bluuebunny/crossref_metadata_2025 huggingface dataset:
Gd2Ti2-XMoXO7-Based Anode Materials for H2S-Air Solid Oxide Fuel Cells
Authors: Zha Shaowu , Cheng Zhe , Liu Meilin
Published: November 2006

The Gd2Ti2-xMoxO7 (x = 0.2, 0.6, and 1.0) pyrochlore solid solutions have been investigated as anode materials for solid oxide fuel cells (SOFCs) powered by H2S-containing gases. While the total electrical conductivity increases with Mo content in reducing atmospheres, the chemical stability in H2 containing 10% H2S is insufficient at high Mo content (x = 1.0 in Gd2Ti2-xMoxO7). Lowering the Mo content to x = 0.6 allows the anode to become chemically stable while retaining high electrical conductivity in H2S-containing atmospheres. The fuel cells based on Gd2Ti1.4Mo0.6O7 anode material show remarkable electrochemical performance. The anode/electrolyte interfacial resistance was 0.2 cm2 at 950oC in a fuel gas mixture of 10%H2S/3%H2O/87%H2, resulting in a peak power density of 342 mW cm-2. This fuel cell also performs well when fed with 10%H2S balanced by N2. The analysis of effluent gas shows that H2S was predominantly converted to elemental sulfur.
Manganese-Cobalt Spinel Oxides as Surface Modifiers for Stainless Steel Interconnects of Solid Oxide Fuel Cells
Authors: Xia Guanguang Gordon , Yang Zhenguo Gary , Stevenson Jeff
Published: November 2006

The adoption of ferritic stainless steels for SOFC interconnects is still under intensive evaluation due to the unresolved issues of chromium poisoning, low electrical conductivity, and long-term instability of the oxide scales. Application of manganese-cobalt spinel protection layers on the steel interconnects may be an effective approach to solve the problems. For an optimized performance, a series of MnxCo3-xO4 (0<x<3) spinels were investigated. It was found that the spinel with x around 1.5 demonstrates a good CTE match to the adjacent cell components, high electrical conductivity (61.6 S/cm at 800oC), and a good thermal stability up to 1250oC. The material suitability was confirmed by a long-term test on the Mn1.5Co1.5O4 protection coating layer that was thermally grown on Crofer22 APU, indicating the spinel protection layer not only significantly decreased the contact resistance between the LSF cathode and the stainless steel interconnect, but also inhibited the sub-scale growth on the stainless steel.
ITM Ceramic Membrane Technology to Produce Synthesis Gas
Authors: Miller Christopher , Carolan Michael , Chen Christopher , Minford Eric , Waldron William , Steppan James
Published: November 2006

Air Products and Chemicals and its partners are developing Ion Transport Membrane (ITM) technology for the production of hydrogen and carbon monoxide (synthesis gas or syngas). The ITM Syngas process is a breakthrough technology that combines air separation and high-temperature synthesis gas generation processes into a single ceramic membrane reactor, with significant savings in the capital cost of synthesis gas production. Because synthesis gas is a feedstock for a range of different processes, ITM Syngas represents a technology platform that has numerous applications, such as hydrogen, clean fuels and chemicals. ITM ceramic membranes are fabricated from non-porous, mixed-metal oxides and operate with exceptionally high oxygen flux and selectivity when exposed to an oxygen chemical potential gradient at high temperatures. This paper describes the development of the ITM Syngas ceramic membrane and the development of the reactor design, resulting in stable oxygen fluxes at our commercial target.
Transport Properties of Potassium-Doped BaZrO3 in Oxygen and Water Vapor Containing Atmospheres
Authors: Virkar Anil V. , Patnaik Abhishek S.
Published: November 2006

The effect of doping potassium on the A-site of BaZrO3 for application as a high temperature proton conductor was investigated. The synthesis of K-doped BaZrO3 and its characterization by XRD, SEM and EDX is described. Four-probe dc conductivity was measured on dense and porous (44% porosity) samples in varying partial pressures of oxygen, , and water vapor pressure, , over a temperature range from 500 to 700oC. The dependence of total conductivity in a dry atmosphere on oxygen partial pressure could be described by the equation . The experimental data were fitted to this equation with good accuracy, from which the electron-hole and oxygen-ion conductivities were determined. The activation energies for oxygen-ion and electron-hole conduction were estimated to be 0.85 and 1.14 eV, respectively. A significant increase in total ionic conductivity was observed in humid atmospheres, which is attributed to high protonic contribution.
Proton Conducting Ba3Ce(PO4)3 Synthesized by Co-precipitation
Authors: Zhang Guojing , Wachsman E. D. , Nino Juan
Published: November 2006

A new proton conducting material, Ba3Ce(PO4)3, was synthesized by co-precipitation, with calcination temperature 1100 {degree sign}C and dwell time 4h. The obtained particle size was around several hundred nanometers. Proton conduction of Ba3Ce(PO4)3 was studied by AC impedance under oxygen, air, nitrogen and hydrogen atmospheres and by electromotive force measurements of dry hydrogen concentration cells. The conductivities of Ba3Ce(PO4)3 in dry and wet 4 vol% hydrogen was 4.04x10-5 and 1.46x10-4 S/cm at 600 {degree sign}C, respectively. The proton transference number was approximately 0.8 in dry hydrogen concentration cells at 600 {degree sign}C.
High Voltage Anodization of a NiTi Shape Memory Alloy
Authors: Kawakita Jin , Hassel Achim , Stratmann Martin
Published: November 2006

