Chemistry Commons^™

Examination Of An Aloe Vera Galacturonate Polysaccharide Capable Of In Situ Gelation For The Controlled Release Of Protein Therapeutics, Shawn David Mcconaughy

Dissertations

A therapeutic delivery platform has been investigated with the ultimate goal of designing a sustained protein release matrix utilizing an in-situ gelling, acidic polysaccharide derived from the Aloe vera plant. The Aloe vera polysaccharide (AvP) has been examined in order to determine how chemical composition, structure, molecular weight and solution behavior affect gelation and protein/peptide delivery. Correlations are drawn between structural characteristics and solution behavior in order to determine the impact of polymer conformation and solvation on gel formation under conditions designed to simulate nasal applications. Steady state and dynamic rheology, classic and dynamic light scattering, zeta potential, pulse field …

Dispersion States And Surface Characteristics Of Physically Blended Polyhedral Oligomeric Silsesquioxane/Polymer Hybrid Nanocomposites, Rahul Misra

Dissertations

Control of dispersion and segregation states of nanostructured additives is one of the biggest challenges in realizing the optimum potential of high-performance hybrid polymer nanocomposites. Polyhedral oligomeric silsesquioxane (POSS) nanostructured chemicals, with their hybrid organic-inorganic nature and flexible functionalization with a variety of organic substituents, yield possibilities to control dispersion and tune compatibility in a wide range of polymer systems. The overall goal of this research is to investigate the fundamental parameters that influence the dispersion and segregation states of POSS nanostructured chemicals and to understand chain dynamics and conformations in physically blended POSS hybrid polymer nanocomposites (HPNC's). Multiple structural …

Synthesis, Propagation Kinetics, And Characterization Of D,L-Lactide-Based Polyols And Polyurethanes Therefrom, Scott Joseph Moravek

Dissertations

In order to expand the usefulness of degradable polyesters, degradable polyurethanes were synthesized using a mixed polyol system including poly(D,L-lactideco- glycolide) (PLGA), a well-known degradable polyester. Two isocyanate systems, methyl 2,6-diisocyantocaproate (LDI) and dicyclohexylmethane-4,4'- diisocyanate(Hi2MDI), were studied in order to achieve optimal physical and thermal properties of the thermoplastic polyurethane (TPU) while maintaining degradablity. The LDI based systems had excellent physical properties as well as thermal properties that may make them suitable for biomedical devices. The H12MDI based TPUs also had excellent physical properties as well as a higher melting temperature. The aforementioned TPUs were synthesized in small batches. Another …

Preparation Of Carboxylic Acid Functionalized Glycopolymers Through Raft And Post-Polymerization Modification For Biomedical Application, Husnu Alp Alidedeoglu

Dissertations

The primary theme of this dissertation involves the synthesis of well-defined primary amine functionalized polymers, subsequent modification of the polymers to produce novel carboxylic acid functionalized glycopolymers and surface polymerization of these systems utilizing controlled polymerization techniques. Additionally, the synthesis of new water-based allylic copolymer latexes is described. Carbohydrates are natural polymers which possess unlimited structural variations. They carry a huge density of information, and play major roles in recognition events and complex biological operations. For example, hyaluronic acid (HA), an anionic glycosaminoglycan, provides lubricating and cushioning properties in the extracellular matrix and has been found to be involved in …

Photopolymerization And Characterization Of Thiol-Enes And Thiourethanes, Qin Li

Dissertations

Compared to conventional acrylic monomer systems, thiol-ene photopolymerization, an efficient click process leading to the formation of dense and uniform molecular networks, has several distinct advantages including relative insensitivity to oxygen inhibition, high monomer conversion and low shrinkage. Although there has been a revival of interest in thiol-enes in the past 6 years, the structure-property relationship of these networks has not been explored in detail. For future applications, thiol-enes with higher shelf-life stability and glass transition temperatures need to be used. Sulfur containing urethanes, thiourethanes and dithiourethanes are a class of widely used materials due to their distinct properties such …

Studies Of Surface Diffusion In Pemfc Electrodes, Jiang-Shui Luo, Jian Chen, Bao-Lian Yi, Chuan-Sin Cha, Hua-Min Zhang

