Analytical Chemistry Commons^™

Synchrotron Study Of Phase Transition And Heterostructures In Metal Oxide Semiconductors, Bingyu Dong

Electronic Thesis and Dissertation Repository

Transition metal oxides, including titanium dioxide (TiO₂), zinc oxide (ZnO) and Tin dioxide (SnO₂) are widely recognized semiconducting photocatalysts. This project engages in a detailed examination of the phase transition of TiO₂ and the synthesis of heterostructured metal oxides using an eco-friendly method of ball-milling. A variety of spectroscopy and microscopy techniques have been used to analyze the products. Synchrotron-based techniques: X-ray Absorption near-edge spectroscopy (XANES), X-ray Emission Spectroscopy and X-ray excited optical luminescence (XEOL) can demonstrate the local structure and bonding. The finding highlights a phase transition in TiO₂ and the formation of …

Effects Of Traps On Photo-Induced Interfacial Charge Transfer Of Ag-Tio2: Photoelectrochemical, Electrochemical And Spectroscopic Characterizations, Zhi-Hao Liang, Jia-Zheng Wang, Dan Wang, Jian-Zhang Zhou, De-Yin Wu

Journal of Electrochemistry

In the field of metal-semiconductor composites based plasmon-mediated chemical reactions, a clear and in-depth understanding of charge transfer and recombination mechanisms is crucial for improving plasmonic photocatalytic efficiency. However, the plasmonic photocatalytic reactions at the solid-liquid interface of the electrochemical systems involve complex processes with multiple elementary steps, multiple time scales, and multiple controlling factors. Herein, the combination of photoelectrochemical and electrochemical as well as spectroscopic characterizations has been successfully used to study the effects of traps on the photo-induced interfacial charge transfer of silver-titanium dioxide (Ag-TiO₂). The results show that the increase of surface hydroxyl groups may …

Introducing High School Biology Students To Biochemistry With A Short, Content-Oriented Module, Archer Harrold, Allison Cruikshank, Bryan Penas, Rebecca Roston

Chemistry Department: Faculty Publications

Many STEM disciplines are underrepresented to High School students. This is problematic as many students' decisions for college are shaped by their experiences and achievements in high school. Short content-oriented modules have been shown to encourage science identity and otherwise benefit the students' learning. Following the ASBMB's outreach protocol, we developed a short content-oriented module aimed at a high school biology classroom. Students interacted with 3D models of DNA and transcription factors while exploring structure–function relationships and introductory biochemistry topics. The high school teacher was impressed with the students' response to the module, specifically the ease with which students learned, …

The Effect Of Hydrogen Peroxide On The Corrosion Dynamics Of Carbon Steel, Kwang Soak Gabriel O'Donnell

Electronic Thesis and Dissertation Repository

The Used Fuel Container (UFC) is a key barrier in Canada’s nuclear fuel disposal plan. Understanding the radiation-induced corrosion of the carbon steel (CS) vessel is critical for predicting the long-term integrity of the UFC. Developing a mechanistic understanding of CS corrosion and the effect of solution parameters is essential.

This work investigates the effects of H₂O₂, the key radiolytic oxidant, on CS corrosion dynamics in small, stagnant solutions. Elementary processes are identified, corrosion rates are calculated, and the effects of H₂O₂ concentration are investigated. Corrosion was studied by quantifying the concentrations of …

Changes In An Enzyme Ensemble During Catalysis Observed By High Resolution Xfel Crystallography, Nathan J. Smith, Medhanjali Dasgupta, David C. Wych, Cole Dolamore, Raymond G. Sierra, Stella Lisova, Darya Marchany-Rivera, Aina E. Cohen, Sébastien Boutet, Mark S. Hunter, Christopher Kupitz, Frédéric Poitevin, Frank R. Moss Iii, Aaron S. Brewster, Nicholas K. Sauter, Iris D. Young, Alexander M. Wolff, Virendra K. Tiwari, Nivesh Kumar, David B. Berkowitz, Ryan G. Hadt, Michael C. Thompson, Alec H. Follmer, Mark A. Wilson

