Physical Chemistry Commons^™

Classical And Ab Initio Qm/Mm Simulations Of Bacterial Enzymes, Sajeewa Walimuni Dewage

Wayne State University Dissertations

This thesis describes analyses performed on three enzyme systems. Chapter 2, 3, and 4 involve studies carried out on the GatCAB enzyme of H. pylori and S. aureus. Since information at the electronic level was not required for these studies, sampling of the configuration space carried out at the molecular mechanics level was adequate. In Chapter 2, the snapshots sampled using MD were used as input for average correlation difference calculations and average RMSD difference calculations to ascertain the existence of a communication pathway between two subunits of GatCAB. Experimental and computational results obtained, suggest the existence of a communication …

Application Of Lipid Styryl Dye For Staining Intracytoplasmic Membranes In Gram-Negative Bacteria, Theodore J. Hammer

Williams Honors College, Honors Research Projects

Intracytoplasmic membranes are structures that form within cells which help facilitate a variety of different metabolic processes. This feature of intracellular membranes makes them particularly valuable for studying compartmentalization and cell dynamics in bacteria. In the past, transmission electron microscopy has been the primary method for imaging bacteria with intracytoplasmic membranes. Because transmission electron microscopy takes images of a cell in fixed slices, it’s impossible to follow a cell’s growth and development over time. Fluorescence microscopy is a particularly effective method of measurement that can combat these issues when evaluating live bacterial cells. Here, standard biochemical laboratory procedures were used …

Extremely Strong Tubular Stacking Of Aromatic Oligoamide Macrocycles, Mark A. Kline, Xiaoxi Wei, Ian J. Horner, Rui Liu, Shuang Chen, Si Chen, Ka Yi Yung, Kazuhiro Yamato, Zhonghou Cai, Frank V. Bright, Xiao Cheng Zeng, Bing Gong

Xiao Cheng Zeng Publications

As the third-generation rigid macrocycles evolved from progenitor 1, cyclic aromatic oligoamides 3, with a backbone of reduced constraint, exhibit extremely strong stacking with an astoundingly high affinity (estimated lower limit of K_dimer > 10¹³ M^–1 in CHCl₃), which leads to dispersed tubular stacks that undergo further assembly in solution. Computational study reveals a very large binding energy (–49.77 kcal mol^–1) and indicates highly cooperative local dipole interactions that account for the observed strength and directionality for the stacking of 3. In the solid-state, X-ray diffraction (XRD) confirms that the aggregation of 3 results …

Cytotoxic Activity Of Triazole-Containing Alkyl Β-D-Glucopyranosides On A Human T-Cell Leukemia Cell Line, E. Davis Oldham, Larissa M. Nunes, Armando Varela-Ramirez, Stephen E. Rankin, Barbara L. Knutson, Renato J. Aguilera, Hans-Joachim Lehmler

Chemistry and Physics

Simple glycoside surfactants represent a class of chemicals that are produced from renewable raw materials. They are considered to be environmentally safe and, therefore, are increasingly used as pharmaceuticals, detergents, and personal care products. Although they display low to moderate toxicity in cells in culture, the underlying mechanisms of surfactant-mediated cytotoxicity are poorly investigated.

On The Catalytic Activity Of Palladium Nanoparticles-Based Anodes Towards Formic Acid Electro-Oxidation: Effect Of Electrodeposition Potential, Islam M. Al-Akraa Dr., Ahmad M. Mohammad Prof, Mohamed S. El-Deab Prof, Bahgat E. El-Anadouli Prof

Chemical Engineering

In this investigation, the catalytic activity of palladium nanoparticles (PdNPs)-modified glassy carbon (GC) (simply noted as PdNPs/GC) electrodes towards the formic acid electro-oxidation (FAO) was investigated. The deposition of PdNPs on the GC substrate was carried out by a potentiostatic technique at different potentials and the corresponding influence on the particles size and crystal structure of PdNPs as well as the catalytic activity towards FAO was studied. Scanning electron microscopy (SEM) demonstrated the deposition of PdNPs in spherical shapes and the average particle size of PdNPs deposited at a potential of 0 V vs. Ag/AgCl/KCl(sat.) was the smallest (ca. 8 …

Advances In Direct Formic Acid Fuel Cells: Fabrication Of Efficient Ir/Pd Nanocatalysts For Formic Acid Electro-Oxidation, Islam M. Al-Akraa, Ahmad M. Mohammad, Mohamed S. El-Deab Prof, Bahgat E. El-Anadouli Prof

Chemical Engineering

No abstract provided.