In order to improve the corrosion resistance of a NiTi shape memory alloy, thick oxide films were fabricated on the surface by an anodic oxidation process. The microscopic observation showed the films had a porous nature and the structural analyses indicated that the films are amorphous. From the chemical analyses, the oxide films mainly contained titanium as metal component, the nickel content of the oxide films depends on pH of the electrolyte and anions could be incorporated from the electrolyte into the films. The asymmetrically rectangle waveform was effective to increase the density of the films. The electrochemical technique showed that the corrosion resistance of the anodised films could improve the resistance against localized corrosion of NiTi.
Corrosion Protection of Steel by Using ZnCoFe Alloy Coating (Replacement for Cadium Coating)
Authors: Lodhi Zeeshan F. , Terryn Herman , De Wit J.H.W . , Hovestad Arjan
Published: November 2006

Zinc and Zinc alloys have been extensively used as a replacement for Cadmium (Cd) coatings. ZnCo and ZnFe alloys with higher amount of Cobalt and Iron are very difficult to achieve due to anomalism associated with these coatings. Anomalous ZnCoFe alloy is a relatively recent addition in the family of Zn alloys. In this paper the corrosion resistance of ZnCoFe alloys with higher amount of Co (>10%) and Fe (>1%) are examined and compared with the pure Zinc, Cadmium and ZnCoFe alloy with low alloying elements (i.e. 0.5%Co+1%Fe). It is found that an increase in amount of Co > 10 % accounts for a shift in the OCP to a level higher than Zn and in case of >20% shifts somewhere near to Cd yet remains electronegative to steel. The coating shows superior corrosion resistance, in terms of its sacrificial and barrier properties, as compared to Zn, Cd and ZnCoFe (0.5%Co+1%Fe).
Salt Fog Accelerated Weathering Testing of High-Silica-Zeolite MFI Coatings on Aluminum Alloy 2024-T3
Authors: Beving Derek , Anderson Nicole , O'Neill Cory , Yan Yushan
Published: November 2006

Zeolites are microporous crystalline aluminosilicates with uniform and molecular sized pores. We have been investigating the application of zeolite films as chromium-free protective coatings on aluminum alloys. We have shown that as-synthesized organic template containing high-silica-zeolite (HSZ) MFI coatings on AA-2024-T3 are non-porous and have excellent corrosion resistance in strong acids, bases, and pitting aggressive media. We have also shown that the in-situ crystallization coating deposition process we used can coat surfaces of complex shapes and in confined spaces. Only one simple pretreatment and a single zeolite formulation are needed to synthesize MFI coatings on several different aluminum alloys. In this paper we show salt-fog accelerated weathering tests performed according to ASTM B117 on 7.5 um thick HSZ MFI coated 2024-T3 and their DC polarization profiles in 5 wt% NaCl aqueous solution. All HSZ MFI coated AA-2024-T3 panels were considered passing after more than 2000 hours continuous salt fog exposure.
High Throughput Corrosion Assessment of AA2024-T3 in the Presence of Corrosion Inhibitors
Authors: Chambers Brian D. , Taylor Shelton
Published: November 2006

New corrosion inhibitors to replace chromate must be discovered and characterized via experimentation. One approach to accelerate the discovery and characterization process is through use of high throughput screening (HTS) methods. This paper presents three methods for rapid screening of potential corrosion inhibitors and identification of their synergistic combinations for aluminum alloy 2024-T3 (AA2024- T3). Methods examined include DC polarization, cyclic voltammetry characterization of surface copper enrichment, and fluorometric detection of Al+3. Tests were conducted on single and binary combinations of the following inhibitors: cerium chloride, yttrium chloride, sodium metatungstate, sodium metavanadate, lanthanum chloride, sodium molybdate, sodium metasilicate, potassium phosphate, sodium phosphate, and barium metaborate. Testing was performed at 3.4 mM total inhibitor concentration in 0.6M NaCl. Testing of the inhibitor combinations revealed both synergistic and antagonistic pairings. Mixtures of rare earth chlorides paired with sodium molybdate rivaled sodium chromate corrosion inhibition using all three HTS methods at pH 7.
Evaluation of the Corrosion Resistance of Different Galvanized Steels Treated in Cerium Salt-Based Solutions
Authors: Mansfeld Florian , Song Yon-Kyun , Speckert Leif
Published: November 2006

Various treatments based on cerium salts have been evaluated in an attempt to develop surface modification treatments for galvanized steels that can replace the presently used processes that are based on hexavalent chromium. The substrates used in this study included pure zinc, electroplated zinc and zinc-nickel as well as hot dipped zinc and zinc-iron. In initial screening tests Zn and hot dipped Zn were immersed in Ce(NO3)3 or CeCl3 + H2O2 solutions at different concentrations and treatment times. The films formed in these solutions were sealed in Na2SiO3. The effect of the substrate chemistry was studied for bare electroplated zinc, zinc-nickel and hot dipped zinc as well as samples treated in a Ce(NO3)3 solution. Based on these results a new conversion coating process for electrogalvanized (EG) steel based on a cerium nitrate solution with several additives such as colloidal silica and silane has been developed that reduces the total treatment time to 70 seconds. The treated EG sample passed the 72 h salt spray test without white rusting. Similar improvements of corrosion resistance were obtained for the other types of galvanized steel.
Cut Edge Corrosion Protection in Organically Coated Galvanized Steels Using Ion Exchanged and Naturally Occurring Clay Mineral Pigments
Authors: Worsley David A. , McMurray Neil , Williams David
Published: November 2006

