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2009

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Articles 391 - 420 of 823

Full-Text Articles in Chemistry

Photoelectrochemical Properties Of Tio2 Nanoparticles, Jie Qu, Ying Li, Qi-Wei Jiang, Xue-Ping Gao Feb 2009

Photoelectrochemical Properties Of Tio2 Nanoparticles, Jie Qu, Ying Li, Qi-Wei Jiang, Xue-Ping Gao

Journal of Electrochemistry

The protonated titanate nanoparticles were obtained at room temperature and subsequently calcined at different temperatures(300 ℃,400 ℃,500 ℃,600 ℃ and 700 ℃) in air.The obtained products were characterized by XRD,TEM and UV-Vis.It is found that the grain sizes of TiO2 nanoparticles calcined at 300 ℃ were about 20 nm,and increased gradually with the temperature rise.Photoelectric performance was measured with I～V curve and electrochemical impedance spectroscopy(EIS).The TiO2 nanoparticles obtained at 500 ℃ showed the best photoelectrochemical properties with a photovoltaic conversion efficiency of 6.39%,which is much higher than those at other temperatures.In addition,it is also demonstrated that the charge …

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Electrooxidation Behaviors Of Tib2 As High Capacity Anodic Material In Neutral Aqueous Electrolytes, Ya-Dong Wang, Xian-Yong Guang, Zhi-Xin Wang, Xin-Ping Ai, Han-Xi Yang Feb 2009

Electrooxidation Behaviors Of Tib2 As High Capacity Anodic Material In Neutral Aqueous Electrolytes, Ya-Dong Wang, Xian-Yong Guang, Zhi-Xin Wang, Xin-Ping Ai, Han-Xi Yang

Journal of Electrochemistry

Titanium diborides were investigated as an anodic material for neutral aqueous batteries. It is revealed that this material shows superiorly high electrochemical activities in the neutral electrolytes. The discharge capacities observed for TiB2 reached 1300 mAh/g at the constant current density of 50 mA/g, exceeding all the metal electrodes reported so far. The electrooxidation of this compound was found to proceed via the electrochemical dissolution of boron to form borofluoride, while titanium remained unchanged at the electrode. These results suggest a possible use of the boride compounds as a new material for constructing neutral aqueous batteries with high electrochemical …

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The Electrochemical Performance Of Ncf-Sulfur Cathode, Chun-Rong Zhao, Zhong-Bao Yu, Wei-Kun Wang, Yu-Sheng Yang Feb 2009

The Electrochemical Performance Of Ncf-Sulfur Cathode, Chun-Rong Zhao, Zhong-Bao Yu, Wei-Kun Wang, Yu-Sheng Yang

Journal of Electrochemistry

The electrochemical performance of NCF-sulfur cathode, with different NCF contents, was investigated by constant current discharge, cyclic voltammetry and AC impedance methods. The morphologies of the cathodes were observed using scanning electron microscopy. The results indicate that the cycle life and rate capability of NCF-sulfur cathode increased. Better performance of sulfur cathode was obtained by 3% and 5% NCF conductive addition. When the current density was 0.4 mA/cm2, the 3% NCF-sulfur cathode had an initial capacity of 880 mAh/g and a reversible capacity of 630 mAh/g after 20 cycles.

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Preparation And Characterization Of Tin-Nickel Alloy Electromagnetic Shielding Fabric, Ke-Jing Chu, Wei Wang, Bin Sun, Mei-Fang Zhu Feb 2009

Preparation And Characterization Of Tin-Nickel Alloy Electromagnetic Shielding Fabric, Ke-Jing Chu, Wei Wang, Bin Sun, Mei-Fang Zhu

Journal of Electrochemistry

A soft electromagnetic shielding fabric was successfully prepared by electroplating tin-nickel alloy on the Cu-plated PET fabric in potassium pyrophosphate system. Results show that the different tin content and different colour can be obtained by changing the ratio of metals in bath. Better corrosion resistance and anti-tarnishing were achieved with the fabric consisting of 68.96% Sn. The tin-nickel alloy surface for the electromagnetic shielding fabric had excellent conductivity, softness, permeability and soft luster, non-sensitized to the human body. Thereby it has broad prospect in EMI field and shielding clothing.

