Chemistry Commons^™

Distinct Ceramide Synthases Regulate Polarized Growth In The Filamentous Fungus Aspergillus NidulansD, Shaojie Li, Liangcheng Du, Gary Yuen, Steven D. Harris

Liangcheng Du Publications

In filamentous fungi, the stabilization of a polarity axis is likely to be a pivotal event underlying the emergence of a germ tube from a germinating spore. Recent results implicate the polarisome in this process and also suggest that it requires localized membrane organization. Here, we employ a chemical genetic approach to demonstrate that ceramide synthesis is necessary for the formation of a stable polarity axis in the model fungus Aspergillus nidulans. We demonstrate that a novel compound (HSAF) produced by a bacterial biocontrol agent disrupts polarized growth and leads to loss of membrane organization and formin localization at …

Supplemental Materials For "Distinct Ceramide Synthases Regulate Polarized Growth In The Filamentous Fungus Aspergillus NidulansD", Shaojie Li, Liangcheng Du, Gary Yuen, Steven D. Harris

Liangcheng Du Publications

Four figures not included in the print edition of the above-referenced article, that was published in Molecular Biology of the Cell, Vol. 17, 1218–1227 (March 2006). :

Figure 1 - barA mutants are resistant to the effects of HPLC-purified HSAF.

Figure 2 - Alignment of Lag1 homologues.

Figure 3 - Alignments of BasA homologues.

Figure 4 - Growth defects of lagA mutants.

Evaluation Of Chlorinated Solvent Removal Efficiency Among Three Wetland Plant Species: A Mesocom Study, Jun Yan

Theses and Dissertations

Different species of plants need to be studied individually to compare the remediation efficiency of each species. This research will study three different wetland plants species and an unplanted control, under a laboratory setting. Each plant has a different characteristic favorable for chlorinated solvent degradation. Eleocharis erythropoda (Spike Rush) are plants with thin tube like leaves and large root mass. Carex comosa (Bearded Sedge) has broad leaves and Scirpus atrovirens (Green Bulrush) are broad leafed wetland plants with a long flowering stem during reproduction. PCE will be injected into the plant mesocosm and any possible PCE degradation will be observed. …

Macrocyclic Antibiotics As Separation Agents, Daniel W. Armstrong

Chemistry Faculty Research & Creative Works

Macrocyclic antibiotics having ring structures with at least 10 members act as separation agents in crystallization, precipitation, filtration, electrophoresis, and chromatography. The macrocyclic antibiotics include ansamacrolides, macrolides, macrocyclic peptides, polyenes and derivatives thereof. The process has been found to be especially advantageous for separation of optical isomers by electrophoresis and chromatography.

Studies On A Total Synthesis Of The Microbial Immunosuppresive Agent Fr901483, Jeffrey E. Kropf, Ivona C. Meigh, Magnus Bebbington, Steven M. Weinreb

Department of Chemistry and Biochemistry Faculty Scholarship and Creative Works

A strategy is outlined for construction of the fungal immunosuppressant FR901483 (1). It was possible to convert 1,4-cyclohexanedione monoethylene ketal in five simple steps to iodoacetamide ketone 10, which was cyclized in good yield to the key bridged keto lactam 11 containing the A/B 2-azabicyclo-[3.3.1] nonane ring system of the natural product. This intermediate could be transformed to N-Boc lactam 16, whose derived enolate underwent stereoselective hydroxylation with the Davis oxaziridine to produce alcohol 17 having the desired C-2 configuration. Compound 17 was then converted in three steps to alkoxy carbamate 20. The N-acyliminium ion derived from intermediate 20 could …

A Formal [3,3]-Sigmatropic Rearrangement Route To Quaternary Α-Vinyl Amino Acids: Use Of Allylic N-Pmp Trifluoroacetimidates, David B. Berkowitz, Bin Wu, Huijie Li

David Berkowitz Publications

Pd(II)-mediated rearrangement of allylic N-PMP (p-methoxyphenyl) trifluoroacetimidates provides the first formal sigmatropic route to quaternary, α-vinylic amino acids, potential suicide substrates for PLP-enzymes. The amino acid side chains enter via transition metal-mediated C-C bond constructions, including (i) Cu(I)-mediated conjugate addition (Ala); (ii) Pd(0)/AsPh₃-mediated Stille coupling (Allyl-Gly, Phe, DOPA, m-Tyr) and (iii) Pd(0)/Pt-Bu₃-mediated Negishi coupling (Leu). In the synthesis of the DOPA decarboxylase inactivator, α-vinyl-m-tyrosine, the new N-PMP trifluoroacetimidate rearranges much more efficiently than the corresponding trichloroacetimidate.

