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Modeling And Simulation Of The Dynamic Behavior Of Monoliths: Effects Of Pore Structure From Pore Network Model Analysis And Comparison With Columns Packed With Porous Spherical Particles, Athanasios I. Liapis, J. J. Meyers, Orrin K. Crosser

Chemical and Biochemical Engineering Faculty Research & Creative Works

A mathematical model is presented that could be used to describe the dynamic behavior, scale-up, and design of monoliths involving the adsorption of a solute of interest. The value of the pore diffusivity of the solute in the pores of the skeletons of the monolith is determined in an a priori manner by employing the pore network modeling theory of Meyers and Liapis [J. Chromatogr. A, 827 (1998) 197 and 852 (1999) 3]. The results clearly show that the pore diffusion coefficient, D(mp), of the solute depends on both the pore size distribution and the pore connectivity, n(T), of the …

12. Pierre Sigwalt, Otto Vogl

Otto Vogl

No abstract provided.

17th International Herman F. Mark Symposium: Polypropylene - A Material Of The Future, Otto Vogl, Helga Roder

Otto Vogl

No abstract provided.

Double Twist In Helical Polymer "Soft" Crystals, Christopher Y. Li, Stephen Z. D. Cheng, Jason J. Ge, Feng Bai, John Z. Zhang, Ian K. Mann, Frank W. Harris, Lang-Chy Chien, Donghang Yan, Tianbai He, Bernard Lotz

College of Polymer Science and Polymer Engineering

In natural and synthetic materials having non-racemic chiral centers, chirality and structural ordering each play a distinct role in the formation of ordered states. Configurational chirality can be extended to morphological chirality when the phase, structures possess low liquid crystalline order. In the crystalline states the crystallization process suppresses the chiral helical morphology due to strong ordering interactions, In this Letter, we report the first observation of helical single lamellar crystals of synthetic non-racemic chiral polymers. Experimental evidence shows that the molecular chains twist along both the long and short axes of the helical lamellar crystals, which is the first …

Investigation Of Sodium Hypophosphite Anodic Oxidizing Behavior In The Process Of Acid Electroless Nickel Deposition, Meiyuan Wang, Yafei Kuang, Yan Xu

Journal of Electrochemistry

The anodic oxidizing behavior of sodium hypophosphite in the process of electroless nickle deposition(pH=5.5) was investigated with the linear potential sweep method and alternating current impedance.The results indicated that,the oxidation of NaH 2PO 2 was a complicated electrochemical process and affected by the concentration of NaH 2PO 2, the temperature of the bath,the sweep rate and the existence of nickel ion. The NaH 2PO 2 electrooxidation reaction was very likely preceded by heterogeneous interface transformation process,which might be the control step of the whole anodic process.

Study On Electrochemical Reduction Properties Of Nitrobenzene, Chuna Ma, Wenkui Zhang, Hui Huang, Yongping Gan

Journal of Electrochemistry

The electrochemical reduction characteristics of nitrobenzene was extensively investigated by using the techniques such as quasi_steady_state polarization,cyclic voltammetry,fast linear potential sweep method and chronoamperometry in this paper.The electroanalytic properties of Cu,Cu_Hg and Cu_Ni electrodes were evaluated.Based on the study of the transient steping behaviour of nitrobenzene to PAP,the reduction mechanism was discussed.The results showed that the transition steps existed on the electrochemical reduction of nitrobenzene in acidic solution,the reactant is also absorbed on electrodes surface. The control step in the reduction of nitrobenzene was ascribed to the diffusion of nitrobenzene and its electrochemical reductive products in the acid solution.

The Electrochemical Behaviors Of Superoxide Dismutase At Promoter Modified Gold Electrode, Xiaqin Wu, Xiaoyun Meng, Zhesu Wang, Zongrang Zhang

Journal of Electrochemistry

The electron_transfer process of superoxide dismutase was investigated by cyclic voltammetry at the 4,4'_dithiodipyridine,L_cysteine,histidine and arginine modified gold wire electrodes repectively.The quasi_reversible behavior was observed at L_cysteine modified gold electrode.An irreversible electrochemical behavior has been observed at hisdinine modified gold wire electrode.

High Performance Proton Exchange Membrane Fuel Cells, Jingrong Yu, Baolian Yi, Ming Han, Xiaoliang Cheng, Zhigang Shao, Jingxin Zhang

Journal of Electrochemistry

Proton_exchange membrane fuel cells(PEMFC) using a perfluorosulfonic acid proton exchange membrane as an electrolyte can simplify water and electrolyte management.In this paper,the effects of thickness of PEM on the performance of PEMFC were studied.The Nafion_112 PEM and low platinum loading E_TEK electrode yielded very high power density,of the order of 0.95 W/cm 2.The energy_conversion efficiency,the degree of platinum utilization and stability for PEMFC using Nafion 112 and E_TEK electrode were also investigated.