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Electrosynthesis Of 2,2-Dimethylolpropionic Acid, Hong-Yan Sun, Zhen-Hai Liang Feb 2009

Electrosynthesis Of 2,2-Dimethylolpropionic Acid, Hong-Yan Sun, Zhen-Hai Liang

Journal of Electrochemistry

The Ti/SnO2+Sb2O4/PbO2 electrode was prepared.The structure phase and valent state were characterized by means of XRD and XPS.The 2,2-dimethylolpropionic acid was synthesized on the Ti/SnO2+Sb2O4/PbO2 anode by direct electro-oxidation of 2,2-dimethylolpropionaldehyde.The product and crude material were analyzed by HPLC,the effects of the concentration of 2,2-dimethylolpropionaldehyde,pH,potential and reaction temperature were studied.The results showed that the optimum conditions were anode potential 1.8 V,pH=1,reaction temperature 15 ℃ and 2,2-dimethylolpropionaldehyde concentration 0.10mol/L.Under the optimum conditions,the selectivity of 36%,the current efficiency of 28% and the conversion of 58% were reached.The reported …

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The Electrochemical Behavior And Determination Of Carbendazim On Iron Montmorillonite Modified Electrode, Xiao-Li Jiang, Rong Li, Xiao-Ying He, Jiang Li, Ying Li Feb 2009

The Electrochemical Behavior And Determination Of Carbendazim On Iron Montmorillonite Modified Electrode, Xiao-Li Jiang, Rong Li, Xiao-Ying He, Jiang Li, Ying Li

Journal of Electrochemistry

The FeCl3 modified clay electrode was made.The electrochemical behavior of carbendazim(BCM) on the modified electrode was studied by cyclic voltammetry.The impacts of pH,scan rate and dosages of modifier were discussed and the important kinetic parameters of the electrochemical process were determined.The results indicated that the process was controlled by diffusion.The effective area of FeMM-CMC/GCE(A)=0.027 cm2,the transfer electron numbers(n)=2 and the diffusion coefficient(D)=5.115×10-6cm2/s.Under the optimized conditions,a good linearity was found between the first order derivative of peak current and concentration of BCM in the range of 2.00×10-5～8.00×10-4mol/L,with i′p=-8.045×10-7-0.0237c,correlation …

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Voltage Delay On Li/Socl2 And Bcx Cells During Discharge, Shu-Tao Liu, Yi-Ping Wu, Hong-Hua Ge, Guo-Ding Zhou Feb 2009

Voltage Delay On Li/Socl2 And Bcx Cells During Discharge, Shu-Tao Liu, Yi-Ping Wu, Hong-Hua Ge, Guo-Ding Zhou

Journal of Electrochemistry

The impedance change of both lithium and carbon electrodes during the process of discharge was studied by AC impedance spectroscopy.It shows that the impedance of lithium electrode at initial stage was reduced by 80%～90% and kept nearly unchanged after wards;the carbon electrode impedance initially did not change much but quickly increased just before the end of discharge.The improvement of voltage delay might be related with the higher open-circuit voltage of BCX cell.It is suggested that the voltage delay problem may be solved by the application of supercapacitor.

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Diaquabis(5-Fluoro-2-Hydroxybenzoato-Κo1)Zinc(Ii), Diana Rishmawi, Jennifer Kelley, Mark D. Smith, Leroy Peterson, Hans-Conrad Zur Loye Feb 2009

Diaquabis(5-Fluoro-2-Hydroxybenzoato-Κo1)Zinc(Ii), Diana Rishmawi, Jennifer Kelley, Mark D. Smith, Leroy Peterson, Hans-Conrad Zur Loye

Faculty Publications

The title compound, [Zn(C7H4FO3)2(H2O)2], is a monomeric ZnII complex. The ZnII atom, which lies on a twofold rotation axis, is situated in a distorted tetrahedral environment composed of two monodentate carboxlyate O atoms and two water O atoms. O-HO hydrogen bonds link these units, forming sheets that are stacked along the c axis.