Journal of Electrochemistry

A PEMFC electrode consisting of dual-layer catalyst layer(CL) was fabricated in this work. The outer CL was Nafion-free,while the inner CL was Nafion-bonded. The effects of Pt/C catalyst in the outer CL that did not contact with Nafion on the current generation in PEMFC electrodes were investigated. Cyclic voltammetric studies indicated that the Pt/C catalyst in the outer CL without direct contact with Nafion was still electrochemically active in taking part in the adsorption/desorption of hydrogen and the electrochemical oxidation/reduction of the oxygen-containing species occurring at the interface of "Pt/Nafion" in the inner CL. The polarization curves showed that the …

Ec-Pt/Cnts Glucose Oxidative Electrode, Jia-Hua Liang, Chun-Mei Zhou, Hong-Juan Wang

Journal of Electrochemistry

A glucose oxidative electrode(GOD),EC-Pt/CNTs glucose oxidative electrode,was constructed by ethyl cellulose(EC) and Pt/CNTs.The sensitivity of the EC-Pt/CNTs GOD is 0.85 μA/mM in the concentration range of 0～4 mmol/L of glucose.After dipped in PBS(4℃) for 18 days,the activity of the EC-Pt/CNTs GOD can reach 80%.It is promising for the EC-Pt/CNTs GOD to be used to construct glucose biosensor.

Corrosion Inhibition Of Magnesium Alloy In 3.5% Nacl Medium By Tungstate, Ling-Jie Li, Zhi-Ming Yao, Jing-Lei Lei, Dong-Hai He, Sheng-Tao Zhang, Fu-Sheng Pan

Journal of Electrochemistry

Electrochemical impedance spectroscopy(EIS),Tafel polarization curves and scanning electron microscopy(SEM) were used to study the corrosion inhibition of AZ61 magnesium alloy in 3.5% NaCl medium with tungstate.Results showed that tungstate demonstrates strong inhibition to the corrosion of AZ61 magnesium alloy.At the concentration of 0.01 mol/L,tungstate has a high inhibition efficiency 75.5%.Tungstate is an anodic inhibitor that mainly inhibited the anodic reactions of magnesium alloy through forming a compact protective layer that covered the magnesium alloy surface active sites.

Behavior Of Copper Electrodeposition In Copper Electroplating Solution With Different Peg Molecular Weight, Lie Yin, Zeng-Lin Wang

Journal of Electrochemistry

The effect of the polyethylene glycol(PEG) molecular weight(MW) upon via-hole filling with diameter of 50 μm and aspect ratio of 1 in the acid copper plating solution was studied.The cathodic polarization in copper electroplating bath with PEG of different molecule weights was investigated by linear sweep voltammetry.The surface roughness,crystallography,and the resistivity of copper films were characterized by X-ray diffraction(XRD),atomic force microscopy(AFM) and the four-point probe measurements.The results showed that the polarization on the cathode and the hole-filling capability of electroplating copper bath were increased evidently with an increase of PEG molecular weight from 600 to 8000.When the PEG MW was …

Voltammetric Determination Of Iodate Ion In Table Salt By Carboxylic Carbon Nanotubes Modified Carbon Paste Electrode, Jun-Hua Li, Fu-Xing Zhang, Jian-Qiu Wang, Zhi-Feng Xu, Rong-Ying Zeng, Yan Yu

Journal of Electrochemistry

A highly-sensitive and mercury-free method of determining iodate ion in table salt was established based on carboxylic carbon nanotubes modified carbon paste electrode.In 0.1 mol/L NaOH solution,there was a sensitive cathodic stripping peak on voltammograms.The stripping peak potential was-0.52 V when accumulation time of IO-3 at the modified electrode was 60 s and the potential scan rate was 300 mV/s.There was a good liner relationship between the peak current and IO-3 concentration in the range of 8.0×10^-10 ～ 5.0×10^-8 mol/L and 1.0×10^-7 ～ 3.0×10^-6 mol/L with the correlation coefficient of 0.999 and 0.998,respectively.The detection limit was …

The Hydrothemal Synthesis Of Nanoscale Lifepo4 And Its Electrochemical Performance, Si-Min Wang, Ming-Sen Zheng, Quan-Feng Dong

