Physical Sciences and Mathematics Commons^™

In Search Of The X2Bo And X2Bs (X = H, F) Free Radicals: Ab Initio Studies Of Their Spectroscopic Signatures, Dennis J. Clouthier

Chemistry Faculty Publications

The F₂BO free radical is a known, although little studied, species but similar X₂BY (X = H, D, F; Y = O, S) molecules are largely unknown. High level ab initio methods have been used to predict the molecular structures, vibrational frequencies (in cm^-1), and relative energies of the ground and first two excited electronic states of these free radicals, as an aid to their eventual spectroscopic identification. The chosen theoretical methods and basis sets were tested on F₂BO and found to give good agreement with the known experimental quantities. In particular, …

Chalcogen Bonds In Complexes Of Soxy (X, Y = F, Cl) With Nitrogen Bases, Luis Miguel Azofra, Ibon Alkorta, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

SOF2, SOFCl, and SOCl2 were each paired with a series of N bases. The potential energy surface of the binary complexes were characterized by MP2 calculations with double and triple-ξ basis sets, extrapolated to complete sets. The most stable configurations contained a S···N chalcogen bond with interaction energies as high as 6.8 kcal/mol. These structures are stabilized by a Nlp→σ*(S−Z) electron transfer (Z = O, F, Cl), complemented by Coulombicattraction of N to theσ-hole opposite the Z atom. N···S−F and N···S−Cl chalcogen bonds are stronger than N···S = O interactions.Formation of each chalcogen bond elongates all of the internalcovalent bonds …

Direct Electrochemistry And Glucose Biosensing Of Glucose Oxidase-Gold Nanoparticles Composite Synthesized By Enzyme Method, Fang He, Xiao-Li Qin, Ying-Chun Fu, Chao Chen, Qing-Ji Xie, Shou-Zhuo Yao

Journal of Electrochemistry

Glucose oxidase (GOx)-gold nanoparticles (AuNPs) composite was synthesized by the one-pot enzyme reaction in the mixture solution of NaAuCl₄, GOx and glucose, and a Nafion/GOx-AuNPs/glassy carbon electrode was fabricated by the cast-coating method to examine the direct electrochemistry of GOx and the biosensing performance on this electrode. Such a GOx-AuNPs composite showed good direct-electrochemistry activity and bioactivity of GOx, probably because the enzyme-mediated AuNPs are close to the redox active centers of GOx. This enzyme electrode exhibited a linear amperometric response to glucose concentration (0.54 mmol·L^-1) at -0.4 V (vs. SCE), and a detection limit of …

Electrochemiluminescence Imaging Focusing: Array Analysis And Visualization Of Latent Fingerprints, Zhen-Yu Zhou, Lin-Ru Xu, Bin Su

Journal of Electrochemistry

Electrochemiluminescence (ECL) imaging, as a novel and powerful analytical method, possesses many distinct advantages, including simplicity, high controllability, high-throughput and visualization. In recent years, it has been used in developing portable and miniaturized ECL sensor, and made remarkable achievements. In this review, the progress of ECL imaging, focusing on array analysis and visualization of latent fingerprints, has been introduced briefly based on our recent investigations and an attempt has been made to propose the future research trend.

Enzyme-Based Dna Electrochemical Biosensors: Recent Trends, Chun-Shui Lin, Yi-Ru Wang, Xi Chen

Journal of Electrochemistry

DNA electrochemical sensors have greatly promoted the development of biosensors for their high sensitivity, good selectivity, short analysis time and low cost. To further improve the detection sensitivity and selectivity, protein enzymes, functional nucleic acid enzymes etc. are often used due to the advantages of high catalytic efficiency and specificity. This review demonstrates the research progress of electrochemical sensors based on enzymatic amplification and analyses some existing problems of electrochemical sensors.