Electro Oxidation Of Phenol On Sno_2/Ti Electrodes Prepared By Thermal Oxidation, Qingsong Zhang, Huihuang Wu

Journal of Electrochemistry

A SnO 2/Ti electrode prepared by thermal oxidation was used as the anode for galvanostatic electrolysis in acidic solution containing phenol, the time_dependances of phenol concentration,chemical oxygen demand in solution(COD)and instantaneous current efficiency were determined during electrolysis.The results show that with the SnO 2/Ti anode instead of Pt,the COD significantly decreases at the same charge passage, and average current efficiency of oxidation increases by three times The mechanism for phenol oxidation at two electrodes was discussed.

Studies On Methods Of Fuel Cells Electrodes Preparation, Jun Gu, Sheng Sui, Guangqiang Li, Zhitong Sui

Journal of Electrochemistry

In fuel cells,the structure of electrodes is an important factor which effect the cell performance.To improve the structure and the performance of electrodes,a new method of providing fuel cell electrodes is proposed in this paper.PTFE(polytetrafluoroethylene) and ethyne black was ground for about half an hour in a high_speed grinder,then the catalyst was added into the grinder and milled for an hour.This milled catalyst was transferred into a mixer followed by the addition of surface_active agent. After a suspension was formed,it was filtered under vacuum condition.Then a thin uniform filter_cake of the catalyst was formed,which was rolled together with a current_collecting …

Simulation And Density Functional Study Of A Simple Membrane Separating Two Restricted Primitive Model Electrolytes, Richard L. Rowley, Dezso Boda, Douglas Henderson, Stefan Sokolowski

Faculty Publications

A simple membrane, supporting charge densities on its inner and outer surfaces, is considered. In addition to the electrostatic potential, the membrane interacts with the surrounding fluid by a short range van der Waals-like potential. The fluid beyond the outer surface is a three-component restricted primitive electrolyte consisting of two cations and one anion. The membrane is impermeable to one of the cations so that the fluid in the membrane and beyond the inner surface is a two-component restricted primitive electrolyte. We use Monte Carlo simulations and density functional theory to study the density profiles of the electrolyte and the …

Thermodynamic Model And The Controlling Variables Of Phosphate Lattice Loss, Mohammad Abutayeh

USF Tampa Graduate Theses and Dissertations

A thermodynamic model was developed based upon five equilibrium reactions to predict the limits of distribution of phosphates between the liquid and the solid phases in a reactor used to extract phosphoric acid from phosphate rock. A computer code was generated to carry out different simulations of the model using several inputs of temperatures and liquid phase sulfuric acid contents. Ideal Solution, Debye-Hückel, and Robinson-Guggenheim-Bates electrolyte activity coefficient models were employed alternately in each simulation to complete the thermodynamic model and the outputs were compared to one another.

Experimental data of equilibrium constants were regressed to adjust the values of …

Method Of Destroying Hazardous Organic Compounds, Dibakar Bhattacharyya, Susan Mawhinney

Chemical and Materials Engineering Faculty Patents

The present invention relates to a method of destroying hazardous vapor phase or aqueous phase organic compound(s) by providing a polymeric siloxane based solvent in a vessel and adding the hazardous organic compound(s) and ozone to the solvent. The solvent may also comprise a mixture of polymeric siloxane based solvent and fluorinated hydrocarbon solvent.

Helical Single-Lamellar Crystals Thermotropically Formed In A Synthetic Nonracemic Chiral Main-Chain Polyester, Christopher Y. Li, Donghang Yan, Stephen Z. D. Cheng, Feng Bai, Jason J. Ge, Bret H. Calhoun, Tianbai He, Liang-Chy Chien, Frank W. Harris, Bernard Lotz

College of Polymer Science and Polymer Engineering

Phase structures and transformation mechanisms of nonracemic chiral biological and synthetic polymers are fundamentally important topics in understanding their macroscopic responses in different environments. It has been known for many years that helical structures and morphologies can exist in low-ordered chiral liquid crystalline (LC) phases. However, when the chiral liquid crystals form highly ordered smectic liquid crystal phases, the helical morphology is suppressed due to the crystallization process. A double-twisted morphology has been observed in many liquid crystalline biopolymers such as dinoflaggellate chromosomes (in Prorocentrum micans) in an in vivo arrangement. Helical crystals grown from solution have been reported in …

13. Josef Schurz, Otto Vogl

Otto Vogl

No abstract provided.