Two bentonite clays Wyoming-(W), Hybond-(H) and versions exchanged with Ce3+, Y3+, La3+ and Ca2+ cations were used as the corrosion inhibitors in the 5μm polyester primer layer on 0.7mm galvanized steel materials coated with a 20μm architectural polyester. Similar primer systems have been prepared containing Strontium Chromate-(Cr), ShieldexTM-(Shd) and Titanium Dioxide-(TiO2). The scanning vibrating electrode technique was used to investigate cut edge corrosion in 5% NaCl. The zinc losses over 24 hours were as follows: Shd (920 μg), Cr (740 μg), W-Y (655 μg), W-Ce (560 μg), W(550 μg) and W-Ca (496 μg). Samples were also subject to salt spray testing and there was good agreement between the SVET and salt spray data. The average maximum cut edge corrosion delamination distances were Cr (14mm), Shd (20mm), TiO2 (100mm), W (13mm), H (17mm), WCa (10mm), HCa (15mm), WCe (9mm), HCe (10mm), WY (13mm) and HY (15mm).
Corrosion Inhibitor Fe Interactions: A Study Combining Surface Science and Electrochemistry
Authors: Bhargava Gaurang , Ramanarayanan Trikur , Gouzman Irina , Bernasek Steven
Published: November 2006

The difference in corrosion inhibition behavior of imidazole deposited on iron by two different methods has been examined using Electrochemical Impedance Spectroscopy (EIS) and X-ray Photoelectron Spectroscopy (XPS). Adding imidazole directly into the aqueous corrosive medium has been observed to provide greater protection against corrosion, in comparison to the direct deposition of the inhibitor onto the metal surface prior to exposure to the corrosive solution. Analysis of the AC impedance spectra revealed that the value of the polarization resistance (Rp) in the case of imidazole addition to the corrosive medium was an order of magnitude higher than in the predeposited case. Results of XPS investigations suggested that in the former case, the imidazole reacts through the pyrrole type nitrogen with the aromatic ring more parallel to the metal surface. In the latter situation pyridine type nitrogen-iron interaction predominates with the imidazole ring more normal to the surface.
Dissolution and Inhibition Mechanism of 1018 Steel in Simulated Cooling Water by Adding Phosphononoacetic Acid Compound under Two Flow Conditions
Authors: Galicia Monica , Hernandez Roberto , Castaneda Homero , Zamudio Luis
Published: November 2006

It was monitored the dissolution process of 1018 steel in simulated cooling water during the transient and steady state conditions with time. Dissolution and growth of corrosion product layers were following using a linear flow cell and flow magnetic-induced cell. By using Electrochemical Impedance Spectroscopy, it was analyzed the dissolution and inhibition process. The growth of a layer when adding hydroxyphosphonoacetic acid, inhibits metal dissolution and it presents two different influences at the interface for impedance response. They showed that new layer forms in a simple array depending on the flow regimen and the hydroxypphosphonoacetic group added to the surface. After stabilization time of 5 hours in absence of inhibitor, continuous growth and dissolution of a layer changed the electrical characteristics for the scaling and corrosion product due to flow regimen. Electrical passive elements described qualitatively the characteristics of the layer formation due to inhibitor addition
The Mechanism of Inhibitor - Scale Interaction in Carbon Dioxide Corrosion of Mild Steel
Authors: Sun Wei , Chokshi Kunal , Nesic Srdjan
Published: November 2006

Investigations were conducted on the interaction between a corrosion inhibition and the precipitating iron carbonate scale, and their effects on the corrosion rate. Both the effects of iron carbonate precipitation on inhibited and uninhibited surfaces and the effects of inhibition on surfaces with iron carbonate scale were studied using electrochemical techniques. Generic imidazoline based inhibitors were added at various points in the iron carbonate scale formation process. The specimens were later analyzed using scanning electron microscopy (SEM). Although no antagonism was found under any condition tested, it was observed that the addition of the inhibitor hindered the corrosion rate, as well as retarded the growth of the iron carbonate scale due to the lower concentration of ferrous ion on the steel surface.
Prediction of Microstructure Evolution of Electroplated Copper Films
Authors: Freundlich Pavel
Published: November 2006

In manufacturing Cu interconnects, the electroplating bath contains organic additives which promote the required plating quality. The as deposited nanocrystalline Cu films undergo a self annealing process to form a micronsized grain structure by abnormal grain growth. Based on the experimental results, the previously proposed model for the observed abnormal grain growth published elsewhere (10) was modified by accounting for high conductivity paths through neighboring connected large grains. The modified model shows excellent agreement with measured data and is capable of predicting the self annealing kinetics in the studied range of deposition and post- deposition conditions.
In Situ Observation by AFM of the Morphology of Copper Metallization during Electrodeposition
Authors: Breathnach Mairead , Ahmed Shafaat , Nakahara Shohei , Buckley D. N.
Published: November 2006

The early stages of the electrodeposition of copper on a polycrystalline gold substrate were examined by in situ atomic force microscopy (AFM). Initial potential sweep measurements were carried out over a potential range of 200 mV to -400 mV (Cu/Cu2+) at a scan rate of 0.5 mV s-1. Potentiostatic deposition was performed at various potentials ranging from - 35 mV to -250 mV (Cu/Cu2+). The nucleation and growth of well- defined pyramidal features was observed. Initial rapid growth was observed to occur at crystal facets followed by a sudden change to a lower growth rate. Excellent agreement between the film thicknesses measured coulometrically and using AFM was obtained at more negative deposition potentials demonstrating that the areas imaged were representative of the electrode as a whole. At deposition potentials less negative than -50 mV (Cu/Cu2+) a discrepancy was observed indicating a higher-than- average density of features in the area imaged.
The Investigation on the Electrical Properties of a-SiCO:H as a Diffusion Barrier to Copper
Authors: Kim Hyeong Joon , Heo Jaeyeong
Published: November 2006