Synthesis Of Namnpo4 By Spraying Drying-High Temperature Sintering And Its Electrochemical Performance, Xiao-Chen Lin, Xiao-Biao Wu, Xu Hou, Yong Yang

Journal of Electrochemistry

As a cathode material for sodium ion batteries, NaMnPO₄/C nanocomposite is successfully synthesized by the combination of spraying drying and high temperature sintering methods. The crystal structure of the as-synthesized phosphate material is confirmed as the natrophilite NaMnPO₄, which possesses orthorhombic symmetry and Pmnb space group. It is shown that the precursors are hollow spherical particles and the obtained product consists of micro-scaled secondary particles, which are composed of NaMnPO₄ nanocrystallites (tens of nanometres) and amorphous carbon networks. The ionic and electronic conductivities of NaMnPO₄ are both effectively enhanced with the help of this …

Kinetics And Mechanism Of Acidic Electroless Ni-P Plating, Zhi-Hui Xie, Gang Yu

Journal of Electrochemistry

Electrochemical behaviors of electroless nickel (EN) plating in three systems, namely, cathodic, anodic and complete bath solutions were investigated by polarization methods. The curves in the complete baths were not entirely consistent with those expected from a combination of the anodic and cathodic polarization curves, which implies that the anodic and cathodic reactions of the EN plating are interdependent. The effects of concentration of nickel ions, hypophosphite and pH on the polarization parameter and deposition rate in a complete bath were also discussed and compared by performing electrochemical and gravimetrical measurements. Based on these variations in the deposition potential and …

Electrochemical Applications Of Single-Walled Carbon Nanohorns, Su-Ping Li, Huai-Min Guan, Shu-Yun Zhu, Muhammad Rehan Hassan Shah Gilani, Saima Hanif, Guo-Bao Xu, Yue-Jin Tong

Journal of Electrochemistry

Single-wall carbon nanohorns (SWCNHs) have unique properties, such as a large specific surface area, good electrical conductivity and biocompatibility. It has been widely utilized in many fields. In the present review, the progress in electrochemistry study of SWCNHs has been summarized and the future research trends have been proposed.

Preparation Of Surface Molecularly Imprinted Magnetic Nanoparticles For Hemoglobin Sensing, Chun-Fang Huang, Gui-Hong Yao, Jian-Ding Qiu

Journal of Electrochemistry

Surface molecularly imprinted magnetic nanoparticles (NPs) were prepared by employing dopamine (DA) as a functional monomer, hemoglobin (Hb) as a template, H₂PtCl₆ as an oxidant triggered DA polymerization on the surface of the Fe₃O₄ NPs. The Hb and the formed platinum nanoparticles (PtNPs) were embedded into the polydopamine (PDA). After removal of the Hb, the surface molecularly imprinted magnetic nanoparticles (imprinted Fe₃O₄/PDA-PtNPs) were formed, and then simply immobilized on the magnetic glassy carbon electrode (imprinted Fe₃O₄/PDA-PtNPs/MGCE) for Hb sensing. The imprinted Fe₃O₄/PDA-PtNPs …

Comparison In Factors Affecting Electrochemical Properties Of Thermal-Reduced Graphene Oxide For Supercapacitors, Peng Xiao, Da-Hui Wang, Jun-Wei Lang

Journal of Electrochemistry

In this paper, thermal-reduced graphene oxide (T-RGO) materials are synthesized by modified Hummer’s method, followed by thermal reduction under argon atmosphere at different temperatures. Electrochemical investigations show that, for T-RGO electrodes, good electrical conductivity is necessary and the surface functional groups play more significant role than the specific surface area in determining the electrochemical capacitance. The T-RGO obtained at 900 °C (T-RGO900) with a relatively high Brunauer-Emmett-Teller (BET) surface area (314 m²·g^-1) and a high electrical conductivity (2421 S·m^-1) shows a low specific capacitance of 56 F·g^-1. In comparison, the T-RGO obtained …

One-Step Synthesis Of Pani/Nihcf Hybrid Film Using Unipolar Pulse Electrodeposition And Its Electrocatalytic Reduction Performance For H2O2 Detection, Sen-Liang Liao, Xiu-Min Li, Xiao-Gang Hao, Yan-Hong Wang, Chun-Feng Xue, Yong-Hong Wang