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Effect Of Irco Intermediate Layer On Electrochemical Property Of Rutisn Anode, Yan Zhao, Gui-Chang Liu, Yong-Lan Liao, Wei-Guang Ji, Shu-Jun Song Feb 2009

Effect Of Irco Intermediate Layer On Electrochemical Property Of Rutisn Anode, Yan Zhao, Gui-Chang Liu, Yong-Lan Liao, Wei-Guang Ji, Shu-Jun Song

Journal of Electrochemistry

The Ti based-RuTiSn anodes with IrCo intermediate layer were prepared by thermal decomposition method. The electrochemical properties of Ti/RuTiSn anodes with different Ir-Co intermediate layers were studied. The surface and elements compositions of the anodes were charactered by scanning electron microscopy(SEM) and electronic probe microanalysis (EPMA). The effects of intermediate layer on the electro-catalytic activity and stability were assessed by chlorine evolution potentials, accelerated lifetime test and cyclic voltammetric curves(CV). It was concluded that the anode, which contained several Ir-Co intermediate layers, could hold not only high electro-catalytic activity but also the increased stability. The enhanced life was up to …

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Synthesis,Characteristics And Electrochemical Performance Of Nano-Sized Snco/Graphite Composites As Anode For Lithium Ion Batteries, Jin-Shu Cai, Ling Huang, Fu-Sheng Ke, Shi-Gang Sun Feb 2009

Synthesis,Characteristics And Electrochemical Performance Of Nano-Sized Snco/Graphite Composites As Anode For Lithium Ion Batteries, Jin-Shu Cai, Ling Huang, Fu-Sheng Ke, Shi-Gang Sun

Journal of Electrochemistry

The nano-structural Sn-Co/graphite composites were prepared by chemical reduction of the alloy electroless deposition solution in graphite suspensions, and the composites were annealed at 500 ℃. The phase structure and surface morphology of the composites were measured by XRD, SEM and Raman. The results indicate that there were high dispersions and high loadings of Sn-Co nanoparticles on graphite by thermal treatment. Electrochemical lithium storage performance was studied preliminarily on the obtained samples. The graphite modified with the Sn-Co nanoparticles possessed a higher electrochemical reversible capacity than that of graphite during the charge and discharge process. The appetency between the Sn-Co …

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Electrochemical Characteristics Of Silicon-Based Composites, Xin-Xin Xu, Jun Yang Feb 2009

Electrochemical Characteristics Of Silicon-Based Composites, Xin-Xin Xu, Jun Yang

Journal of Electrochemistry

The nano-porous Si/G/C composite was obtained by two-step ball milling with SiO, Al and graphite, along with HCl acid etching followed by carbon incorparation. This composite demonstrated the reversible capacity of 600 mAh/g with excellent cycling stability, but low initial cycle efficiency is low.A high-temperature treatment after ball-milling of SiO and A1 could promote the complete reduction of SiO. However, the crystalline structure of Al2O3 product changed from γ-phase to α-phase, which it can no longer be etched by HCl. The Si/Al2O3/G/C composite exhibited higher efficiency at the first cycle but relatively poorer …

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Polymer Microfluidic Devices For Bioanalysis, Xuefei Sun Feb 2009

Polymer Microfluidic Devices For Bioanalysis, Xuefei Sun

Theses and Dissertations

Polymeric microchips have received increasing attention in chemical analysis because polymers have attractive properties, such as low cost, ease of fabrication, biocompatibility and high flexibility. However, commercial polymers usually exhibit analyte adsorption on their surfaces, which can interfere with microfluidic transport in, for example, chemical separations such as chromatography or electrophoresis. Usually, surface modification is required to eliminate this problem. To perform stable and durable surface modification, a new polymer, poly(methyl methacrylate-co-glycidyl methacrylate) (PGMAMMA) was prepared for microchip fabrication, which provides epoxy groups on the surface. Whole surface atom transfer radical polymerization (ATRP) and in-channel ATRP approaches were employed to …

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Isolation And Characterization Of Aromatase Inhibitors From Brassaiopsis Glomerulata (Araliaceae), Marcy J. Balunas, Bin Su, Soedarsono Riswan, Harry H.S. Fong, Robert W. Brueggemeier, John M. Pezzuto, A. Douglas Kinghorn Feb 2009

Isolation And Characterization Of Aromatase Inhibitors From Brassaiopsis Glomerulata (Araliaceae), Marcy J. Balunas, Bin Su, Soedarsono Riswan, Harry H.S. Fong, Robert W. Brueggemeier, John M. Pezzuto, A. Douglas Kinghorn

