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Articles 121 - 150 of 664

Full-Text Articles in Chemistry

Tenvr: Matlab-Based Toolbox For Environmental Research, Aleksandar I. Goranov, Rachel L. Sleighter, Dobromir A. Yordanov, Patrick G. Hatcher Jan 2023

Tenvr: Matlab-Based Toolbox For Environmental Research, Aleksandar I. Goranov, Rachel L. Sleighter, Dobromir A. Yordanov, Patrick G. Hatcher

Chemistry & Biochemistry Faculty Publications

With the advancements in science and technology, datasets become larger and more multivariate, which warrants the need for programming tools for fast data processing and multivariate statistical analysis. Here, the MATLAB-based Toolbox for Environmental Research "TEnvR" (pronounced "ten-ver") is introduced. This novel toolbox includes 44 open-source codes for automated data analysis from a multitude of techniques, such as ultraviolet-visible, fluorescence, and nuclear magnetic resonance spectroscopies, as well as from ultrahigh resolution mass spectrometry. Provided are codes for processing data (e.g., spectral corrections, formula assignment), visualization of figures, calculation of metrics, multivariate statistics, and automated work-up of large datasets. TEnvR allows …

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Extracting High-Molecular Weight Dna From Cyanobacteria Using Promega's Wizard® Hmw Dna Extraction Kit With A Modified Protocol, Metis, Megan A. Hept, Lesley H. Greene Jan 2023

Extracting High-Molecular Weight Dna From Cyanobacteria Using Promega's Wizard® Hmw Dna Extraction Kit With A Modified Protocol, Metis, Megan A. Hept, Lesley H. Greene

Chemistry & Biochemistry Faculty Publications

Extraction of high molecular weight (HMW) DNA for long read sequencing with little to no fragmentation and high purity is difficult to acquire from cyanobacterial species. Here we describe a modified method of extraction using Promega's Wizard® HMW DNA Extraction Kit to acquire high molecular weight DNA from cyanobacterial species. The protocol used in the kit is the “3.D. Isolating HMW DNA from Gram-Positive and Gram-Negative Bacteria” protocol. During a key step in the protocol, the lingering remnants of the mucilage layer of the cyanobacterial species is removed, preventing it from sticking to the DNA pellet produced. This customized modification …

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Abiotic Stress Mitigation: A Case Study From 21 Trials Using A Natural Organic Matter Based Biostimulant Across Multiple Geographies, Rachel L. Sleighter, Terry Hanson, David Holden, Kristen M. Richards Jan 2023

Abiotic Stress Mitigation: A Case Study From 21 Trials Using A Natural Organic Matter Based Biostimulant Across Multiple Geographies, Rachel L. Sleighter, Terry Hanson, David Holden, Kristen M. Richards

Chemistry & Biochemistry Faculty Publications

Crop productivity and yields can be greatly diminished by abiotic stress events including drought, extreme temperatures, excess moisture, and saline irrigation water. Multiple stressors occurring simultaneously can further exacerbate the strain on plants. Various types of biostimulants have been shown to mitigate abiotic stress and here, the results of 21 trials on corn, wheat, soybean, and various high-value crops are discussed in the context of the abiotic stress that either occurred naturally or was experimentally induced. Treatments in these trials included stressed and non-stressed plants, as well as either an untreated control or grower standard fertilizer applications alone and in …

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Sound The (Smaller) Alarm: The Triphosphate Magic Spot Nucleotide Pgpp, Areej Malik, Megan A. Hept, Erin B. Purcell Jan 2023

Sound The (Smaller) Alarm: The Triphosphate Magic Spot Nucleotide Pgpp, Areej Malik, Megan A. Hept, Erin B. Purcell

Chemistry & Biochemistry Faculty Publications

It has recently become evident that the bacterial stringent response is regulated by a triphosphate alarmone (pGpp) as well as the canonical tetra- and pentaphosphate alarmones ppGpp and pppGpp [together, (p)ppGpp]. Often dismissed in the past as an artifact or degradation product, pGpp has been confirmed as a deliberate endpoint of multiple synthetic pathways utilizing GMP, (p)ppGpp, or GDP/GTP as precursors. Some early studies concluded that pGpp functionally mimics (p)ppGpp and that its biological role is to make alarmone metabolism less dependent on the guanine energy charge of the cell by allowing GMP-dependent synthesis to continue when GDP/GTP has been …

