Chemistry Commons^™

Surface Chemical Properties Of Mo2C, W2C, Mo2N And W2N Probed With Co, Co2 And O2 Adsorption: A Dft Analysis, Jingyun Ye, Tianyu Zhang, Lingyun Xu, Shuxia Yin, Krishanthi Weerasinghe, Pamela Ubaldo, Ping He, Qingfeng Ge

Journal of Electrochemistry

Transition metal carbides and nitrides are attractive materials for electrodes in many electrochemical energy storage and conversion applications. In the present study, we use density functional theory slab calculations to characterize the surface chemical properties of molybdenum (Mo) and tungsten (W) carbides and nitrides, namely, Mo₂C, W₂C, Mo₂N and W2N with the adsorption of CO, CO₂ and O₂. These probing molecules provide measures of in both acidity/basicity and redox property of for the surfaces of these carbides and nitrides. Our results show that Lewis basic sites were responsible for CO_{2 …}

An Electrochemical Dissolution Study Of Ilmenite Fraction Of Beach Sand In Sulphuric Acid Solution, Rostom Ali M., K. Biswas R., Golam Zakaria Md.

Journal of Electrochemistry

Electrochemical techniques have been used to investigate the dissolution behaviors of ilmenite fraction of beach sand of Bangladesh in sulfuric acid solutions at various temperatures. It is seen from the cyclic voltammetric studies indicated that the dissolution of ilmenite is was very difficult without the addition of carbon powder in ilmenite. The effects of ilmenite-carbon ratio, acid concentration and temperature on cyclic voltammograms have been investigated to understand the dissolution process of ilmenite. The investigated results showed that the dissolution rate of ilmenite (FeTiO₃) is was slow at low applied reduction potentials and temperatures. However, the dissolution rate …

Preface For Special Issue On Theoretical And Computational Electrochemistry, Jun Cheng

Journal of Electrochemistry

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Thermo-Stability And Active Site Structure Of Fe/N/C Electrocatalyst For Oxygen Reduction Reaction, Chi Chen, Yu-Jiao Lai, Zhi-You Zhou, Xin-Sheng Zhang, Shi-Gang Sun

Journal of Electrochemistry

The development of Fe/N/C electrocatalyst for oxygen reduction reaction (ORR) is vital for the large-scale applications of proton exchange membrane fuel cells. Understanding the active site structure will contribute to the rational design of highly active catalysts. In this study, the as-prepared Fe/N/C catalyst based on poly-m-phenylenediamine (PmPDA-FeN_x/C) catalyst with the high ORR activity was subjected to the high-temperature heat treatment again at 1000 ~1500 ^oC. The degradation of in the ORR activity of PmPDA-FeN_x/C by with various heat treatments was correlated to the change of elemental compositions, chemical states and textural properties. As the …

Electric Current Induced Flow And Electrocapillary Deformation Of Liquid Wood Alloy In Naoh Aqueous Solution, Guo-Di Zhang, Qiao-Li Lin, Jian-Hong Cheng, Rui Cao

Journal of Electrochemistry

The phenomena of the electric current induced flow and electrocapillary deformation for a liquid Wood alloy in a NaOH electrolyte were studied. Electrocapillary behaviors for the liquid Wood alloy in NaOH electrolytes by applying external low voltages were investigated. The electrode reaction (redox reaction) induced the formation or removing removal of an oxide film, and further caused the drop deformation by decreasing or increasing an interfacial tension. The same polar charge in the electric double layer would also decrease the interfacial tension. In order to maintain the stability of system, the contact area of the interface would be expanded, and …

An Investigation Of The Synergistic Effect Between (1,3-Dioxolan-2-Ylmethyl)Triphenylphosphonium Bromide And Iodide Ion For The Corrosion Inhibition Of Zinc In Citric Acid, Saadawy M.

