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2017

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Articles 31 - 60 of 166

Full-Text Articles in Physical Chemistry

Lithium Ion Hybrid Capacitor With High Energy Density, Xian-Zhong Sun, Xiong Zhang, Kai Wang, Yan-Wei Ma Oct 2017

Lithium Ion Hybrid Capacitor With High Energy Density, Xian-Zhong Sun, Xiong Zhang, Kai Wang, Yan-Wei Ma

Journal of Electrochemistry

Lithium ion hybrid capacitors are electrochemical energy storage devices combining the advantages of both Li-ion battery and electrochemical capacitor. They can be extensively used in many fields. However, the commercialization of lithium ion hybrid capacitor has been encountered several problems, e.g., the device structure design, the screening of materials, the pre-lithiation process, and the interface between electrolyte and electrode, etc. This review summarizes the recent research advances in lithium ion hybrid capacitor with high energy density, including the selection of the active materials in cathode/anode and the separator, the pre-lithiation method using the three-electrode structure, the high- and low-temperature performances, …


Template Induced Fabrication Of Nitrogen Doped Carbon Sheets As Electrode Materials In Supercapacitors, Tao Huang, Guang-Zhi Tao, Chong-Qing Yang, Deng Lu, Lie Ma, Dong-Qing Wu Oct 2017

Template Induced Fabrication Of Nitrogen Doped Carbon Sheets As Electrode Materials In Supercapacitors, Tao Huang, Guang-Zhi Tao, Chong-Qing Yang, Deng Lu, Lie Ma, Dong-Qing Wu

Journal of Electrochemistry

Due to the good electrical conductivity, high specific surface area, and excellent chemical/mechanical stability, carbon nanomaterials with two-dimensional morphology have gradually become the hot topic of the research on supercapacitors. Herein, we report for the first time the fabrication of nitrogen doped carbon sheets (NCSs). In our approach, the sheet-like magnisum aluminum (MgAl) layered double hydroxide was used as the hard template, which was mixed with o-phenylene diamine and iron chloride. The following thermal treatment could render the polymerization and carbonization of o-phenylene diamine. The NCSs with ordered hexagonal architectures were formed by final etching process of the thermally treated …


Preparation And Characterization Of Cellulose Acetate-Based Separator For Lithium-Ion Batteries, Hua-Feng Luo, Yuan-Dong Qiao Oct 2017

Preparation And Characterization Of Cellulose Acetate-Based Separator For Lithium-Ion Batteries, Hua-Feng Luo, Yuan-Dong Qiao

Journal of Electrochemistry

To improve the electrolyte wettability and thermal resistance of separators used for lithium-ion battery, a novel cellulose acetate (CA)-based separator is facilely prepared by non-solvent induced phase separation (NIPS) wet-process and investigated in lithium-ion batteries. Systematical investigations including morphological characterization, electrolyte wettability and thermal resistance testing were carried out. The results demonstrated that the CA-based separator exhibited well developed three-dimensional porous structures with porosity up to 65%, which is 1.5 times higher than that of PE separator. The CA separator also showed excellent electrolyte uptake (285%) and thermal stability at 150 oC for 30 min. Compared with the commercial …


An Aqueous Zn-Ion Capacitor, Jing-Wen Zhao, Jia-Jia Li, Peng-Xian Han, Guang-Lei Cui Oct 2017

An Aqueous Zn-Ion Capacitor, Jing-Wen Zhao, Jia-Jia Li, Peng-Xian Han, Guang-Lei Cui

Journal of Electrochemistry

We first present a new aqueous zinc-ion (Zn-ion) capacitor based on vanadium pentoxide (V2O5) cathode, activated carbon (AC) anode, and 2 mol·L-1 zinc trifluoromethanesulfonate (Zn(TfO)2) electrolyte. The Zn-ion capacitor possesses a wide electrochemical window of 1.4 V, good rate capability and cycling stability. The XRD data demonstrates that the Zn2+ ion serving as the charge carrier could be reversibly intercalated into the V2O5. This capacitor delivered a power density of 181 W·kg-1 and an energy density of 4.5 Wh·kg-1 at 1000 mA·g-1. This work …