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Infrared Spectra Of Small Radicals For Exoplanetary Spectroscopy: Oh, Nh, Cn, And Ch: The State Of Current Knowledge, Svatopluk Civiš, Adam Pastorek, Martin Ferus, Sergei N. Yurchenko, Noor-Ines Boudjema Jan 2023

Infrared Spectra Of Small Radicals For Exoplanetary Spectroscopy: Oh, Nh, Cn, And Ch: The State Of Current Knowledge, Svatopluk Civiš, Adam Pastorek, Martin Ferus, Sergei N. Yurchenko, Noor-Ines Boudjema

Chemistry & Biochemistry Faculty Publications

In this study, we present a current state-of-the-art review of middle-to-near IR emission spectra of four simple astrophysically relevant molecular radicals—OH, NH, CN and CH. The spectra of these radicals were measured by means of time-resolved Fourier transform infrared spectroscopy in the 700–7500 cm−1 spectral range and with 0.07–0.02 cm−1 spectral resolution. The radicals were generated in a glow discharge of gaseous mixtures in a specially designed discharge cell. The spectra of short-lived radicals published here are of great importance, especially for the detailed knowledge and study of the composition of exoplanetary atmospheres in selected new planets. Today, …

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Thermotrophy Exploratory Study, James Weifu Lee Jan 2023

Thermotrophy Exploratory Study, James Weifu Lee

Chemistry & Biochemistry Faculty Publications

The question of whether environmental heat energy could be utilized as a source of energy for biological metabolism is the center of this exploratory research. In 1979, this author postulated a hypothesis for the existence of thermotrophs that could isothermally utilize environmental heat energy as a source of their energy on Earth. According to this hypothesis, the thermotrophs could be the first primitive forms of life in the early Earth environment. The chemotrophs and phototrophs that we currently are all well familiar with might have been evolved somehow from the primitive thermotrophs. Furthermore, all the organisms currently regarded as the …

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Halogen Bonding Interactions Of Haloaromatic Endocrine Disruptors And The Potential For Inhibition Of Iodothyronine Deiodinases, Craig A. Bayse Jan 2023

Halogen Bonding Interactions Of Haloaromatic Endocrine Disruptors And The Potential For Inhibition Of Iodothyronine Deiodinases, Craig A. Bayse

Chemistry & Biochemistry Faculty Publications

Halogen bonding (XB) is a potential mechanism for the inhibition of the thyroid-activating/deactivating iodothyronine deiodinase family of selenoproteins through interactions with halogenated endocrine disrupting compounds (EDCs). Trends in XB interactions were examined using density functional theory for a series of polyhalogenated dibenzo-1,4-dioxins, biphenyls, and other EDCs with methylselenolate, a simple model of the Dio active site selenocysteine. The strengths of the interactions depend upon the halogen (Br>Cl), the degree of substitution, and the position of the acceptor. In terms of donor-acceptor energies, interactions at the meta position are often the strongest, suggesting a link to the topology of THs, …

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Para-Methoxybenzylidene Acetal-Protected D-Glucosamine Derivatives As Ph-Responsive Gelators And Their Applications For Drug Delivery, Jonathan Bietsch, Logan Baker, Anna Duffney, Alice Mao, Mary Foutz, Cheandri Ackermann, Guijun Wang Jan 2023

Para-Methoxybenzylidene Acetal-Protected D-Glucosamine Derivatives As Ph-Responsive Gelators And Their Applications For Drug Delivery, Jonathan Bietsch, Logan Baker, Anna Duffney, Alice Mao, Mary Foutz, Cheandri Ackermann, Guijun Wang

Chemistry & Biochemistry Faculty Publications

Carbohydrate-based low molecular weight gelators (LMWGs) are compounds with the capability to self-assemble into complex molecular networks within a solvent, leading to solvent immobilization. This process of gel formation depends on noncovalent interactions, including Van der Waals, hydrogen bonding, and π–π stacking. Due to their potential applications in environmental remediation, drug delivery, and tissue engineering, these molecules have emerged as an important area of research. In particular, various 4,6-O-benzylidene acetal-protected D-glucosamine derivatives have shown promising gelation abilities. In this study, a series of C-2-carbamate derivatives containing a para-methoxy benzylidene acetal functional group were synthesized and characterized. These compounds exhibited good …

