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Full-Text Articles in Chemistry

Soft Microreactors For The Deposition Of Microstructures And The Related Surface Chemistries Of Polymeric Materials, Jessica Wagner Dec 2023

Soft Microreactors For The Deposition Of Microstructures And The Related Surface Chemistries Of Polymeric Materials, Jessica Wagner

Dissertations and Doctoral Documents from University of Nebraska-Lincoln, 2023–

The precise control over small volumes of liquids is of great interest to various fields such as biotechnology, drug development, and diagnostics. Working at small scales reduces cost, time, and waste, which is why microfluidic lab – on – chip technologies have become popular in a wide range of industries and applications. Additionally, there are differences in properties such as mass transport and heat dissipation at the micron scale compared to in bulk. Microfluidic devices contain several interfaces to consider when preparing to fabricate devices. The substrate/device, substrate/solution, and solution/device interfaces are all of importance and must carefully be tuned …


Enhancing Urban Water Quality Through Biological-Chemical Treatment: Aquatic Macroinvertebrate Community And Temporal Chlorophyll-A Response, Matthew Chaffee Dec 2023

Enhancing Urban Water Quality Through Biological-Chemical Treatment: Aquatic Macroinvertebrate Community And Temporal Chlorophyll-A Response, Matthew Chaffee

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

With a growing human population, urbanization is impeding a plethora of natural waterways. Of these, urban ponds play a vital role in nutrient sequestration, flood prevention, and habitat sanctuaries. However, nutrient loading can reduce habitat effectiveness and promote harmful algae blooms. To reduce internal nutrient loads, a biological-chemical treatment strategy consisting of floating treatment wetlands (FTWs) and lanthanum were applied to two urban retention ponds, Densmore and Wilderness Ridge Ponds. To measure effectiveness, chlorophyll-a samples were collected and correlated with Sentinel-2. A novel band algorithm termed 3BR1 produced a strong correlation (R2 = 0.72) to physical chlorophyll-a …


Characterization Of Interlayer Laser Shock Peening During Fused Filament Fabrication Of Polylactic Acid (Pla), Fabien Denise Dec 2023

Characterization Of Interlayer Laser Shock Peening During Fused Filament Fabrication Of Polylactic Acid (Pla), Fabien Denise

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

The field of additive manufacturing (AM) has gained a significant amount of popularity due to the increasing need for more sustainable manufacturing techniques and the adaptive development of complex product geometries. The problem is that AM parts routinely exhibit flaws or weaknesses that affect functionality or performance. Over the years, surface treatments have been developed to compensate certain flaws or weaknesses in manufactured products. Combining surface treatments with the modularity of additive manufacturing could lead to more adaptable and creative improvements of product functions in the future. The current work evaluates the feasibility of pursuing a new research axis in …


Hydroxyapatite-Based Coatings On Silicon Wafers And Printed Zirconia, Antoine Chauvin Nov 2023

Hydroxyapatite-Based Coatings On Silicon Wafers And Printed Zirconia, Antoine Chauvin

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Dental surgery needs a naturally attract implant design that can ensure both osseointegration and soft tissue integration. Hydroxyapatite (HAp), the main mineral constituent of dentine and tooth enamel, is commonly used as a coating component, notably for overlaying titanium– or ceramics–based implants. This thesis aims to investigate the behavior of a HAp-based coating, specifically designed to be compatible with a porous substrate. Coating layers are made by sol–gel dip coating by immersion of porous substrates made by additive manufacturing into solutions of HAp, having been mixed with polyethyleneimine (PEI), to improve the adhesion of HAp on the substrate. First, the …


Postsynthetic Modification Of The Nonanuclear Node In A Zirconium Metal−Organic Framework For Photocatalytic Oxidation Of Hydrocarbons, Rebecca Shu Hui Khoo, Christian Fiankor, Sizhuo Yang, Wenhui Hu, Chongqing Yang, Jingzhi Lu, Martha D. Morton, Xu Zhang, Yi Liu, Jier Huang, Jian Zhang Oct 2023