Nucleotide-Dependent Preferential Localization Of Ras In Model Membranes With Lipid Raft Nanodomains, Anna Shishina Oct 2017

Nucleotide-Dependent Preferential Localization Of Ras In Model Membranes With Lipid Raft Nanodomains, Anna Shishina

Dissertations (1934 -)

Membrane proteins constitute a third of all proteins in the cell and more than 50% of drug targets. However, the analysis of membrane proteins has many challenges owing to their partially hydrophobic surfaces, flexibility and lack of stability. One example of an essential membrane protein is Ras superfamily. Ras is a small monomeric GTPase involved in regulation of cell growth, proliferation and differentiation. Therefore, Ras and its effectors are among the most important targets for cancer therapy. A detailed knowledge of the processes occurring during signal propagation via Ras might help to elucidate the mechanisms of the involved signal cascades. …


Spin-Imbalance In A 2d Fermi-Hubbard System, Peter Brown, Debayan Mitra, Elmer Guardado-Sanchez, Peter Schauß, Stanimir Kondov, Ehsan Khatami, Thereza Paiva, Nandini Trivedi, David Huse, Waseem Bakr Sep 2017

Spin-Imbalance In A 2d Fermi-Hubbard System, Peter Brown, Debayan Mitra, Elmer Guardado-Sanchez, Peter Schauß, Stanimir Kondov, Ehsan Khatami, Thereza Paiva, Nandini Trivedi, David Huse, Waseem Bakr

Faculty Publications

The interplay of strong interactions and magnetic fields gives rise to unusual forms of superconductivity and magnetism in quantum many-body systems. Here, we present an experimental study of the two-dimensional Fermi-Hubbard model—a paradigm for strongly correlated fermions on a lattice—in the presence of a Zeeman field and varying doping. Using site-resolved measurements, we revealed anisotropic antiferromagnetic correlations, a precursor to long-range canted order. We observed nonmonotonic behavior of the local polarization with doping for strong interactions, which we attribute to the evolution from an antiferromagnetic insulator to a metallic phase. Our results pave the way to experimentally mapping the low-temperature …


Phase Behavior Of Binary And Polydisperse Suspensions Of Compressible Microgels Controlled By Selective Particle Deswelling, A. Scotti, U. Gasser, E. S. Herman, Jun Han, A. Menzel, L. Andrew Lyon, A. Fernandez-Nieves Sep 2017

Phase Behavior Of Binary And Polydisperse Suspensions Of Compressible Microgels Controlled By Selective Particle Deswelling, A. Scotti, U. Gasser, E. S. Herman, Jun Han, A. Menzel, L. Andrew Lyon, A. Fernandez-Nieves

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

We investigate the phase behavior of suspensions of poly(N-isopropylacrylamide) (pNIPAM) microgels with either bimodal or polydisperse size distribution. We observe a shift of the fluid-crystal transition to higher concentrations depending on the polydispersity or the fraction of large particles in suspension. Crystallization is observed up to polydispersities as high as 18.5%, and up to a number fraction of large particles of 29% in bidisperse suspensions. The crystal structure is random hexagonal close-packed as in monodisperse pNIPAM microgel suspensions.We explain our experimental results by considering the effect of bound counterions. Above a critical particle concentration, these cause deswelling of the largest …


Distinct Ice Patterns On Solid Surfaces With Various Wettabilities, Jie Liu, Chongqin Zhu, Kai Liu, Ying Jiang, Yanlin Song, Joseph S. Francisco, Xiao Cheng Zeng, Jianjun Wang Sep 2017

Distinct Ice Patterns On Solid Surfaces With Various Wettabilities, Jie Liu, Chongqin Zhu, Kai Liu, Ying Jiang, Yanlin Song, Joseph S. Francisco, Xiao Cheng Zeng, Jianjun Wang

