Physical Chemistry Commons^™

Mitochondrial Energetics With Transmembrane Electrostatically Localized Protons: Do We Have A Thermotrophic Feature?, James Weifu Lee

Chemistry & Biochemistry Faculty Publications

Transmembrane electrostatically localized protons (TELP) theory has been recently recognized as an important addition over the classic Mitchell’s chemiosmosis; thus, the proton motive force (pmf) is largely contributed from TELP near the membrane. As an extension to this theory, a novel phenomenon of mitochondrial thermotrophic function is now characterized by biophysical analyses of pmf in relation to the TELP concentrations at the liquid-membrane interface. This leads to the conclusion that the oxidative phosphorylation also utilizes environmental heat energy associated with the thermal kinetic energy (k_BT) of TELP in mitochondria. The local pmf is now calculated to be in …

Relating Detonation Parameters To The Detonation Synthesis Of Nanomaterials, Martin Langenderfer

Doctoral Dissertations

“This research investigates the physical and chemical processes that contribute to the detonation synthesis of silicon carbide nanoparticles. Bulk production of SiC nanoparticles through detonation is possible due to pressures achieved over 20 GPa and temperatures over 2000 K as well as quenching rates in excess of 13 billion K/second. These conditions catalyze reaction and bottom-up molecular growth while retaining particles < 100 nm in diameter. In this work, detonation synthesis of SiC was demonstrated by incorporation of polycarbosilane, an SiC precursor material, into an RDX/TNT explosive matrix prior to detonation. Detonation Synthesis of SiC was also accomplished by reacting elemental silicon with carbon liberated by the detonation of negatively oxygen balanced TNT. Hydrodynamic simulation of a 60:40 mass ratio RDX/TNT detonation created conditions thermodynamically suitable to produce cubic silicon carbide within the first 500 nanoseconds after the passage of the detonation wave while carbon remains chemically reactive for molecular formation. Simulations and experimental tests indicated that loading configuration and impedance mismatch of the precursor additives used in detonation synthesis results in conditions in the additives that exceed the accepted detonation pressure of the explosive by greater than three times. Finally, a full factorial experimental design showed increasing silicon concentration, reducing silicon size, and reducing oxygen balance by adjusting the ratio of RDX to TNT decreased the explosives detonation pressure by 20% and increased the soot yield and concentration of SiC observed in the detonation products by 82% and 442% respectively”--Abstract, page iv.

Identification Of New Pathways For Co Oxidation On Rh(111) & Spatial And Structural Control Of O-Induced Reconstruction Of Ag(111), Marie Turano

Dissertations

Understanding the fundamentals of oxygen surface structures under a variety of conditions is pivotal to determining reactivity of heterogeneous catalysis. Exposure of catalytically active metal surfaces to high oxygen coverages results in a myriad of surface structures. A further complication is the formation of subsurface oxygen (Osub) or oxygen present in the near subsurface region of the metal. It is known to form in transition metals yet the absorption of oxygen and resultant formation of Osub is not equivalent across all catalytically relevant metals. As a result, it is difficult to predict the stability and efficacy of the formation of …

Predicting Material Properties: Applications Of Multi-Scale Multiphysics Numerical Modeling To Transport Problems In Biochemical Systems And Chemical Process Engineering, Tom Pace

Theses and Dissertations--Physics and Astronomy

Material properties are used in a wide variety of theoretical models of material behavior. Descriptive properties quantify the nature, structure, or composition of the material. Behavioral properties quantify the response of the material to an imposed condition. The central question of this work concerns the prediction of behavioral properties from previously determined descriptive properties through hierarchical multi-scale, multiphysics models implemented as numerical simulations. Applications covered focus on mass transport models, including sequential enzyme-catalyzed reactions in systems biology, and an industrial chemical process in a common reaction medium.