Journal of Electrochemistry

The cathode materials of LiFePO₄ were prepared via a hydrothermal reduction method using FeCl₃ as Fe source and iron as a reducing agent.The results showed that ferric salt could be reduced to ferrous salt completely under the hydrothermal condition and pure-phase LiFePO₄ was obtained based on the test results of XRD and FTIR. Carbon-coated LiFePO₄ was synthesized by pyrolysisng glucose at high temperature. The morphologies of pure LiFePO₄ displayed cluster-like while the LiFePO₄/C displayed sphere-like particles. The electrochemical test showed that the LiFePO₄/C had good rate performance,while LiFePO₄ delivered much …

Synthesis Of The Lifepo4 By Co Reduction: Reaction Mechanism And Kinetics, Yun-Hua Chen, Yong Yang

Journal of Electrochemistry

LiFePO₄ cathode material was synthesized by CO reducing FePO₄ and LiOH precursors.The structure,morphology and electrochemical performances of such LiFePO₄ material were characterized by XRD,SEM and charge-discharge tests.It was shown that the particle size of the LiFePO₄ synthesized with 5% excess of LiOH in the precursor was about 200 nm.By carbon coating,the LiFePO₄ electrode was able to deliver a reversible capacity of 158 mAh·g^-1 at 0.1C discharge rate.Temperature-programmed X-ray diffraction was employed to monitor the reaction during the formation of LiFePO₄,and Li₃Fe₂(PO₄)₃ was found to be …

Primary Study Of Tiron As Active Materials For The Redox Flow Battery, Yan Xu, Yue-Hua Wen, Jie Cheng, Yu-Sheng Yang, Zi-Li Xie

Journal of Electrochemistry

Effects of solution pH on the electrochemical behavior of tiron(sodium 4,5-dihydroxy-1,3-benzendisulfonic) couple(on a graphite electrode) were studied by cyclic voltammetry in aqueous solutions.It is shown that at pH<4,tiron exhibited a redox process at a relatively high potential with a good reversibility.A redox flow battery was formed employing tiron as the positive active species and V(III)/V(II) as the negative redox couple.In sulfuric acid medium,the coulombic efficiency of the tiron-V redox flow cell was more than 90% with a good cycle life.The decay in the cycle performance was minimal.Therefore,the feasibility of tiron as active materials for redox flow battery application is demonstrated.

Combustion Product Characterization Of The Iron-Heated Powders In Thermal Batteries, Jin Chong, Xue-Ping Gao, Ji-Qiang Wang

Journal of Electrochemistry

The combustion products of thermal battery used iron-heated powders have been studied.It is identified by X-ray diffraction (XRD) analysis that the main compositions of the combustion products are Fe, FeO and KCl. The transmission electron microscopy(TEM) shows a typical core-shell structure with un-reacted Fe particle core coated by FeO shell with a shell thickness of around 200 nm. The combusted iron-heated powders exhibit no metal property, which is contrast to previous assumption. Further measurement indicates that at the ambient temperature the combustion products show semiconductor property of the p-type with conductivity in the order of 103 S·cm^-1, which …

Preparation And Electrocatalystic Performance Of Ir/C Catalyst For Ammonia Oxidation, Qing-Mei Kong, Yi-Ping Han, Ling-Juan Deng, Tian-Hong Lu, Ya-Wen Tang

Journal of Electrochemistry

The Ir/C catalyst with 30%(by mass) Ir was prepared in the CH₃CH₂OH and H₂O binary system.The X-ray diffraction(XRD) data showed that the average sizes of the Ir particles in the Ir/C catalyst was about 2.2 nm.The results of the electrochemical measurements indicated that the electrocatalytic activity of the Ir/C catalyst for the ammonia oxidation in the neutral NaClO₄ solution was similar to the Ir catalyst,while electrocatalytic stability was much better than that of the Ir catalyst.Furthermore,the peak current density of the ammonia oxidation at the Ir/C catalyst electrode showed a good linear relationship …

Direct Electrochemistry Of Chloroperoxidase At Gc Electrode Modified With Swnts, Hong-Xia Zhang, Xia-Qin Wu, Wen-Jing Hou, Wen Xie, Zhong-Qing Lu, Rong Wang, He-Xing Li

Journal of Electrochemistry

The chloroperoxidase(CPO) was immobilized onto the surface of SWNTs modified electrodes.The electrochemical behaviors of modified electrode have been investigated by cyclic voltammetry.The appearance of a pair of well-defined redox peaks in the CV curve indicated that SWNTs can promote the electron transfer reaction of CPO.The results of cyclic voltammetry in PBS of different pH,from 3~9,showed that the reaction of CPO on the modified electrode was with equal numbers of electron and protein.This readily prepared SWNTs modified electrode showed excellent stability and good catalysis to O₂.