Preparation Of Silica-Coated Lanthanum-Strontium Manganite Particles With Designable Curie Point, For Application In Hyperthermia Treatments, Vuk Uskoković, Aljoša Košak, Miha Drofenik

Pharmacy Faculty Articles and Research

Silica-coated lanthanum–strontium manganite particles with La_0.76Sr_0.24MnO_3+δ stoichiometric formula, exhibiting Curie temperature at ∼40°C, were prepared by using a traditional solid-state method of synthesis of magnetic ceramic particles, followed by milling and a low-temperature coating procedure in an aqueous alcoholic alkali medium. The properties of the obtained material establish it as a potential candidate for self-regulated power-absorbing and temperature-controlling materials in hyperthermia treatments. Moreover, core-comprising LaSr–manganites with different stoichiometries, ranging from La_0.5Sr_0.5MnO_3+δ to LaMnO_3+δ, were synthesized, with magnetic and structural properties examined thereof. Herein reported findings can potentially be …

Kinetic And Spectroscopic Characterization Of The E134a- And E134d-Altered Dape-Encoded N-Succinyl-L,L-Diaminopimelic Acid Desuccinylase From Haemophilus Influenzae, Ryan S. Davis, David L. Bienvenue, Sabina I. Swierczek, Danuta M. Gilner, Lakshman Rajagopal, Brian Bennett, Richard C. Holz

Physics Faculty Research and Publications

Glutamate-134 (E134) is proposed to act as the general acid/base during the hydrolysis reaction catalyzed by the dapE-encoded N-succinyl-l,l-diaminopimelic acid desuccinylase (DapE) from Haemophilus influenzae. To date, no direct evidence has been reported for the role of E134 during catalytic turnover by DapE. In order to elucidate the catalytic role of E134, altered DapE enzymes were prepared in which E134 was substituted with an alanine and an aspartate residue. The Michaelis constant (K _m) does not change upon substitution with aspartate but the rate of the reaction changes drastically in the following order: glutamate (100% …

The Electrochemical Separation Of Curium And Americium: Quaterly Report January - March, 2006, David W. Hatchett, Kenneth Czerwinski

Separations Campaign (TRP)

This research report outlines the current status and progress associated with the electrochemical separation of Curium and Americium. For two and a half years, research has been actively performed on this project, and is currently on schedule for the proposed timelines.

Progress:

• The electrochemical characterization of Ce and Eu complexed with EDTA, NTA, and Citrate has been completed.

• Synthesis of the polymer substrate and the chelating ligand is underway. Approximately 50 grams of disulfide has been produced to produce the chelating thiol group required for the last set of studies.

• Gold substrates have been prepared to perform …

Applications Of Acoustic Wave Devices For Sensing In Liquid Environments, Jeanne Hossenlopp

Chemistry Faculty Research and Publications

Acoustic wave devices such as thickness shear mode (TSM) resonators and shear horizontal surface acoustic wave (SH-SAW) devices can be utilized for characterizing physical properties of liquids and for chemical sensor applications. Basic device configurations are reviewed and the relationships between experimental observables (frequency shifts and attenuation) and physical properties of liquids are presented. Examples of physical property (density and viscosity) determination and also of chemical sensing are presented for a variety of liquid phase applications. Applications of TSMs and polymer-coated guided SH-SAWs for chemical sensing and uncoated SH-SAWs for “electronic tongue” applications are also discussed.

Orientational Disorder In Sodium Cadmium Trifluoride Trihydrate, Nacdf3·3h2o, Robert W. Smith, Arthur Mar, Jianjun Liu, Stan Schnell, John R. Hardy

Chemistry Faculty Publications

Attempts to synthesize the hypothetical anhydrous fluoroperovskite NaCdF₃, which has been predicted to be stable, resulted instead in a hydrated fluoride of nominal composition NaCdF₃·3H₂O. It decomposes to sodium fluoride, cadmium fluoride, and water at 60 °C. Its structure has been determined by single-crystal X-ray diffraction. Na_0.92(2)Cd_1.08F_3.08·2.92H₂O crystallizes in the cubic space group with a = 8.2369(4) Å and Z = 4. The structure is based on the NaSbF₆-type (an ordered variant of the ReO₃-type) and features tilted sodium- and cadmium-centred octahedra …

Nanometal Containing Nanocomposites And Photolithographic Polyaniline Nanofibers, Frank D. Blum, Sunil K. Pillalamarri, Lalani K. Werake, J. Greg Story, Massimo F. Bertino, Akira Tokuhiro