Postsynthetic Modification Of The Nonanuclear Node In A Zirconium Metal−Organic Framework For Photocatalytic Oxidation Of Hydrocarbons, Rebecca Shu Hui Khoo, Christian Fiankor, Sizhuo Yang, Wenhui Hu, Chongqing Yang, Jingzhi Lu, Martha D. Morton, Xu Zhang, Yi Liu, Jier Huang, Jian Zhang

Chemistry Department: Faculty Publications

Heterogeneous catalysis plays an indispensable role in chemical production and energy conversion. Incorporation of transition metals into metal oxides and zeolites is a common strategy to fine-tune the activity and selectivity of the resulting solid catalysts, as either the active center or promotor. Studying the underlying mechanism is however challenging. Decorating the metal-oxo clusters with transition metals in metal−organic frameworks (MOFs) via postsynthetic modification offers a rational approach to construct well-defined structural models for better understanding of the reaction mechanism. Therefore, it is important to expand the materials scope beyond the currently widely studied zirconium MOFs consisting of Zr6 …


Machine Learning‑Assisted Low‑Dimensional Electrocatalysts Design For Hydrogen Evolution Reaction, Jin Li, Naiteng Wu, Jian Zhang, Hong‑Hui Wu, Kunming Pan, Yingxue Wang, Guilong Liu, Xianming Liu, Zhenpeng Yao, Qiaobao Zhang Oct 2023

Machine Learning‑Assisted Low‑Dimensional Electrocatalysts Design For Hydrogen Evolution Reaction, Jin Li, Naiteng Wu, Jian Zhang, Hong‑Hui Wu, Kunming Pan, Yingxue Wang, Guilong Liu, Xianming Liu, Zhenpeng Yao, Qiaobao Zhang

Chemistry Department: Faculty Publications

Efficient electrocatalysts are crucial for hydrogen generation from electrolyzing water. Nevertheless, the conventional "trial and error" method for producing advanced electrocatalysts is not only cost-ineffective but also time-consuming and labor-intensive. Fortunately, the advancement of machine learning brings new opportunities for electrocatalysts discovery and design. By analyzing experimental and theoretical data, machine learning can effectively predict their hydrogen evolution reaction (HER) performance. This review summarizes recent developments in machine learning for low-dimensional electrocatalysts, including zero-dimension nanoparticles and nanoclusters, one-dimensional nanotubes and nanowires, two-dimensional nanosheets, as well as other electrocatalysts. In particular, the effects of descriptors and algorithms on screening low-dimensional electrocatalysts …


Strengthening Brain Research In Africa, Abdullahi Tunde Aborode, Nike Jesutofunmi Idowu, Samuel Tundealao, Joseph Jaiyeola, Ogunware Adedayo Emmanuel Sep 2023

Strengthening Brain Research In Africa, Abdullahi Tunde Aborode, Nike Jesutofunmi Idowu, Samuel Tundealao, Joseph Jaiyeola, Ogunware Adedayo Emmanuel

Chemistry Department: Faculty Publications

This paper explores the emerging field of neuroscience in Africa, considering the unique genetic diversity, sociocultural determinants, and health inequalities in the continent. It presents numerous brain research initiatives, such as ABDRN, AMARI, APCDR, and H3Africa, aimed at understanding genetic and environmental factors influencing brain disorders in Africa. Despite numerous challenges like the brain drain phenomenon, inadequate infrastructure, and scarce research expertise, significant progress has been achieved. The paper proposes solutions, including international collaboration, capacity-building efforts, and policies to promote neuroscience research, to enhance the understanding of brain function and address brain-related health issues within the African context.