Chemistry Department: Faculty Publications

Enzymes populate ensembles of structures with intrinsically different catalytic proficiencies that are difficult to experimentally characterize. We use time-resolved mix-and-inject serial crystallography (MISC) at an X-ray free electron laser (XFEL) to observe catalysis in a designed mutant (G150T) isocyanide hydratase (ICH) enzyme that enhances sampling of important minor conformations. The active site exists in a mixture of conformations and formation of the thioimidate catalytic intermediate selects for catalytically competent substates. A prior proposal for active site cysteine charge-coupled conformational changes in ICH is validated by determining structures of the enzyme over a range of pH values. A combination of large …

On The Boundary Of The Cosmos, Daniel Linford

Chemistry Department: Faculty Publications

Intuitively, the totality of physical reality – the Cosmos – has a beginning only if (i) all parts of the Cosmos agree on the direction of time (the Direction Condition) and (ii) there is a boundary to the past of all non-initial spacetime points such that there are no spacetime points to the past of the boundary (the Boundary Condition). Following a distinction previously introduced by J. Brian Pitts, the Boundary Condition can be conceived of in two distinct ways: either topologically, i.e., in terms of a closed boundary, or metrically, i.e., in terms of the Cosmos having a finite …

Investigating Novel Luminescent Materials Towards Applications In Light Emitting Electrochemical Cells, Kenneth Chu

Electronic Thesis and Dissertation Repository

The search for new and better luminescent materials is becoming increasingly important, as there are significant cost-savings in using luminophores that are brighter and more efficient. Carbon quantum dots (CQDs) and other luminescent materials such as Pt-Ag nanoclusters and TADF compounds are an extremely appealing alternative to existing light-emitting materials, as they are low-cost, easy to synthesize, and non-toxic.

This thesis explores the properties and performance of different luminescent materials to be used in light-emitting electrochemical cells (LECs). In this work, we focused on LECs as their low cost and ease of fabrication aligns well with the ethos of CQDs …

Chirality, Symmetry-Breaking, And Chemical Substitution In Multiferroics, Kiman Park

Doctoral Dissertations

Multiferroic materials attract significant attention due to their potential utility in a broad range of device applications. The inclusion of heavy metal centers in these materials enhances their magnetoelectric properties, yielding fascinating physical phenomena such as the Dzyaloshinskii–Moriya interaction, nonreciprocal directional dichroism, enhancement of spin-phonon coupling, and spin-orbit-entangled ground states. This dissertation provides a comprehensive survey of magnetoelectric multiferroics containing heavy metal centers and explores spectroscopic techniques under extreme conditions. A microscopic examination of phase transitions, symmetry-breaking, and structure-property relationships enhances the fundamental understanding of coupling mechanisms.

In A2Mo3O8 (A = Fe, Zn, Ni, and Mn), we use optical spectroscopy …

Inkjet-Printed Electrochemical Sensors For Lead Detection, Annatoma Arif

Open Access Theses & Dissertations

This PhD dissertation research has developed a simple, miniaturized, sensitive, selective, reproducible, and disposable 3D (inkjet printed – additive manufacturing technology) gold (Au) plated electrochemical sensor (ECS) on shape memory polymer (SMP) for aqueous lead detection. This technology has shown promising performance in the application of electrochemical sensing (lead (II) detection) due to increased effective electrode surface area (7.25 mm^2 ± 0.15 mm^2) despite miniaturizing lateral surface area (4.19 mm^2). The design, fabrication processes, optimization including bismuth functionalization, evaluation, uncertainty analysis, and cost analysis of the novel SMP based inkjet printed Au plated sensor have been delineated in this manuscript …

Removal Of Nonylphenols From Water And Wastewater Using Alginate-Activated Carbon Beads, Angelica Araly Chacon

Open Access Theses & Dissertations

The presence of contaminants of emerging concern (CECs) have been affecting water quality in recent years. The United States Environmental Protection Agency (U.S EPA) defines CECs as toxic chemicals without regulatory status and with adversely impact on the wildlife and people. Among the CECs, nonylphenols (NPs) are frequently found in all water systems and are categorized as endocrine-disrupting compounds (EDCs) due to their ability to mimic hormones causing reproductive and developmental effects in humans and animals. The main sources of discharge and distribution of NPs into the environment are wastewater treatment plants (WWTPs) which are not designed to remove them. …