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Telp Theory: Elucidating The Major Observations Of Rieger Et Al. 2021 In Mitochondria, James Weifu Lee Jan 2023

Telp Theory: Elucidating The Major Observations Of Rieger Et Al. 2021 In Mitochondria, James Weifu Lee

Chemistry & Biochemistry Faculty Publications

The transmembrane-electrostatically localized protons (TELP) theory may represent a complementary development to Mitchell's chemiosmotic theory. The combination of the two together can now excellently explain the energetics in mitochondria. Our calculated transmembrane-attractive force between an excess proton and an excess hydroxide explains how TELP may stay within a 1-nm thin layer at the liquid-membrane interface. Consequently, any pH sensor (sEcGFP) located at least 2–3 nm away from the membrane surface will not be able to see TELP. This feature as predicted from the TELP model was observed exactly in the experiment of Rieger et al., 2021. In contrast to their …

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Synthesis And Self-Assembling Properties Of Carbohydrate- And Diarylethene-Based Photoswitchable Molecular Gelators, Pramod Aryal, Joedian Morris, Surya B. Adhikari, Jonathan Bietsch, Guijun Wang Jan 2023

Synthesis And Self-Assembling Properties Of Carbohydrate- And Diarylethene-Based Photoswitchable Molecular Gelators, Pramod Aryal, Joedian Morris, Surya B. Adhikari, Jonathan Bietsch, Guijun Wang

Chemistry & Biochemistry Faculty Publications

Carbohydrate-based low-molecular-weight gelators are interesting new materials with many potential applications. These compounds can be designed to include multiple stimuli-responsive functional groups. In this study, we designed and synthesized several chemically responsive bola-glycolipids and dimeric carbohydrate- and diarylethene-based photoswitchable derivatives. The dimeric glycolipids formed stable gels in a variety of solvent systems. The best performing gelators in this series contained decanedioic and dithienylethene (DTE) spacers, which formed gels in eight and nine of the tested solvents, respectively. The two new DTE-containing esters possessed interesting photoswitching properties and DTE derivative 7 was found to have versatile gelation properties in many solvents, …

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Detection And Quantification Of Antiviral Drug Tenofovir Using Silver Nanoparticles And Surface Enhanced Raman Spectroscopy (Sers) With Spatially Resolved Hotspot Selection, Marguerite R. Butler, Jana Hrncirova, Terry A. Jacot, Sucharita Dutta, Meredith R. Clark, Gustavo F. Doncel, John B. Cooper Jan 2023

Detection And Quantification Of Antiviral Drug Tenofovir Using Silver Nanoparticles And Surface Enhanced Raman Spectroscopy (Sers) With Spatially Resolved Hotspot Selection, Marguerite R. Butler, Jana Hrncirova, Terry A. Jacot, Sucharita Dutta, Meredith R. Clark, Gustavo F. Doncel, John B. Cooper

Chemistry & Biochemistry Faculty Publications

This study introduces a convenient and ultra-sensitive method of detection and quantification of the antiviral drug, tenofovir (TFV), by surface-enhanced Raman spectroscopy (SERS). Novel spatially resolved instrumentation for spectral acquisition and subsequent statistical analysis for hot spot selection was developed for convenient quantification of TFV in an aqueous matrix. Methods of statistical analysis include the use of partial least squares (PLS) regression vector analysis and spectral ranking by quality indices computed using CHAOS theory. Hydroxylamine-reduced Ag colloidal nanoparticles evaporated to dryness on an aluminum well-plate were used as the SERS substrate. To our knowledge, quantification of TFV down to 25 …

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S-Type Stars: Line List For The A²Π-X²Σ⁺ Band System Of Lao, P. F. Bernath, R. Dodangodage, J. Liévin Jan 2023

S-Type Stars: Line List For The A²Π-X²Σ⁺ Band System Of Lao, P. F. Bernath, R. Dodangodage, J. Liévin

Chemistry & Biochemistry Faculty Publications

LaO bands are found in the spectra of cool S-type stars. The bands of the A2Π–X2Σ+ transition with v' ⩽ 3 and v'' ≤ 4 are rotationally analyzed, providing spectroscopic constants for the A2Π state. Line strengths are calculated using an ab initio transition dipole moment function, and radiative lifetimes for the A2Π state have also been computed. A line list for the A2Π–X2Σ+ transition of LaO is provided and can be used to determine LaO stellar abundances.