Chemistry Faculty Publications

The hexane- and ethyl acetate-soluble extracts of the leaves of Brassaiopsis glomerulata (Blume) Regel (Araliaceae), collected in Indonesia, were found to inhibit aromatase, the rate-limiting enzyme in the production of estrogens from androgens, in both enzyme- and cell-based aromatase inhibition (AI) assays. Bioassay-guided fractionation led to the isolation of six known compounds of the steroid and triterpenoid classes (1–6) from the hexane extract, of which 6β-hydroxystimasta-4-en-3-one (5), was moderately active in the cell-based AI assay. Fractionation of the ethyl acetate extract afforded seven pure isolates (7–13) of the modified peptide, fatty acid, monoterpenoid, and benzenoid types, including six known compounds …

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Multivalent Recognition Of Peptides By Modular Self-Assembled Receptors, Joseph J. Reczek, Aimee A. Kennedy, Brian T. Halbert, Adam R. Urbach Feb 2009

Multivalent Recognition Of Peptides By Modular Self-Assembled Receptors, Joseph J. Reczek, Aimee A. Kennedy, Brian T. Halbert, Adam R. Urbach

Chemistry Faculty Research

Developing nontraditional approaches to the synthesis and characterization of multivalent compounds is critical to our efforts to study and interface with biological systems and to build new noncovalent materials. This paper demonstrates a biomimetic approach to the construction of discrete, modular, multivalent receptors via molecular self-assembly in aqueous solution. Scaffolds presenting 1−3 viologen groups recruit a respective 1−3 copies of the synthetic host, cucurbit[8]uril, in a noncooperative manner and with a consistent equilibrium association constant (Ka) value of 2 × 106 M−1 per binding site. The assembled mono-, di-, and trivalent receptors bind to their …

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Characterization Of Putative Self-Resistance Genes In The Biosynthetic Gene Cluster Of Hygromycin A From Streptomyces Hygroscopicus Nrrl 2388, Vidya Dhote Feb 2009

Characterization Of Putative Self-Resistance Genes In The Biosynthetic Gene Cluster Of Hygromycin A From Streptomyces Hygroscopicus Nrrl 2388, Vidya Dhote

Dissertations and Theses

Streptomyces hygroscopicus NRRL 2388 produces an aminocyclitol antibiotic called hygromycin A (HA), which targets bacterial protein synthesis by inhibiting the peptidyl transferase reaction. The hyg6, hygl9, hyg21, hyg28, and hyg29 genes in the biosynthetic gene cluster of HA are predicted to confer self-resistance to the producer strain by different mechanisms. Targeted gene disruptions and in vitro characterization of recombinant proteins were carried out to elucidate the functions of these genes. The hyg21 gene encodes an O-phosphotransferase with a proposed role in HA inactivation by phosphorylation. Disruption of hyg21 led to a significant decrease in HA production but did not …

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Synthesis Of Aptamer-Porphyrin Conjugate For Photodynamic Therapy & Synthesis And Stability Of Mixed Thiol/Lipid Coated Gold Nanoparticles, Sarita Sitaula Feb 2009

Synthesis Of Aptamer-Porphyrin Conjugate For Photodynamic Therapy & Synthesis And Stability Of Mixed Thiol/Lipid Coated Gold Nanoparticles, Sarita Sitaula

Dissertations and Theses

An underlying problem in Photodynamic Therapy (PDT) is low selectivity of photosensitizers currently being used for the treatment of tumors. This thesis is focused on developing new PDT drugs and is divided into two parts. The first chapter describes a method for selective delivery of the photosensitizers to the tumor site by conjugating porphyrins to an aptamer for the targeted PDT. To achieve this, a novel synthesis of 2'-porphyrin-modified uridine was developed. The 3'-H-phosphonate derivatives of both 2'-porphyrin and 2'-dithiaporphyrin modified uridine were also synthesized. The 3'41-phosphonate derivative of 2'-porphyrin-modified uridine was conjugated to a 19-mer DNA and to a …

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Supramolecular Complexation Of N-Alkyl- And N,N′-Dialkylpiperazines With Cucurbit[6]Uril In Aqueous Solution And In The Solid State, Mikhail V. Rekharsky, Hatsuo Yamamura, Tadashi Mori, Akihiro Sato, Motoo Shiro, Sergey V. Lindeman, Rajendra Rathore, Kouhei Shiba, Young Ho Ko, Narayanan Selvapalam, Kimoon Kim, Yoshihisa Inoue Feb 2009

