Other Chemistry Commons^™

Characterization Of Three-Dimensional Fractional Viscoelastic Models Through Complex Modulus Analysis And Polar Decomposition, Avradip Ghosh, Avinash Kumar Both, Chin Li Cheung

Department of Chemistry: Faculty Publications

Soft materials such as gels, elastomers, and biological tissues have diverse applications in nature and technology due to their viscoelastic nature. These soft materials often exhibit complex rheology and display elastic and viscous characteristics when undergoing deformation. In recent years, fractional calculus has emerged as a promising tool to explain the viscoelastic behavior of soft materials. Scalar constants are primarily used to quantify viscoelastic elements such as springs and dashpots. However, in three-dimensional (3D) space, not all materials show the same elastic or viscoelastic properties in all directions, especially under elastic/viscoelastic wave propagation (or anisotropy). Though previously reported studies on …

Integrating Conformational Dynamics And Perturbation-Based Network Modeling For Mutational Profiling Of Binding And Allostery In The Sars-Cov-2 Spike Variant Complexes With Antibodies: Balancing Local And Global Determinants Of Mutational Escape Mechanisms, Gennady M. Verkhivker, Steve Agajanian, Ryan Kassab, Keerthi Krishnan

Mathematics, Physics, and Computer Science Faculty Articles and Research

n this study, we combined all-atom MD simulations, the ensemble-based mutational scanning of protein stability and binding, and perturbation-based network profiling of allosteric interactions in the SARS-CoV-2 spike complexes with a panel of cross-reactive and ultra-potent single antibodies (B1-182.1 and A23-58.1) as well as antibody combinations (A19-61.1/B1-182.1 and A19-46.1/B1-182.1). Using this approach, we quantify the local and global effects of mutations in the complexes, identify protein stability centers, characterize binding energy hotspots, and predict the allosteric control points of long-range interactions and communications. Conformational dynamics and distance fluctuation analysis revealed the antibody-specific signatures of protein stability and flexibility of the …

Multiplexed Monitoring Of Neurochemicals Via Electrografting- Enabled Site-Selective Functionalization Of Aptamers On Field-Effect Transistors, Zan Gao, Guangfu Wu, Yang Song, Huijie Li, Yuxuan Zhang, Michael J. Schneider, Yingqi Qiang, Jackson Kaszas, Zhengyan Weng, He Sun, Bryan D. Huey, Rebecca Lai, Yi Zhang

Department of Chemistry: Faculty Publications

Neurochemical corelease has received much attention in understanding brain activity and cognition. Despite many attempts, the multiplexed monitoring of coreleased neurochemicals with spatiotemporal precision and minimal crosstalk using existing methods remains challenging. Here, we report a soft neural probe for multiplexed neurochemical monitoring via the electrografting-assisted site-selective functionalization of aptamers on graphene field-effect transistors (G-FETs). The neural probes possess excellent flexibility, ultralight mass (28 mg), and a nearly cellular-scale dimension of 50 μm × 50 μm for each G-FET. As a demonstration, we show that G-FETs with electrochemically grafted molecular linkers (−COOH or −NH2) and specific aptamers can be used …

A Protein-Based Therapeutic Combination For The Treatment Of Hard-To-Heal Wounds, Graham L. Strauss

USF Tampa Graduate Theses and Dissertations

Chronic wounds present many clinical challenges in relation to the successful treatment and closure of the damaged tissue. Most current treatment methods focused on one or two aspects to drive wound closure, while most chronic wounds are multifactorial environments with many of those dependencies relying on the termination of one another to effectively gain tissue construction, closure, and full skin thickness and composition. Natural wound healing processes allude to potential biologics that can impede the chronic breakdown of tissue, while restoring deposition of new tissue, and effectively leading to a healed wound. Proteases secreted by the body’s immune system lay …

Asymmetrical Spectral Continuum Between Anti-Stokes And Stokes Scattering Revealed In Low-Frequency Surface-Enhanced Raman Spectroscopy, Shuo Sun, Dhanusha T.N. Rathnayake, Yinsheng Guo