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Enhancing The Conformational Stability Of The Cl-Par-4 Tumor Suppressor Via Site-Directed Mutagenesis, Samjhana Pandey, Krishna K. Raut, Antoine Baudin, Lamya Djemri, David S. Libich, Komala Ponniah, Steven M. Pascal Jan 2023

Enhancing The Conformational Stability Of The Cl-Par-4 Tumor Suppressor Via Site-Directed Mutagenesis, Samjhana Pandey, Krishna K. Raut, Antoine Baudin, Lamya Djemri, David S. Libich, Komala Ponniah, Steven M. Pascal

Chemistry & Biochemistry Faculty Publications

Intrinsically disordered proteins play important roles in cell signaling, and dysregulation of these proteins is associated with several diseases. Prostate apoptosis response-4 (Par-4), an approximately 40 kilodalton proapoptotic tumor suppressor, is a predominantly intrinsically disordered protein whose downregulation has been observed in various cancers. The caspase-cleaved fragment of Par-4 (cl-Par-4) is active and plays a role in tumor suppression by inhibiting cell survival pathways. Here, we employed site-directed mutagenesis to create a cl-Par-4 point mutant (D313K). The expressed and purified D313K protein was characterized using biophysical techniques, and the results were compared to that of the wild-type (WT). We have …

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Synthesis Of A Series Of Trimeric Branched Glycoconjugates And Their Applications For Supramolecular Gels And Catalysis, Jonathan Bietsch, Anji Chen, Dan Wang, Guijun Wang Jan 2023

Synthesis Of A Series Of Trimeric Branched Glycoconjugates And Their Applications For Supramolecular Gels And Catalysis, Jonathan Bietsch, Anji Chen, Dan Wang, Guijun Wang

Chemistry & Biochemistry Faculty Publications

Carbohydrate-derived molecular gelators have found many practical applications as soft materials. To better understand the structure and molecular gelation relationship and further explore the applications of sugar-based gelators, we designed and synthesized eight trimeric branched sugar triazole derivatives and studied their self-assembling properties. These included glucose, glucosamine, galactose, and maltose derivatives. Interestingly, the gelation properties of these compounds exhibited correlations with the peripheral sugar structures. The maltose derivative did not form gels in the tested solvents, but all other compounds exhibited gelation properties in at least one of the solvents. Glucose derivatives showed superior performance, followed by glucosamine derivatives. They …

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Reduced Metal Nanocatalysts For Selective Electrochemical Hydrogenation Of Biomass-Derived 5-(Hydroxymethyl)Furfural To 2, 5-Bis(Hydroxymethyl)Furan In Ambient Conditions, Baleeswaraiah Muchharla, Moumita Dikshit, Ujjwal Pokharel, Ravindranath Garimella, Adetayo Adedeji, Kapil Kumar, Wei Cao, Hani Elsayed-Ali, Kishor Kumar Sadasivuni, Naif Abdullah Al-Dhabi, Sandeep Kumar, Bijandra Kumar Jan 2023

Reduced Metal Nanocatalysts For Selective Electrochemical Hydrogenation Of Biomass-Derived 5-(Hydroxymethyl)Furfural To 2, 5-Bis(Hydroxymethyl)Furan In Ambient Conditions, Baleeswaraiah Muchharla, Moumita Dikshit, Ujjwal Pokharel, Ravindranath Garimella, Adetayo Adedeji, Kapil Kumar, Wei Cao, Hani Elsayed-Ali, Kishor Kumar Sadasivuni, Naif Abdullah Al-Dhabi, Sandeep Kumar, Bijandra Kumar

Chemistry & Biochemistry Faculty Publications

Selective electrochemical hydrogenation (ECH) of biomass-derived unsaturated organic molecules has enormous potential for sustainable chemical production. However, an efficient catalyst is essential to perform an ECH reaction consisting of superior product selectivity and a higher conversion rate. Here, we examined the ECH performance of reduced metal nanostructures i.e., reduced Ag (rAg) and reduced copper (rCu) prepared via electrochemical or thermal oxidation and electrochemical reduction process, respectively. Surface morphological analysis suggests formation of nanocoral and entangled nanowire structure formation for rAg and rCu catalysts. rCu exhibits slight enhancement in ECH reaction performance in comparison to the pristine Cu. However, the rAg …