Differential Membrane Binding Of Α/Β-Peptide Foldamers: Implications For Cellular Delivery And Mitochondrial Targeting, Tzong-Hsien Lee, James W. Checco, Tess Malcolm, Chelcie H. Eller, Ronald T. Raines, Samuel H. Gellman, Erinna F. Lee, W. Douglas Fairlie, Marie-Isabel Aguilar

Chemistry Department: Faculty Publications

The intrinsic pathway of apoptosis is regulated by the Bcl-2 family of proteins. Inhibition of the anti-apoptotic members represents a strategy to induce apoptotic cell death in cancer cells. We have measured the membrane binding properties of a series of peptides, including modified α/β-peptides, designed to exhibit enhanced membrane permeability to allow cell entry and improved access for engagement of Bcl-2 family members. The peptide cargo is based on the pro-apoptotic protein Bim, which interacts with all anti-apoptotic proteins to initiate apoptosis. The α/β-peptides contained cyclic β-amino acid residues designed to increase their stability and membrane-permeability. Dual polarisation interferometry was …

From Waste To Energy: The Electrochemical Reduction Of Co2 Using Recycled Nanostructured Catalysts, Ibrahim Badawy

Theses and Dissertations

The reduction of carbon dioxide (CO₂RR) using electrochemistry is a promising solution for the burgeoning global energy crisis. The overall vision of its implementation relies on renewable energy sources to power the reaction creating carbon neutral products and effectively closing the carbon cycle. Research in this field has come a long way since its inception in the mid-1900s. However, there remain significant hurdles and important considerations to overcome in order to reach full commercialization. Most electrocatalysts tested for CO₂RR have been designed solely for maximum performance while ignoring the environmental consequences if such a material were …

Temperature-Pressure Phase Diagram Of Confined Monolayer Water/Ice At First-Principles Accuracy With A Machine-Learning Force Field, Bo Lin, Jian Jiang, Xiao Cheng Zeng, Lei Li

Chemistry Department: Faculty Publications

Understanding the phase behaviour of nanoconfined water films is of fundamental importance in broad fields of science and engineering. However, the phase behaviour of the thinnest water film – monolayer water – is still incompletely known. Here, we developed a machine-learning force field (MLFF) at first-principles accuracy to determine the phase diagram of monolayer water/ice in nanoconfinement with hydrophobic walls. We observed the spontaneous formation of two previously unreported high-density ices, namely, zigzag quasi-bilayer ice (ZZ-qBI) and branched-zigzag quasi-bilayer ice (bZZ-qBI). Unlike conventional bilayer ices, few inter-layer hydrogen bonds were observed in both quasi-bilayer ices. Notably, the bZZ-qBI entails a …

Metal-Organic Frameworks For Electrochemical And Electrochemiluminescent Immunoassay, Xiao-Li Qin, Zi-Ying Zhan, Sara Jahanghiri, Kenneth Chu, Cong-Yang Zhang, Zhi-Feng Ding

Journal of Electrochemistry

Development of ultrasensitive, highly accurate and selective immunosensors is significant for the early diagnosis, screening, and monitoring of diseases. Electrochemical and electrochemiluminescent (ECL) immunoassays have both attracted great attention and become a current research hotspot due to their advantages such as good stability, high sensitivity and selectivity, wide linear range, and good controllability. Metal-organic frameworks (MOFs), as a new class of porous crystalline materials, have been widely applied in electrochemical and ECL immunosensors owing to their large specific surface area, good chemical stability, as well as adjustable pore size and nanoscale framework structures. Various MOF nanomaterials with different properties for …

Colorful “Stars” In The Dark, Chao Jing, Yi-Tao Long

Journal of Electrochemistry

Plasmonic nanoparticles such as Au and Ag with localized surface plasmon resonance (LSPR) property exhibit unique scattering and absorption features. The plasmonic scattering and absorption bands are mainly located at visible light region which can be easily applied in visual detections. By modulating the size, shape, and composition of gold and silver colloid solutions, plenty of colorimetric methods have been constructed for the detection of metal ions, biomolecules, and environmental contaminants, etc. For many years, the LSPR-based measurements are implemented in reagent tubes. Since 2000, the plasmon resonance scattering (PRS) light of metal nanoparticles captured by dark-field microscopy enables the …