Department of Chemistry: Faculty Publications

An asymmetrical spectral continuum is observed in low-frequency surface-enhanced Raman spectroscopy (LF-SERS) in the terahertz (THz) region. This background continuum appears as a flat baseline in the Stokes side and a slope in the anti-Stokes side. Analysis shows this asymmetry originates from the different scaling of anti-Stokes and Stokes scattering with respect to the Bose−Einstein distribution. Such asymmetry is readily visible, under room temperature, in the low-frequency THz spectral range. Accounting for this spectral intensity asymmetry reveals the intrinsic continuum background of electronic origin, differing from local normal modes and collective relaxational motions. We also describe a numerical method, independent …

Improved Performance Of Silica-Supported La0.5Ba0.5Feo3 In The Reverse Water Gas Shift - Chemical Looping Process For Carbon Dioxide Reduction – A Density Functional Theory Study, Jiawei Guo

USF Tampa Graduate Theses and Dissertations

Global warming is increasingly obvious, and the reduction of greenhouse gases is an effective way to heal. Increasing the efficiency of catalysts that is applied in the industry can significantly reduce the emission of greenhouse gases. Reverse water gas shift chemical looping (RWGS-CL) is a promising reaction to convert CO2 to CO. La0.5Ba0.5FeO3 (LBF) is a good candidate for RWGS-CL, which shows increased conversion yield when supported on silica. This research focuses on identifying the mechanism of RWGS-CL via silica-supported LBF by exploring the oxygen vacancy formation energy (EO-vac). Density Functional Theory (DFT) is a powerful computational method to solve …

Calcium Bistriflimide-Mediated Sulfur(Vi)–Fluoride Exchange (Sufex): Mechanistic Insights Toward Instigating Catalysis, Brian Han, Samuel R. Khasnavis, Matthew Nwerem, Michael Bertagna, Nicholas D. Ball, O. Maduka Ogba

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

We report a mechanistic investigation of calcium bistriflimide-mediated sulfur(VI)–fluoride exchange (SuFEx) between sulfonyl fluorides and amines. We determine the likely pre-activation resting state─a calcium bistriflimide complex with ligated amines─thus allowing for corroborated calculation of the SuFEx activation barrier at ∼21 kcal/mol, compared to 21.5 ± 0.14 kcal/mol derived via kinetics experiments. Transition state analysis revealed: (1) a two-point calcium-substrate contact that activates the sulfur(VI) center and stabilizes the leaving fluoride and (2) a 1,4-diazabicyclo[2.2.2]octane additive that provides Brønsted-base activation of the nucleophilic amine. Stable Ca–F complexes upon sulfonamide formation are likely contributors to inhibited catalytic turnover, and a proof-of-principle redesign …

Noncanonical Amino Acid Mutagenesis In Response To Recoding Signal-Enhanced Quadruplet Codons, Yan Chen, Xinyuan He, University Of Nebraska-Lincoln, Kun Liu, Tian Gao, Wei Niu, Jiantao Guo

Department of Chemistry: Faculty Publications

While amber suppression is the most common approach to introduce noncanonical amino acids into proteins in live cells, quadruplet codon decoding has potential to enable a greatly expanded genetic code with up to 256 new codons for protein biosynthesis. Since triplet codons are the predominant form of genetic code in nature, quadruplet codon decoding often displays limited efficiency. In this work, we exploited a new approach to significantly improve quadruplet UAGN and AGGN (N = A, U, G, C) codon decoding efficiency by using recoding signals imbedded in mRNA. With representative recoding signals, the expression level of mutant proteins containing …

Advanced Cnc/Peg/Pdmaa Semi-Ipn Hydrogel For Drug Delivery Management In Wound Healing, Samia Afrin, Md. Shahruzzaman, Papia Haque, Md. Sazedul Islam, Shafiul Hossain, Taslim Ur Rashid, Tanvir Ahmed, Makoto Takafuji, Mohammed Mizanur Rahman