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Expanding Our Grasp Of Two-Component Signaling In Clostridioides Difficile, Orlando Berumen Alvarez, Erin B. Purcell Jan 2023

Expanding Our Grasp Of Two-Component Signaling In Clostridioides Difficile, Orlando Berumen Alvarez, Erin B. Purcell

Chemistry & Biochemistry Faculty Publications

The intestinal pathogen Clostridioides difficile encodes roughly 50 TCS, but very few have been characterized in terms of their activating signals or their regulatory roles. A. G. Pannullo, B. R. Zbylicki, and C. D. Ellermeier (J Bacteriol 205:e00164-23, 2023, https://doi.org/10.1128/jb.00164-23) have identified both for the novel C. difficile TCD DraRS. DraRS responds to antibiotics that target lipid-II molecules in the bacterial cell envelope, and regulates the production of a novel glycolipid necessary for bacitracin and daptomycin resistance in C. difficile.

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Authigenic Iron Is A Significant Component Of Oceanic Labile Particulate Iron Inventories, Laura E. Sofen, Olga A. Antipova, Kristen N. Buck, Salvatore Caprara, Lauren Chacho, Rodney J. Johnson, Gabriella Kim, Peter Morton, Daniel C. Ohnemus, Sara Rauschenberg, Peter N. Sedwick, Alessandro Tagliabue, Benjamin S. Twining Jan 2023

Authigenic Iron Is A Significant Component Of Oceanic Labile Particulate Iron Inventories, Laura E. Sofen, Olga A. Antipova, Kristen N. Buck, Salvatore Caprara, Lauren Chacho, Rodney J. Johnson, Gabriella Kim, Peter Morton, Daniel C. Ohnemus, Sara Rauschenberg, Peter N. Sedwick, Alessandro Tagliabue, Benjamin S. Twining

OES Faculty Publications

Particulate phases transport trace metals (TM) and thereby exert a major control on TM distribution in the ocean. Particulate TMs can be classified by their origin as lithogenic (crustal material), biogenic (cellular), or authigenic (formed in situ), but distinguishing these fractions analytically in field samples is a challenge often addressed using operational definitions and assumptions. These different phases require accurate characterization because they have distinct roles in the biogeochemical iron cycle. Particles collected from the upper 2,000 m of the northwest subtropical Atlantic Ocean over four seasonal cruises throughout 2019 were digested with a chemical leach to operationally distinguish labile …

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Potential Interactions Between Diatoms And Bacteria Are Shaped By Trace Element Gradients In The Southern Ocean, Alexa R. Sterling, Laura Z. Holland, Randelle M. Bundy, Shannon M. Burns, Kristen N. Buck, P. Dreux Chappell, Bethany D. Jenkins Jan 2023

Potential Interactions Between Diatoms And Bacteria Are Shaped By Trace Element Gradients In The Southern Ocean, Alexa R. Sterling, Laura Z. Holland, Randelle M. Bundy, Shannon M. Burns, Kristen N. Buck, P. Dreux Chappell, Bethany D. Jenkins

OES Faculty Publications

The growth of diatoms in the Southern Ocean, especially the region surrounding the West Antarctic Peninsula, is frequently constrained by low dissolved iron and other trace metal concentrations. This challenge may be overcome by mutualisms between diatoms and co-occurring associated bacteria, in which diatoms produce organic carbon as a substrate for bacterial growth, and bacteria produce siderophores, metal-binding ligands that can supply diatoms with metals upon uptake as well as other useful secondary compounds for diatom growth like vitamins. To examine the relationships between diatoms and bacteria in the plankton (diatom) size class (> 3 mu m), we sampled both …

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Atmospheric Input And Seasonal Inventory Of Dissolved Iron In The Sargasso Sea: Implications For Iron Dynamics In Surface Waters Of The Subtropical Ocean, Peter N. Sedwick, Bettina M. Sohst, K. N. Buck, S. Caprara, R. J. Johnson, D. C. Ohnemus, L. E. Sofen, A. Tagliabue, B. S. Twining, Tara E. Williams Jan 2023

Atmospheric Input And Seasonal Inventory Of Dissolved Iron In The Sargasso Sea: Implications For Iron Dynamics In Surface Waters Of The Subtropical Ocean, Peter N. Sedwick, Bettina M. Sohst, K. N. Buck, S. Caprara, R. J. Johnson, D. C. Ohnemus, L. E. Sofen, A. Tagliabue, B. S. Twining, Tara E. Williams