Xiao Cheng Zeng Publications

No relationship has been established between surface wettability and ice growth patterns, although ice often forms on top of solid surfaces. Here, we report experimental observations obtained using a process specially designed to avoid the influence of nucleation and describe the wettability-dependent ice morphology on solid surfaces under atmospheric conditions and the discovery of two growth modes of ice crystals: along-surface and off-surface growth modes. Using atomistic molecular dynamics simulation analysis, we show that these distinct ice growth phenomena are attributable to the presence (or absence) of bilayer ice on solid surfaces with different wettability; that is, the formation of …


Avoiding The Cubic Equation In Finding The Van Der Waals Fluid's Vapor Pressures, Carl W. David Sep 2017

Avoiding The Cubic Equation In Finding The Van Der Waals Fluid's Vapor Pressures, Carl W. David

Chemistry Education Materials

The van der Waals coexistence curve of liquid and vapor volumes as functions of the temperature (all in reduced coordinates) as well as the correspponding vapor pressures at these temperatures, is obtained using SageMath, a symbolic calculus/algebra computer programming language.The lack of correspondence of the coexistence locus’ analytical form as obtained herein and those of Lekner remains disconcerting.


Optical Studies Of The Solution Phase Reduction And Stabilization Of Indigo Tetrasulfonate In Polyelectrolyte Complexes, Becca Hoene, Dion Rivera Sep 2017

Optical Studies Of The Solution Phase Reduction And Stabilization Of Indigo Tetrasulfonate In Polyelectrolyte Complexes, Becca Hoene, Dion Rivera

All Faculty Scholarship for the College of the Sciences

Ultraviolet-visible (UV-vis) and fluorescence spectroscopy have been used to characterize the polyelectrolyte complexes (PECs) formed when potassium indigo tetrasulfonate (ITS) interacts with poly diallydimethylammonium chloride (PDADMAC) through columbic attraction in the presence of the reducing agent sodium bisulfite, NaHSO3. The PDADMAC facilitates both the reduction of the ITS and the stabilization of the reduced state of the ITS in an atmospheric oxygen environment. Dilutions of the dye solution show that the PEC is stable to dilutions of at least 1 to 1000. UV–vis studies indicate that the reduced ITS (ITSred) forms what is likely a J-aggregate in the presence of …


Special Issue: 15th National Symposium On Organic Electrochemistry And Electrochemical Industry, Xinsheng Zhang, Chengchu Zeng Aug 2017

Special Issue: 15th National Symposium On Organic Electrochemistry And Electrochemical Industry, Xinsheng Zhang, Chengchu Zeng

Journal of Electrochemistry

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Density Functional Investigation On Cathode/Electrolyte Interface In Solid-State Lithium Batteries, Xuelong Wang, Ruijuan Xiao, Yong Xiang, Hong Li, Liquan Chen Aug 2017

Density Functional Investigation On Cathode/Electrolyte Interface In Solid-State Lithium Batteries, Xuelong Wang, Ruijuan Xiao, Yong Xiang, Hong Li, Liquan Chen

Journal of Electrochemistry

The rapidly expanding application of lithium ion batteries stimulates research interest on energy storage devices with higher energy density, better safety and faster charge/discharge speed. All-solid-state lithium batteries have been considered as promising candidates because of their fewer side reactions and better safety compared with conventional lithium-ion batteries with organic liquid electrolytes. Looking for well-matched electrode/electrolyte interfaces is one of the keys to ensuring good comprehensive performance of solid-state lithium batteries. In this report, with the aid of first-principles simulations, the local structure and lithium ions transportation properties of electrolyte surfaces and cathode/electrolyte interfaces are investigated. The β-Li3PS …


Effects Of Surface Modification Modes On Proton-Over-Vanadium Ion Selectivity Of Nafion®Membrane For Application In Vanadium Redox Flow Battery, Qing-Long Tan, Hai-Ning Wang, Shan-Fu Lu, Da-Wei Liang, Chun-Xiao Wu, Yan Xiang Aug 2017