Department of Chemistry: Faculty Publications

A Semi Interpenetrating Polymer Network (semi-IPN) hydrogel was prepared and loaded with an antibiotic drug, gentamicin, to investigate the wound healing activity of this system. The semi-IPN hydrogel was synthesized by combining natural polymer cellulose nanocrystal (CNC) and synthetic polymer polyethylene glycol (PEG) and poly (N,N0-dimethyl acrylamide) (PDMAA), which was initially added as a monomer dimethyl acrylamide (DMAA). CNC was prepared from locally obtained jute fibers, dispersed in a PEG-NaOH solvent systemand then mixed with monomer DMAA, where polymerization was initiated by an initiator potassium persulphate (KPS) and cross-linked by N,N0-methylenebisacrylamide (NMBA). The size, morphology, biocompatibility, antimicrobial activity, thermal and …

Understanding The Effects Of Temperature On Electrostatic Dna Denaturation, Jeffrey Taylor

Master's Theses

In this work, the electrostatic denaturation of 18-bp DNA duplexes was investigated via Square Wave Voltammetry (SWV) to determine the extent of melting (∆) and rate of melting (𝝉). Electrostatic denaturation was observed over the temperature range of 20-50 °C, and purely electrostatic melting was defined from 27.5°C. In contrast, electrostatic denaturation for 30 °C was defined as a mixture of thermal melting thiol desorption + electrostatic melting. Electrostatic denaturation is a temperature-dependent process, and the amount of melting of the dsDNA increased with temperature. It was also observed that the ∆ and 𝝉 values increase with temperature further …

Biomaterials: From Scaffold Design To Implant Optimization, Jennifer Marie Armen

Electronic Theses and Dissertations

This work encompasses three individual projects concerning biomaterials and their modifications. Chemically-Induced Cross-Linking of Peptidic Fibrils for Scaffolding Polymeric Particles and Macrophages EAK16-II (EAK) is a self-assembling peptide (SAP) that forms β-sheets and βfibrils through ionic-complementary interactions at physiological ionic strengths. The soft materials can be injected in vivo, creating depots of drugs and cells for rendering pharmacological and biological actions. The scope of the applications of EAK is sought to extend to tissues through which the flow of extracellular fluid tends to be limited. In such anatomical locales the rate and extent of the fibrilization are limited insofar as …

Long-Term Trends And Variability Of Pm₂.₅ Mass, Chemical Components, And Sources Over Nys, Hesham Abdelmonem Hassan

Legacy Theses & Dissertations (2009 - 2024)

Eighteen years of ambient PM2.5 mass and major components are used in this study to harmonize the carbonaceous fraction of PM2.5 data, and to examine long-term trends and seasonal variability changes. The major decreasing trend of PM2.5 mass and major inorganic ions reflects the ambient concentration response to clean air regulations and policies.Although elemental carbon shows a decreasing trend in agreement with most other PM2.5 components, organic carbon shows a different behavior of no-trend to slightly increasing trend in some sites. Organic carbon behavior indicates the growing role of non-combustion sources at the expense of decreasing combustion sources. Seasonal trends …

Synthesis Of Inorganic-Organic Perovskite Hybrid Materials Via A Microwave Assisted Method, Anamika Poduval

LSU New Orleans Theses and Dissertations

The research presented here focusses on fabrication of organic modified inorganic two-dimensional and three-dimensional materials via microwave assisted methods. These hybrid materials are of importance due to their capacity to incorporate the characteristics of both organic and inorganic components. Microwave methods have been utilized to expedite the topochemical modification of layered perovskites. In one set of studies, microwave assisted grafting reactions were performed on layered perovskite (HLaNb₂O₇) materials with a series of hydroxy carboxylic acids. The reactivities of these organic compounds with the layered perovskites and the influence of precursor, temperature and time are demonstrated. The …

Diffusion Of A Salt In An Aqueous Media, Aldaly Pineda Hernandez

Chemical Engineering Undergraduate Honors Theses

Diffusion is defined as the net transfer of a molecule from a high concentration region to a low concentration region. The concept of diffusion is used in a very important process called "desalination." Desalination is a separation process used to reduce the salt content dissolved in brackish water to make it suitable for human consumption, irrigation, and industrial use.