In this paper, we attempted to deposit low dielectric constant a-SiCO:H as a copper diffusion barrier by PECVD method using a organosilicon precursor, bis-trimethylsilylmethane (BTMSM, C7H20Si2). The dielectric constant of a-SiCO:H films increases from 2.5 to 3.2 with increasing the deposition temperature from room temperature to 280°C. Refractive index gradually increases with deposition temperature, indicating that film has a denser structure as well as a higher dielectric constant. FT-IR and XPS analyses resulted that chemical structure of Si atoms in the films changed from D moiety to T moiety with increasing the deposition temperature. The electrical conduction mechanism of the a-SiCO:H films was determined to be Schottky emission current at high field region (E > 0.4MV/cm).
Copper Electrodeposition on Osmium: A Potential Barrier for Damascene Processing
Authors: Josell Daniel , Witt Christian A. , Moffat Thomas
Published: November 2006

Direct electrodeposition of copper on osmium is described. Effective superfilling of sub-micrometer trenches by direct copper electrodeposition onto the osmium barrier layer is demonstrated. Surface modification of osmium prior to copper deposition demonstrated herein, including electrochemical reduction in sulfuric acid and exposure to plating additives, presents an avenue for future process optimization. The work suggests further examination of Os as a diffusion barrier and/or adhesion layer for Damascene metallization.
Stress Evolution in Electrodeposited Copper Metallization during Room-Temperature Aging
Authors: Chowdhury Tamjid , Ahmed Shafaat , Buckley D. N. , Laugier Michael , Nakahara Shohei , Heffernan Colm
Published: November 2006

Stress changes in electrodeposited copper films during room temperature aging were monitored by measuring the bending of the substrate using an optical fiber displacement sensor. Electrodeposition was carried out galvanostatically on evaporated copper films on borosilicate glass substrates in a stirred acidic copper sulphate bath at room temperature. It was observed that stress increases rapidly in the tensile direction reaching a plateau after ~1 hour of room temperature aging. The magnitude of the change was observed to increase with increasing current density but to decrease with increasing film thickness. The effect of additives to the bath was investigated. Films deposited in the presence of added chloride ions subsequently showed an increased change in stress during room-temperature aging but the effect did not increase significantly with concentration. Films deposited with BTA as an additive also showed an increased change in stress during aging and the effect increased significantly with increasing concentration. The effect of added PEG was small while the addition of thiourea had a significant and complex effect.
Investigating the Role of Stress in SOG-filled Shallow-Trench-Isolation Structures of sub-70 nm Device
Authors: Das Arabinda , Klipp Andreas , Sperlich Hans-Peter , Nitsche Robert
Published: November 2006

In this work, the role of stress and shrinkage during the processing of the sub-70nm shallow-trench isolation (STI) structures filled with a spin-on glass (SOG) material containing perhydro-polysilazane is discussed. The stress behavior of this material on blanket and patterned structures are compared. The different parameters for adjusting the stress and their influences on wet-etching properties and uniformity over the wafer are discussed. Finally, the effect of stress on electrical parameters is presented.
Synthesis and Controlling the Morphology of SnO2 Nanocrystals via Hydrothermal Treatment
Authors: Jain Kiran , Shrivastava Abhilasha , Rashmi Rashmi
Published: November 2006

SnO2 nanocrystals were synthesized via a hydrothermal method with and without a pre-addition of various surfactants. Powders were characterized by TEM for their particle size and morphology. The size and morphology of SnO2 nanocrystals was controlled by hydrothermal synthesis Tin oxide nanorods with a high aspect ratio were produced by hydrothermal treatment even without any surfactant addition when the hydrothermal treatment was made under a nitrogen atmosphere of about 40 atmosphere pressure. The size of these nanorods can be controlled by the temperature and time of the synthesis temperature. The addition of surfactants such as AOT and CTAB resulted in a drastic change in grain morphology from nanorods to spherical shaped particles with decreased particle size.
Surface Characterization and Manipulation of SWCNT for Sensor Applications
Authors: Buttner William J. , Chung G.H. , Evans L. , Hunter G. , Stetter Joseph R. , Jeong J.S. , Xu J. , Wang Rong , Vander Wal Randy
Published: November 2006

Development of practical SWCNT-based chemical sensors is impeded because of difficulties in controlling both orientation/morphology in a MEMs-based sensor platform and the purity of nano-material. Methods to purify CNTs, prior to and following device fabrication are described. More critically, methodology to control the physical morphology of SWCNT on a MEMs platform has been applied for sensor applications.
Jonny Galvo: A Small, Low Cost Wireless Galvanostat
Authors: Steingart Daniel A. , Redfern Andrew , Ho Christine , Wright Paul , Evans James
Published: November 2006

A wireless, high resolution galvanostat is fabricated using smart dust technology for under $100 dollars using free software and general use hardware. We demonstrate a design that uses either PWM or DAC to set a current with up to 100 picoamp resolution for any value between -15 and 15 mA. An ADC measures the potential of the battery during charge cycles using a short (~400 µs) interrupt. A small foot print Java program controls the galvanostat and logs the ADC data. The device preforms well when tested against calibrated values for a variety of capacitors and resistors.
A Bi-Layer Structured Biosensor for the Direct Measurement of Biopolymers and the Effects of Different Size and Levels of Branching
Authors: Cui Yue , Barford John , Renneberg Reinhard
Published: November 2006

