projects. Polymer gels are widely used to mitigate high-permeability channels; however, conventional systems exhibit limited plugging efficiency and short lifetimes in ultra-high-temperature reservoirs due to poor thermal stability. This study presents a novel ultra-high-temperature-resistant preformed particle gel (UHT-PPG) developed for conformance control in reservoirs with temperatures of 150–275 °C and severe super-K or channeling problems. The material was evaluated in …

Progression Toward Terminal Oxidation Of Starch Via Hybrid Organic–Enzymatic Bioanode For Renewable Carbohydrate Conversion, Adam Milam, Jose Intano, Shelley D. Minteer

Chemistry Faculty Research & Creative Works

The performance of starch-based biofuel cells is fundamentally limited by inefficient utilization of the fuel's inherent energy density. Sequential oxidation of carbohydrate fuels, such as glucose, the monomeric unit of starch, using minimal catalyst systems has therefore emerged as a promising strategy to improve biofuel cell efficiency. Here, we extend a previously reported three-catalyst, organic–enzymatic glucose oxidation cascade to polymeric carbohydrate fuels by integrating enzymatic starch depolymerization with downstream electrochemical oxidation. To our knowledge, this represents the first demonstration of a defined hybrid organic–enzymatic cascade designed to drive progression of starch-derived glucose equivalents toward terminal oxidation using a minimal catalyst …

Concerted Proton Transfer In Homogeneous And Heterogeneous Cyclic Hydrogen-Bonded Clusters Of H2o, Hf, And Hcl, Max R. Tucker, Yuan Xue, Nathan R. Speake, Eden Nickolson, Jeremy M. Carr, Gregory S. Tschumper

Chemistry Faculty Research & Creative Works

This work examines various homogeneous and heterogeneous clusters of hydrogen-bonded (HF)x(H₂O)y(HCl)z complexes, where x + y + z = 3 or 4. For each unique cyclic structure associated with the xyz permutations, the geometries of the reactant, product, and transition state (TS) for concerted proton transfer (CPT) were fully optimized using second-order Møller-Plesset perturbation theory (MP2) with a mixed basis set consisting of cc-pVTZ for H atoms and aug-cc-pVTZ for O, Cl, and F atoms (denoted haTZ). Harmonic vibrational frequencies were also computed at the same level of theory to verify the nature of the stationary points. Intrinsic …

Synthesis Of The Naga(S1−Xsex)2 Solid Solution From Mechanically Activated Precursors, Louisiane Verger, Julien Trébosc, Santhoshkumar Sundaramoorthy, Amitava Choudhury, Olivier Hernandez, Eric Furet, Sébastien Chenu, David Le Coq, Laurent Calvez, Olivier Lafon

Chemistry Faculty Research & Creative Works

NaGaS₂ and NaGaSe₂ are two recently discovered compounds that crystallize in the same structure type. In this work, NaGa(S_1−xSe_x)₂ (x = 0.5, 0.75 and 1) are prepared using an alternative synthesis route, mechanochemistry followed by heat treatment. Na₂S, Na₂Se, Ga₂S₃ and Ga₂Se₃ are milled in stoichiometric proportions. Differential scanning calorimetry, X-ray diffraction and solid-state nuclear magnetic resonance (²³Na and ⁷¹Ga) show that the compounds after milling are composed of crystalline NaGa(S_1−xSe_x)₂ with an amorphous part. …

Volatile Organic Compound Analysis Of Humboldt Penguin (Spheniscus Humboldti) Preen Oil: A Pilot Study, Dante E. Rojas, Mitchell M. Mccartney, Eva Borras, Michael O. Eze, Abigail Pietrow, Jennifer J. Valvo, Cristina E. Davis

Chemistry Faculty Research & Creative Works

Avian olfaction has gained prominence in recent decades for its roles in social communication and behavior. In penguins, the chemical characterization of preen oil remains limited. In this exploratory study, we characterized the volatile organic compound (VOC) profile of preen oil from Humboldt Penguins (Spheniscus humboldti). Preen oil from 12 captive individuals was analyzed using headspace sorptive extraction (HSSE) coupled to gas chromatography–mass spectrometry (GC–MS). Chemometric analyses examined variation in VOC profiles by sex, age class, and breeding activity. We detected 54 compounds (20 tentatively identified), including linear alcohols, methyl ketones, carboxylic acids, saturated hydrocarbons, oxygenated and nitrogen-containing organics, prenolipids, …