OES Faculty Publications

Constraining the role of dust deposition in regulating the concentration of the essential micronutrient iron in surface ocean waters requires knowledge of the flux of seawater-soluble iron in aerosols and the replacement time of dissolved iron (DFe) in the euphotic zone. Here we estimate these quantities using seasonally resolved DFe data from the Bermuda Atlantic Time-series Study region and weekly-scale measurements of iron in aerosols and rain from Bermuda during 2019. In response to seasonal changes in vertical mixing, primary production and dust deposition, surface DFe concentrations vary from ∼0.2 nM in early spring to >1 nM in late summer, …

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Global Oceanic Diazotroph Database Version 2 And Elevated Estimate Of Global N2 Fixation, Zhibo Shao, Yangchun Xu, Hua Wang, Weicheng Luo, Lice Wang, Yuhong Huang, Nona Sheila R. Agawin, Ayaz Ahmed, Mar Benavides, Mikkel Bentzon-Tilia, Ilana Berman-Frank, Hugo Berthelot, Isabelle C. Biegala, Mariana B. Bif, Antonio Bode, Sophie Bonnet, Deborah A. Bronk, Mark V. Brown, Lisa Campbell, Ya-Wei Luo Jan 2023

Global Oceanic Diazotroph Database Version 2 And Elevated Estimate Of Global N2 Fixation, Zhibo Shao, Yangchun Xu, Hua Wang, Weicheng Luo, Lice Wang, Yuhong Huang, Nona Sheila R. Agawin, Ayaz Ahmed, Mar Benavides, Mikkel Bentzon-Tilia, Ilana Berman-Frank, Hugo Berthelot, Isabelle C. Biegala, Mariana B. Bif, Antonio Bode, Sophie Bonnet, Deborah A. Bronk, Mark V. Brown, Lisa Campbell, Ya-Wei Luo

OES Faculty Publications

Marine diazotrophs convert dinitrogen (N2) gas into bioavailable nitrogen (N), supporting life in the global ocean. In 2012, the first version of the global oceanic diazotroph database (version 1) was published. Here, we present an updated version of the database (version 2), significantly increasing the number of in situ diazotrophic measurements from 13 565 to 55 286. Data points for N2 fixation rates, diazotrophic cell abundance, and nifH gene copy abundance have increased by 184 %, 86 %, and 809 %, respectively. Version 2 includes two new data sheets for the nifH gene copy abundance of non-cyanobacterial …

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Outstanding Advantages, Current Drawbacks, And Significant Recent Developments In Mechanochemistry: A Perspective View, Silvina Pagola Jan 2023

Outstanding Advantages, Current Drawbacks, And Significant Recent Developments In Mechanochemistry: A Perspective View, Silvina Pagola

Chemistry & Biochemistry Faculty Publications

Although known since antiquity, mechanochemistry has remained dormant for centuries. Nowadays, mechanochemistry is a flourishing research field at the simultaneous stages of gathering data and (often astonishing) observations, and scientific argumentation toward their analysis, for which the combination of interdisciplinary expertise is necessary. Mechanochemistry’s implementation as a synthetic method is constantly increasing, although it remains far from being fully exploited, or understood on the basis of fundamental principles. This review starts by describing many remarkable advantages of mechanochemical reactions, simplifying and “greening” chemistry in solutions. This description is followed by an overview of the current main weaknesses to be addressed …

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More On The Demons Of Thermodynamics, Daniel P. Sheehan, Garret Moddel, James W. Lee Jan 2023

More On The Demons Of Thermodynamics, Daniel P. Sheehan, Garret Moddel, James W. Lee

Chemistry & Biochemistry Faculty Publications

No abstract provided.