Fabrication Of Metal-Silicon Nanostructures By Reactive Laser Ablation In Liquid, Eric J. Broadhead

Theses and Dissertations

Metal-silicon nanostructures are a growing area of research due to their applications in multiple fields such as biosensing and catalysis. In addition, silicon can provide strong support effects to metal nanoparticles while being more cost effective than traditionally used supports, like titania. Traditional wet-chemical methods are capable of synthesizing metal-silicon nanostructures with a variety of composition and nanoparticle shapes, but they often require high temperatures, toxic solvents, strong reducing agents, or need capping agents added to stabilize the nanoparticles. Laser processing is an emerging technique capable of synthesizing metal-silicon composite surfaces that offers a faster, simpler, and greener synthesis route …

Understanding The Relationship Between Local Environmental Changes And The Function Of The Ph Low Insertion Peptide, Violetta Burns Casamayor

Graduate Theses, Dissertations, and Problem Reports (ETD)

Cancer is the second leading cause of death in the US with over 1.7 million new cases each year. Current cancer treatments tend to also target healthy tissues due to similarities with cancerous ones, resulting in acute side effects. Early detection is the best approach towards defeating cancer, however, modern imaging techniques require sizeable samples, often implying a late stage in the disease. One common attribute of tumors is their acidic microenvironment, which can be taken advantage of.

The pH Low Insertion Peptide (pHLIP) is a membrane-active peptide that can take advantage of the acidic microenvironment surrounding cancer cells. pHLIP …

Modified Firearm Discharge Residue Analysis Utilizing Advanced Analytical Techniques, Complexing Agents, And Quantum Chemical Calculations, William J. Feeney

Graduate Theses, Dissertations, and Problem Reports (ETD)

The use of gunshot residue (GSR) or firearm discharge residue (FDR) evidence faces some challenges because of instrumental and analytical limitations and the difficulties in evaluating and communicating evidentiary value. For instance, the categorization of GSR based only on elemental analysis of single, spherical particles is becoming insufficient because newer ammunition formulations produce residues with varying particle morphology and composition. Also, one common criticism about GSR practitioners is that their reports focus on the presence or absence of GSR in an item without providing an assessment of the weight of the evidence. Such reports leave the end-used with unanswered questions, …

Cobalt, Molybdenum, And Nickel Complexes, Natural Zeolites, Epoxidation, And Free Radical Reactions, Nicholas K. Newberry

Dissertations, Master's Theses and Master's Reports

Chapter 2 is based on the synthesis and study of the compounds of the bidentate ligand ((5-phenyl-1H-pyrazol-3-yl)methyl)phosphine oxide with molybdenum and cobalt as the transition metal. The complexes were analyzed via FTIR, NMR, UV-Vis, Fluorescence Spectroscopy, TGA, DFT, and XRD. Chapter 3 resulted in the synthesis of the complexes [Ni(II)SSRRL](PF6)2 and [Ni(II)SRSRL](Cl)(PF6) of which [Ni(II)SRSRL](Cl)(PF6) had not been previously analyzed. Both products were analyzed via FTIR, NMR, UV-Vis, CV, DFT, and XRD. Chapter 5 contains the results of the characterization and modification of 4 natural zeolites (AZLB-Na, AZLB-Ca, NM-CA, NV-Na) from the United States in an attempt to increase the …

Numerical Simulations Of Current And Temperature Distribution Of Symmetrical Double-Cathode Solid Oxide Fuel Cell Stacks Based On The Theory Of Electric-Chemical-Thermal Coupling, Cheng-Rong Yu, Jian-Guo Zhu, Cong-Ying Jiang, Yu-Chen Gu, Ye-Xin Zhou, Zhuo-Bin Li, Rong-Min Wu, Zheng Zhong, Wan-Bing Guan

Journal of Electrochemistry

Solid oxide fuel cell (SOFC) is a high-efficient clean conversion device for future energy management. Because of the low antioxidant reduction ability and complex thermal stress, the structure of traditional asymmetrical thin anode-supported planar SOFC is easily to be broken under stack operating conditions. To overcome these defects, a new complete symmetrical SOFC based on double-sided cathodes was developed. To study the influences of gas flow direction and current collection mode on the cell performance inside stack, a numerical model was established by finite element method based on the theory of electro-thermo-chemo multiphysical coupling. By applying this model, the molar …

Effect Of Stereotaxically-Constructed Graphene On The Negative Electrode Performance Of Lead-Acid Batteries, Pin-Song Chen, Yi-Tao Hu, Xin-Yi Zhang, Pei-Kang Shen

Journal of Electrochemistry

With the advantages of high ratio surface area, excellent conductivity and high stability, the stereotaxically-constructed graphene (SCG) material was added to the negative active material (NAM) of lead-acid battery for improving battery performance. XRD, SEM and cyclic voltammetry tests were carried out to analyze the influence of SCG on negative active material. It is found that the conversion efficiency of lead sulfate to lead in the negative active material added with SCG material was higher than that of control group, and the particle size of the lead sulfate obtained after the discharge reaction was smaller, which are favorable factors for …