Journal of Electrochemistry

The effect of (1,3-Dioxolan-2-ylmethyl)-triphenylphosphonium bromide (DTPB) on the zinc corrosion in 0.5 mol·L^-1 citric acid solution was investigated at 30 ^oC using weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. An ecofriendly bath was used for acid cleaning of zinc, which has not been widely used in literatures. The results showed that DTPB could serve as an effective inhibitor for the zinc corrosion in a citric acid solution with the inhibition efficiency of 98.9% at the DTPB concentration of 3×10^-3 mol·L^-1. A synergistic effect between DTPB and potassium iodide (KI) enhanced the inhibition …

A New Type Carbon Composited Molybdenum Doped Vanadium Oxide Nanowires As A Cathode Material For Sodium Ion Batteries, Guang-Rui Zhang, Li-Qiang Hu, Bao-Zhu Zhang

Journal of Electrochemistry

In recent years, the development of lithium ion batteries (LIBs) has been limited due to the insufficient lithium resource and increasing cost. As a promising candidate, sodium ion batteries (SIBs) with the similar electrochemical mechanism and lower cost than LIBs are developing rapidly. However, as a result of the larger radius of Na⁺ compared with Li⁺, the crystalline structures of the most electrode materials are damaged severely during the intercalation of Na⁺, which limits the electrochemical properties of SIBs. Thus, developing new types of electrode materials for SIBs is particularly important. Among the cathode materials, …

Identification Of Hydrated And Dehydrated Lipids And Protein Secondary Structures In Seeds Of Cotton (Gossypium Hirsutum) Line, Diwas Kumar Silwal, Nsoki Phambu, Bharat Pokharel, Ahmad Naseer Aziz

Chemistry Faculty Research

Cottonseeds from two parents (TM-1 and 3-79) and their 17 progeny (chromosomal substitution) lines were analyzed for various secondary structures of proteins and moisture content of lipids, separately in hulls and kernels. Fourier transform infrared spectroscopy (FTIR) was used on mature seeds from Upland cotton (G. hirsutum) progeny lines and parents. Based on secondary structures of proteins and hydration levels of lipids, differences were observed among the cottonseeds. The two progeny lines – CS-B12sh and CS-B22sh retained lipid moisture content and protein secondary structures similar to both parents, while CS-B06, CS-B15sh and CS-B16 remained distinct from either parent. On the …

Differential Uptake Of Gold Nanoparticles By 2 Species Of Tadpole, The Wood Frog (Lithobates Sylvaticus) And The Bullfrog (Lithobates Catesbeianus), Lucas B. Thompson, Gerardo L.F. Carfagno, Kurt Andresen, Andrea J. Sitton, Taylor B. Bury, Laura L. Lee, Kevin T. Lerner, Peter P. Fong

Biology Faculty Publications

Engineered nanoparticles are aquatic contaminants of emerging concern that exert ecotoxicological effects on a wide variety of organisms. We exposed cetyltrimethylammonium bromide–capped spherical gold nanoparticles to wood frog and bullfrog tadpoles with conspecifics and in combination with the other species continuously for 21 d, then measured uptake and localization of gold. Wood frog tadpoles alone and in combination with bullfrog tadpoles took up significantly more gold than bullfrogs. Bullfrog tadpoles in combination with wood frogs took up significantly more gold than controls. The rank order of weight-normalized gold uptake was wood frogs in combination > wood frogs alone > bullfrogs in combination …

Life’S Late Digital Revolution And Why It Matters For The Study Of The Origins Of Life, David A. Baum, Niles Lehman

Chemistry Faculty Publications and Presentations

The information contained in life exists in two forms, analog and digital. Analog information is manifest mainly in the differing concentrations of chemicals that get passed from generation to generation and can vary from cell to cell. Digital information is encoded in linear polymers such as DNA and RNA, whose side chains come in discrete chemical forms. Here, we argue that the analog form of information preceded the digital. Acceptance of this dichotomy, and this progression, can help direct future studies on how life originated and initially complexified on the primordial Earth, as well as expected trajectories for other, independent …

Calcium-Mediated Control Of S100 Proteins: Allosteric Communication Via An Agitator/Signal Blocking Mechanism., Yiming Xiao, Gary S Shaw, Lars Konermann