Soft-Chemical Scalable One-Pot Aqueous-Medium Synthesis Of Na3(Vo)2(Po4)2f-Based Cathodes: Compositional Tuning And Electrochemical Performance In Na- And Li-Ion Batteries, Prashanth Sandineni, Subal Chandra Manna, Sutapa Bhattacharya, Santhoshkumar Sundaramoorthy, Ramesh Deokate, Milad Aghayi-Anaraki, George E. Sterbinsky, Kartik Ghosh, Amitava Choudhury

Chemistry Faculty Research & Creative Works

One of the most important cathode materials for Na-ion batteries, Na₃(VO)₂(PO₄)₂F, and its compositional variants have been synthesized using four different and facile one-step soft chemical routes. The as-synthesized compounds, Na_2.95(VO)₂(PO₄)₂F (I), Na_2.93(VO)₂(PO₄)₂F (II), and Na_2.58(VO)₂(PO₄)₂F (IV), crystallize in the tetragonal crystal system in the P4₂/mnm space group, while Na₃(VO)₂(PO₄)₂F (III) crystallizes in the orthorhombic crystal system in …

Closing The Nitrogen Loop In Groundwater With Biohybrid Technologies, Linjie Zhou, Biao Li, Jianhua Guo, Shelley D. Minteer, Yifeng Zhang

Chemistry Faculty Research & Creative Works

Nitrate in groundwater should be treated as a nitrogen source rather than a contaminant. Biohybrid technologies coupling microbial selectivity with renewable electro(photo)chemical energy offer opportunities to convert nitrate to value-added ammonium, although challenges remain in scalability, microbial stability, material–microbe integration, process engineering, regulatory compliance, and economic feasibility.

Evaluation Of Chromium-Crosslinked Amps-Hpam Copolymer Gels: Effects Of Key Parameters On Gelation Time And Strength, Maryam Sharifi Paroushi, Baojun Bai, Thomas P. Schuman, Yin Zhang, Mingzhen Wei

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Controlling CO₂ channeling in heterogeneous reservoirs remains a major challenge for both enhanced oil recovery (EOR) and secure geological storage. AMPS-HPAM copolymers exhibit high-temperature resistance and brine tolerance compared with conventional HPAM gels, making them well suited for the harsh environments associated with CO₂ injection. Chromium-based crosslinkers (CrAc and CrCl₃) were investigated because sulfonic acid groups in AMPS can coordinate with trivalent chromium ions, enabling dual ionic crosslinking and the formation of a robust gel network. While organic crosslinked AMPS-HPAM gels have been widely studied, the behavior of chromium-crosslinked AMPS-containing systems, particularly their gelation kinetics under …

Theoretical Study Of Long-Range Molecular Interactions, Adrian Luis Batista-Planas

Doctoral Dissertations

Describing intermolecular forces is fundamental to modeling and predicting the behavior of molecular systems. In particular, long-range molecular interactions—with electrostatic, induction, and dispersion as main components—play a critical role, especially for low-temperature and low-density regimes. Long-range interactions are often described through perturbation theory, representing the electronic charge distribution via multipolar series of the moments and polarizability tensors corresponding to each molecule. However, while the theory is well-established, obtaining the resulting analytical expressions (and their practical implementation) constitutes a highly complex and system-dependent task. To address this challenge, we developed Long-Range-Fit (LRF), an interactive and user-friendly software package designed to automate …

Exploring New Poly-Anion Based Materials For Lithium – Ion Battery Cathodes, Sutapa Bhattacharya

Doctoral Dissertations

The escalating global demand for sustainable energy storage solutions has driven intensive research into novel electrode materials. Polyanion-based cathode materials have emerged as promising candidates due to their structural stability, safety, and voltage tunability enabled by the inductive effect of polyanionic groups. This research explores the synthesis, crystal structure, and electrochemical performance of new polyanion-based cathode materials featuring vanadium, molybdenum, and iron within phosphate and selenite frameworks.