This work reports a protocol that uses bilayer structured immobilization matrix by covalent binding to construct an amperometric biosensor for the rapid and direct biopolymer measurement within 5 min. It overcomes the normal barrier of biopolymers not being able to enter into the enzyme matrix due to their branched nature and large size. The outer layer containing enzymes covalent bind to the inner layer which links the enzymes to the surface of electrode. A biosensor for a polysaccharide (glycogen) is developed to demonstrate this strategy. The sensor shows good performance. The different size and branching level of the substrates (glucose)n result in them exhibiting different signal responses, even they are composed of the same monomer, the reason of which has been tentatively analyzed. The method also has the advantages of being cost effective and having a simple immobilization preparation procedure.
An Oxygen-rich Enzyme Matrix for Biosensor Construction Based on Clark Oxygen Electrode
Authors: Cui Yue , Barford John , Renneberg Reinhard
Published: November 2006

We report a novel strategy to develop an oxygen-rich enzyme matrix biosensor based on the Clark oxygen electrode. For biosensors based on oxygen detection, the oxygen concentration in the enzyme matrix will significantly affect the biosensor performance. We demonstrate that, by using catalase in the enzyme matrix and hydrogen peroxide in the buffer solution, the concentration of oxygen in the enzyme matrix will be increased significantly. This is due to the release of oxygen from hydrogen peroxide through the enzymatic reaction by catalase. Consequently, the linear detection range will be broadened and the present oxygen-dependence will be alleviated significantly.
Regulation of lipopolysaccharide-induced increases in neutrophil glucose uptake
Authors: Schuster Daniel P. , Brody Steven L. , Zhou Zhaohui , Bernstein Matt , Arch Robert , Link Daniel , Mueckler Michael
Published: November 2006

The pathogenesis of many lung diseases involves neutrophilic inflammation. Neutrophil functions, in turn, are critically dependent on glucose uptake and glycolysis to supply the necessary energy to meet these functions. In this study, we determined the effects of p38 mitogen-activated protein kinase and hypoxia-inducible factor (HIF)-1, as well as their potential interaction, on the expression of membrane glucose transporters and on glucose uptake in murine neutrophils. Neutrophils were harvested and purified from C57BL/6 mice and stimulated with lipolypolysaccharide (LPS) in the presence or absence of specific p38 and HIF-1 inhibitors. Glucose uptake was measured as the rate of [3H]deoxyglucose (DG) uptake. We identified GLUT-1 in mouse neutrophils, but neither GLUT-3 nor GLUT-4 were detected using Western blot analysis, even after LPS stimulation. LPS stimulation did not increase GLUT-1 protein levels but did cause translocation of GLUT-1 from the cell interior to the cell surface, together with a dose-dependent increase in [3H]DG uptake, indicating that glucose uptake is regulated in these cells. LPS also activated both p38 and the HIF-1 pathway. Inhibitors of p38 and HIF-1 blocked GLUT-1 translocation and [3H]DG uptake. These data suggest that LPS-induced increases in neutrophil glucose uptake are mediated by GLUT-1 translocation to the cell surface in response to sequential activation of neutrophil p38 and HIF-1α in neutrophils. Given that neutrophil function and glucose metabolism are closely linked, control of the latter may represent a new target to ameliorate the deleterious effects of neutrophils on the lungs.
Paraoxonase-2 deficiency enhancesPseudomonas aeruginosaquorum sensing in murine tracheal epithelia
Authors: Stoltz David A. , Ozer Egon A. , Ng Carey J. , Yu Janet M. , Reddy Srinivasa T. , Lusis Aldons J. , Bourquard Noam , Parsek Matthew R. , Zabner Joseph , Shih Diana M.
Published: November 2006

Pseudomonas aeruginosa is an important cause of nosocomial infections and is frequently present in the airways of cystic fibrosis patients. Quorum sensing mediates P. aeruginosa's virulence and biofilm formation through density-dependent interbacterial signaling with autoinducers. N-3-oxododecanoyl homoserine lactone (3OC12-HSL) is the major autoinducer in P. aeruginosa. We have previously shown that human airway epithelia and paraoxonases (PONs) degrade 3OC12-HSL. This study investigated the role of PON1, PON2, and PON3 in airway epithelial cell inactivation of 3OC12-HSL. All three PONs were present in murine tracheal epithelial cells, with PON2 and PON3 expressed at the highest levels. Lysates of tracheal epithelial cells from PON2, but not PON1 or PON3, knockout mice had impaired 3OC12-HSL inactivation compared with wild-type mice. In contrast, PON1-, PON2-, or PON3-targeted deletions did not affect 3OC12-HSL degradation by intact epithelia. Overexpression of PON2 enhanced 3OC12-HSL degradation by human airway epithelial cell lysates but not by intact epithelia. Finally, using a quorum-sensing reporter strain of P. aeruginosa, we found that quorum sensing was enhanced in PON2-deficient airway epithelia. In summary, these results show that loss of PON2 impairs 3OC12-HSL degradation by airway epithelial cells and suggests that diffusion of 3OC12-HSL into the airway cells can be the rate-limiting step for degradation of the molecule.
Left Ventricular Hypertrophy in Severe Obesity
Authors: Avelar Erick , Cloward Tom V. , Walker James M. , Farney Robert J. , Strong Michael , Pendleton Robert C. , Segerson Nathan , Adams Ted D. , Gress Richard E. , Hunt Steven C. , Litwin Sheldon E.
Published: November 2006