Journal of Electrochemistry

Organic–inorganic hybrid films composed of polyaniline/nickel hexacyanoferrate (PANI/NiHCF) were fabricated on platinum substrates using unipolar pulse one-step electrodeposition. The deposition mechanism of hybrid film was proposed: Due to high potential of unipolar pulse electrodeposition, which avoided the reduction of Fe(CN)₆^3-, the films with high electrocatalytic property and “insoluble” form of NiHCF were achieved. The morphology and composition of PANI/NiHCF hybrid film were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and Fourier transform infrared spectroscopy (FT-IR). The effect of pulse potential on the electrochemical performance of hybrid film was investigated in detail. Results showed that …

Nafion/Thionine/Platinum Nanowires-Modified Electrode For Electrocatalyzing Glucose, Yu-Ping Lin, You-Xiu Lin, Qian Zhou, Dian-Ping Tang

Journal of Electrochemistry

A new amperometric biosensor based on Nafion, thionine and latinum nanowires was developed for sensitive detection of glucose. Initially, positively charged thionine molecules were immobilized onto the surface of Nafion-modified glassy carbon electrode through the interaction between -SO₃^- and -NH₃⁺, and glucose oxidase was then assembled on the modified electrode by using platinum nanowires as the cross-linkage. The preparation process was characterized by using cyclic voltammetry. Two enzymatic biosensors modified with and without platinum nanowires were used for the detection of glucose, and the improved analytical properties were obtained with platinum nanowires. Experimental results indicated …

Platinum Hollow Nanospheres With Different Sizes: Controllable Synthesis And Electrocatalytic Oxidation Toward Methanol, Xuan Lin, Mei-Qin Cheng, Zhong-Jin Shang, Ting Xiong, Xian-Tu Zhang, Wei Tian, Jian-Yun Lin, Qi-Ling Zhong, Bin Ren

Journal of Electrochemistry

The selenium (Se) templates and hollow platinum (Pthollow) nanospheres with different sizes were controllably synthesized by adjusting the concentration of sodium dodecyl sulphonate (SDSN) (CSDSN, μmol·L-1) which was used as a surfactant. Accordingly, the Pthollow nanospheres modified glassy carbon (GC) electrode (Pthollow/GC) was prepared. The morphology and composition of Pthollow nanospheres were characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), energy dispersive X-ray spectroscopy (EDX), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) and X-ray diffraction (XRD) techniques. The electrocatalytic activities of Pthollow/GC and electrodeposited Pt nanoparticles modified glassy carbon electrode (Ptnano/GC) toward methanol oxidation …

Resolve Mono-Electronic Process In The Voltammetric Behaviors Of Multi-Redox Bis-Coenzyme Q0, Hao Zhou, Yi-Tao Long

Journal of Electrochemistry

A widely held concept in electrochemistry is that truly elementary electron-transfer reactions always involve the exchange of one electron, therefore, an overall process involving a change of n electrons must involve n distinct electron-transfer steps. It is highly desirable to resolve multiple-step electron transfer reactions into each electron transfer step. The electrochemical behaviors of coenzyme Q₀ and methylene-bridged Bis-coenzyme Q₀ were investigated by cyclic voltammetry and square wave voltammetry in nonaqueous dichloromethane containing 0.15 mol·L^-1 Bu₄NClO₄ as the supporting electrolyte. The redox reaction of coenzyme Q₀ is well described as two chemically reversible …

Density Functional Theory Study On The Structures Of Solvent-Ion In The Electrolyte Of Lithium Ion Battery, Li-Dan Xing, Ru Yang, Xian-Wen Tang, Wen-Na Huang, Qi-Feng Liu, Qi-Peng Yu, Wei-Shan Li

Journal of Electrochemistry

In this work, the possible structures of solvent-ion complex, resulting from the electrostatic interaction in the propylene carbonate (PC) base electrolyte of lithium ion battery, have been investigated using the density functional theory. The calculated results show that the structure of solvent-ion complex depends on the solvent number. In the PC base electrolyte, maximum number of PC solvents that coexist in the Li⁺-solvent sheath is four. Additionally, the salt anion exists in a complex with the positively charged alkyl group of PC rather than in a free state. The calculated results give a good explanation to the reported …