Experimental And Computational Investigation Of Selected Β-Hydroxy Carbenes, Joseph D. Deangelo

Honors Theses

The photolytic precursor to the sterically hindered β-bis(tert)-butanol carbene, 3-(1a,9b-dihydro-1H-cyclopropa[l]phenanthren-1-yl)-2,2,4,4-tetramethylpentan-3-ol was prepared in three steps from phenanthrene. Photolysis of the precursor generates the desired β-hydroxy carbene, an intermediate, which subsequently rearranges into two different observed products from an intramolecular C-H insertion and alkyl shift. Four intramolecular mechanisms were ultimately considered to account for the possible rearrangement pathways. Computational studies using density functional theory are also presented.

In addition, the photolytic precursors to two cyclic β-hydroxy carbenes, 1-(1a,9b-dihydro-1H-cyclopropa[l]phenanthren-1-yl)cyclopropan-1-ol and 1-(1a,9b-dihydro-1H-cyclopropa[l]phenanthren-1-yl)cyclobutan-1-ol, were also prepared through different synthetic routes from phenanthrene. …

The Role Of Hydroxyl Channel In Defining Selected Physicochemical Peculiarities Exhibited By Hydroxyapatite, Vuk Uskoković

Pharmacy Faculty Articles and Research

Mysteries surrounding the most important mineral for the vertebrate biology, hydroxyapatite, are many. Perhaps the Greek root of its name, απαταo, meaning ‘to deceive’ and given to its mineral form by the early gem collectors who confused it with more precious stones, is still applicable today, though in a different connotation, descriptive of a number of physicochemical peculiarities exhibited by it. Comparable to water as the epitome of peculiarities in the realm of liquids, hydroxyapatite can serve as a paradigm for peculiarities in the world of solids. Ten of the peculiar properties of hydroxyapatite are sketched in this review piece, …

A Molecular-Level View Of The Physical Stability Of Amorphous Solid Dispersions, Xiaoda Yuan

Theses and Dissertations--Pharmacy

Many pharmaceutical compounds being developed in recent years are poorly soluble in water. This has led to insufficient oral bioavailability of many compounds in vitro. The amorphous formulation is one of the promising techniques to increase the oral bioavailability of these poorly water-soluble compounds. However, an amorphous drug substance is inherently unstable because it is a high energy form. In order to increase the physical stability, the amorphous drug is often formulated with a suitable polymer to form an amorphous solid dispersion. Previous research has suggested that the formation of an intimately mixed drug-polymer mixture contributes to the stabilization …

The Spectroscopic Characterization Of Newly Developed Emissive Materials And The Effects Of Environment On Their Photophysical Properties, Louis Edward Mcnamara

Electronic Theses and Dissertations

The development of new materials capable of efficient charge transfer and energy storage has become increasingly important in many areas of modern chemical research. This is especially true for the development of emissive optoelectronic devices and in the field of solar to electric energy conversion. The characterization of the photophysical properties of new molecular systems for these applications has become critical in the design and development of these materials. Many molecular building blocks have been developed and understanding the properties of these molecules at a fundamental level is essential for their successful implementation and future engineering. This dissertation focuses on …

Note: Improved Line Strengths Of Rovibrational And Rotational Transitions Within The X3Σ⁻ Ground State Of Nh, James S.A. Brooke, Peter F. Bernath, Colin M. Western

Chemistry & Biochemistry Faculty Publications

Recently, a line list including positions and transition strengths was published for the NH X³Σ⁻ rovibrational and rotational transitions. The calculation of the transition strengths requires a conversion of transition matrix elements from Hund’s case (b) to (a). The method of this conversion has recently been improved during other work on the OH X²Π rovibrational transitions, by removing an approximation that was present previously. The adjusted method has been applied to the NH line list, resulting in more accurate transition strengths. An updated line list is presented that contains all possible transitions with v′ and …

Electronic Structures And Electronic Spectra Of All-Boron Fullerene B40, Rongxing He, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

This study is motivated by the recent discovery of the first all-boron fullerene analogue, a B₄₀ cluster with D_2d point-group symmetry, dubbed borospherene (Nat. Chem., 2014, 6, 727). Insight into the electronic structures and spectral properties of B₄₀ is timely and important to understand the borospherene and the transition from open-ended plate or ribbon-like structures to a hollow-cage structure at B₄₀. Optimized geometries of borospherene B₄₀ for both the ground state and the first excited state allow us to compute spectral properties including UV-vis absorption, infrared (IR) and Raman spectra. Highly resolved absorption and …

Spectroscopic Characterization Of Lanthanum-Mediated Hydrocarbon Activation, Dilrukshi C. Hewage

Theses and Dissertations--Chemistry

Lanthanum (La)-promoted hydrocarbon activation reactions were carried out in a laser vaporization metal cluster beam source. Reaction products were identified by time-of-flight mass spectrometry, and the approximate ionization thresholds of La-hydrocarbon complexes were located with photoionization efficiency spectroscopy. The accurate ionization energies and vibrational frequencies of the La complexes were measured using mass analyzed threshold ionization (MATI) spectroscopy. Their molecular structures and electronic states were investigated by combing the MATI spectroscopic measurements with quantum chemical and Franck-Condon factor calculations.