Introducing High School Biology Students To Biochemistry With A Short, Content-Oriented Module, Archer Harrold, Allison Cruikshank, Bryan Penas, Rebecca Roston Aug 2023

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, …


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 Aug 2023

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 Aug 2023

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 …


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 Aug 2023

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 …


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 Jul 2023

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 …


Stepwise Assembly Of Quinary Multivariate Metal−Organic Frameworks Via Diversified Linker Exchange And Installation, Yuchen Hu, Xin Zhang, Rebecca Shu Hui Khoo, Christian Fiankor, Xu Zhang, Jian Zhang Jun 2023

Stepwise Assembly Of Quinary Multivariate Metal−Organic Frameworks Via Diversified Linker Exchange And Installation, Yuchen Hu, Xin Zhang, Rebecca Shu Hui Khoo, Christian Fiankor, Xu Zhang, Jian Zhang

Chemistry Department: Faculty Publications

Multivariate MOFs (MTV-MOFs) constructed from multiple components with atomistic precision hold the promise for many fascinating developments in both fundamental sciences and applications. Sequential linker installation can be an effective method to introduce different functional linkers into an MOF that contains coordinatively unsaturated metal sites. However, in many cases, these linkers must be installed according to a specific sequence and the complete synthetic flexibility and freedom is yet to be realized. Here, we rationally decreased the size of the primary ligand used in NPF-300, a Zr-MOF with scu topology (NPF = Nebraska Porous Framework), and synthesized its isostructure, NPF-320. NPF-320 …


Long-Term Degradation Mechanisms In Application-Implemented Radical Thin Films, Ewa Malgorzata Nowik-Boltyk, Tobias Junghoefer, Mathias Glaser, Erika Giangrisostomi, Ruslan Ovsyannikov, Shuyang Zhang, Chan Shu, Andrzej Rajca, Arrigo Calzolari, M. Benedetta Casu Jun 2023

Long-Term Degradation Mechanisms In Application-Implemented Radical Thin Films, Ewa Malgorzata Nowik-Boltyk, Tobias Junghoefer, Mathias Glaser, Erika Giangrisostomi, Ruslan Ovsyannikov, Shuyang Zhang, Chan Shu, Andrzej Rajca, Arrigo Calzolari, M. Benedetta Casu

Chemistry Department: Faculty Publications

Blatter radical derivatives are very attractive due to their potential applications, ranging from batteries to quantum technologies. In this work, we focus on the latest insights regarding the fundamental mechanisms of radical thin film (long-term) degradation, by comparing two Blatter radical derivatives. We find that the interaction with different contaminants (such as atomic H, Ar, N, and O and molecular H2, N2, O2, H2O, and NH2) affects the chemical and magnetic properties of the thin films upon air exposure. Also, the radical-specific site, where the contaminant interaction takes place, plays …


Synthesis And Study Of High-Spin Stable Organic Radicals For Electrical Conductors And Mannosamine Nitroxide For Mri Contrast Agents, Shuyang Zhang Jun 2023

Synthesis And Study Of High-Spin Stable Organic Radicals For Electrical Conductors And Mannosamine Nitroxide For Mri Contrast Agents, Shuyang Zhang

Department of Chemistry: Dissertations, Theses, and Student Research

In the first project, we describe the synthesis of an ambient stable high spin organic diradical 4 based on the Blatter moiety. The high-spin (S = 1) organic diradical 4, which consists of two Blatter radical moieties in a conjugated structure, exhibits a nearly exclusive population (88%) on triplet ground state at room temperature as a consequence of a large single-triplet energy gap (ΔEST = 0.5 kcal/mol). The target diradical molecule is synthesized over five steps with structural confirmation by single-crystal X-ray diffraction. The thermogravimetric analysis (TGA) shows the onset of decomposition at ~264 oC, indicating the diradical molecule has …


Halide Exchange And Transport In Halide Perovskite Lattices, Temban Acha Billy May 2023