Obese subjects have a high prevalence of left ventricular (LV) hypertrophy. It is unclear to what extent LV hypertrophy results directly from obesity or from associated conditions, such as hypertension, impaired glucose homeostasis, or obstructive sleep apnea. We tested the hypothesis that LV hypertrophy in severe obesity is associated with additive effects from each of the major comorbidities. Echocardiography and laboratory testing were performed in 455 severely obese subjects with body mass index 35 to 92 kg/m
2
and 59 nonobese reference subjects. LV hypertrophy, defined by allometrically corrected (LV mass/height
2.7
), gender-specific criteria, was present in 78% of the obese subjects. Multivariable regression analyses showed that average nocturnal oxygen saturation <85% was the strongest independent predictor of LV hypertrophy (
P
<0.001), followed by systolic blood pressure (
P
<0.015) and then body mass index (
P
<0.05). With regard to LV mass, there were synergistic effects between hypertension and body mass index (
P
interaction <0.001) and between hypertension and reduced nocturnal oxygen saturation. Severely obese subjects had normal LV endocardial fractional shortening (35±6% versus 35±6%) but mildly decreased midwall fractional shortening (15±2% versus 17±2%;
P
<0.001), indicating subtle myocardial dysfunction. In conclusion, more severe nocturnal hypoxemia, increasing systolic blood pressure, and body mass index are all independently associated with increased LV mass. The effects of increased blood pressure seem to amplify those of sleep apnea and more severe obesity.
Effect of Tryptophan Hydroxylase 1 Deficiency on the Development of Hypoxia-Induced Pulmonary Hypertension
Authors: Morecroft Ian , Dempsie Yvonne , Bader Michael , Walther Diego J. , Kotnik Katarina , Loughlin Lynn , Nilsen Margaret , MacLean Margaret R.
Published: November 2006

Tryptophan hydroxylase 1 catalyzes the rate-limiting step in the synthesis of serotonin in the periphery. Recently, it has been shown that expression of the tryptophan hydroxylase 1 gene is increased in lungs and pulmonary endothelial cells from patients with idiopathic pulmonary arterial hypertension. Here we investigated the effect of genetic deletion of
tryptophan hydroxylase 1
on hypoxia-induced pulmonary arterial hypertension in mice by measuring pulmonary hemodynamics and pulmonary vascular remodeling before and after 2 weeks of hypoxia. In wild-type mice, hypoxia increased right ventricular pressure and pulmonary vascular remodeling. These effects of hypoxia were attenuated in the
tryptophan hydroxylase 1
−/−
mice. Hypoxia increased right ventricular hypertrophy in both wild-type and
tryptophan hydroxylase 1
−/−
mice suggesting that in vivo peripheral serotonin has a differential effect on the pulmonary vasculature and right ventricular hypertrophy. Contractile responses to serotonin were increased in pulmonary arteries from
tryptophan hydroxylase 1
−/−
mice. Hypoxia increased serotonin-mediated contraction in vessels from the wild-type mice, but this was not further increased by hypoxia in the
tryptophan hydroxylase 1
−/−
mice. In conclusion, these results indicate that tryptophan hydroxylase 1 and peripheral serotonin play an essential role in the development of hypoxia-induced elevations in pulmonary pressures and hypoxia-induced pulmonary vascular remodeling. In addition, the results suggest that, in mice, serotonin has differential effects on the pulmonary vasculature and right ventricular hypertrophy.
Intracerebral Hemorrhage With Severe Ventricular Involvement
Authors: Huttner Hagen B. , Nagel Simon , Tognoni Elena , Köhrmann Martin , Jüttler Eric , Orakcioglu Berk , Schellinger Peter D. , Schwab Stefan , Bardutzky Jürgen
Published: November 2006

Background and Purpose—

The objective was to analyze the feasibility of a lumbar drainage (LD) for a communicating malresorptive hydrocephalus in patients with supratentorial hemorrhage (intracerebral hemorrhage) accompanied by severe ventricular involvement (intraventricular hemorrhage) who required an external ventricular drain (EVD).

Methods—

In this retrospective study, 16 patients received an EVD and concurrent LD and were compared with 39 historical patients treated with EVD alone. The duration of required EVD and need for permanent ventriculoperitoneal-shunt were analyzed.

Results—

LD was inserted after 12 (4 to 18) days. In LD-treated patients, the LD was capable to replace repeated EVD exchanges, resulting in a shorter EVD-duration (12 versus 16 days) compared with patients treated with EVD alone. The overall duration of extracorporal cerebrospinal fluid drainage was longer (16 days EVD versus 21 days EVD+LD) and the frequency of ventriculoperitoneal-shunt lower (18.75% versus 33%;
P
<0.03) in LD-treated patients.

Conclusion—

Our data suggest that LD is safe and feasible for treatment of nonpersistent communicating hydrocephalus after intracerebral hemorrhage. After adequate treatment of the occlusive hydrocephalus using an EVD in the acute phase, LD discloses an alternative for further extracorporal cerebrospinal fluid drainage.
Macrophage-Derived Matrix Metalloproteinase-2 and -9 Promote the Progression of Cerebral Aneurysms in Rats
Authors: Aoki Tomohiro , Kataoka Hiroharu , Morimoto Masafumi , Nozaki Kazuhiko , Hashimoto Nobuo
Published: November 2006

Background and Purpose—

Mechanisms of initiation, progression and rupture of cerebral aneurysms have not yet been fully understood despite its clinical significance. Matrix metalloproteinases (MMPs) are a family of proteinases which are involved in the remodeling of vascular walls. In the present study, we investigated the significance of MMPs in the progression of cerebral aneurysms.

Methods—

Cerebral aneurysms were experimentally induced in 7-week-old male Sprague-Dawley rats. MMP-2 and MMP-9 expression was examined by immunohistochemistry and RT-PCR. Gelatinase activity in aneurysmal walls was assessed by in situ zymography. A selective inhibitor for MMP-2, -9 and -12, tolylsam, was used to examine the effect of inhibition of MMP-2 and MMP-9.

