bluuebunny/crossref_metadata_2025 huggingface dataset:
Stability and EPD of Concentrated Suspensions of Alumina with Nanosized Titania
Authors: Molina Tamara , Vicent Monica , Sánchez Enrique , Moreno Rodrigo
Published: March 2012

Alumina-aluminium titanate (A-AT) composites and laminates have been recently investigated because they can provide improved flaw tolerance and toughness associated to a microcracking mechanism. A-AT composites have been produced by slip casting and reaction sintering of submicron sized alumina and titania powders. This work deals with the preparation of thick self-sustained A-AT films from mixtures of submicron sized alumina and nanosized titania. Suspensions were prepared in water to high solids loadings ranging from 30 to 50 vol.%. The stability of diluted suspensions was studied through zeta potential measurements as a function of pH and deflocculant type and concentration. The stability of the concentrated suspensions as a function of deflocculant content, sonication time and solids loadings was studied from rheological measurements. Self-sustained films were obtained by aqueous EPD using graphite substrates under constant current density conditions. The evolution of mass per unit area with current density and deposition time was recorded. The films were characterized in the green state and after debinding and sintering by density measurements, and electron microscopy observations.
Preparation of Perovskite-Type Oxide Thick-Film Device by EPD Method and its Application for Electrochemical Hydrogen-Phosphate Ion Sensor
Authors: Inagaki Toru , Matsumoto Toshikazu , Takase Satoko , Shimizu Youichi
Published: March 2012

Perovskite-type oxide (LaCoO3) fine powders were prepared by a polymer precursors (PP) methods at 300~500°C. The LaCoO3fine powder could be prepared at 380°C when the use of EDA and PEG for organic-and polymer-additives, respectively. The surface area of LCO was ca. 39m2/g. LCO thick-film could be prepared from the steady state suspension with the addition of AcAc or PVAby the EPD method at +10V, 3min.The current density of the LaCoO3film sensor was changed with changing HPO42-concentration at +1.00 V vs. SCE. The device showed relatively good amperometoric response to H2PO4-from 1.0x10-5M to 1.0x10-3M with the 90% response time of ca 2min. The LaCoO3-based sensor also showed a good selectivity among the examined anions of NO3-, Cl-and SCN-.
Orientation Control of Hematite via Transformation of Textured Goethite Prepared by EPD in a Strong Magnetic Field
Authors: Uchikoshi Tetsuo , Suzuki Tohru , Sakka Yoshio
Published: March 2012

Fabrication of textured hematite was achieved from paramagnetic goethite by electrophoretic deposition in a strong magnetic field followed by thermal treatment via topotactic phase transformation. The textured microstructure of the hematite was characterized by XRD and SEM observations. It was confirmed that the a,b-axes of the goethite were taken over the c-axis of the hematite through the topotactic phase transformation The magnetization vs magnetic field measurement using a VSM revealed that the textured hematite showed an anisotropic magnetic property depending on the direction of the crystalline orientation.
Electrophoretic Deposition onto Ionic Liquid Layers
Authors: Neirinck Bram , Schaltin Stijn , Marzouk Hijjit , Fransaer Jan , Van der Biest Omer , Vleugels Jef
Published: March 2012

Electrophoretic deposition is a promising method for the near net shaping of ceramics if deposit damage during removal from the electrode can be prevented. The latter can be achieved by providing a lubricated interface between electrode and deposit. During application of such a lubricant care must be taken that none of the electrode surface details are lost. Hence thins layers which closely represent the original electrode surface are needed. In the present work electrophoretic deposition of alumina powder on a thin layer of ionic liquid applied on polymer electrodes is described. After deposition this ionic liquid layers serves as a shear plane during the deposit removal. The resulting deposits exhibit a smooth surface quality and high green density. Furthermore experiments show that the ionic liquid can be used as a means for producing electrodes with areas at which deposition is locally prevented.
Thin Films of Europium (III) Doped-TiO2 Prepared by Electrophoretic Deposition from Nanoparticulate Sols
Authors: Borlaf Mario , Colomer Maria Teresa , Titzel Howard , Dickerson James H. , Moreno Rodrigo
Published: March 2012