Halide Exchange And Transport In Halide Perovskite Lattices, Temban Acha Billy

Department of Chemistry: Dissertations, Theses, and Student Research

In recent years, metal-halide perovskites (MHPs) have risen quickly to prominence as promising materials across a variety of fields, from photovoltaics to optoelectronics in general. We show here a facile solution growth for creating a variety of mixed halide MAPbBr3-xIx crystals, which we will use to study halide exchange and transport in halide perovskites. We generated a calibration curve between the optical response and chemical composition in mixed Br/I MHPs at room temperature. All mixed Br/I MHP crystals were subjected to measurements of photoluminescence (PL) and Raman spectroscopy. A subset of mixed-halide MHP crystals exhibited multiple emission …


Science Club, Danielle Gibson, Krista Andersen Apr 2023

Science Club, Danielle Gibson, Krista Andersen

Honors Expanded Learning Clubs

Honors After School program for elementary age children to engage with scientific principles. Students performed hands-on experiments to explore various STEM fields. Each weekly lesson consisted of a different concept to be learned or explored by early elementary aged students.


Diffractive Imaging Of Laser Induced Molecular Reactions With Kiloelectron-Volt Ultrafast Electron Diffraction, Yanwei Xiong Apr 2023

Diffractive Imaging Of Laser Induced Molecular Reactions With Kiloelectron-Volt Ultrafast Electron Diffraction, Yanwei Xiong

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

Capturing the structural changes during a molecular reaction with ultrafast electron diffraction (UED) requires a high spatiotemporal resolution and sufficiently high signal-to-noise to record the signals with high fidelity. In this dissertation, I have focused on the development of a tabletop gas phase keV-UED setup with a femtosecond temporal resolution. A DC electron gun was employed to generate electron pulses with a high repetition rate of 5 kHz. The space charge effect in the electron pulse was ameliorated by compressing the 90 keV electron pulse longitudinally with a time varying electric field in an RF cavity. The velocity mismatch between …


The Concentration Of Heavy Metals In Lincoln Nebraska's Tap Water, Evan Neuhaus Mar 2023

The Concentration Of Heavy Metals In Lincoln Nebraska's Tap Water, Evan Neuhaus

Honors Theses

Heavy metals are commonplace in nature, and are typically found in scarce quantities in all drinking sources. However, in high enough concentrations, they can have a myriad of negative health effects. This study seeks to find the concentrations of such metals in the Lincoln water supply utilizing the resources of the Water Center at the University of Nebraska at Lincoln. To test for discrete concentrations of trace elements, a method of using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was implemented. ICP-MS uses plasma to ionize and atomize a sample which is then filtered into a series of cones into a …


Chatgpt As Metamorphosis Designer For The Future Of Artificial Intelligence (Ai): A Conceptual Investigation, Amarjit Kumar Singh (Library Assistant), Dr. Pankaj Mathur (Deputy Librarian) Mar 2023

Chatgpt As Metamorphosis Designer For The Future Of Artificial Intelligence (Ai): A Conceptual Investigation, Amarjit Kumar Singh (Library Assistant), Dr. Pankaj Mathur (Deputy Librarian)

Library Philosophy and Practice (e-journal)

Abstract

Purpose: The purpose of this research paper is to explore ChatGPT’s potential as an innovative designer tool for the future development of artificial intelligence. Specifically, this conceptual investigation aims to analyze ChatGPT’s capabilities as a tool for designing and developing near about human intelligent systems for futuristic used and developed in the field of Artificial Intelligence (AI). Also with the helps of this paper, researchers are analyzed the strengths and weaknesses of ChatGPT as a tool, and identify possible areas for improvement in its development and implementation. This investigation focused on the various features and functions of ChatGPT that …


Ultra-Fast Bioorthogonal Spin-Labeling And Distance Measurements In Mammalian Cells Using Small, Genetically Encoded Tetrazine Amino Acids, Subhashis Jana, Eric G. B. Evans, Hyo Sang Jang, Shuyang Zhang, Hui Zhang, Andrzej Rajca, Sharona E. Gordon, William N. Zagotta, Stefan Stoll, Ryan A. Mehl Jan 2023