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The Effect Of Metalation On Antimicrobial Piscidins Imbedded In Normal And Oxidized Lipid Bilayers, Ana Dreab, Craig A. Bayse Jan 2023

The Effect Of Metalation On Antimicrobial Piscidins Imbedded In Normal And Oxidized Lipid Bilayers, Ana Dreab, Craig A. Bayse

Chemistry & Biochemistry Faculty Publications

Metalation of the N-terminal Amino Terminal Cu(II)- and Ni(II)-binding (ATCUN) motif may enhance the antimicrobial properties of piscidins. Molecular dynamics simulations of free and nickelated piscidins 1 and 3 (P1 and P3) were performed in 3 : 1 POPC/POPG and 2.6 : 1 : 0.4 POPC/POPG/aldo-PC bilayers (POPC, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine: POPG, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol; aldo-PC, 1-palmitoyl-2-(9′-oxo-nonanoyl)-sn-glycero-3-phosphocholine) bilayer models. Nickel(II) binding decreases the conformation dynamics of the ATCUN motif and lowers the charge of the N-terminus to allow it to embed deeper in the bilayer without significantly changing the overall depth due to interactions of the charged half-helix …

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Ultrasensitive Tapered Optical Fiber Refractive Index, Erem Ujah, Meimei Lai, Gymama Slaughter Jan 2023

Ultrasensitive Tapered Optical Fiber Refractive Index, Erem Ujah, Meimei Lai, Gymama Slaughter

Electrical & Computer Engineering Faculty Publications

Refractive index (RI) sensors are of great interest for label-free optical biosensing. A tapered optical fiber (TOF) RI sensor with micron-sized waist diameters can dramatically enhance sensor sensitivity by reducing the mode volume over a long distance. Here, a simple and fast method is used to fabricate highly sensitive refractive index sensors based on localized surface plasmon resonance (LSPR). Two TOFs (l = 5 mm) with waist diameters of 5 µm and 12 µm demonstrated sensitivity enhancement at λ = 1559 nm for glucose sensing (5-45 wt%) at room temperature. The optical power transmission decreased with increasing glucose concentration due …

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High Figure Of Merit Spin Polarized Electron Sources Grown Via Mocvd, Benjamin Belfore, Adam Masters, Deewakar Poudel, Greg Blume, Stephen Polly, Erdong Wang, Seth M. Hubbard, Marcy Stutzman, Joseph M. Grames, Matt Poelker, Matt Grau, Sylvain Marsillac Jan 2023

High Figure Of Merit Spin Polarized Electron Sources Grown Via Mocvd, Benjamin Belfore, Adam Masters, Deewakar Poudel, Greg Blume, Stephen Polly, Erdong Wang, Seth M. Hubbard, Marcy Stutzman, Joseph M. Grames, Matt Poelker, Matt Grau, Sylvain Marsillac

Electrical & Computer Engineering Faculty Publications

Spin polarized photocathodes are key to the future operation of electron accelerators such as the ones at Thomas Jefferson National Accelerator Facility and Brookhaven National Laboratory. Currently, these photocathodes come in short supply due to limited production by molecular beam epitaxy. By developing a process to implement similar structures using metal organic chemical vapor deposition, the availability of these devices can be increased. In this paper, we detail the implementation of recent photocathode advancements via metal organic chemical vapor deposition process and show an improvement in both polarization and quantum efficiency of our devices compared to those fabricated via molecular …

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Interactions Of Bioactive Trace Metals In Shipboard Southern Ocean Incubation Experiments, Shannon M. Burns, Randelle M. Bundy, William Abbott, Zuzanna Abdala, Alexa R. Sterling, P. Dreux Chappell, Bethany D. Jenkins, Kristen N. Buck Jan 2023

Interactions Of Bioactive Trace Metals In Shipboard Southern Ocean Incubation Experiments, Shannon M. Burns, Randelle M. Bundy, William Abbott, Zuzanna Abdala, Alexa R. Sterling, P. Dreux Chappell, Bethany D. Jenkins, Kristen N. Buck

OES Faculty Publications

In the Southern Ocean, it is well‐known that iron (Fe) limits phytoplankton growth. Yet, other trace metals can also affect phytoplankton physiology. This study investigated feedbacks between phytoplankton growth and dissolved Fe, manganese (Mn), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), and cadmium (Cd) concentrations in Southern Ocean shipboard incubations. Three experiments were conducted in September–October 2016 near the West Antarctic Peninsula: Incubations 1 and 3 offshore in the Antarctic Circumpolar Current, and Incubation 2 inshore in Bransfield Strait. Additions of Fe and/or vitamin B12 to inshore and offshore waters were employed and allowed assessment of metal (M) …