Results—

Macrophages infiltrated in arterial walls of experimentally induced rat cerebral aneurysms and expressed MMP-2 and -9. Macrophage infiltration and MMP expression was increased with the progression of aneurysms. Gelatinase activity attributable to MMP-2 and MMP-9 increased in arterial walls of rat cerebral aneurysms. Furthermore, tolylsam reduced the ratio of advanced aneurysms in our rat model.

Conclusions—

These data suggest that macrophage-derived MMP-2 and -9 may play an important role in the progression of cerebral aneurysms. The findings of this study will shed a new light into the pathogenesis of cerebral aneurysms and highlight the importance of inflammatory response causing the degeneration of extracellular matrix in the process of this disease.
Stent-Based Local Delivery of Nuclear Factor-κB Decoy Attenuates In-Stent Restenosis in Hypercholesterolemic Rabbits
Authors: Ohtani Kisho , Egashira Kensuke , Nakano Kaku , Zhao Gang , Funakoshi Kouta , Ihara Yoshiko , Kimura Satoshi , Tominaga Ryuji , Morishita Ryuichi , Sunagawa Kenji
Published: November 2006

Background—

Nuclear factor-κB (NF-κB) plays a critical role in the vascular response to injury. However, the role of NF-κB in the mechanism of in-stent restenosis remains unclear. We therefore tested the hypothesis that blockade of NF-κB by stent-based delivery of a cis-element “decoy” of NF-κB reduces in-stent neointimal formation.

Methods and Results—

Stents were coated with a polymer containing or not containing NF-κB decoy, which represented a fast-release formulation (<7 days). Bare, polymer-coated, and NF-κB decoy–eluting stents were implanted in iliac arteries of hypercholesterolemic rabbits. Increased NF-κB activity was noted at early stages after stenting, which was suppressed by stent-based delivery of NF-κB decoy. NF-κB decoy–eluting stents also reduced monocyte infiltration and monocyte chemoattractant protein-1 expression and suppressed CD14 activation on circulating leukocytes. Importantly, NF-κB decoy–eluting stents attenuated neointimal formation on day 28. There was no evidence of an incomplete healing process (persistent inflammation, hemorrhage, fibrin deposition, impaired endothelial regeneration) at the site of NF-κB decoy–eluting stents. Transfection of NF-κB decoy suppressed proliferation of human coronary artery smooth muscle cells in vitro. No systemic adverse effects of NF-κB decoy were detected.

Conclusions—

Stent-based local delivery of NF-κB decoy reduced in-stent neointimal formation with no evidence of incomplete healing. These data suggest that this strategy may be a practical and promising means for prevention of in-stent restenosis in humans.
“What” and “Where” in Word Reading: Ventral Coding of Written Words Revealed by Parietal Atrophy
Authors: Vinckier Fabien , Naccache Lionel , Papeix Caroline , Forget Joaquim , Hahn-Barma Valerie , Dehaene Stanislas , Cohen Laurent
Published: November 2006

The visual system of literate adults develops a remarkable perceptual expertise for printed words. To delineate the aspects of this competence intrinsic to the occipitotemporal “what” pathway, we studied a patient with bilateral lesions of the occipitoparietal “where” pathway. Depending on critical geometric features of the display (rotation angle, letter spacing, mirror reversal, etc.), she switched from a good performance, when her intact ventral pathway was sufficient to encode words, to severely impaired reading, when her parietal lesions prevented the use of alternative reading strategies as a result of spatial and attentional impairments. In particular, reading was disrupted (a) by rotating word by more than 50°, providing an approximation of the invariance range for words encoding in the ventral pathway; (b) by separating letters with double spaces, revealing the limits of letter grouping into perceptual wholes; (c) by mirror-reversing words, showing that words escape the default mirror-invariant representation of visual objects in the ventral pathway. Moreover, because of her parietal lesions, she was unable to discriminate mirror images of common objects, although she was excellent with reversible pseudowords, confirming that the breaking of mirror symmetry was intrinsic to the occipitotemporal cortex. Thus, charting the display conditions associated with preserved or impaired performance allowed us to infer properties of word coding in the normal ventral pathway and to delineate the roles of the parietal lobes in single-word recognition.
Patterns of Regional Brain Hypometabolism Associated with Knowledge of Semantic Features and Categories in Alzheimer's Disease
Authors: Zahn Roland , Garrard Peter , Talazko Jochen , Gondan Matthias , Bubrowski Philine , Juengling Freimut , Slawik Helen , Dykierek Petra , Koester Bernd , Hull Michael
Published: November 2006

The study of semantic memory in patients with Alzheimer's disease (AD) has raised important questions about the representation of conceptual knowledge in the human brain. It is still unknown whether semantic memory impairments are caused by localized damage to specialized regions or by diffuse damage to distributed representations within nonspecialized brain areas. To our knowledge, there have been no direct correlations of neuroimaging of in vivo brain function in AD with performance on tasks differentially addressing visual and functional knowledge of living and nonliving concepts. We used a semantic verification task and resting 18-fluorodeoxyglucose positron emission tomography in a group of mild to moderate AD patients to investigate this issue. The four task conditions required semantic knowledge of (1) visual, (2) functional properties of living objects, and (3) visual or (4) functional properties of nonliving objects. Visual property verification of living objects was significantly correlated with left posterior fusiform gyrus metabolism (Brodmann's area [BA] 37/19). Effects of visual and functional property verification for non-living objects largely overlapped in the left anterior temporal (BA 38/20) and bilateral premotor areas (BA 6), with the visual condition extending more into left lateral precentral areas. There were no associations with functional property verification for living concepts. Our results provide strong support for anatomically separable representations of living and nonliving concepts, as well as visual feature knowledge of living objects, and against distributed accounts of semantic memory that view visual and functional features of living and nonliving objects as distributed across a common set of brain areas.
Listening to the Mind Listening: An Analysis of Sonification Reviews, Designs and Correspondences
Authors: Barrass Stephen , Whitelaw Mitchell , Bailes Freya
Published: November 2006