Ultra-Fast Bioorthogonal Spin-Labeling And Distance Measurements In Mammalian Cells Using Small, Genetically Encoded Tetrazine Amino Acids, Subhashis Jana, Eric G. B. Evans, Hyo Sang Jang, Shuyang Zhang, Hui Zhang, Andrzej Rajca, Sharona E. Gordon, William N. Zagotta, Stefan Stoll, Ryan A. Mehl

Chemistry Department: Faculty Publications

Studying protein structures and dynamics directly in the cellular environments in which they function is essential to fully understand the molecular mechanisms underlying cellular processes. Site-directed spin-labeling (SDSL)—in combination with double electron–electron resonance (DEER) spectroscopy—has emerged as a powerful technique for determining both the structural states and the conformational equilibria of biomacromolecules. In-cell DEER spectroscopy on proteins in mammalian cells has thus far not been possible due to the notable challenges of spin-labeling in live cells. In-cell SDSL requires exquisite biorthogonality, high labeling reaction rates and low background signal from unreacted residual spin label. While the bioorthogonal reaction must be …


Exploring The Complementarity Of Measures Of Instructional Practices, Lu Shi, Robert M. Erdmann, Anthony Pellegrini, Victoria Johnson, Binh Le, Trina Popple, Zachary Nelson, Molly Undersander Gaston, Marilyne Stains Jan 2023

Exploring The Complementarity Of Measures Of Instructional Practices, Lu Shi, Robert M. Erdmann, Anthony Pellegrini, Victoria Johnson, Binh Le, Trina Popple, Zachary Nelson, Molly Undersander Gaston, Marilyne Stains

Chemistry Department: Faculty Publications

The assessment of instructional quality has been and continues to be a desirable, yet difficult endeavor in higher education. The development of new teaching evaluation frameworks along with instruments to measure various aspects of teaching practices holds promise. The challenge rests in the implementation of these frameworks and measures in authentic settings. Part of this challenge is for instructors, researchers, and administrators to parse through and select a meaningful set of tools from the plethora of existing instruments. In this study, we aim to start clarifying the landscape of measures of instructional practice by exploring the complementarity of two existing …


Identification And Biosynthetic Study Of The Siderophore Lysochelin In The Biocontrol Agent Lysobacter Enzymogenes, Amanda Lynn Miller, Shanren Li, Catherine D. Eichhorn, Yongbiao Zheng, Liangcheng Du Jan 2023

Identification And Biosynthetic Study Of The Siderophore Lysochelin In The Biocontrol Agent Lysobacter Enzymogenes, Amanda Lynn Miller, Shanren Li, Catherine D. Eichhorn, Yongbiao Zheng, Liangcheng Du

Liangcheng Du Publications

Lysobacter is a genus of bacteria emerging as new biocontrol agents in agriculture. Although iron acquisition is essential for the bacteria, no siderophore has been identified from any Lysobacter. Here, we report the identification of the first siderophore, N1,N8-bis(2,3-dihydroxybenzoyl)spermidine (lysochelin), and its biosynthetic gene cluster from Lysobacter enzymogenes. Intriguingly, the deletion of the spermidine biosynthetic gene encoding arginine decarboxylase or SAM decarboxylase eliminated lysochelin and the antifungals, HSAF and its analogues, which are key to the disease control activity and to the survival of Lysobacter under oxidative stresses caused by excess iron. The production of …


Multiplatform Untargeted Metabolomics, Micah J. Jeppesen, Robert Powers Jan 2023

Multiplatform Untargeted Metabolomics, Micah J. Jeppesen, Robert Powers

Robert Powers Publications

Metabolomics samples like human urine or serum contain upwards of a few thousand metabolites, but individual analytical techniques can only characterize a few hundred metabolites at best. The uncertainty in metabolite identification commonly encountered in untargeted metabolomics adds to this low coverage problem. A multiplatform (multiple analytical techniques) approach can improve upon the number of metabolites reliably detected and correctly assigned. This can be further improved by applying synergistic sample preparation along with the use of combinatorial or sequential non-destructive and destructive techniques. Similarly, peak detection and metabolite identification strategies that employ multiple probabilistic approaches have led to better annotation …