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Isotopic Evidence For Sources Of Dissolved Carbon And The Role Of Organic Matter Respiration In The Fraser River Basin, Canada, Britta M. Voss, Timothy I. Eglinton, Bernhard Peucker-Ehrenbrink, Valier Galy, Susan Q. Lang, Cameron Mcintyre, Robert G.M. Spencer, Ekaterina Bulygina, Zhaohui Aleck Wang, Katherine A. Guay Jan 2023

Isotopic Evidence For Sources Of Dissolved Carbon And The Role Of Organic Matter Respiration In The Fraser River Basin, Canada, Britta M. Voss, Timothy I. Eglinton, Bernhard Peucker-Ehrenbrink, Valier Galy, Susan Q. Lang, Cameron Mcintyre, Robert G.M. Spencer, Ekaterina Bulygina, Zhaohui Aleck Wang, Katherine A. Guay

OES Faculty Publications

Sources of dissolved and particulate carbon to the Fraser River system vary significantly in space and time. Tributaries in the northern interior of the basin consistently deliver higher concentrations of dissolved organic carbon (DOC) to the main stem than other tributaries. Based on samples collected near the Fraser River mouth throughout 2013, the radiocarbon age of DOC exported from the Fraser River does not change significantly across seasons despite a spike in DOC concentration during the freshet, suggesting modulation of heterogeneous upstream chemical and isotopic signals during transit through the river basin. Dissolved inorganic carbon (DIC) concentrations are highest in …

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Systemic Analyses Of Radiocarbon Ages Of Coexisting Planktonic Foraminifera, Jörg Lippold, Julia Gottschalk, Jean Lynch-Stieglitz, Matthew W. Schmidt, Sönke Szidat, Andre Bahr Jan 2023

Systemic Analyses Of Radiocarbon Ages Of Coexisting Planktonic Foraminifera, Jörg Lippold, Julia Gottschalk, Jean Lynch-Stieglitz, Matthew W. Schmidt, Sönke Szidat, Andre Bahr

OES Faculty Publications

We compare radiocarbon (14C) ages of coexisting planktonic foraminifera species from sediment cores VM12-107 and KNR166-2-26JPC from the Equatorial Atlantic Ocean for three time periods (Holocene, Heinrich Stadial 1, last glacial maximum). We find a maximum inter-species difference of 1200 14C yr. On average, the 14C ages deviate by ∼300 yr between Globigerinoides ruber and other species. In most cases, this exceeds the analytical uncertainty range of the measurements and thus renders the choice of species for generating age models as important as sample weight. While modern stratified water-column profiles imply an increase in 14C …

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Using Ftir-Atr And Chemometric Methods To Detect Sucrose Adulteration In Commercial Honey Samples, Dylan T. Roberts, Kevin Kittredge Oct 2022

Using Ftir-Atr And Chemometric Methods To Detect Sucrose Adulteration In Commercial Honey Samples, Dylan T. Roberts, Kevin Kittredge

Virginia Journal of Science

Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR–ATR) was used to analyze pure and adulterated honey samples. The FTIR spectra was analyzed using principal component analysis (PCA) and partial least squares (PLS) regression analysis to determine if these methods could differentiate between pure, commercial, and sucrose-adulterated honey samples. PCA showed a clear distinction between pure and adulterated honey samples. Commercial honey samples showed clustering around the unadulterated samples. PLS regression analysis correctly identified 81.8% of the standards and samples used in the PCA analysis. The five commercial samples were tested and shown to have a concentration of less than 3% adulterant, …

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Design, Synthesis And Characterization Of Triazole Based Glycoconjugates And 4,6-Acetal Protected D-Glucosamine Derivatives As Low Molecular Weight Gelators, Pooja Sharma Aug 2022

Design, Synthesis And Characterization Of Triazole Based Glycoconjugates And 4,6-Acetal Protected D-Glucosamine Derivatives As Low Molecular Weight Gelators, Pooja Sharma

Chemistry & Biochemistry Theses & Dissertations

Low molecular weight gelators (LMWGs) are small molecules that can form gels in either organic solvents or water in their pure form or as mixtures. LMWGs self-assemble through noncovalent interactions such as hydrogen bonding, halogen bonding, van der Waals interactions and hydrophobic forces in solvents. They have shown great potential in biomedical industry, catalysis and environmental remediation to name a few. Moreover, the formation of metallogels can be used for detection of various ions as well as catalysis, which adds a new dimension to their applications. Among many classes of LMWGs based on the type of functional groups used, carbohydrate …

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