Boronate Affinity-Assisted Electrochemically Controlled Atrp For Ultrasensitive Electrochemical Aptasensing Of Carcinoembryonic Antigen, Qiong Hu, Shi-Qi Li, Yi-Yi Liang, Wen-Xing Feng, Yi-Lin Luo, Xiao-Jing Cao, Li Niu

Journal of Electrochemistry

As an acidic glycoprotein, carcinoembryonic antigen (CEA) is of great value as a broad-spectrum tumor marker in the differential diagnosis and surveillance of malignant tumors. In this work, we report an electrochemical aptasensor for the ultrasensitive and highly selective detection of CEA, taking advantage of the dual amplification by the boronate affinity-assisted electrochemically controlled atom transfer radical polymerization (BA-eATRP). Specifically, the BA-eATRP-based electrochemical aptasensing of CEA involves the capture of target antigens by nucleic acid aptamers, the covalent crosslinking of ATRP initiators to CEA antigens via the selective interactions between the phenylboronic acid (PBA) group and the cis-diol group of …

Preface To The Special Issue On Interfactial Regulation And Electrochemical Sensors, Jing-Hong Li, Yang Tian, Yuan-Hong Xu, Li-Min Zhang

Journal of Electrochemistry

No abstract provided.

Recent Advances In Electrochemical Impedance Spectroscopy-Based Pathogenic Bacteria Sensing, Tao Chen, Yuan-Hong Xu, Jing-Hong Li

Journal of Electrochemistry

Pathogenic bacteria have been throwing great threat on human health for thousands of years. Their real-time monitoring is in urgent need as it could effectively halt the spread of pathogenic bacteria and thus reducing the risk to human health. Up till now, diverse technologies such as electrochemistry, optics, piezoelectricity and calorimetry have been developed for bacteria sensing. Therein, electrochemical impedance spectroscopy (EIS)-based sensors show great potential in point-of-care bacterial analysis because of their low-cost, short read-out time, good reproducibility, and portable equipment construction. In this review, we will primarily summarize the typical applications of electrochemical impedance technology in bacteria sensing …

N–((2–Acetylphenyl)Carbamothioyl)Benzamide: Synthesis, Crystal Structure Analysis, And Theoretical Studies, Akin Oztaslar, Hakan Arslan

Karbala International Journal of Modern Science

N–((2–Acetylphenyl)carbamothioyl)benzamide has been synthesized and characterized. The molecular conformation of the investigated compound is stabilized by C16–H16B⋅⋅⋅O2ⁱ (i: 1+x, y, z) intermolecular and C14–H14⋅⋅⋅S1, N2–H2⋅⋅⋅O2, and N2–H2⋅⋅⋅O1 intramolecular H–bonds. All DFT calculations have been implemented at the B3LYP level with the 6–311G(d,p) basis set. The optimized molecular structure parameters have been compared with the experimental one in the solid phase. The energy gap, global chemical reactivity descriptor parameters, MEP, Fukui functions, DoS, NLO, and NBO analysis were also computed and investigated. The intermolecular interactions and their energies are evaluated using Hirshfeld surface and energy framework analyses. To determine …

Tio2 Crystallization At Room Temperature And Preparation Of Transparent Carbon Counter Electrode For Low-Cost Dye-Sensitized Solar Cells, Muhammad Iqbal Syauqi, Afiten Rahmin Sanjaya, Mohammad Jihad Madiabu, Munawar Khalil, Jarnuzi Gunlazuardi

Makara Journal of Science

We developed a low-cost dye-sensitized solar cell (DSSC) using TiO₂ fabricated via rapid breakdown anodization (RBA) and ultrafast room-temperature crystallization (URTC). The prepared TiO₂ was deposited on a self-made fluorine-doped tin oxide (FTO) conductive glass, and the FTO/TiO₂ system was sensitized using curcumin dye. The DSSC was constructed by sandwiching the FTO/TiO₂/curcumin electrode with an I⁻/I₂ electrolyte and a transparent carbon counter electrode prepared using a liquid–liquid interface system. The characterization results showed that the TiO₂ freshly prepared via URTC was transformed into an anatase crystalline phase, which exhibited a 3.10 …