The Reversible Low-Temperature Instability Of Human Dj-1 Oxidative States, Tessa Andrews, Javier Seravallic, Robert Powers Jan 2023

The Reversible Low-Temperature Instability Of Human Dj-1 Oxidative States, Tessa Andrews, Javier Seravallic, Robert Powers

Robert Powers Publications

DJ-1 is a homodimeric protein that is centrally involved in various human diseases including Parkinson disease (PD). DJ-1 protects against oxidative damage and mitochondrial dysfunction through a homeostatic control of reactive oxygen species (ROS). DJ-1 pathology results from a loss of function, where ROS readily oxidizes a highly conserved and functionally essential cysteine (C106). The over-oxidation of DJ-1 C106 leads to a dynamically destabilized and biologically inactivated protein. An analysis of the structural stability of DJ-1 as a function of oxidative state and temperature may provide further insights into the role the protein plays in PD progression. NMR spectroscopy, circular …


Histidine Enhances The Anticancer Effect Of Gemcitabine Against Pancreatic Cancer Via Disruption Of Amino Acid Homeostasis And Oxidant—Antioxidant Balance, Narendra Kumar, Satyanarayana Rachagani, Gopalakrishnan Natarajan, Alexandra Crook, Thiyagarajan Gopal, Vinothkumar Rajamanickam, Jyoti B. Kaushal, Sirpu N. Nagabhishek, Robert Powers, Surinder K. Batra, Viswanathan Saraswathi Jan 2023

Histidine Enhances The Anticancer Effect Of Gemcitabine Against Pancreatic Cancer Via Disruption Of Amino Acid Homeostasis And Oxidant—Antioxidant Balance, Narendra Kumar, Satyanarayana Rachagani, Gopalakrishnan Natarajan, Alexandra Crook, Thiyagarajan Gopal, Vinothkumar Rajamanickam, Jyoti B. Kaushal, Sirpu N. Nagabhishek, Robert Powers, Surinder K. Batra, Viswanathan Saraswathi

Robert Powers Publications

Simple Summary: Amino acid metabolism is aberrantly altered in pancreatic cancer (PC). Evidence suggests that circulating histidine (His) levels are low in PC. However, the role of His in modulating the progression of PC remains unknown. We determined the role of His in altering the therapeutic effectiveness of gemcitabine (Gem) against PC. We provide evidence that the expression of histidine ammonia lyase (HAL), an enzyme involved in His catabolism, is greatly increased in mouse and human pancreatic tumors. We show that combining His with Gem led to enhanced cytotoxic effects against aggressive PC cell lines. Our metabolomics analysis revealed that …


Progress In 7sk Ribonucleoprotein Structural Biology, Momodou B. Camara, Amr M. Sobeh, Catherine D. Eichhorn Jan 2023

Progress In 7sk Ribonucleoprotein Structural Biology, Momodou B. Camara, Amr M. Sobeh, Catherine D. Eichhorn

Chemistry Department: Faculty Publications

The 7SK ribonucleoprotein (RNP) is a dynamic and multifunctional regulator of RNA Polymerase II (RNAPII) transcription in metazoa. Comprised of the noncoding 7SK RNA, core proteins, and numerous accessory proteins, the most wellknown 7SK RNP function is the sequestration and inactivation of the positive transcription elongation factor b (P-TEFb). More recently, 7SK RNP has been shown to regulate RNAPII transcription through P-TEFb-independent pathways. Due to its fundamental role in cellular function, dysregulation has been linked with human diseases including cancers, heart disease, developmental disorders, and viral infection. Significant advances in 7SK RNP structural biology have improved our understanding of 7SK …