Supramolecular Complexation Of N-Alkyl- And N,N′-Dialkylpiperazines With Cucurbit[6]Uril In Aqueous Solution And In The Solid State, Mikhail V. Rekharsky, Hatsuo Yamamura, Tadashi Mori, Akihiro Sato, Motoo Shiro, Sergey V. Lindeman, Rajendra Rathore, Kouhei Shiba, Young Ho Ko, Narayanan Selvapalam, Kimoon Kim, Yoshihisa Inoue

Chemistry Faculty Research and Publications

Water seeds: Complex stoichiometry/composition and degree of oligomerization (oligomeric supramolecular complex formation) of cucurbit[6]uril (CB[6]) with N-alkyl- and N,N′-dialkylpiperazine were investigated in aqueous solutions by means of isothermal titration calorimetry (ITC), ESI-MS, NMR and light scattering measurements. Complex stoichiometry/composition and degree of oligomerization (oligomeric supramolecular complex formation) of cucurbit[6]uril (CB[6]) with N-alkyl- and N,N′-dialkylpiperazine were investigated in aqueous solutions by means of isothermal titration calorimetry (ITC), ESI-MS, NMR and light scattering measurements. It was found that the complex stability and the degree of oligomerization increase with elongating the alkyl chain attached …

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Hygroscopic Behavior And Liquid-Layer Composition Of Aerosol Particles Generated From Natural And Artificial Seawater, Matthew E. Wise, Evelyn J. Freney, Corey A. Tyree, Jonathan O. Allen, Scot T. Martin, Lynn M. Russell, Peter R. Buseck Feb 2009

Hygroscopic Behavior And Liquid-Layer Composition Of Aerosol Particles Generated From Natural And Artificial Seawater, Matthew E. Wise, Evelyn J. Freney, Corey A. Tyree, Jonathan O. Allen, Scot T. Martin, Lynn M. Russell, Peter R. Buseck

CUP Faculty Research

Sea-salt aerosol (SSA) particles affect the Earth's radiative balance and moderate heterogeneous chemistry in the marine boundary layer. Using conventional and environmental transmission electron microscopes (ETEM), we investigated the hygroscopic growth and liquid-layer compositions of particles generated from three types of aqueous salt solutions: sodium chloride, laboratory-synthesized seawater (S-SSA particles), and natural seawater (N-SSA particles). Three levels of morphological change were observed with the ETEM as the laboratory-generated particles were exposed to increasing relative humidity (RH). The first level, onset of observable morphological changes, occurred on average at 70, 48, and 35% RH for the NaCl, S-SSA, and N-SSA particles, …

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Light-Regulated Sampling Of Protein Kinase Activity (I), Collaborative Project Feb 2009

Light-Regulated Sampling Of Protein Kinase Activity (I), Collaborative Project

Dyson College- Seidenberg School of CSIS : Collaborative Projects and Presentations

This entry adheres to the use of the quad chart template to provide a succint description only of the current research project undertaken by the participants. It provides for the following information

1. Participants and Affiliation
2. Overall Project goals
3. Illustrative picture
4. Specific research/artistic/pedagogic foci.

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Colorimetric And Ratiometric Sensors For Manganese (Ii), Collaborative Project Feb 2009

Colorimetric And Ratiometric Sensors For Manganese (Ii), Collaborative Project

Dyson College- Seidenberg School of CSIS : Collaborative Projects and Presentations

This entry adheres to the use of quad chart template to provide a succint description only of the current research project undertaken by the participants. It provides for the following information:

1. Participants and Affiliations
2. Overall Project Goals
3. Illustrative picture
4. Specific research/artistic/pedagogic foci

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Development And Validation Of An Empirical Free Energy Function For Calculating Protein–Protein Binding Free Energy Surfaces, Joseph Audie Feb 2009

Development And Validation Of An Empirical Free Energy Function For Calculating Protein–Protein Binding Free Energy Surfaces, Joseph Audie