Chemistry Faculty Research & Creative Works

A report on recent progress from our laboratories on the nanostructures produced from novel synthesis techniques will be discussed. Using high-energy radiation (γ-rays) we have been able to produce conducting polymer nanofibers and nanorods of polyaniline and polypyrrole without the use of a separate template or capping agent. This technique has been extended, with the addition of metal ions, to a "one pot" synthesis, producing conducting nanocomposites. These nanocomposites contain metal nanoparticles which decorate the conducting nanofibers. We have also recently shown that these systems can be photopatterned to produce novel structures. We believe that these systems will be useful …

Nmr Studies Of Escherichia Coli Acyl Carrier Protein: Dynamic And Structural Differences Of The Apo- And Holo-Forms, Yangmee Kim, Evgenii L. Kovrigin, Ziad Eletr

Chemistry Faculty Research and Publications

Two indicators of conformational variability of Escherichia coli acyl carrier protein (ACP) have been investigated, namely backbone dynamics and chemical shift variations of ACP. Hydrophobic interactions between the 4′-PP prosthetic group and the hydrophobic pocket enclosed by the amphipathic helices resulted in chemical shift perturbations in the residues near the prosthetic group binding sites and contact sites in the hydrophobic pockets upon conversion from apo- to holo-forms. At pH 7.9, destabilization of ACP due to negative charge repulsions and the deprotonated state of His 75 resulted in observed chemical shift changes in the C-terminal region. Model-free analysis showed that the …

Flammability Of Styrenic Polymer Clay Nanocomposites Based On A Methyl Methacrylate Oligomerically-Modified Clay, Xiaoxia Zheng, David D. Jiang, Dongyan Wang, Charles A. Wilkie

Chemistry Faculty Research and Publications

Nanocomposites of polystyrene, high impact polystyrene, acrylonitrile–butadiene–styrene terpolymer, polypropylene, and polyethylene were prepared using a methyl methacrylate oligomerically-modified clay by melt blending and the thermal stability and fire retardancy were studied. These nanocomposites were characterized by X-ray diffraction, transmission electron microscopy, thermogravimetric analysis and cone calorimetry. The results show a mixed morphology, depending on the polymer.

Conductivity Of Comb Polyether Pure Solid Polymer Electrolyte, Lin Ye, Peng Gao, Zeng-Guo Feng, Feng Wu, Shi Chen, Guo-Qing Wang

Journal of Electrochemistry

A comb polymer was synthesized through cationic ring-opening polymerization starting from a monomer 3-hydroxymethyl-3-methyl-oxetane.The ion conductivity was measured by CHI660A electrochemical station under various lithium salt concentrations and various temperatures.The highest ion conductivity was recorded to be 10^-4.43 S/cm at room temperature and 10^-3.44 S/cm at 80 ℃.DSC results showed that the segment moves more difficultly with the increasing of lithium salts concentration.XPS found the existence of aggregating lithium ions in POE5 and POE10,and it suggested that POE20 had a suitable lithium concentration for polymer electrolyte.

Studies On Pva-Cmc-Koh-H2O Alkaline Polymer Electrolytes, An-Bao Yuan, Jun Zhao

Journal of Electrochemistry

A given amount of sodium carboxymethyl cellulose(CMC)was added to PVA complex and thus the PVA-CMC-KOH-H₂O alkaline polymer electrolyte with this modification was prepared.The properties of the polymer electrolyte films were characterized by AC impedance,cyclic voltammetry,differential thermal analysis and infrared spectroscopic analysis methods.The polymer electrolyte exhibited a high ionic conductivity,typically 10^-2S·cm^-1 with an electrochemical stability window of about 1.6 V on stainless steel blocking electrodes.The influence of the film composition such as KOH,H₂O and CMC on ion conductivity was investigated.In addition,a preliminary study was carried out on the polymer electrolyte for Ni/MH battery.It was …

Anodic Behaviors Of Pb-Ca-Sn-Re Alloy And Tradditional Pb-Ca-Sn Alloy In Sulfuric Acid Solutions, Dang-Guo Li, Gen-Shu Zhou, Liang Yao, Guan-Fa Lin, Mao-Sheng Zheng

Journal of Electrochemistry

The anodic behaviors of Pb-Ca-Sn-Re and Pb-Ca-Sn alloys were investigated at 1.28 V(vsHg/(H₂SO₄)) in 4.5 mol/L sulfuric acid solution by means of ac voltammetry,ac impedance and cyclic voltammetry.The results showed that the corrosion-resistance property of Pb-Ca-Sn-Re alloy is better than that of tradditional Pb-Ca-Sn alloy,the growth of Pb(Ⅱ) compounds was inhibited in the film of Pb-Ca-Sn-Re alloy,and the film impedance of Pb-Ca-Sn-Re alloy was decreased,indicating that the conductivity of the film was(increased),which is helpful to enhance the deep recycling property for lead acid battery.