Real-Time Kinetic Studies Of Bacillus Subtilis Oxalate Decarboxylase And Ceriporiopsis Subvermispora Oxalate Oxidase Using Luminescent Oxygen Sensor, Laura Molina, Thomas Goodall, Umar Twahir, Ellen W. Moomaw

Faculty and Research Publications

Oxalate decarboxylase (OxDC), an enzyme of the bicupin superfamily, catalyzes the decomposition of oxalate into carbon dioxide and formate at an optimal pH of 4.3 in the presence of oxygen. However, about 0.2% of all reactions occur through an oxidase mechanism that consumes oxygen while producing two equivalents of carbon dioxide and one equivalent of hydrogen peroxide. The kinetics of oxidase activity were studied by measuring the consumption of dissolved oxygen over time using a luminescent oxygen sensor. We describe the implementation of and improvements to the oxygen consumption assay. The oxidase activity of wild type OxDC was compared to …

Farmer To Pharmacist: Curcumin As An Anti-Invasive And Antimetastatic Agent For The Treatment Of Cancer, Debasish Bandyopadhyay

Chemistry Faculty Publications and Presentations

A huge number of compounds are widely distributed in nature and many of these possess medicinal/biological/pharmacological activity. Curcumin, a polyphenol derived from the rhizomes (underground stems) of Curcuma longa Linn (a member of the ginger family, commonly known as turmeric) is a culinary spice and therapeutic used in India for thousands of years to induce color and flavor in food as well as to treat a wide array of diseases. The origin of turmeric as spice and folklore medicine is so old that it is lost in legend. Curcumin has many beneficial pharmacological effects which includes, but are not limited …

Can Acute Dermal Systemic Toxicity Tests Be Replaced With Oral Tests? A Comparison Of Route-Specific Systemic Toxicity And Hazard Classifications Under The Globally Harmonized System Of Classification And Labelling Of Chemicals (Ghs), Nigel P. Moore, David J. Andrew, Donald L. Bjerke, Stuart Creton, David Dreher, Thomas Holmes, Pilar Prieto, Troy Seidle, Tim G. Rowan

Troy Seidle, PhD

Acute systemic toxicity data (LD50 values) and hazard classifications derived in the rat following oral administration and dermal application have been analysed to examine whether or not orally-derived hazard classification or LD50 values can be used to determine dermal hazard classification. Comparing the oral and dermal classifications for 335 substances derived from oral and dermal LD50 values respectively revealed 17% concordance, and indicated that 7% of substances would be classified less severely while 76% would be classified more severely if oral classifications were applied directly to the dermal route. In contrast, applying the oral LD50 values within the dermal classification …

The Development Of New Concepts For Assessing Reproductive Toxicity Applicable To Large Scale Toxicological Programmes, S. Bremer, C. Pellizzer, S. Hoffmann, T. Seidle, T. Hartung

Troy Seidle, PhD

Large scale toxicological testing programmes which are currently ongoing such as the new European chemical legislation REACH require the development of new integrated testing strategies rather than applying traditional testing schemes to thousands of chemicals. The current practice of requiring in vivo testing for every possible adverse effect endanger the success of these programmes due (i) to limited testing facilities and sufficient capacity of scientific/technical knowledge for reproductive toxicity; (ii) an unacceptable number of laboratory animals involved (iii) an intolerable number of chemicals classified as false positive.

A key aspect of the implementation of new testing strategies is the determination …

Enzymes From Fungal And Plant Origin Required For Chemical Diversification Of Insecticidal Loline Alkaloids In Grass-Epichloë Symbiota, Juan Pan, Minakshi Bhardwaj, Padmaja Nagabhyru, Robert B. Grossman, Christopher L. Schardl