Chemistry & Physics Faculty Publications

In a previous paper, we described a novel empirical free energy function that was used to accurately predict experimental binding free energies for a diverse test set of 31 protein–protein complexes to within ≈1.0 kcal. Here, we extend that work and show that an updated version of the function can be used to (1) accurately predict native binding free energies and (2) rank crystallographic, native-like and non-native binding modes in a physically realistic manner. The modified function includes terms designed to capture some of the unfavorable interactions that characterize non-native interfaces. The function was used to calculate one-dimensional binding free …

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Ratiometric Single-Nanoparticle Oxygen Sensors For Biological Imaging, Changfeng Wu, Barbara Bull, Kenneth Christensen, Jason Mcneill Feb 2009

Ratiometric Single-Nanoparticle Oxygen Sensors For Biological Imaging, Changfeng Wu, Barbara Bull, Kenneth Christensen, Jason Mcneill

Publications

It makes sense: Conjugated polymer nanoparticles doped with a platinum porphyrin dye exhibit bright phosphorescence that is highly sensitive to the concentration of molecular oxygen. The small size, extraordinary brightness, excellent sensitivity, and ratiometric emission, together with the demonstration of single-particle sensing and cellular uptake, indicate the potential of the nanoparticle sensors for quantitative mapping of local molecular oxygen concentration.

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Ultrafast Energy Transfer In Oligofluorene−Aluminum Bis(8-Hydroxyquinoline)Acetylacetone Coordination Polymers, Victor A. Montes, Grigory V. Zyryanov, Evgeny Danilov, Neeraj Agarwal, Manuel A. Palacios, Pavel Anzenbacher Jr. Feb 2009

Ultrafast Energy Transfer In Oligofluorene−Aluminum Bis(8-Hydroxyquinoline)Acetylacetone Coordination Polymers, Victor A. Montes, Grigory V. Zyryanov, Evgeny Danilov, Neeraj Agarwal, Manuel A. Palacios, Pavel Anzenbacher Jr.

Chemistry Faculty Publications

Understanding the excited-state dynamics in conjugated systems can lead to their better utilization in optical sensors, organic photovoltaics (OPVs), and organic light-emitting diodes (OLEDs). We present the synthesis of self-assembled coordination polymers comprising two types of fluorescent moieties: discrete fluorene oligomers of a well-defined length (n = 1-9) connected via aluminum(III) bis(8-quinolinolate)acetylacetone joints. Due to their well-defined structure, these materials allowed for a detailed study of energy migration processes within the materials. Thus, femtosecond transient spectroscopy was used to study the ultrafast energy transfer from the oligofluorene to the quinolinolate moieties, which was found to proceed at a rate …

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Influence Of The Rare-Earth Element On The Effects Of The Structural And Magnetic Phase Transitions In Cefeaso, Prfeaso And Ndfeaso, Michael A. Mcguire, Raphäel P. Hermann, Athena S. Sefat, Brian C. Sales, Rongying Jin, David Mandrus, Fernande Grandjean, Gary J. Long Feb 2009

Influence Of The Rare-Earth Element On The Effects Of The Structural And Magnetic Phase Transitions In Cefeaso, Prfeaso And Ndfeaso, Michael A. Mcguire, Raphäel P. Hermann, Athena S. Sefat, Brian C. Sales, Rongying Jin, David Mandrus, Fernande Grandjean, Gary J. Long

Chemistry Faculty Research & Creative Works

We present results of transport and magnetic properties and heat capacity measurements on polycrystalline CeFeAsO, PrFeAsO and NdFeAsO. These materials undergo structural phase transitions, spin density wave-like magnetic ordering of small moments on iron and antiferromagnetic ordering of rare-earth moments. The temperature dependence of the electrical resistivity, Seebeck coefficient, thermal conductivity, Hall coefficient and magnetoresistance are reported. The magnetic behavior of the materials have been investigated using Mössbauer spectroscopy and magnetization measurements. Transport and magnetic properties are affected strongly by the structural and magnetic transitions, suggesting significant changes in the band structure and/or carrier mobilities occur, and phonon-phonon scattering is …

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Probing Single-Molecule Interfacial Electron Transfer Dynamics Of Porphyrin On Tio2 Nanoparticles, Yuanmin Wang, Xuefei Wang, Sujit Kumar Ghosh, H. Peter Lu Feb 2009