Novel selenite-based materials, such as LiFe(SeO₃)₂ and Li₀.₂₅V₂O₃(SeO₃)₂, were synthesized and characterized, revealing stable electrochemical cycling associated with Fe2+/Fe3+ and V⁴⁺/V⁵⁺ transitions. Additionally, a systematic investigation was conducted on molybdenum phosphate compounds, including …

Accessing Cation And Anion Redox In Mixed-Valent One-Dimensional Iron-Chalcogenides, Na1.5fe1s2–Xsex(X = 0, 1, And 2), For Na-Ion Batteries, Santhoshkumar Sundaramoorthy, Milad Aghayi-Anaraki, Sutapa Bhattacharya, Amitava Choudhury

Chemistry Faculty Research & Creative Works

Sodium-ion batteries (NIBs) have attracted considerable attention as a cost-effective and sustainable alternative to lithium-ion batteries (LIBs), owing to the abundance and low cost of sodium resources. Here, we investigate previously reported mixed-valent (Fe^3+/2+) one-dimensional (1D) iron chalcogenides: Na1.5FeS2, its selenide analogue Na1.5FeSe2, and newly developed solid solution Na1.5FeSSe, focusing on their synthesis, structural characterization, and electrochemical performance in NIBs. While the full Fe²⁺sulfide version (NaFeS2) of the compound is explored in solid-state cells for its dual cation–anion redox mechanism, we reveal the effect of anion substitution on the electrochemical behavior of Na1.5FeS2–xSex(x = 0, 1, …

Engineered Multifunctional Drug-Loaded Dendrimer Nanoparticles For Glaucoma: Triple Mechanism Via Antioxidant Activity, Iron Chelation, And Enhanced Ocular Transport, Burhan Ates, Ashish Trital, Vimalin Jeyalatha Mani, Lei Xu, Jonathan Kenlee, Nuran Ercal, Hu Yang

Chemistry Faculty Research & Creative Works

In this study, we developed multifunctional nanoparticles based on polyamidoamine (PAMAM) dendrimers functionalized with caffeic acid (CA) and poly (ethylene glycol) maleimide (PEGM) for the topical delivery of hydrophobic antiglaucoma drugs brimonidine (BM) and betaxolol (BX). The PAMAM-CA and PAMAM-CA-PEGM conjugates exhibited antioxidant and iron-chelating activities in a dose-dependent manner. BM- and BX-loaded dendrimer nanoparticles produced using a multi-inlet vortex mixer showed uniform spherical morphology (∼80 nm by TEM) and hydrated sizes of ∼135-144 nm by DLS. Both nano formulations demonstrated high cytocompatibility with human corneal epithelial cells and were nonirritant in the HET-CAM assay, with PEGM further improving cytocompatibility. …

Catalytic Synthesis Of Iron-Doped Graphitic Aerogels From Poly(Phloroglucinol-Terephthalaldehyde – Urethane) Precursors, Stephen Yaw Owusu, Rushi U. Soni, Chariklia Sotiriou-Leventis

Chemistry Faculty Research & Creative Works

We report a new class of graphitic carbon aerogel precursors based on iron oxide-doped poly(phloroglucinol-terephthalaldehyde–urethane) (T-POL/PU-FeOx) networks. The hybrid polymeric network incorporates a rigid aromatic triisocyanate, tris(4-isocyanatophenyl)methane, which reacts in situ with the hydroxyl groups of phloroglucinol to form a polyurethane-containing framework. Monolithic aerogels derived from this system undergo catalytic graphitization at significantly reduced temperatures (800–1500 °C) compared to conventional graphitization (2500–3300 °C). An oxidative ring fusion aromatization step (240 °C, air) prior to pyrolysis enhanced the degree of graphitization. The resulting graphitic aerogels were characterized by XRD, Raman spectroscopy, TGA, TEM, SEM, XPS, and N₂ sorption porosimetry. Compared to …

Synergistic Doping And Coating Strategy For Boosting Na0.7mno2 Cathode Performance In Sodium-Ion Batteries, Ahmad Helaley, Han Yu, Manashi Nath, Xinhua Liang