Mechanism Of Self Discharge Performance Improvement In The Ni-Mh Batteries With Naoh Electrolyte, Xiao-Feng Li, Tong-Chi Xia, Hui-Chao Dong, Yan-Wei Wei

Journal of Electrochemistry

The self-discharge performance and charge efficiency at 60 ℃ for Ni-MH battery can be markedly enhanced by using NaOH electrolyte instead of KOH electrolyte.Both the results of electrochemical impedance spectroscopy and cyclic voltammetry tests indicate that the separation of H₂ from the negative electrode may be partly blocked in the former because of the change of the adsorption/desorption behavior of H on the surface of the negative electrode,thus results in an improvement of self-discharge performance of the battery.

2006 National Conference On Corrosion Electrochemistry And Measuring Methods, Editorial Office Of J.Electrochem.

Journal of Electrochemistry

No abstract provided.

Development On Hydriding/Dehydriding Kinetics Of Mg Nano-Materials For Hydrogen Storage, Wei Mo, Hong-Liang Sun, Hai-Chang Zhang, Hua-Bin Yang, Zuo-Xiang Zhou

Journal of Electrochemistry

The development of Mg nano-materials for hydrogen storage in the recent decade has been reviewed in this paper.It was shown the Mg nano-powders prepared by high-energy ball milling showed promising hydriding and dehydriding performance with the transition metal oxides and other types of hydrogen storage alloys(ABx)as the catalysts.

Electrocatalytic Oxidation Of Glucose On Nano Pt/C Electrode, Cui-Lian Chen, Xiao-Lan Wei, Pei Kang Shen

Journal of Electrochemistry

Nano Pt/C electrocatalysts were prepared by intermittent microwave heating method.The electrooxidation of glucose on smooth Pt and～Pt/C electrodes has been studied and compared.The results showed that the electrochemical properties on nano Pt/C were improved due to the reduction of the overpotential and the increase in the kinetic rate.The surface area would be significantly increased when the particle size of the catalyst was reduced to nano-scale,resulting in the increase in the activity.The enhancement in the resistance to poisoning could be explained that the oxygen-containing species are easier to react with poisoning species on nano Pt/C and re-active the electrode.

Effects Of Sulfide Ions On The Inhibiting Efficiency Of Eda As A Copper Corrosion Inhibitor In Dilute Hcl Solution, Wen-Juan Qu, Rong-Gui Du, Chang-Jian Lin

Journal of Electrochemistry

The anticorrosion action of EDA on copper in dilute HCl solution and the effect of sulfide ions on the inhibiting efficiency were studied by the Tafel plot method.The corrosion potential of Cu shifted to more positive value and the corrosion current density decreased after the addition of Na₂S to the solution.The results indicated that sulphide ions could increase the inhibiting efficiency of EDA because of the synergistic inhibition effect between EDA and Na₂S,resulting from the adsorption of HS^- on the surface of Cu,facilitated the adsorption of EDA to form a highly protective adsorbed layer which …

The Complex Of Pasp And Tungstate As Inhibitors Of Cupronickel B10′S Corrosion In 3% Nacl Solution, Qun-Jie Xu, Guo-Ding Zhou, Hui-Feng Wang, Wen-Bin Cai

Journal of Electrochemistry

AC impedance and polarization curve measurements were conducted to study the effects of environ-ment-friendly inhibitors PASP,Na₂WO₄ and their complexes on the corrosion of cupronickel B10 in 3%NaCl solution.The results indicate that PASP or Na₂WO₄ alone does inhibit the corrosion of B10,and most effectiveconcentrations are 40 mg/L and 60 mg/L for PASP and Na₂WO₄,respectively.With the total concentration of 40mg/L for the complex inhibitors,the optimum complex ratio of PASP to Na₂WO₄ was 3:1.The complex of such a combination showed a significantly synergetic inhibition effect on the corrosion of B10.