Preparations Of Composite Electrodes Of Pt With HXWo3 And Catalytic Activity Toward Oxygen Reduction Reaction, Pan-Pan Guo, You-Ju Huang, Hong-Yan Yang, Wei Li, Qing-Long Zhang, Wei-Shan Li

Journal of Electrochemistry

Three composite electrodes of platinum with hydrogen tungsten bronze(H_xWO₃)were prepared by voltammetry: hydrogen tungsten bronze deposited on platinum(H_xWO₃/Pt);platinum deposited on hydrogen tungsten bronze(Pt/H_xWO₃) and codeposited platinum and hydrogen tungsten bronze(Pt-H_xWO₃).The eletro-catalytic activities of three electrodes toward oxygen reduction reaction were studied.It is found that the catalytic activity of platinum can be improved by introducing with hydrogen tungsten bronze.Among these composite electrodes Pt/H_xWO₃,and the electrode shows the best eletro-catalytic activity toward oxygen reduction reaction,hence,provides a new way for reducing loading of …

High Performance Fuel Cell Catalyst And 5kw Pemfc Stack Without Humidification At Room Temperature And Atmosphere, Xin-Fa Hu, Min Chen, Shi-Jun Liao

Journal of Electrochemistry

The Pt/C catalyst with high dispersion and high performance was prepared successfully by an organic colloidal method and small batch production(10g) of Pt/C catalyst has been realized.The particle sizes of the active components in the catalyst could be as small as 2.8 nm and the active surface area was up to 450 m²/g.A high performance membrane-electrode assembly(MEA) with surface area of 275 cm² has been prepared by using the home-made catalyst with a catalyst coated membrane method invented in the lab,and a 5 kW stack has been assembled.The stack showed working 10 h at room temperature,atmosphere and …

Ceo2/Pt Composite Electrodes And Their Catalytic Performance, Ying Fu, Zi-Dong Wei, Yong-Chao Feng, Xin-Li Ma, Ming-Jia Liao, Chao Liao, Jie Zhang, Huan Zhang

Journal of Electrochemistry

In this paper,the cerium oxide(CeO₂) nanoparticles were electrochemically deposited on a Pt electrode by potentiostatic deposition(psd) and potential pulse deposition(ppd) to form CeO₂/Pt composite electrodes,CeO₂/Pt(psd) and CeO₂/Pt(ppd).The properties of the CeO₂ were characterized by field emission scanning electron microscope(FESEM) and X-ray diffraction(XRD).The results showed that the CeO₂ nanoparticles prepared by psd and ppd were homogeneous and dense.The methanol oxidation reaction(MOR) and oxygen reduction reaction(ORR) on the Pt electrode were enhanced with the introduction of CeO₂ into Pt.In addition,the catalytic capability of the CeO₂/Pt electrode can be further …

Application Of Self-Assembly Technique In The Process Of Metallized Fabric, Yue-Hui Ma, Wei Wang, Dan Yu, Jin-Xin He

Journal of Electrochemistry

After the pretreatment of nylon fabric by functional chitosan,the self-assembly technique was used in the process of activation before electroless plating to produce the CS-Pd membrane.The nanosized palladium particles with nanoscal have large relative surface and high catalyzed activity.Electromagnetic wave shielding fabric was prepared by electroless plating of Ni-P alloy with the activated fabric.The optimal process condition of CS finishing was given with the orthogonal and single factor experiments.The variation of fabric surface structure was characterized by SPM,SEM.Based on the Schelkunoff theory.The electromagnetic shielding effectiveness comes above 30 dB,which corresponds to shielding 96.0 percent of the electromagnetic wave or more.