Colloidal sol-gel is a common method used for the preparation of stable and homogeneous sols and thin films. The nanoparticulate sols can be easily deposited by EPD, which is a versatile technique for producing denser and thicker coatings than those produced by other techniques like dipping. A complete characterization of the sols, such as colloidal stability and electrophoretic mobility, which can be determined through zeta potential measurements, as well as the influence of deflocculants in the surface properties, is needed before using electrophoretic deposition. In this work, we have prepared sols of TiO2with an alkoxide:water molar ratio of 50:1 and Eu (III) doped-TiO2(2 mole % Eu (III)) using as precursors titanium (IV) isopropoxide and europium (III) acetate hydrate, respectively. The stability of the particulate sols was studied in terms of conductivity, zeta potential and viscosity evolution. Anatase stable sols, after peptization and without the use of any additive, were deposited on stainless steel substrates by electrophoretic deposition under both constant current and constant voltage conditions. Using different intensities and deposition times we have obtained thin films with different features (thicknesses and morphology) and different optical properties. The presence of europium (III) increases particle size, viscosity and peptization time and decreases the band gap of TiO2.
Selective Deposition of TiO2 during Monolayer Formation of TiO2 and Iron Oxide Nanocrystals by Electrophoretic Deposition in Non-Polar Solvents
Authors: Gonzalo-Juan Isabel , Krejci Alex J. , Dickerson James H.
Published: March 2012

The electrophoretic deposition of TiO2 iron oxide nanocrystal monolayers from stable, mixed colloidal suspensions by electrophoretic deposition using non polar solvents is reported. The selective deposition of TiO2 was accomplished by controlling the mobility of the nanocrystals and the voltage during electrophoretic deposition. The effect of the electrophoretic deposition processing parameters (voltage and particle mobility) on the promotion and suppression of nanocrystal deposition was investigated.
Application of Laser Remelting Treatments to Improve the Properties of Ti6Al4V Alloy
Authors: Amaya-Vázquez M.R. , Sánchez-Amaya J.M. , Boukha Z. , El Amrani K. , Botana Francisco Javier
Published: March 2012

Ti6Al4V is the α-β alloy most employed in industry. The modification of its properties can be achieved with conventional heat treatments and/or with laser processing. Laser remelting (LR) has been applied to Ti6Al4V by other authors with excimer and Nd-YAG laser, employing pure argon as shielding gas to prevent risk of oxidation. In the present contribution, LR has been applied for the first time with a high power diode laser shielded with argon to improve the properties of Ti6Al4V. Results showed that remelted samples (with medium energy densities) have higher microhardness and better corrosion resistance than Ti6Al4V base metal.
Development of a Laser Hardening Simulation Method Including Material Characterization for Rapid Heating Rates
Authors: Martínez S. , Ukar Eneko , Tabernero I. , Lamikiz Aitzol
Published: March 2012

The main disadvantage for industrial application of new processes based on laser surface treatments, such as laser hardening, quenching or precipitation hardening, is the prior experimentation needed to determinate the optimum conditions for processes. The presented work is focused on the development of a tool based on a semi-empirical model to predict accurately the thermal field and thickness of the head affected zone in laser surface treatments in order to avoid the previous experimental setups of this processes. The conventional thermal models are focused on solving the differential equation of temperature field, considering the laser as heat source and thermal properties of each material. However, during the rapid heating treatment processes of metal surfaces are some unknown heat sinks such us metallurgical transformations or a changeable material absortivity that must be taken into account. The model has been adjusted and validated with experimental data for AISI 1045.
Analysis of the Laser Weldability under Conduction Regime of 2024, 5083, 6082 and 7075 Aluminium Alloys
Authors: Sánchez-Amaya J.M. , Boukha Z. , Amaya-Vázquez M.R. , González-Rovira L. , Botana Francisco Javier
Published: March 2012