Multiomics Approach Captures Hepatic Metabolic Network Altered By Chronic Ethanol Administration, Isin Tuna Sakallioglu, Bridget Tripp, Jacy Kubik, Carol A. Casey, Paul G. Thomes, Robert Powers Dec 2022

Multiomics Approach Captures Hepatic Metabolic Network Altered By Chronic Ethanol Administration, Isin Tuna Sakallioglu, Bridget Tripp, Jacy Kubik, Carol A. Casey, Paul G. Thomes, Robert Powers

Chemistry Department: Faculty Publications

Using a multiplatform and multiomics approach, we identified metabolites, lipids, proteins, and metabolic pathways that were altered in the liver after chronic ethanol administration. A functional enrichment analysis of the multiomics dataset revealed that rats treated with ethanol experienced an increase in hepatic fatty acyl content, which is consistent with an initial development of steatosis. The nuclear magnetic resonance spectroscopy (NMR) and liquid chromatography–mass spectrometry (LC-MS) metabolomics data revealed that the chronic ethanol exposure selectively modified toxic substances such as an increase in glucuronidation tyramine and benzoyl; and a depletion in cholesterol-conjugated glucuronides. Similarly, the lipidomics results revealed that ethanol …


Uv-Light-Tunable P-/N-Type Chemiresistive Gas Sensors Based On Quasi-1d Tis3 Nanoribbons: Detection Of Isopropanol At Ppm Concentrations, Victor V. Sysoev, Andrey V. Lashkov, Alexey Lipatov, Ilya A. Plugin, Michael Bruns, Dirk Fuchs, Alexey S. Varezhnikov, Mustahsin Adib, Martin Sommer, Alexander Sinitskii Dec 2022

Uv-Light-Tunable P-/N-Type Chemiresistive Gas Sensors Based On Quasi-1d Tis3 Nanoribbons: Detection Of Isopropanol At Ppm Concentrations, Victor V. Sysoev, Andrey V. Lashkov, Alexey Lipatov, Ilya A. Plugin, Michael Bruns, Dirk Fuchs, Alexey S. Varezhnikov, Mustahsin Adib, Martin Sommer, Alexander Sinitskii

Chemistry Department: Faculty Publications

The growing demand of society for gas sensors for energy-efficient environmental sensing stimulates studies of new electronic materials. Here, we investigated quasi-one-dimensional titanium trisulfide (TiS3) crystals for possible applications in chemiresistors and on-chip multisensor arrays. TiS3 nanoribbons were placed as a mat over a multielectrode chip to form an array of chemiresistive gas sensors. These sensors were exposed to isopropanol as a model analyte, which was mixed with air at low concentrations of 1–100 ppm that are below the Occupational Safety and Health Administration (OSHA) permissible exposure limit. The tests were performed at room temperature (RT), as …


Threonine Phosphorylation Of An Electrochemical Peptide-Based Sensor To Achieve Improved Uranyl Ion Binding Affinity, Channing C. Thompson, Rebecca Lai Nov 2022

Threonine Phosphorylation Of An Electrochemical Peptide-Based Sensor To Achieve Improved Uranyl Ion Binding Affinity, Channing C. Thompson, Rebecca Lai

Chemistry Department: Faculty Publications

We have successfully designed a uranyl ion (U(VI)-specific peptide and used it in the fabrication of an electrochemical sensor. The 12-amino acid peptide sequence, (n) DKDGDGYIpTAAE (c), originates from calmodulin, a Ca(II)-binding protein, and contains a phosphothreonine that enhances the sequence’s affinity for U(VI) over Ca(II). The sensing mechanism of this U(VI) sensor is similar to other electrochemical peptide-based sensors, which relies on the change in the flexibility of the peptide probe upon interacting with the target. The sensor was systematically characterized using alternating current voltammetry (ACV) and cyclic voltammetry. Its limit of detection was 50 nM, which is lower …