Electrochemical Behavior And Determination Of Paracetamol On Activated Glassy Carbon Electrode, Bao-Yu Tan, Fang Liao, Xiao-Ying He, Qing-Tao Zhu, Jun Hua, Xiao-Li Jiang

Journal of Electrochemistry

The electrochemical behavior of paracetamol(PCT) was studied at glassy carbon electrode activated by cyclic voltammetry.In HAc-NaAc buffer solution(pH=4.00),a couple of sensitive redox peaks were recorded about 0.54 V in the cyclic voltammograms.The result indicated that the process was controlled by adsorption and nearly reversible.The reaction electron and proton numbers were estimated,respectively,to be two.Excllent linearity was observed in the correlation between the oxidation peak current and the concentration of PCT in the range of 8.00×10^-6～2.00×10^-4 mol·L-1.The correlative coefficient was-0.999 18.The detection limit was 6.34×10^-6 mol·L^-1.This method can be used for the determination of PCT real …

Fabrication Of Superhydrophilic Aluminum Oxide Through Single-Step Anodic Oxidation, Qin Zhang, Qi-Ming Yin, Jia-Ming Ye, Yuan-Rong Zhu

Journal of Electrochemistry

Hydrophilic aluminum oxide is popularly used for heat exchanger of air-condition.Herein,we developed a simple method to prepare superhydrophilic aluminum oxide on the surface of aluminum through single-step electrochemical oxidization.The morphologies and water contact angles on surfaces of alumina fabricated under different electrochemical conditions were investgated.Superhydrophilic surfaces fabricated by this method have good stability and high mechanical strength with water contact angle almost 0°.Coated with low surface energy materials,superhydrophilc alumina will be converted to superhydrophobic.

Voltammetric Determination Of L-Cysteine At Bipyrine Bridged Copper(Ⅱ) Complex Modified Glassy Carbon Electrode, Ming-Yan Wang, Fan Yang, Sheng-Yu Zhang, Xing-You Xu, Xu-Jie Yang

Journal of Electrochemistry

A modified electrode has been constructed by depositing a novel copper(Ⅱ) complex 2biPy(ClO₄)₄ on the glassy carbon electrode through the method of cyclic voltammetry(CV).It was found that the modified electrode exhibited high electrocatalytic activity toward L-Cysteine oxidation with good reproducibility and high sensitivity.The peak current of semi-derivative linear scan was proportional to the concentration of L-cys in the range of 1×10^-6～3×10^-4 mol·L^-1.The detection limit was 5×10^-7 mol·L^-1.

Localised Galvanic Corrosion Processes In Thermal Spray Coated/Cast Aluminium Alloy Systems, David Culliton, Tony Betts, David Kennedy

Conference Papers

Cast Aluminium Alloys, because of the propensity of aluminium to react with impurities and alloying elements, are prone to developing IM impurities during the solidification process. These IM phases can act, in some fluids, as initiation sites for localised corrosion processes, resulting in degradation phenomena, such as pitting. Whilst Thermal Spray coatings can improve the wear resistance of Cast Aluminium Alloys, their corrosion performance may be hampered by the presence of through porosity within the coating.

The present work details some preliminary studies of the localised corrosion processes occurring at the interface area between a Thermal Spray coating and a …

Temperature Dependence Investigation Of Dissipation Processes In Strongly Anisotropic High-Temperature Superconductors Of Bi-Pb-Sr-Ca-Cu-O System Synthesized Using Solar Energy, J Chigvinadze, Juana Acrivos, S. Ashimov, D. Gulamova, T. Machaidze, D Uskenbaev

Faculty Publications, Chemistry

The investigation of temperature dependence of damping and period of vibrations of HTSC superconductive cylinder of Bi-Pb-Sr-Ca-Cu-O system suspended by a thin elastic thread and performing axial-torsional vibrations in a magnetic field at temperatures above the critical one for the main phase Tc=107 K were carried out. It was observed some "chaos" temperature region in the temperature interval 107-138 K, where it is seen separate ripples of dissipation and oscillation frequency. It is assumed that the "chaos" region could point to a possibility of existence of other magnetic and more high-temperature phases as single islands in a normal materials matrix.