Laser beam welding (LBW) show clear advantages compared with other techniques, as the low heat input, the high localization ability, the high welding speed, the high flexibility, the high weld quality and the high production rate. However, its applicability to aluminium alloys is limited, as they generally have high reflectivity, high thermal conductivity and low viscosity. In the present study, the laser weldability of four aluminium alloys (2024, 5083, 6082 and 7075) under conduction regime is analysed. High penetration butt welds could be obtained with a High Power Diode Laser (HPDL) under conduction regime. The properties of the weld beads such as the microstructure and microhardness were analysed. A linear function between the input laser fluence and the volume of melted material was obtained for the four alloys.
FEA of the Influence of Assembly Parameters on the Fatigue Life of Metal-Composite Bolted Joints
Authors: Álvarez I. , Doblas F.J. , Vallellano C. , Portal A. , Arroyo P.J.
Published: March 2012

This paper presents a numerical analysis of the influence on the fatigue life of hybrid metal/CFRP bolted joints of some deviations in certain assembly parameters. Two types of hybrid joints typically used in aircraft are analyzed, the Ti-6Al-4V/CFRP and the Al-2024-T3/CFRP, riveted with blind bolts. The parameters analyzed are: the thickness of sealant between metal sheet and composite laminate, the angle of countersunk and the adjustment or chamfer at the countersunk-drill zone. The analysis highlights critical areas for fatigue failure and the relative influence of these parameters on the fatigue resistance of the joint.
Microstructure and Texture Evolutions in AA1200 Aluminum Alloy Deformed by Accumulative Roll Bonding Method
Authors: Bogucka Joanna , Paul Henryk , Bieda Magdalena , Baudin Thierry
Published: March 2012

The results of studies carried out on AA1200 aluminum alloy deformed by Accumulative Roll Bonding (ARB) are presented in this paper. The commercial purity material was deformed up to 10 cycles (equivalent plastic strain of 8) at room temperature. The deformed microstructures and the crystallographic textures were characterized by transmission (TEM) and scanning (SEM) electron microscopes and high resolution orientation mapping. It was found that increased deformation leads to a strong increase of quantity of high angle (>15°) grain boundaries and strong grain refinement (up to 200-300 nm). The microstructure observations and TEM and SEM local orientation measurements allowed identifying fine and strongly disoriented planar dislocation structure of nanolayers described by strong texture components close to two nearly complementary positions of {112} orientation.
Gradient Microstructure of FeCr30Co8 Hard Magnetic Alloy Subjected to Plastic Deformation by Tension Combined with Torsion at 700 and 720°C
Authors: Korneva Anna
Published: March 2012

The article presents the results of microstructure evolution studies of the FeCr30Co8 hard magnetic alloy, subjected to deformation by tension and torsion at 700 and 720 °C. The observations in the longitudinal section of the samples in the scanning electron microscope (SEM) showed a formation of gradient microstructure with the maximum grain refinement in the surface layer of the material. The EBSD examination confirmed the refinement of structure in the surface layer and the presence of sub-grained structure of the material. A little larger refinement of α phase grains was observed at temperature of deformation 700 °C than at 720 °C. However, the deformation was inhomogeneous along the whole longitudinal section of the sample. The highest deformation degree resulted from the torsion.
Structure-Property Relationship in a Haynes® 242TM Alloy Subjected to Long-Term Exposure at 650°C
Authors: Stępniowska Elżbieta , Dymek Stanisław
Published: March 2012

This paper characterizes the microstructure and mechanical properties of the nickel-based superalloy with the nominal composition Ni–25Mo–8Cr (wt.%) after long-term annealing (4000, 6000 and 8000 h) at 650°C. The microstructure was characterized by TEM and SEM. Mechanical properties were measured trough tensile testing. The microstructure, composed initially of a dispersive Ni2(Mo,Cr) strengthening phase in a Ni-based solid solution, decomposed during annealing into a mixture of intermetallic (Ni3Mo- and Ni4Mo-type) phases and recrystallized Mo-lean Ni-based solid solution. The dominant new phase was a plate-shaped Ni3Mo-type phase. Regions adjacent to the plates of the Ni3Mo phase are recrystallized and free from the Ni2(Mo,Cr) strengthening phase.
Tem and CL Investigations of Pd Nanograins Included in Carbonaceous Film
Authors: Sobczak Kamil , Dłużewski Piotr , Witkowski Bartlomiej S. , Dabrowski Jerzy , Kozlowski Miroslaw , Kowalska Ewa , Czerwosz Elzbieta
Published: March 2012