Chemistry Publications

Allosteric proteins possess dynamically coupled residues for the propagation of input signals to distant target binding sites. The input signals usually correspond to "effector is present" or "effector is not present". Many aspects of allosteric regulation remain incompletely understood. This work focused on S100A11, a dimeric EF-hand protein with two hydrophobic target binding sites. An annexin peptide (Ax) served as the target. Target binding is allosterically controlled by Ca²⁺ over a distance of ∼26 Å. Ca²⁺ promotes formation of a [Ca₄ S100 Ax₂] complex, where the Ax peptides are accommodated between helices III/IV and III'/IV'. …

Chemistry And Biochemistry News, Georgia Southern University

Biochemistry, Chemistry & Physics: News & Publications (2012-2023)

• Chemistry Faculty Win Excellence Awards

Optical Sensing And Separation Based On Ordered Three-Dimensional Nanostructured Surfaces, Mathias Schubert, Tino Hofmann, Daniel Schmidt, Patrick H. Dussault, Andrea Homes, Rebecca Lai

Patrick Dussault Publications

A sensor having a substrate is provided in which structures are disposed on a surface of the substrate . The structures can be , e . g . , nanostructures . Polarized light is directed toward the sensor , and birefringence of the structures with respect to the light is measured . Target particles that interact with the structures are detected based on changes in the measured birefringence .

Molecular Basis For The Substrate Specificity Of Quorum Signal Synthases, Shi-Hui Dong, Nicole D. Frane, Quin H. Christensen, E. Peter Greenberg, Rajesh Nagarajan, Satish K. Nair

Chemistry and Biochemistry Faculty Publications and Presentations

In several Proteobacteria, LuxI-type enzymes catalyze the biosynthesis of acyl–homoserine lactones (AHL) signals using S-adenosyl– L-methionine and either cellular acyl carrier protein (ACP)-coupled fatty acids or CoA–aryl/acyl moieties as progenitors. Little is known about the molecular mechanism of signal biosynthesis, the basis for substrate specificity, or the rationale for donor specificity for any LuxI member. Here, we present several cocrystal structures of BjaI, a CoAdependent LuxI homolog that represent views of enzyme complexes that exist along the reaction coordinate of signal synthesis. Complementary biophysical, structure–function, and kinetic analysis define the features that facilitate the unusual acyl conjugation with S-adenosylmethionine …

Nonlinear Oscillatory Dynamics Of The Hardening Of Calcium Phosphate Bone Cements, Vuk Uskoković, Julietta V. Rau

Pharmacy Faculty Articles and Research

Here we report on the nonlinear, oscillatory dynamics detected in the evolution of phase composition during the setting of different calcium phosphate cements, two of which evolved toward brushite and one toward hydroxyapatite as the final product. Whereas both brushite-forming cements contained iondoped b-tricalcium phosphate as the initial phase, the zinc-containing one yielded scholzite as an additional phase during setting and the oscillations between these two products were pronounced throughout the entire 80 h setting period, long after the hardening processes was over from the mechanical standpoint. Oscillations in the copper-containing system involved the amount of brushite as the main …

Cytidine Deaminase As A Molecular Target In Cancer: An Insight, Claudia A. Almaraz, Debasish Bandyopadhyay

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Cancer is one of the leading causes of death globally. Although more than 400 varieties of cancer have been reported, based on cell lines, still the actual reason of all types of cancer is not very clear. Several internal and external factors have been identified and the study is ongoing. Up to now about 73 proteins have been identified that are capable to influence directly various phases of cancer including mutation, cell proliferation, invasion, angiogenesis, and metastasis. Cytidine deaminase is one of the important proteins that is responsible for various types of cancer that includes gastric, liver, biliary tract, bladder, …