Effects Of Surface Modification Modes On Proton-Over-Vanadium Ion Selectivity Of Nafion®Membrane For Application In Vanadium Redox Flow Battery, Qing-Long Tan, Hai-Ning Wang, Shan-Fu Lu, Da-Wei Liang, Chun-Xiao Wu, Yan Xiang

Journal of Electrochemistry

The effect of surface modification modes on proton-over-vanadium ion selectivity was studied by spin-coating chitosan-Phosphotungstic Acid (PWA) as a single or double layer on Nafion membrane surface. To suppress the vanadium ions permeation through the Nafion? membrane in a vanadium redox flow battery (VRFB), the single surface-modified Nafion membrane (Nafion/chitosan-PWA)S and double surface-modified Nafion membrane (Nafion/chitosan-PWA)D demonstrated a 89.9% and 92.7% reduction of vanadium ion permeability in comparison with pristine Nafion, respectively. The (Nafion/chitosan-PWA)D exhibited betterhigher selectivity between proton and vanadium ions than the (Nafion/chitosan-PWA)S at the same layer thickness. Furthermore, the columbic efficiency for the VRFB single cell based …


Tetrabutylammonium Hexafluorophosphate As Flame Retardant Additive For Lithium Ion Batteries, Qing Zhao, Qian Zhang, Jing-Min Fan, Ming-Sen Zheng, Quan-Feng Dong Aug 2017

Tetrabutylammonium Hexafluorophosphate As Flame Retardant Additive For Lithium Ion Batteries, Qing Zhao, Qian Zhang, Jing-Min Fan, Ming-Sen Zheng, Quan-Feng Dong

Journal of Electrochemistry

Safety issues have been attracted more and more attentions due to the wide applications of lithium ion batteries. Introducing flame retardant additives are one of the effective strategies to improve the safety of lithium-ion batteries. In this paper, the tetrabutylammonium hexafluorophosphate (TBAPF6) as a flame retardant additive was added to the electrolyte as a flame retardant additive to enhance the safety of lithium ion batteries. The self-extinguishing time (SET) and ionic conductivities of the electrolytes with different TBAPF6 contents were investigated. It is found that TBAPF6 dramatically reduced the flammability of the electrolyte while slightly decreasing ionic …


Electrochemical Performance Of Sodium Difluoro(Oxalato)Borate As The Additive Of Non-Aqueous Electrolytes For Sodium-Ion Batteries, Ding Zhang, Qin Zhu, Ying Wang, Cheng-Long Zhao, Shi-Bin Liu, Shou-Dong Xu Aug 2017

Electrochemical Performance Of Sodium Difluoro(Oxalato)Borate As The Additive Of Non-Aqueous Electrolytes For Sodium-Ion Batteries, Ding Zhang, Qin Zhu, Ying Wang, Cheng-Long Zhao, Shi-Bin Liu, Shou-Dong Xu

Journal of Electrochemistry

Sodium ion battery has attracted worldwide and intensive attention recently, while the adoption of electrolyte additives has been considered as one effective strategy to promote the cell performance. Within this work sodium difluoro(oxalato)borate (NaDFOB) was prepared and adopted as an additive for the general non-aqueous electrolyte formula of 1 mol·L-1 NaClO4/EC/PC (Vol: Vol=1:1), and the effects of the additive concentration on ionic conductivity and oxidization decomposition voltage were investigated in detail. In addition, the cell performance evaluated by NaNi0.5Mn0.5O2 as the cathode was also studied. It reveals that the addition of NaDFOB into the NaClO4/EC/PC electrolyte resulted in the significantly …


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 Aug 2017

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 CO2 …


An Electrochemical Dissolution Study Of Ilmenite Fraction Of Beach Sand In Sulphuric Acid Solution, Rostom Ali M., K. Biswas R., Golam Zakaria Md. Aug 2017

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 Aug 2017

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

Journal of Electrochemistry

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Electrostatic Interactions Of Water In External Electric Field: Molecular Dynamics Simulations, Qiang Zhu, Zigui Kan, Jing Ma Aug 2017