Probing Single-Molecule Interfacial Electron Transfer Dynamics Of Porphyrin On Tio2 Nanoparticles, Yuanmin Wang, Xuefei Wang, Sujit Kumar Ghosh, H. Peter Lu

Chemistry Faculty Publications

Single-molecule interfacial electron transfer (ET) dynamics has been studied by using single-molecule fluorescence spectroscopy and microscopic imaging. For a single-molecule zinc-tetra (4-carboxyphenyl) porphyrin (ZnTCPP)/TiO2 nanoparticle system, the single-molecule fluorescence trajectories show strong fluctuation and blinking between bright and dark states. The intermittency and fluctuation of the single-molecule fluorescence are attributed to the variation of the reactivity of interfacial electron transfer. The nonexponential autocorrelation function and the power-law distribution of the probability density of dark times imply the dynamic and static inhomogeneities of the interfacial ET dynamics. On the basis of the power-law analysis, the variation of single-molecule interfacial ET reactivity …

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Paramagnetic Resonance Studies Of Bistrispyrazolylborate Cobalt(Ii) And Related Derivatives, William K. Myers Jan 2009

Paramagnetic Resonance Studies Of Bistrispyrazolylborate Cobalt(Ii) And Related Derivatives, William K. Myers

Chemistry and Chemical Biology ETDs

Herein, a systematic frozen solution electron-nuclear double resonance (ENDOR) study of high-spin Co(II) complexes is reported to demonstrate the efficacy of methyl substitutions as a means of separating dipolar and contact coupling, and further, to increase the utility of high-spin Co(II) as a spectroscopic probe for the ubiquitous, but spectroscopically-silent Zn(II) metalloenzymes. High-spin (hs) Co(II) has been subject of paramagnetic resonance studies for over 50 years and has been used as a spectroscopic probe for Zn metalloenzymes for over 35 years. However, as will be seen, the inherent complexity of the electronic properties of the cobaltous ion remains to be …

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One Rna Plays Three Roles To Provide Catalytic Activity To A Group I Intron Lacking An Endogenous Internal Guide Sequence, Nilesh Vaidya, Niles Lehman Jan 2009

One Rna Plays Three Roles To Provide Catalytic Activity To A Group I Intron Lacking An Endogenous Internal Guide Sequence, Nilesh Vaidya, Niles Lehman

Chemistry Faculty Publications and Presentations

Catalytic RNA molecules possess simultaneously a genotype and a phenotype. However, a single RNA genotype has the potential to adopt two or perhaps more distinct phenotypes as a result of differential folding and/or catalytic activity. Such multifunctionality would be particularly significant if the phenotypes were functionally inter-related in a common biochemical pathway. Here, this phenomenon is demonstrated by the ability of the Azoarcus group I ribozyme to function when its canonical internal guide sequence (GUG) has been removed from the 5? end of the molecule, and added back exogenously in trans. The presence of GUG triplets in noncovalent fragments of …

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Guessing Harmonic Oscillator Wavefunctions Using Maple, Carl W. David Jan 2009

Guessing Harmonic Oscillator Wavefunctions Using Maple, Carl W. David

Chemistry Education Materials

The guessing of eigenfunctions is not trivial at higher quantum numbers, no matter what the system being considered. Instead of guessing, one can employ a symbolic calculus progam (Maple in this case) to aid in the reasoning process.

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The Driven Harmonic Oscillator In Chemistry, Carl W. David Jan 2009

The Driven Harmonic Oscillator In Chemistry, Carl W. David

Chemistry Education Materials

The molecular dynamical simulation of the normal vibrational mode of water which involves H-O-H angle deformation, when driven by an external force, can be used to see how a driven harmonic oscillator, classically, is associated with the infra-red spectrum of water (and the absorption for this particular normal mode).

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Synthesis And Applications Of Polycationic Organic Salts, Collaborative Project Jan 2009

Synthesis And Applications Of Polycationic Organic Salts, Collaborative Project

Dyson College- Seidenberg School of CSIS : Collaborative Projects and Presentations

This entry adheres to the use of the quad chart template to provide a succint description only of the current research project undertaken by the participants. It provides for the following information

1. Participants and Affiliations
2. Overall Project Goals
3. Illustrative Picture
4. Specific research/artistic/pedagogic foci

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