Neurological Impact Of Zinc Excess And Deficiency In Vivo, Ronald Bartzatt

Chemistry Faculty Publications

Zinc is an essential mineral that can cause pathological effects whether in excess or deficiency. Zinc is a component for over 250 enzymes and is required for cell growth, cell division, and cell function. Zinc is found in muscle and bones, with the prostrate, liver, skin, and kidney having detectable levels of zinc. However, zinc present in excess or deficiency can cause significant pathology in patients that include deleterious effects neurologically. Zinc in excess in vivo can cause focal neuronal pathology, while zinc deficiency can bring about mental lethargy, neuropsychiatric disorders, and reduced nerve conduction. Zinc is assimilated within the …

The Effect Of Hydrogen Bonding In Enhancing The Ionic Affinities Of Immobilized Monoprotic Phosphate Ligands, Spiro D. Alexandratos, Xiaoping Liu

Publications and Research

Environmental remediation requires ion-selective polymers that operate under a wide range of solution conditions. In one example, removal of trivalent and divalent metal ions from waste streams resulting from mining operations before they enter the environment requires treatment at acidic pH. The monoethyl ester phosphate ligands developed in this report operate from acidic solutions. They have been prepared on polystyrene-bound ethylene glycol, glycerol, and pentaerythritol, and it is found that intra-ligand hydrogen bonding affects their metal ion affinities. The affinity for a set of trivalent (Fe(III), Al(III), La(III), and Lu(III)) and divalent (Pb(II), Cd(II), Cu(II), and Zn(II)) ions is greater …

Biophysical And Computational Studies Of The Vcci:Vmip-Ii Complex, Anna Nguyen, Nai-Wei Kuo, Laura Showalter, Ricardo Ramos, Cynthia Dupureur, Michael Colvin, Patricia Liwang

Chemistry & Biochemistry Faculty Works

Certain viruses have the ability to subvert the mammalian immune response, including interference in the chemokine system. Poxviruses produce the chemokine binding protein vCCI (viral CC chemokine inhibitor; also called 35K), which tightly binds to CC chemokines. To facilitate the study of vCCI, we first provide a protocol to produce folded vCCI from Escherichia coli (E. coli.) It is shown here that vCCI binds with unusually high affinity to viral Macrophage Inflammatory Protein-II (vMIP-II), a chemokine analog produced by the virus, human herpesvirus 8 (HHV-8). Fluorescence anisotropy was used to investigate the vCCI:vMIP-II complex and shows that vCCI binds to …

Selective Inhibitors Of Human Mpges-1 From Structure-Based Computational Screening, Ziyuan Zhou, Yaxia Yuan, Shuo Zhou, Kai Ding, Fang Zheng, Chang-Guo Zhan

Molecular Modeling and Biopharmaceutical Center Faculty Publications

Human mPGES-1 is recognized as a promising target for next generation of anti-inflammatory drugs. Although various mPGES-1 inhibitors have been reported in literature, few have entered clinical trials and none has been proven clinically useful so far. It is highly desired for developing the next generation of therapeutics for inflammation-related diseases to design and discover novel inhibitors of mPGES-1 with new scaffolds. Here, we report the identification of a series of new, potent and selective inhibitors of human mPGES-1 with diverse scaffolds through combined computational and experimental studies. The computationally modeled binding structures of these new inhibitors with mPGES-1 provide …

Mri In Cancer: Improving Methodology For Measuring Vascular Properties And Assessing Radiation Treatment Effects In Brain, Chong Duan

Arts & Sciences Graduate Student Theses and Dissertations

Tumors cannot survive, progress and metastasize without recruiting new blood vessels. Vascular properties, including perfusion and permeability, provide valuable information for characterizing cancers and assessing therapeutic outcomes. Dynamic contrast-enhanced (DCE) MRI is a non-invasive imaging technique that affords quantitative parameters describing the underlying vascular structure of tissue. To date, the clinical application of DCE-MRI has been hampered by the lack of standardized and validated quantitative modeling approaches for data analysis.From a therapeutic perspective, radiation therapy is a central component of the standard treatment for patients with cancer. Besides killing cancer cells, radiation also induces parenchymal and stromal changes in normal …