Phase Structures And Morphologies Determined By Competitions Among Self-Organization, Crystallization, And Vitrification In A Disordered Poly(Ethylene Oxide)-B-Polystyrene Diblock Copolymer, Lei Zhu, Yan Chen, Anqui-Q. Zhang, Bret. H. Calhoun, Moonseok Chun, Stephen Z. D. Cheng, Benjamin S. Hsiao, Fengji Yeh, Takeji Hashimoto

College of Polymer Science and Polymer Engineering

A poly(ethylene oxide)-b-polystyrene (PEO-b-PS) diblock copolymer having a number-average molecular weight ((M) over bar(n)) of 11000 g/mol in the PEO blocks and an (M) over bar(n) of 5200 g/mol in the PS blocks has been synthesized (with a volume fraction of the PEO blocks of 0.66 in the molten state). Differential scanning calorimetry results show that this copolymer possesses a single endotherm, which is attributed to the melting of the PEG-block crystals. Based on real-time resolved synchrotron small-angle x-ray scattering (SAXS) observations, the diblock copolymer is in a disordered state above the glass transition temperature of the PS-rich phase (T-g(PS)) …

Rhythmic Growth Of Target And Spiral Spherulites Of Crystalline Polymer Blends, Thein Kyu, Hw Chiu, Aj Guenthner, Y Okabe, H Saito, T Inoue

College of Polymer Science and Polymer Engineering

Numerical calculations reveal that the target and spiral growth patterns in spherulites can be generated from the time-dependent Ginzburg-Landau equations (model C) by coupling a conserved compositional order parameter and a nonconserved crystal ordering parameter. Of particular interest is that the periodic concentric rings (target) or the spirals at the spherulitic core remain stationary in both the crystal (orientational) ordering field and the concentration field. Another intriguing observation is that the growth of target and spiral spherulites occurs in a stepwise fashion in synchronism with the rhythmic energy dissipation during crystallization.

14. Paolo Galli, Otto Vogl, Anna Maria Marcon-Galli

Otto Vogl

No abstract provided.

15. Clement Henry Bamford, Otto Vogl, Daphne Stephen-Bamford

Otto Vogl

No abstract provided.

Modeling Of Solid Phase Detonations, C Richter, Hendrik J. Viljoen, N.F.J Van Rensburg

Papers in Reaction Kinetics

In contrast to conventional explosives which constitute rapid decomposition of the molecular structure acconlpanied by the release of large volumes of gaseous products, heterogeneous mixtures in the SHS realm react by progression of a thermal wave at velocities far below the speed of sound in such mixtures. Interestingly, ultrafast solid phase reactions can be initiated under the right conditions. A shock wave compresses the solid mixture to densities well beyond the theoretical mean ambient density (TMD) and compression becomes the major form of preheating. In addition, elastic potential energy is pumped into the lattice structure to induce severe distortion and …

Study Of The Effects Of Deuterium Implantation Upon The Performance Of Thin-Oxide Cmos Devices, Sumit Kishore

Theses

The use of ultra thin oxide films in modem semiconductor devices makes them increasingly susceptible to damage due to the hot carrier damage. Deuterium in place of hydrogen was introduced by ion implantation at the silicon oxide-silicon interface during fabrication to satisfy the dangling bonds. Deuterium was implanted at energies of 15, 25 and 35 keV and at a dose of 1x10¹⁴/cm². Some of the wafers were subjected to N₂O annealing following gate oxide growth. It was demonstrated that ion implantation is an effective means of introduction of deuterium. Deuterium implantation brings about a …

Chemical Volatilization Of Heavy Metals For Waste Separation And Real Time Metals Analysis, Mohammad Nasr Ul-Alam

Theses

One of the major challenges in environmental analysis concerns the rapid and sensitive detection of metals emitted from combustion stacks. An interesting concept for real time analysis is to convert airborne metal oxide particles in a flow reactor into relatively volatile compounds of a single class, and then analyze in the gas phase. In this project, kinetics of chemical volatilization reaction between Sb₂O₃ and HCl was investigated. To achieve this a laboratory volatilization flow reactor was built and data was collected for the volatilization reaction in terms of conversion, inlet and outlet concentrations and flow rates. A …

The Ac Impedance Analysis For Pluse Oxide Film Of Aluminium Alloy, Ailing Du, Xicheng Ma, Heming Zhang

Journal of Electrochemistry

Bode diagrams for aluminum PC (abbreviated from pulse current) oxide films were first obtained by AC impedance measurements in a wide range of frequency.The experimental results show that different kinds of electrical equivalent circuits can be used for representing PC films and DC (abbreviated from direct current) oxide films separately,the main differences between them are their porous layers,the PC films are more even with little defects.Those are also verified by SEM and V I characteristic curve measurements.