Electrostatic Interactions Of Water In External Electric Field: Molecular Dynamics Simulations, Qiang Zhu, Zigui Kan, Jing Ma

Journal of Electrochemistry

A series of molecular dynamics simulations with or without external electric field have been carried out for a bulk water with periodic boundary condition. The difference in radial distribution function of interatomic O…O distance is subtle, with and without external electric field, except for the orientation of dipole moments of water molecules. Without the applied external electric field, distribution of the orientation angle of dipole moments is rather broad. The induced local electric field is analyzed as a function of altitude in direction of electric field. The variation of the local induced electric field is increased as the increase of …


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 Aug 2017

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-FeNx/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-FeNx/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 Aug 2017

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. Aug 2017

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 Aug 2017

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, …


Influence Of Typical Anions In Seawater Environments On Corrosion Behaviors Of 5083 Aluminum Alloy, Yang-Fan Tu, Li-Ming Feng, Zhi-Gang Fang, Hai-Tao Liu, Ming-Hua Jing, Yong Guan Aug 2017

Influence Of Typical Anions In Seawater Environments On Corrosion Behaviors Of 5083 Aluminum Alloy, Yang-Fan Tu, Li-Ming Feng, Zhi-Gang Fang, Hai-Tao Liu, Ming-Hua Jing, Yong Guan

Journal of Electrochemistry

The interaction effects of typical anions, namely, Cl-, HCO3- and SO42-, presented in seawater environments on corrosion resistance behaviors of AA5083 aluminum alloy have been studied. The corrosion resistances of the 5083 aluminum alloy in different simulated seawater environments were tested by factorial analysis method. The polarization curves, the corrosion potentials, corrosion current densities and the breakdown potentials were examined in different concentrations of Cl-, HCO3- and SO42-.The corrosion behavior was analyzed by electrochemical impedance spectroscopy (EIS). The results showed that both Cl-,  and …


Effects Of Temperature On The Nucleation And Growth Mechanism Of Pbo2 Electrodeposition, Lei Wang, Juan-Qin Xue, Li-Hua Yu, Chang-Bin Tang, Qiang Bi Aug 2017

Effects Of Temperature On The Nucleation And Growth Mechanism Of Pbo2 Electrodeposition, Lei Wang, Juan-Qin Xue, Li-Hua Yu, Chang-Bin Tang, Qiang Bi

Journal of Electrochemistry

In order to investigate the effects of temperature on the nucleation and growth of lead dioxide (PbO2), the in situ electrochemical depositions of PbO2 were carried out on the glassy carbon electrode at different temperatures, namely, 25℃,35℃, 45℃, 55℃, and 65℃.The cyclic voltammetric curves, the time-current and the time-potential curves,SEM images and XRD patterns of the PbO2 coatings deposited at different temperatures were obtained. The results showed that the PbO2 underwent nucleation and grew at different temperatures. The 3D continuous nucleation mode of PbO2 electrodeposition remained unchanged with the increase of temperature. However, the …


Nanoparticle-Based Drug-Delivery Systems Studied By Second Harmonic Generation, Raju Ram Kumal Aug 2017

Nanoparticle-Based Drug-Delivery Systems Studied By Second Harmonic Generation, Raju Ram Kumal

LSU Doctoral Dissertations

Second harmonic generation (SHG) is used to study different types of colloidal nanoparticle drug-delivery systems. The surface charge density, electrostatic surface potentials, and ion adsorptions of 50 nm colloidal gold nanoparticle samples coated with mercaptosuccinic acid are determined using SHG measurements under varying NaCl and MgCl2 concentrations in water. Numerical solutions to the spherical Poisson-Boltzmann equation are fit to the SHG results to account for the nanoparticle surface curvature and ion adsorption to the Stern layer interface, showing excellent agreement with electrophoretic mobility measurements. In another study, nanoparticles of gold, silver and polystyrene are functionalized with microRNA using a …


Raman Spectroscopy Of Oxygen Evolution Catalysts And Psii Manganese Model Compounds, Sergei Shmakov, Daniel A. Hartzler, Alireza Karbakhsh Ravari, Yulia Pushkar Aug 2017