Chemistry Faculty Research & Creative Works

Advancing sodium-ion battery (SIB) technology requires novel approaches to optimize cathode materials for improved electrochemical performance. In this study, we employ atomic layer deposition (ALD) to precisely modify the surface of P2-type Na_0.7MnO₂ cathodes with different coating materials including ZnO, NiO, and Al₂O₃, followed by post-annealing at 750°C for 10 hours. The strategic combination of ALD and thermal treatment can achieve thin film coating on particle surface and promote element doping into the near-surface lattice, as confirmed by electron energy loss spectroscopy (EELS) analysis. The incorporation of Zn, Al, and Ni results in …

Unraveling Hydration- And Temperature-Induced Structural Transformations Of Linear Poly(Ethylenimine) Using Raman Microscopy And Numerical Unmixing, Miharu Koh, Jay P. Kitt, Andrew D. Pendergast, Joel M. Harris, Shelley D. Minteer, Carol Korzeniewski

Chemistry Faculty Research & Creative Works

Linear poly(ethylenimine) (LPEI) is a hydration-sensitive polymer of interest for its breadth of application in areas that include medicine, energy, and materials science. To facilitate advances, this work demonstrates in situ Raman microscopy and self-modeling curve resolution (SMCR) analysis as an approach for investigating changes in LPEI structure during melting and crystallization under controlled heating and cooling conditions. With focus on neutral (freebase) LPEI, SMCR analysis of Raman data sets showed that the melting transition of anhydrous LPEI was well described by a pair of spectral vectors representing anhydrous crystalline and amorphous states. However, the transition from the melted to …

Elucidating The Effects Of Water Activity On The Hydration Kinetics And Thermodynamics Of Ye’Elimite–Calcium Sulfate Hydrate Systems, Godwin I. Ogbuehi, Rupack R. Halder, Aditya Kumar, Gaurav Sant, Monday U. Okoronkwo

Materials Science and Engineering Faculty Research & Creative Works

Relative humidity and water activity (aH) reductions have been known to suppress the hydration of anhydrous cement clinker phases. However, the relationship between ye'elimite (C4A3$) hydration kinetics and water activity remain unclear. This study employs experimental and thermodynamic modeling approaches to investigate the influence of water activity on ye'elimite hydration in the "C4A3$ + water", and "C4A3$ + gypsum + water" systems. Experimental findings indicate that as water activity decreases, C4A3$ hydration diminishes until the reaction is brought to a halt at a threshold aH. The critical aHand corresponding solubility constant of C4A3$ (KC4A3S¯) estimated from thermodynamic analysis are 0.46 …

Bioaccumulation Pattern Of Per- And Polyfluoroalkyl Substances (Pfas) In Fish Tissues From Two Freshwater Systems, Margaret D. Taiwo, Husam Kafeenah, David D. Duvernell, Michael O. Eze

Biological Sciences Faculty Research & Creative Works

Per- and polyfluoroalkyl substances (PFAS) are known for their persistence, ubiquity, bioaccumulation in different matrices of the environment and their detrimental effect on human health. In this study, we used EPA 1633 to examine the prevalence of ten PFAS compounds in two freshwater systems and investigated their bioaccumulation pattern across different tissues of grass carp fish (Ctenopharyngodon idella), common carp (Cyprinus carpio), and flathead catfish (Pylodictis olivaris). Among the PFAS compounds analyzed, PFBS exhibited the highest concentration in the freshwater sample, exceeding the U.S. EPA regulatory limit of 4 ng/L for drinking water. The total PFAS concentrations in the muscle, …

Defect-Driven Degradation Of Mxenes In Aqueous Environments And Mitigation Strategies: Insights From First-Principles, Ana Maria Stratulat, Valentina Nesterova, Vladislav Korostelev, Majid Beidaghi, Vadym Mochalin, Konstantin Klyukin

Chemistry Faculty Research & Creative Works

MXenes have attracted considerable attention due to their tunable surface chemistry, high electrical conductivity, and ease of solution processing, making them promising candidates for a wide array of applications. The inherent tendency of MXenes to degrade under environmental conditions constrains their compositional diversity and limits certain practical applications. Our computational study shows that degradation of defect-free Ti₃C₂Txis kinetically limited, whereas common defects markedly lower the activation barriers for water attack. Using ab initio molecular dynamics simulations (AIMD) combined with thermodynamic analysis, we show that titanium vacancies VTiact as active sites for the protonation of subsurface carbon …