Synthesis, Characterization, And Biological Activity Of Spherical Nucleic Acid (Sna) Constructs For Cancer Therapy And Imaging, Colin Calabrese

Arts & Sciences Graduate Student Theses and Dissertations

This dissertation focuses on the development of biocompatible oligonucleotide-based nanomaterials, known as spherical nucleic acids (SNAs), as therapeutic and diagnostic agents for intracellular gene regulation and in vivo cancer imaging by positron emission tomography (PET). SNAs consist of a nanoparticle core functionalized with a dense shell of oligonucleotides such as deoxyribonucleic acid (DNA). Detailed synthetic procedures and characterization of novel SNAs with purpose-built biocompatible core materials are described. The SNAs exhibit comparable chemical, physical and biological properties regardless of core composition. The functionalities of the SNAs were further tailored by deliberate design and chemical modification of their oligonucleotide sequences. The …

Mass Spectrometry-Based Structural Proteomics: Methodology And Application Of Fast Photochemical Oxidation Of Proteins (Fpop), Ben Niu

Arts & Sciences Graduate Student Theses and Dissertations

The dissertation will be solely focused on using mass spectrometry to characterize protein high order structures (HOS), it emphasizes the use of hydroxyl radical footprinting (FPOP) coupled to bottom-up MS approach. A detailed background information about FPOP, and the corresponding method developments as well as applications will be covered.The first chapter will be a comprehensive review regarding the FPOP. Following this, chapter 2, 3, and 4 will be focused on the method developments. Chapter 2 describes an isotope dilution GC-MS method to quantitate OH radicals in FPOP; chapter 3 describes the incorporation of Leu-enkephalin as reporter peptide for a more …

Effects Of Nucleosome Structure On Dna Photoproduct Formation And Deamination, Kesai Wang

Arts & Sciences Graduate Student Theses and Dissertations

Cyclobutane pyrimidine dimers (CPDs) are DNA photoproducts linked to skin cancer, whose mutagenicity depends in part on their frequency of formation and deamination. Nucleosomes modulate CPD formation, favoring outside facing sites, and disfavoring inward facing sites. A similar pattern of CPD formation in protein-free DNA loops suggest that DNA bending causes the modulation of photoproduct formation in nucleosomes. To systematically study the cause and effect of nucleosome structure on CPD formation and deamination, we had developed a circular permutation synthesis strategy for positioning a target sequence at different superhelix locations (SHLs) across a nucleosome in which the DNA has been …

Studies Of Magic-Size Ii-Vi Nanoclusters And Surface Exchange On Flat Colloidal Nanocrystals, Yang Zhou

Arts & Sciences Graduate Student Theses and Dissertations

This dissertation presents the isolation, characterization and reactivity of two magic size clusters, (ZnSe)34 and (CdTe)34, as well as the L-, Z- and X-type ligand exchange on the CdSe QBs or CdS QP surface.The dissertation first reports the spectroscopically observed magic-size nanoclusters (ZnSe)34 and (CdTe)34 are isolable as amine derivatives. The nanoclusters [(ZnSe)34(n-octylamine)29±6(di-n-octylamine)5±4] and [(CdTe)34(n-octylamine)4±3(di-n-pentylamine)13±3] are fully characterized by UV-visible spectroscopy, IR spectroscopy, elemental analysis, and mass spectrometry. Amine derivatives of both (ZnSe)34 and (CdTe)34 are observed to convert to the corresponding (ZnSe)13 and (CdTe)13 derivatives, indicating that the former are kinetic products and the latter thermodynamic products, under the …

Hydroformylation And Aldehyde-Water Shift Catalysis By Dirhodium Tetraphosphine Complexes, Marshall Douglas Moulis