Preparations And Photoelectrochemical Performances Of Rgo-Tio2 Nanotubes Arrays, Ze-Yang Zhang, Lan Sun, Chang-Jian Lin

Journal of Electrochemistry

Decorating TiO₂ nanotube arrays with RGO to improve the photocatalytic activity of TiO₂ nanotube arrays has been reported. For the reported RGO-TiO₂ nanotube arrays, TiO₂ nanotube arrays were prepared by anodizing the high-purity Ti foil in an organic electrolyte for multiple-step treatments, while RGO were deposited on TiO₂ nanotube arrays by using cyclic voltammetry or other electrical reduction methods. To enhance the reduction degree and the coverage of RGO on the resultant RGO-TiO₂ nanotube arrays, in this work, the one-step electrochemical anodization in hydrofluoric acid was used to fabricate TiO₂ nanotube arrays with …

Effect Of Reaction Conditions On Cu⁃Catalyzed Co2 Electroreduction, Chang Zhu, Wei Chen, Yan-Fang Song, Xiao Dong, Gui-Hua Li, Wei Wei, Yu-Han Sun

Journal of Electrochemistry

Electrochemical conversion of carbon dioxide (CO₂) driven by renewable electricity that can meet both carbon emission reduction and renewable energy utilization has been rapidly developed in recent years. Copper (Cu) catalyst has long been a promising candidate for CO₂ electroreduction applications because of its natural abundance and specific capability of producing a substantial amount of C2 products. However, various metallic Cu electrodes reported have been significantly influenced by the adsorption of certain cation/anion ions, resulting in wide-span catalytic activities and selectivity for various products. In addition, a recent report demonstrated that by virtue of gas-diffusion flow cell …

Preparation And Process Optimization Of Cathode Materials For Lithium-Sulfur Batteries, Kai Wu

Journal of Electrochemistry

Lithium-sulfur (Li-S) batteries represent promising candidates for next-generation energy storage system due to their high energy density and low material cost. However, the industrial application of Li-S batteries remains challenges because of the shuttle effect from lithium polysulfides and the lack of facial routes for Li-S battery preparation. To solve these problems, a cathode consisting of different commercial carbon materials, namely, acetylene black (SP), Ketjen Black (KB) and carbon nanotube (CNT), with sulfur (S) is prepared separately for Li-S battery. After the process of 8-h ball milling for KB/S composite, together with the polyvinyl pyrrolidone (PVP) binder, the cathode could …

Novel Electrochemical Sensor Based On Integration Of Nanoporous Gold With Molecularly Imprinted Polymer For Detection Of Arsenic Ion(Iii), Wu-Wei Ma, Qi-Gang Chang, Xiong-Fang Shi, Yan-Bin Tong, Li Zhou, Bang-Ce Ye, Jian-Jiang Lu, Jin-Hu Zhao

Journal of Electrochemistry

Arsenic, a toxic chemical element, is detrimental to environment and human health in particular. Therefore, the development of simple, fast, and accurate arsenic ion (As³⁺) detection methods has attracted extensive attention. In this work, an electrochemical sensor based on molecular imprinted polymer (MIP) and nano-porous gold (NPG) modified indium tin oxide (ITO) electrode (MIP/NPG/ITO) was developed for determination of As³⁺ in water with different quality. NPG with high conductivity, large specific surface area and high biocompatibility was prepared in situ on ITO surface by a green electrodeposition method using simple and controllable steps. Then, a layer of …

Synergistic Effect Of Dissolving O2 And Wavelength On The Photo-Assisted Anodic Deposition Of Ceo2 Thin Films, Tong-Zheng Jin, Yu-Meng Yang, Sheng-Hui Fan, Guo-Ying Wei, Zhao Zhang

Journal of Electrochemistry

Cerium dioxide (CeO₂) thin films have been applied as new material in many technical fields such as solid oxide fuel cells, catalysts, UV absorbents, pharmacology, and coatings for corrosion protection of many metals and alloys. Electrodeposition is widely considered to be one of the best preparation methods for CeO₂ film. In this work, the CeO₂ films were prepared by photo-assisted anodic deposition in the bath solutions containing 0.05 mol·L^-1 cerium (III) nitrate, 0.1 mol·L^-1 ammonia acetate and 70% (V/V) ethanol onto 316L stainless steel (SS) surface. The synergistic effects of …