Effect Of Applied Potentials On The Formation Of Self-Assembled Monolayers Of Alkanethiol, Peng Diao, Xiao-Ning Wang, Qun-Chao Hou, Min Guo, Min Xiang, Qi Zhang

Journal of Electrochemistry

The self-assembled monolayers(SAMs)of n-dodecanethiol were prepared on gold substrates under electrochemical conditions using potential step technique.Electrochemical impedance spectroscopy was employed to characterize the SAMs prepared under different substrate potentials.It is found that the potential applied to gold substrate has great influence on the formation of SAMs.Within potential regime-0.8 V to 1.2 V,the increase of applied potential firstly leads to the formation of SAMs with higher packing density,better ordering and less defects.However,after reaching the maximum at 0.4 V,the packing density and the ordering of SAMs begin to deteriorate when the substrate potential is further increased.This work provides solid experimental basis for …

The Effect Of Solution Concentration On Properties Of Ru-Ti-Ir Oxide Anode Coatings, Ke Wang, Yan Han, Jun-Tao Wang, Xiao-Ling Zhang, Yu-Pu Sun

Journal of Electrochemistry

The anode coatings of Ru-Ti-Ir oxide with various solution concentrations were prepared by thermal decomposition.The scanning electron microscope(SEM),energy dispersive X-ray detector(EDX),X-ray diffraction(XRD),accelerated life,polarization curve,cyclic voltammetry and electrochemical impedance.spectroscopy(EIS)tests were carried out.The results showed that there was an obvious effect of solution concentrations on the morphology of the coatings,but little effect on polarization of chlorine evolution.Voltammetric charges and double layer capacitances of anode coatings had a tendency to fall down firstly then increase afterwards as the solution concentration increased.

Electrochemical Reduction Behavior Of Benzaldehyde In The Ionic Liquids, Ning Zhao, Wen-Ju Dong, Qi-Zeng Shi

Journal of Electrochemistry

In this paper, the electrochemical reduction of benzaldehyde was investigated in C₄MIMBF₄, C₆MIMBF₄  and C₈MIMBF₄ ionic liquids by cyclic linear sweep voltammetry,cyclic square-wave voltammetry and chronocoulometry.Benzaldehyde exhibits two successive one-electron irreversible reduction(E_P1=-1.39 V, E_P2=1.69 V) with GC electrode in C₄MIMBF₄, the voltammetric data for benzaldehyde give diffusion coefficients of 1.5*10^-8cm²/s and 1.3*10⁸cm²/s. There is one current peak in C₆MIMBF₄  and C₈MIMBF₄ ionic liquids due to their stronger alkalinity …

Oxygen Enrichment Effect Of Ceo2 To The Cathode Performance Of Proton Exchange Membrane Fuel Cell, Xiang-Li Hou, Hong-Feng Xu, Jian-Hua Dong, Xin Sun

Journal of Electrochemistry

CeO₂ was added to Pt/C catalyst in the cathode of PEMFC by both sol and impregnation methods.The samples were evaluated by TEM,cyclic voltammogram techniques and proton exchange membrane fuel cell performance test.The addition of CeO₂ obviously improved the performance of PEMFC and represented a notable function of oxygen enrichment in the cathode side.But with the addition of CeO₂,part of the catalyst surface was covered and led to the performance drop of the PEMFC.The best content of CeO₂ is 1% when it is added by impregnation method and 3% when it is added by sol method.

In-Situ Detection Of The Effect Of Brighter In The Solution For Nickel And Phosphor Alloy, Jian Zheng, Ning Li, De-Yu Li, Guo-Feng Cui

Journal of Electrochemistry

In this work,the gold-plated mica was used for the substrate,the concentration of 5% of normal plating solution for the nickel was used as the mother solution,and the effect for the deposition by the brighter with ECSTM was in-situ detected.The solution for deposition without the brighter has no brightness,though the values of the roughness and the H_(A-V) have reduced in evidence after deposition;the solution for deposition with the complete brighter although has great brightness,the values of the roughness and the H_(A-V) have increased(after) deposition;the solution for deposition with the half brighter has a moderate effect on the H_(A-V) and (brightness).Hence,the brighter …

25th Ccs Congress (Notes Of The First Circular), Editorial Office Of J.Electrochem.

Journal of Electrochemistry

No abstract provided.

Special Photoelectrochemical Response Of Nano-Crystalline Tio2 Electrode, Bi-Bo Lan, Jian-Zhang Zhou, Yan-Yan Xi, Hong-Xiang Chen, Guang-Hua Yao, Zhong-Hua Lin

Journal of Electrochemistry

The nano-crystalline TiO₂ electrodes were prepared by spread method,electrodeposition and sol-gel method.The experimental results show that the nano-crystalline TiO₂ electrodes have special photoelectrochemical response-the photocrrent-potential curves appear peaks.The special photoelectrochemical behaviors of nano-(crystalline) TiO₂  electrodes are ascribed to nano-structure as well as special light induced redox reaction mechanism of nano-crystalline semiconductor electrodes.