Chemistry Faculty Publications

The lolines are a class of bioprotective alkaloids that are produced by Epichloë species, fungal endophytes of grasses. These alkaloids are saturated 1-aminopyrrolizidines with a C2 to C7 ether bridge, and are structurally differentiated by the various modifications of the 1-amino group: -NH₂ (norloline), -NHCH₃ (loline), -N(CH₃)₂ (N-methylloline), -N(CH₃)Ac (N-acetylloline), -NHAc (N-acetylnorloline), and -N(CH₃)CHO (N-formylloline). Other than the LolP cytochrome P450, which is required for conversion of N-methylloline to N-formylloline, the enzymatic steps for loline diversification have not yet been established. …

Investigating The Links Between Ozone And Organic Aerosol Chemistry In A Biomass Burning Plume From A Prescribed Fire In California Chaparral, M. J. Alvarado, C. R. Lonsdale, Robert Yokelson, S. K. Akagi, H. Coe, J. S. Craven, E. V. Fischer, G. R. Mcmeeking, J. H. Seinfeld, T. Soni, J. W. Taylor, D. R. Weise, C. E. Wold

Chemistry and Biochemistry Faculty Publications

Within minutes after emission, rapid, complex photochemistry within a biomass burning smoke plume can cause large changes in the concentrations of ozone (O₃) and organic aerosol (OA). Being able to understand and simulate this rapid chemical evolution under a wide variety of conditions is a critical part of forecasting the impact of these fires on air quality, atmospheric composition, and climate. Here we use version 2.1 of the Aerosol Simulation Program (ASP) to simulate the evolution of O₃ and secondary organic aerosol (SOA) within a young biomass burning smoke plume from the Williams prescribed burn in chaparral, …

Studies Directed Toward The Synthesis Of Amphibian Alkaloids Via Iridium Catalyzed N-Heterocyclization Reactions, Kiran Kumar Thota

University of New Orleans Theses and Dissertations

The pyrrolidine and piperidine ring systems are present in a variety of different classes of amphibian alkaloids. We have found the iridium catalyzed N-heterocylization reaction of diols with amines to be very useful for the construction of novel pyrrolidine, piperidine and piperazine derivatives. The scope and utility of the iridium catalyzed N-heterocyclization reaction for the construction of novel anuran scaffolds using amino diols and triols are presented. Studies directed towards the total synthesis of 4,6-disubstituted quinolizidine and (±)-epiquinamide are discussed.

The second study is focused on the selective conversion of terminal dienes to primary diols. This conversion has always had …

Incorporation Of Charge Transfer Into Classical Molecular Dynamics Force Fields With Applications In Physical Chemistry., Marielle Soniat

University of New Orleans Theses and Dissertations

The presence of charge transfer (CT) interactions is clear in a variety of systems. In CT, some electron density is shifted from one molecule to another (non-bonded) molecule. The importance of this CT interaction is unclear. Previous attempts to look at the conse- quences of CT required the use of ab initio molecular dynamics (AIMD), a computationally intensive method. Herein, a method for including CT in force field (FF) simulations is described. It is efficient, produces charges in agreement with AIMD, and prevents long- ranged CT.

This CT MD method has been applied to monatomic ions in water. When solvated, …

Template-Assisted Fabrication Of Ferromagnetic Nanomaterials, Jagnyaseni Tripathy

University of New Orleans Theses and Dissertations

Abstract

Template assisted deposition was used to produce various nanomaterials including simple nanowires, nanorods, multi-segmented metal nanowires, core-shell nanowires, alloy and polymer wires and tubes. Anodized aluminum oxide (AAO) membranes were used as templates for the growth of the various structures using an electrochemical deposition method and also by wetting the porous templates. In the electrochemical deposition method, the pore size of the templates affects the rate of synthesis and the structures of the nanomaterials while in the wetting method, the viscosity and reaction time in the polymer solution influence the structures of the nanomaterials.

A conventional two-step anodization procedure …

Total Synthesis Of Clavatadine A, Stephanie J. Conn, Shannon M. Vreeland, Alexandra N. Wexler, Rebecca H. Pouwer, Ronald J. Quinn, Stephen Chamberland

All Faculty Scholarship for the College of the Sciences

The first total synthesis of the potent and selective human blood coagulation factor XIa inhibitor clavatadine A (1) is described. Direct, early-stage guanidinylation enabled rapid, convergent access to an immediate clavatadine A precursor. Concomitant lactone hydrolysis and guanidine deprotection with aqueous acid cleanly provided clavatadine A (1) in only four steps (longest linear sequence, 41–43% overall yield).