Preparations And Properties Of Low Cost Sulfide Solid Electrolytes Li6-XPs5-XClX, Na-Chuan Yang, Yu Wang, Yi Shuai, Kang-Hua Chen

Journal of Electrochemistry

With the shortage of energy and environmental pollution, the storage of electric energy is getting more attention all over the world. In order to improve the energy density and safety performance of batteries, uses of solid electrolyte become more and more popular. However, because the conductivity of solid electrolyte is not comparable to that of liquid electrolyte, the solid electrolyte application has certain limitations. With the efforts of researchers from various countries, there are several different solid electrolytes having better conductivity, for instance, sulfide solid electrolyte and oxide solid electrolyte. Sulfide solid electrolyte is a highly promising solid electrolyte material …

Step-By-Step Modification Of Graphite Felt Electrode For Vanadium Redox Flow Battery, Jing-Yuan Lou, Dong-Jiang You, Xue-Jing Li

Journal of Electrochemistry

As a well-known electrode material of the vanadium redox flow battery (VRFB),graphite felt electrode is the frequently-used electrode material in VRFB, and its low electrochemical activity is one of the key factors for the low power density of VRFB. In this work, we proposed a step-by-step modification method, which used KMnO₄ to oxidize graphite felt first and then placed in an activation solution to excite its reactivity, to improve the electrochemical performance of the graphite felt electrode. According to the results from cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) characterizations …

Degradation And Thermal Characteristics Of Lini0.8Co0.15Al0.05O2/Graphite Lithium Ion Battery After Different State Of Charge Ranges Cycling, Cun Wang, Wei-Jiang Zhang, Teng-Fei He, Bo Lei, You-Jie Shi, Yao-Dong Zheng, Wei-Lin Luo, Fang-Ming Jiang

Journal of Electrochemistry

The LiNi_0.8Co_0.15Al_0.05O₂ (NCA) cathode exhibits high energy density and large reversible capacity, which plays an essential role in the field of electric vehicles (EVs). However, low capacity retention and poor thermal stability limit its application. Few literatures are found for the capacity degradation mechanism of NCA/graphite batteries at home and abroad. The different state of charge (SOC) ranges cycle degradation behaviors of 18650-type NCA/graphite (2.4 Ah) battery were studied in this paper. The SOC ranges considered were 0% ~ 20% (low), 20% ~ 70% (medium), 70% ~ 100% (high), and 0% ~ 100% …

Preparations And Sodium Storage Properties Of Ni3S2@Cnt Composite, Ming-Tao Duan, Yan-Shuang Meng, Hong-Shuai Zhang

Journal of Electrochemistry

Transition metal sulfides (TMSs)-based electrode materials with highly reversible sodium storage have attracted extensive attentions as one of the most prospective electrode materials for sodium ion batteries (SIBs). However, low cycling stability and rate property caused by large volume expansion and poor electronic conductivity during the electrochemical reaction still hamper their further practical application. In this work, in-situ encapsulated Ni₃S₂ nanoparticles in carbon nanotubes (Ni₃S₂@CNT) have been successfully fabricated as an anode material for high-performance SIBs by a one-step solid-phase calcination process. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), …

Core-Shell Structured Ru@Ptru Nanoflower Electrocatalysts Toward Alkaline Hydrogen Evolution Reaction, Xue-Liang Wang, Yuan-Yuan Cong, Chen-Xi Qiu, Sheng-Jie Wang, Jia-Qi Qin, Yu-Jiang Song

Journal of Electrochemistry

Water electrolysis for hydrogen production is beneficial for solving the problem of energy crisis and environmental issues. It is necessary to study highly active and cost-effective catalysts toward hydrogen evolution reaction (HER) to reduce the consumption of noble metals. Herein, we report the synthesis of core-shell structured Ru@Pt_0.24Ru nanoflowers electrocatalyst by stepwise reduction of Ru and Pt precursors in the mixture of oleylamine and benzyl alcohol at 160 ^oC. The average diameter of the resultant Ru@Pt_0.24Ru was 16.5±4.0 nm with a bulk atomic ratio between Pt and Ru of 0.24:1 and a surface ratio of …