Electrochemical Reductive Behaviors Of 3,4,5,6-Tetrachloro-2-Trichloromethylpyridine At Ag Electrode, Chun-An Ma, Yi-Jiao Hu, Ying-Hua Xu

Journal of Electrochemistry

The electrochemical reductive behavior of 3,4,5,6-tetrachloro-2-trichloropyridine(heptachloropyridine) on silver electrode in the mixture of acetonitrile and water solutions containing TBAP was investigated by cyclic voltammetry.The influences of scan rate,concentration and temperature on the electrochemical behavior were discussed.It was shown that the reduction of heptachloropyridine on the silver electrode was a diffusion-controlled irreversible process.The diffusion coefficient of heptachloropyridine in the acetonitrile solution was 3.0×10^-5 cm²/s.The mechanism of the dechloration of 3,4,5,6-tetrachloro-2-trichloropyridine was also discussed.

Electrochemical Synthesis, Characterization And Fluorescence Property Of Nano Na2Sif6, Guo-Xu Qin, Xin-Jun Wan, Xi-Mei Yuan, Dao-Bao Chu

Journal of Electrochemistry

The nano TiO₂ film was prepared by sol-gel process and characterized with X-ray diffraction(XRD) and scanning electron microscope(SEM).It was found that the average size of pore diameter was about 80 nm for the nano TiO₂ film.The Nano Na₂SiF₆ was synthesized by electrochemical deposition on the nanoporous film electrode and characterized with XRD and transmission electron microscope(TEM).The result showed that the average size of nanoparticle was 20 nm for the nano Na₂SiF₆.The fluorescence property of nano Na₂SiF₆ was also studied briefly.The result indicated that the nano Na₂SiF …

Electricity Generation In Microbial Fuel Cells Catalyzed By Mixed Culture And Pure Culture, Chen-Dong Shuang, En-Ren Zhang, Guo-Wang Diao, Fang-Fang Fan, Jie Yuan

Journal of Electrochemistry

Microbial fuel cells(MFCs) were constructed by inoculating fresh sedimentary microorganisms.Effect of phenol on performance of MFCs was investigated.The results showed that the generation of electrical current was induced by bacteria attached on the surface of the anode.Presence of phenol reduced the rate of glucose consumption and extended the duration of electricity generation with the same addition of glucose.In addition,the electricity generation by a single strain(belonging to pseudomonas species) separated from the sedimentary MFC was also investigated.The experimental results indicated that the presence of metabolic intermediates which exhibited electrochemical activity was necessary for the electricity production.Analysis of GC-MS showed that the …

Sucrose Modification On Li4Ti5O12 Anode Material, Zhi-Hong Tian, Hai-Lei Zhao, Zhi-Feng Wang, Jie Wang

Journal of Electrochemistry

The carbon modified Li4Ti5O12 was prepared by solid state reaction by using sucrose as carbon source. The XRD results showed that the incorporation of carbon did not change the spinel crystal structure of Li4Ti5O12 but it could prevent the particle agglomeration. The sample with 10%(by mass) sucrose displayed the best electrical performance, a 179.1 mAh/g of initial specific capacity was obtained at 0.2C, while 143.8 and 129.4 mAh/g at 2C and 3C, respectively. The CV and EIS studies revealed that carbon modification lowered the electrode polarization and electrode reaction resistance of Li4Ti5O12.

Formation Of Copper Microcrystals On Porous Silicon Films, Lan-Li Chen, Fu-Fang Zhou, Bao-Gai Zhai, Yuan-Ming Huang

Journal of Electrochemistry

Microcrystals of metallic copper were electrochemically deposited onto the surface of porous silicon films in the aqueous electrolyte of copper(II) chloride.The microstructures of electrochemically deposited copper microcrystals on the porous silicon films were characterized by using scanning electron microscopy.The results have demonstrated that both center-hollowed and center-solid equilateral triangles in the sizes of several micrometers can be formed on the smooth bed of copper microcrystals.As the deposition duration increased from 0 to 28 hours,the fractal dimensions of the porous silicon was decreased from 2.608 to 2.252,suggesting that the electrochemical deposition can smooth the rough surface of porous silicon films.Compared to …