Raman Spectroscopy Of Oxygen Evolution Catalysts And Psii Manganese Model Compounds, Sergei Shmakov, Daniel A. Hartzler, Alireza Karbakhsh Ravari, Yulia Pushkar

The Summer Undergraduate Research Fellowship (SURF) Symposium

Photosynthesis is the basis of life on earth, and oxygen evolution catalysts are key components of this complicated, yet not fully understood process. Photosystem II, a large membrane bound pigment-protein complex, is the key system that facilitates oxygenic photosynthesis via the oxygen evolving complex (a natural oxygen evolving catalyst). It is a key component in oxygen producing catalysts, which can be used in fields such as energy production and biomimetic catalysts. The oxygen evolution cycle, or Kok cycle going within it is still not studied completely. In this project, we were studying the vibrational (and structural) state of a Manganese …


Applying Machine Learning To Computational Chemistry: Can We Predict Molecular Properties Faster Without Compromising Accuracy?, Hanjing Xu, Pradeep Gurunathan, Lyudmila Slipchenko Aug 2017

Applying Machine Learning To Computational Chemistry: Can We Predict Molecular Properties Faster Without Compromising Accuracy?, Hanjing Xu, Pradeep Gurunathan, Lyudmila Slipchenko

The Summer Undergraduate Research Fellowship (SURF) Symposium

Non-covalent interactions are crucial in analyzing protein folding and structure, function of DNA and RNA, structures of molecular crystals and aggregates, and many other processes in the fields of biology and chemistry. However, it is time and resource consuming to calculate such interactions using quantum-mechanical formulations. Our group has proposed previously that the effective fragment potential (EFP) method could serve as an efficient alternative to solve this problem. However, one of the computational bottlenecks of the EFP method is obtaining parameters for each molecule/fragment in the system, before the actual EFP simulations can be carried out. Here we present a …


Temperature-Dependent Exciton Dynamics Of Superacid Treatment In Monolayers Of The Metal Dichalcogenide Mos2, Mingwei Zhou, Long Yuan, Jordan Snaider, Libai Huang Aug 2017

Temperature-Dependent Exciton Dynamics Of Superacid Treatment In Monolayers Of The Metal Dichalcogenide Mos2, Mingwei Zhou, Long Yuan, Jordan Snaider, Libai Huang

The Summer Undergraduate Research Fellowship (SURF) Symposium

To improve optoelectronic semiconductor materials, one of the most efficient research areas is the two-dimensional (2D) transition-metal dichalocogenides (TMDCs). It has been shown that organic nonoxidizing superacid bis(trifluoromethane)sulfonamide (TFSI) treatment of molybdenum disulfide (MoS2) monolayer could uniformly enhance its photoluminescence by more than two orders of magnitude and also extend the lifetime of excitons. This could greatly improve the efficiency of the solar energy usage, but the mechanism behind it has not been fully understood. Extreme low temperatures (approximately 7K), which slow the surface exciton mobility, were applied to investigate the changes of treated MoS2 monolayer surfaces. …


Transient Absorption Studies Of Cdse Nanocluster Passivated With Phenyldithiocarbamate Ligands., Yizhou Xie Aug 2017

Transient Absorption Studies Of Cdse Nanocluster Passivated With Phenyldithiocarbamate Ligands., Yizhou Xie

Electronic Theses and Dissertations

Semiconductor nanocluster (SCNC) research is a rapidly growing field driven by the promising fact that properties of such materials can be tailored by modifying their size, shape, and structure. Combination of nanocluster and organic ligands provides even wider possibilities of design and development of effective and task-specific nanostructures. Understanding of and, eventually, control of energetics, interfacial interaction, and photoinduced processes in such highly heterogeneous structures is critical to invention of novel materials including those in photovoltaic devices. In the newly established Ultrafast Laser Facility (ULF), transient absorption pump-probe spectroscopy (TAPPS) has been employed to investigate the electron transfer (ET) and …