Listening to the Mind Listening (LML) explored whether sonifications can be more than just “noise” in terms of perceived information and musical experience. The project generated an unprecedented body of 27 multichannel sonifications of the same dataset by 38 composers. The design of each sonification was explicitly documented, and there are 88 analytical reviews of the works. The public concert presenting 10 of these sonifications at the Sydney Opera House Studio drew a capacity audience. This paper presents an analysis of the reviews, the designs and the correspondences between timelines of these works.
Scotian Shelf 1 and Scotian Shelf 2
Authors: Wimmer Tonya
Published: November 2006

Sounds of seismic survey and delphinid (dolphins or pilot whales) whistles and clicks recorded in the Atlantic Ocean off Nova Scotia, May 2001.
N. April 16, 2006
Authors: Polli Andrea , Gilmore Joe
Published: November 2006

Sonification of measured (National Oceanic and Atmospheric Administration's Arctic program) and model weather data, April 2006. Data modeling by Patrick Market, University of Missouri.
Bridge Vibrations
Authors: Flejter Rafal
Published: November 2006

Contact microphone recording of St. Saviour's Dock Bridge beside the River Thames, London, January 2006.
Magnetic Nets
Authors: Kubisch Christina
Published: November 2006

Composed from electromagnetic recordings of security (antitheft) gates of major shops in Europe, Japan, China and the United States.
Möbius Fields (soundwalk)
Authors: Stankievech Charles
Published: November 2006

Conventional and electromagnetic recordings made in Montréal, Canada, March 2006.
Interactive Sonification: Aesthetics, Functionality and Performance
Authors: Weinberg Gil , Thatcher Travis
Published: November 2006

The authors present a sonification installation that allows a group of players to interact with an auditory display of neural activity. The system is designed to represent electrical spike propagation in a neuron culture through sound propagation in space. Participants can simulate neural spikes by using a set of specially designed controllers, experimenting and sonically investigating the electrical activity of the brain. The article discusses some aesthetic and functional aspects of sonification and describes the authors' approach for group interaction with auditory displays. It concludes with the description of a performance piece for the system and ideas for improvements and future work.
Nanostructured CaWO4, CaWO4 : Pb2+ and CaWO4 : Tb3+ Particles: Polyol-Mediated Synthesis and Luminescent Properties
Authors: Wang Zhenling , Li Guangzhi , Quan Zewei , Kong Deyan , Liu Xiaoming , Yu Min , Lin Jun
Published: November 2006

Nano-submicrostructured CaWO4, CaWO4 : Pb2+ and CaWO4 : Pb3+ particles were prepared by polyol method and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy
(TEM), Fourier transform infrared spectra (FT-IR), thermogravimetry-differential thermal analysis (TG-DTA), photoluminescence (PL), cathodoluminescence (CL) spectra and PL lifetimes. The results of XRD indicate that the as-prepared samples are well crystallized with the scheelite structure
of CaWO4. The FE-SEM images illustrate that CaWO4 and CaWO4 : Pb2+ and CaWO4 : Tb3+ powders are composed of spherical particles with sizes around 260, 290, and 190 nm respectively, which are the aggregates of smaller nanoparticles
around 10–20 nm. Under the UV light or electron beam excitation, the CaWO4 powders exhibits a blue emission band with a maximum at about 440 nm. When the CaWO4 particles are doped with Pb2+, the intensity of luminescence is enhanced to some extent and
the luminescence band maximum is red shifted to 460 nm. Tb3+-doped CaWO4 particles show the characteristic emission of Tb3+ 5D4–7FJ (J = 6 – 3) transitions due to an energy transfer from
WO42− groups to Pb3+.
Spin Transport in Spin Filtering Magnetic Tunneling Junctions
Authors: Li Yun , Lee Eok Kyun
Published: November 2006

Taking into account spin-orbit coupling and s–d interaction, we investigate spin transport properties of the magnetic tunneling junctions with spin filtering barrier using Landauer-Büttiker formalism implemented with the recursive algorithm to calculate the real-space Green
function. We predict completely different bias dependence of negative tunnel magnetoresistance (TMR) between the systems composed of nonmagnetic electrode (NM)/ferromagnetic barrier (FB)/ferromagnet (FM) and NM/FB/FM/NM spin filtering tunnel junctions (SFTJs). Analyses of the results provide
us possible ways of designing the systems which modulate the TMR in the negative magnetoresistance regime.
Fast Colorimetric Detection of Copper Ions Using L-Cysteine Functionalized Gold Nanoparticles
Authors: Yang Wenrong , Gooding J. Justin , He Zhicong , Li Qiong , Chen Guonan
Published: November 2006

This communication reports an efficient visual detection method of Cu2+ by L-cysteine functionalized gold nanoparticles in aqueous solution. Upon exposure to Cu2+, the gold nanoparticle solution changed from red to blue, in response to surface plasmon absorption
of dispersed and aggregated nanoparticles. This colorimetric sensor allows a rapid quantitative assay of Cu2+ down to the concentration range of 10−5 M. Recognition of Cu2+ and formation of the aggregates are proposed to occur via a 2 : 1 sandwich complex
between L-cysteine and Cu2+.