LSU Doctoral Dissertations

The use of a unique tetraphosphine ligand (et,ph-P4) allows for the chelating of two rhodium centers to perform bimetallic coopertivity in hydroformylation reactions to better the yields the linear aldehyde product. The proposed catalyst is [Rh₂(μ-H)₂(CO)₄(rac-et,ph-P4)]²⁺ and has been studied by in situ FT-IR and NMR. When tested in a polar phasic acetone/water (30 % by vol.), the catalyst forms a monocationic system [Rh₂(μ-H)₂(CO)₄(rac-et,ph-P4)]⁺ that has an initial TOF of 26 min^-1, selectivity of 27:1 L:B, and low byproducts of …

Ab Initio Study Of The Mechanism Of Carboxylic Acids Cross-Ketonization On Monoclinic Zirconia Via Condensation To Beta-Keto Acids Followed By Decarboxylation, Alexey Ignatchenko, James P. Mcsally, Marc D. Bishop, Joshua Zweigle

Chemistry Faculty/Staff Publications

Catalytic mechanism of acetic and isobutyric acids mixture conversion into two symmetrical and one cross-ketone product on monoclinic zirconia (111) surface was extensively modeled by Density Functional Theory for periodic structures. Several options were evaluated for each mechanistic step by calculating their reaction rate constants. The best option for each kinetically relevant step was chosen by matching calculated rates of reaction with experimental values.

Four zirconium surface atoms define each catalytic site. The most favorable pathway includes condensation between surface carboxylates, one of which is enolized through alpha-hydrogen abstraction by lattice oxygen. Condensation of gas phase molecules with the enolized …

Universal Surface Engineering Of Transition Metals For Superior Electrocatalytic Hydrogen Evolution In Neutral Water, Bo You, Xuan Liu, Guoxiang Hu, Sheraz Gul, Junko Yano, De-En Jiang, Yujie Sun

Chemistry and Biochemistry Faculty Publications

The development of low-cost hybrid water splitting-biosynthetic systems that mimic natural photosynthesis to achieve solar-to-chemical conversion is of great promise for future energy demands, but often limited by the kinetically sluggish hydrogen evolution reaction (HER) on the surface of nonprecious transition metal catalysts in neutral media. It is thus highly desirable to rationally tailor the reaction interface to boost the neutral HER catalytic kinetics. Herein, we report a general surface nitrogen modification of diverse transition metals (e.g. iron, cobalt, nickel, copper, and nickel-cobalt alloy), accomplished by a facile low-temperature ammonium carbonate treatment, for significantly improved hydrogen generation from neutral water. …

(Co)Polymers Containing Boron Difluoride 3-Cyanoformazanate Complexes: Emission Enhancement Via Random Copolymerization, Joe Gilroy, Samantha Novoa

Chemistry Publications

Ring-opening metathesis polymerization was used to produce polymers bearing an asymmetrically substituted boron difluoride 3-cyanoformazanate complex. The polymers were found to retain many of the unique characteristics of molecular boron difluoride complexes of 3-cyanoformazanates, including intense light absorption at ca. 560 nm and reversible electrochemical reductions implicating the radical anion and dianion forms of the formazanate complexes in the repeating unit of the polymer backbone. The polymers were also found to be emissive, with emission maxima centred at ca. 665 nm. The monomer employed in this study had a fluorescence quantum yield of 30%, while homopolymers were weakly emissive and …

Lanthanum-Mediated Dehydrogenation Of 1- And 2-Butynes: Spectroscopy And Formation Of La(C4H4) Isomers, Wenjin Cao, Dilrukshi C. Hewage, Dong-Sheng Yang

Chemistry Faculty Publications

La atom reactions with 1-butyne and 2-butyne are carried out in a laser-vaporization molecular beam source. Both reactions yield the same La-hydrocarbon products from the dehydrogenation and carbon-carbon bond cleavage and coupling of the butynes. The dehydrogenated species La(C₄H₄) is characterized with mass-analyzed threshold ionization (MATI) spectroscopy and quantum chemical computations. The MATI spectra of La(C₄H₄) produced from the two reactions exhibit two identical transitions, each consisting of a strong origin band and several vibrational intervals. The two transitions are assigned to the ionization of two isomers: La(η⁴–CH₂CCCH …