Production And Applications Of Formaldehyde-Free Phenolic Resins Using 5-Hydroxymethylfurfural Derived From Glucose In-Situ, Yongsheng Zhang

Electronic Thesis and Dissertation Repository

The phenol-formaldehyde (PF) resin manufacturing industry is facing a growing challenge with respect to concerns over human health, due to the use of carcinogenic formaldehyde and sustainability due to the use of petroleum-based phenol in PF resin manufacture. Glucose and its derivative, 5-hydroxymethylfurfural (5-HMF), have proven to be potential substitutes for formaldehyde in the synthesis of phenolic novolac resins.

This thesis investigated a number of glucose and 5-HMF resin systems including the curing of phenol-glucose novolac resin (PG) with a bis-phenol-A type epoxy. The curing process was modeled according to the Sestak-Berggren equation (S, B) using Málek methods. This was …

The Effect Of Ph And Counterion On The Size Distribution And Luminescence Lifetime Of Terbium-Doped Lanthanum Nanocrystals, Sarah Baker

Undergraduate Honors Theses

In recent years, nanoparticles have been applied to and have gained prevalence in fields such as chemistry, biology, the medical sciences, and biotechnology,and have attracted the attention of medical researchers as potential microscopic drug delivery systems in the human body. In particular, nanoparticles made with the lanthanides have shown themselves to be useful to many biological applications due to their unique luminescent properties. It is crucial to determine optimum synthetic parameters so that nanoparticles are both small enough to pass through the kidneys and also have the ability to attach different functional groups so that they may be relevant to …

Poly-3-Hexylthiophene Nanorods As A Donor For Organic Photovoltaics, Dharmesh Patel

Mahurin Honors College Capstone Experience/Thesis Projects

Poly-3-hexylthiophene functionalized silsesquioxane nanorods (P3HT-NRs) were prepared by direct hydrolysis and condensation of P3HT-silane precursor using the modified Stöber method. The silane precursor was stirred in a mixture of two solvents in the presence of a base under room temperature for three different reaction times. The size, shape, and morphology of these novel nanostructures were visualized using the transmission electron microscope (TEM) and scanning electron microscope (SEM). The composition of the P3HT-NRs was confirmed by FTIR and its silane by proton NMR. Future work will focus on evaluating photovoltaic performance of these nanorods as a donor for organic photovoltaics.

Study Of Ii-Vi Colloidal Semiconductor Magic-Size Nanoclusters And Crystalline Quantum Platelets, Yuanyuan Wang

Arts & Sciences Electronic Theses and Dissertations

The main objective of this project is to prepare and isolate the smallest, discrete, magic-size nanoclusters of cadmium selenide (CdSe) and to grow crystalline, wurtzite CdSe quantum platelets (QPs) at room temperature. The achievement of these goals enables us to provide a general synthesis of II-VI semiconductor magic-size nanoclusters and low-temperature routes to well-passivated nanocrystals having a range of compositions and morphologies.

The magic-size nanocluster (CdSe)13 is grown in a lamellar-bilayer soft template at room temperature. The results described in this thesis strongly suggest that [(CdSe)13(n-octylamine)13] is the most thermodynamically stable nanocluster and serves as a key intermediate in the …

Universal Two-Electron Correlation Operator On Excited States, Bryan Thomas Nichols

Theses and Dissertations

Excited states of chemical systems are extremely important in understanding spectra, chemical phenomena, as well as how a particular compound behaves in reactions. Computationally, excited states are normally very expensive to calculate. The difficulty in calculating these states with wavefunction based methods can be mainly attributed to the calculation of large multi-determinant wavefunctions. One reason to use a complicated multi-determinant wavefunction is to include some of the effects of correlation energy. The quantity of correlation energy can most simply be defined as the reduction in energy caused by any two or more electrons trying to avoid each other. The most …