Structural And Electrochemical Studies On Lithium Manganese Oxide Containing Li + Prepared By Hydrothermal Method For Lithium Ion Batteries, Deyao Liu, Jinkua You, Wei Chu, Yong Yang, Zugeng Lin

Journal of Electrochemistry

In this paper, Todorokite manganese oxides containing Li + with large tunnel structure(sample M5) have been synthesized by hydrothermal methods from natural manganese oxide nano fiber (sample M4). The structure and composition of the samples were characterized and analyzed by XRD, ICP, TGA and DTA. Its electrochemical behavior as a cathode materials for rechargeable lithium ion insertion were studied by galvanostatic charge/discharge measurements. XRD results show that the sample M4 is mainly composed of Birnessite and Vernadite structure. Although the sample M4 shows a high initial capacity of approximately 150 mAh/g, its performances decrease gradually over 30 cycles. It is …

The Techniques Of The Paired Electrosynthesis, Hongkun Zhang, Dengping Gu

Journal of Electrochemistry

In this Paper,we introduce our work on paired electrosynthesis.In conjunction with our research practice,we introduce electrolytic conditions,such as material of electrode ,courrent density and electrolytic temperature etc,as reference for researcher.We categorize the paired electrosynthesis techniques to widen our view on the paired electroorganic synthesis and to promote the deveopments of paired electrosynthesis techniques.

Study On Synthesizing Of 2_Methylbutanoic Acid By Indirect Electrooxidation, Chongta Zhao, Zeshan Zhu

Journal of Electrochemistry

The working conditions of synthesizing 2_methylbutanoic acid by oxidizing 2_methyl_1_butanol with tetrabutylammonium hydrosulfate(TBAS) or tetrabutylammonium perchlorate(TBAP) as phase transfer catalyst in sulfuric acid Cr(Ⅵ) oxidation medium was studied. The Cr(Ⅵ) oxidation medium could be electrolytic regenerated from Cr(Ⅲ), during above oxidation reaction.Under the optinum condition,the yield of 2_methylbutanoic acid is more than 95%.

Electrochemical Synthesis Of Fes Electrode And Its Behavior Measurement, Congsheng Guan

Journal of Electrochemistry

The Potential for the electrochemical synthesis of FeS electrode has been obtained by cyclic voltammetry.FeS electrodes were synthesiaed by controlling Fe electrode at -1.0 V in LiCl_KCl_Li 2S and Li(FClI)_Li 2S melts and their behavior were measured also.The FeS electrode synthesized in molten Li(FClI)_Li 2S has the best charge and discharge properties.

Deactivation Of Nickel Oxide/Hydroxide To Electrooxidation Of H 2po - 2 Anions On Nickel Electrodes In Alkaline Solutions, Taixiang Jiang, Huihuang Wu

Journal of Electrochemistry

Electrooxidation of hypophosphite anions on polycrystalline nickel in alkaline solutions has been investigated by cyclic voltammetry and open circuit potential measurements.The results are explained based on the mechanism that the first step of hypophosphite oxidation is the adsorption of hypophosphite ions on nickel,followed by the homolysis of its hydrogen bond with the formation of radicals.The oxidation of hypophosphite on nickel in alkaline medium occurs at lower potentials between ca.-0.8 V—-1.1 V(SCE)and phosphite ion is the only oxidation product.There is no indication of hypophosphite oxidation at higher potentials.Severe deactivation of the surface occurs when the nickel surface is covered with surface …

Network Modeling Of The Convective Flow And Diffusion Of Molecules Adsorbing In Monoliths And In Porous Particles Packed In A Chromatographic Column, J. J. Meyers, Athanasios I. Liapis

Chemical and Biochemical Engineering Faculty Research & Creative Works

A cubic lattice network of interconnected pores was constructed to represent the porous structure existing in a monolith (continuous bed) or in a column packed with porous chromatographic particles. Expressions were also constructed and utilized to simulate, through the use of the pore network model, the intraparticle interstitial velocity and pore diffusivity of adsorbate molecules in porous chromatographic particles or in monoliths under retained and unretained conditions. The combined effects of steric hindrance at the entrance to the pores and frictional resistance within the pores, as well as the effects of pore size, pore connectivity, n(T), of the porous network, …

16. Eli M. Pearce, Otto Vogl, Judith Pearce

Otto Vogl

No abstract provided.