In desalination plants, it is important to monitor the constantly changing salt content of water, partly due to the diffusive effect. The main purpose of this experiment was to study the diffusion of NaCl in water at two NaCl concentrations. The …

Valorization Of Biopolymers And Biomass To Produce Materials For A More Circular Economy, Moira Lauer

All Dissertations

With a globally increasing population and largely unchecked consumption of raw materials, human society is on track for devastating consequences. Two industries responsible for utilizing massive amounts of raw materials and generating equally gargantuan quantities of waste are the packaging and infrastructure sectors. In 2017 in Europe, for example, packaging reached a record 173 kg of packaging waste per capita. One of the largest packaging consumers is the food industry, in which 40% of packaging is made of petroleum-derived single-use plastic, leading to a massive carbon imbalance. “The Built Environment,” on the other hand, is responsible for about 50% of …

How Student Attitudes Have Changed Toward Chemistry Due To The Implementation Of Hybrid Labs, Erica Bronwyn Mobley

ONU Student Research Colloquium

Hybrid chemistry labs in schools and universities have become much more common due to the COVID-19 pandemic. Previous research on student perceptions of chemistry has shown a correlation between their attitudes and performance in this subject that educators are still seeking to understand. This mixed methods study compared perceptions of students in traditional, in-person labs (pre-COVID, 2017) with students in a mixture of virtual and in-person labs (during COVID, 2020) over the course of a semester. The Attitude toward the Study of Chemistry Inventory (ASCI) survey was given to both cohorts of students and focused on five areas related to …

Designing Experiments: The Impact Of Peer Review Structure On Organic Chemistry Students' Experimental Designs, Katie Patterson

Department of Chemistry: Dissertations, Theses, and Student Research

To better understand how peer review can be used to support students when designing experiments, the current thesis examined how the structure of the peer review template affects the kinds of feedback students give and the revisions that they make. I utilized a quasi-experimental design to investigate the effects that the peer review template had on the outcome of an experimental design task. A sample of 195 students enrolled in an Organic Chemistry I course participated in the study. The students were divided into two groups, one of which was given a scaffolded peer review template and the other was …

Ketal-Azaborine Versus Ketal-Azaborine With A Spacer: Structural Effects On The Photophysical Properties Of Tunable Heteroaromatic Polycyclic Chromophores, Albert Campbell, Janiyah Riley, Samuel Moore, Albert Campbell

Symposium of Student Scholars

Flat-structured heteroaromatic polycyclic compounds with extended conjugated π-systems such as azaborines are in high demand in the material and imaging technology markets because of their unique features such as simultaneous tunability of fluorescence color and intensity. We have designed, synthesized, and investigated a series of novel conjugated thermally stable ketal-azaborine chromophores that contain a phenyl ring as a spacer between electronic moieties and the ketal-azaborine core as easily tunable high-luminescent organic materials. We investigated the impact of the phenyl spacer on the ketal-azaborine unit. We examined the structural effects on their photophysical properties by incorporating electron –donating and –withdrawing substituents …

Azaborine Versus Azaborine With A Spacer: Structural Effects On The Photophysical Properties Of Tunable Azaborine Chromophores, Kaia Ellis, Janiyah Riley, Lyric Gordon, Janiyah Riley

Symposium of Student Scholars

Azaborines are fascinating compounds because of their valuable and interesting optical properties making them suitable to be utilized in many optoelectronic devices. We have designed, synthesized, and investigated a series of novel conjugated thermally stable azaborine chromophores by incorporating a phenyl ring as a spacer linking the chromophore to different electronic moieties as easily tunable high-luminescent organic materials. We investigated the effect of the phenyl spacer on the azaborine unit. The substituent effects of different electronic moieties were investigated by the insertion of electron –withdrawing and –donating moieties to the phenyl spacer. We examined the role of the electron –donating …

Comparing And Contrasting Therapeutic Drugs Vs. Lifestyle Changes That Combattype-Ii Diabetes, Alexander Cline Helmuth

Chemistry & Biochemistry Student Projects

In this thesis, I will be presenting various preventive approaches to combat type-II diabetes. The focus of this paper will be comparing and contrasting therapeutic drug targets such as Metformin and Sulfonylureas that are prescribed for type-II diabetic patients versus taking preventative steps such as making lifestyle changes including weight management, physical activity, and having a balanced diet that prevents onset of type-II diabetes or helps patients manage type-II diabetes. From this paper, one will gain insight on how there are multiple approaches to combat type-II diabetes that are not in the form of the pill.