In this dissertation, La-mediated C-H and C-C bond activation reactions were investigated for several small alkynes (acetylene, propyne) and alkenes (propene, …

Dispersant Effects On Zinc Dialkyldithiophosphate (Zddp) Tribofilm Structure And Composition, Makaye Tabibi

Theses and Dissertations

For decades, global regulations and government mandates have driven technological developments to improve vehicle fuel economy. Tribological components found in all automotive engines contain metal-on-metal contact zones that may result in increased friction and wear, reducing overall engine efficiency. Lubricant additives such as antiwear and friction modifying components are added to motor oils to prevent some of the damages that may occur at contact zones and improve friction. The effects of other additive components, such as dispersants, that are prevalent in a lubricant additive package on the anti-wear layer remain relatively unknown. Polyisobutenyl Succinimide (PIBSI) dispersants were evaluated for their …

Gas-Phase Reactions And Mechanistic Details Of Gold, Silver, And Iridium Complexes, Christopher Swift

Theses and Dissertations

The ever increasing demand for more efficient and environmentally benign routes for synthesizing target compounds, has led to the use of organometallic catalysts. This demand has created the need to understand the mechanistic details that are at work in these organometallic catalytic cycles. Along with this, there is a demand for new organometallic catalysts that are tailored for specific transformations. This presents a myriad of challenges for organometallic chemists. Unfortunately, it is often difficult to gain an understanding of the reaction mechanisms at work when the intermediates are too short lived to be observed in the condensed phase. It is …

Colloidal Synthesis And Optical Characterizations Of Semiconductor Nanocrystals From Nontoxic Elements, Minh Q. Ho

Theses and Dissertations

To date, the search efforts have shifted from the toxic II-VI, III-V and IV-VI semiconductors to more environmentally friendly materials. Among Group II-V semiconductors, Zn₃P₂ has shown to be a more benign option, similar to Group IV (Ge, Si) materials, for future applications in photovoltaics and optoelectronics. This work is dedicated to the development of wet-chemical synthetic routes of (1) Zn₃P₂ and (2) Group IV (Ge, Si, Si_1-xGe_x) nanocrystals with precise control over composition, crystal structure, size and dispersity by adjusting different reaction parameters such as temperature, time and solvent …

Computational Investigations Of Potential Energy Function Development For Metal-Organic Framework Simulations, Metal Carbenes, And Chemical Warfare Agents, Christian R. Cioce

USF Tampa Graduate Theses and Dissertations

Metal-Organic Frameworks (MOFs) are three-dimensional porous nanomaterials with a variety of applications, including catalysis, gas storage and separation, and sustainable energy. Their potential as air filtration systems is of interest for designer carbon capture materials. The chemical constituents (i.e. organic ligands) can be functionalized to create rationally designed CO2 sequestration platforms, for example. Hardware and software alike at the bleeding edge of supercomputing are utilized for designing first principles-based molecular models for the simulation of gas sorption in these frameworks. The classical potentials developed herein are named PHAST -- Potentials with High Accuracy, Speed, and Transferability, and thus are designed …

The Effect Of Milling Additives On Powder Properties And Sintered Body Microstructure Of Nio, L. Jay Deiner, Michael A. Rottmayer, Bryan C. Eigenbrodt

Publications and Research

The evolution of powder particle size, crystal structure, and surface chemistry was evaluated for micron scale NiO powders subjected to impact milling with commonly employed milling additives: methanol, Vertrel XF, and amorphous carbon. The effect of the different comminution protocols on sintered body microstructure was evaluated for high temperature sintering in inert atmosphere (N2). X-ray photoelectron spectroscopy showed that NiO powder surface chemistry is surprisingly sensitive to milling additive choice. In particular, the proportion of powder surface defect sites varied with additive, and methanol left an alcohol or alkoxy residue even after drying. Upon sintering to intermediate temperatures (1100 ℃), …

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 …

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 …

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 …

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 …

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 …

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 …

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.

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.

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 …

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 …

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.

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 …