In this paper we presented results of investigation of carbonaceous-palladium materials obtained in the CVD (Chemical Vapor Deposition) process. This investigations were carried out with transmission electron microscopy (TEM) and scanning electron microscopy (SEM), equipped with spectrum imaging for cathodoluminescence (CL). The composites will be applied as a active layers in hydrogen and also hydrocarbons detectors. Our measurements showed that some of Pd nanoparticles have a graphite shell and also are optically active. This particle in CL spectrum reveal the peak wavelength around 525 nm (2,36 eV).
Cathodoluminescence and Electroluminescence of Semiconductor Structures in SEM
Authors: Płuska Mariusz , Czerwiński Andrzej , Ratajczak Jacek , Szerling Anna , Kątcki Jerzy
Published: March 2012

Cathodoluminescence (CL) in SEM and electroluminescence (EL) techniques are widely used for investigation of optical properties of electronic structures. It is assumed that the CL signal represents the local properties of the region irradiated by the electron beam. However, this assumption is true if there is no electric field in the excitation region. In the opposite case the electron-hole pairs generated by the electron beam are separated by the electric field and the local voltage source is generated. The voltage is distributed all over the structure through resistance paths and it causes a current flow, which presence affects the registered CL signal. A range of this effect depends on the resistance distribution within the structure and on the value of electron beam current. The range may be much longer than the diffusion length of minority carriers. When EL signal is measured in SEM, it represents the mean properties of the whole structure. The comparison of the CL results with the EL ones detected in SEM gives valuable information about the examined structures, as will be shown in the present investigations. The AlGaAs/GaAs heterostructures with 8 nm InGaAs quantum well have been examined. For that aim also special test structures for CL and EL measurements have been formed on standard epitaxial structures.
Formation and Properties of Amorphous/Crystalline Ductile Composites in Ni-Ag-P Immiscible Alloys
Authors: Ziewiec Krzysztof , Malczewski Piotr , Boczkal Grzegorz , Prusik Krystian
Published: March 2012

The aim of the work was to investigate the influence of silver as a modifying constituent on structure formation in Ni-P based glass forming matrix. Nickel-phosphorus-based Ni80P20, Ni78Ag2P20 and Ni76Ag4P20 alloys were prepared from 99.95 wt % Ni, 99.95 wt % Ag, and Ni-P master alloy. The alloys were melt-spun in helium. The microstructure of the melt-spun ribbons was investigated by XRD, a light microscope and a transmission electron microscope. Then the tensile tests were performed. The alloys with silver show lower tensile strength with respect to the fully amorphous Ni80P20 ribbon. The ductility of the amorphous matrix melt-spun Ni78Ag2P20 and Ni76Ag4P20 alloys was improved by addition of silver forming fcc-Ag precipitates in comparison with Ni80P20amorphous alloy. SEM observations of the fracture surfaces show different character of the fractured samples. The pattern and the number of the crack lines changes, depending on the silver content. For the fully amorphous Ni80P20 alloy simple brittle cracks are observed, however the alloys with silver content show more developed surfaces near the fractured regions and form crack lines arranged 60° with loading direction.
Microstructure and Deposition Relations in Alumina Particle Strengthened Ni-W Matrix Composites
Authors: Indyka Paulina , Beltowska-Lehman Ewa , Bieda Magdalena , Morgiel Jerzy , Tarkowski Leszek
Published: March 2012

The nanostructured Ni-W/Al2O3 composite coatings were prepared by electrodeposition technique on ferritic steel substrates from aqueous electrolyte solutions containing ultrafine alumina particles in suspension. The effects of plating parameters like current density, inert particle concentration in plating bath and ultrasonic field frequency on the incorporation of α-Al2O3 particles (TM-DAR Taimicron) into an Ni-W matrix were investigated. The MMC coatings microstructure, phase and chemical composition were studied by means of scanning (E-SEM FEI XL-30) and transmission (TECNAI G2 SuperTWIN) electron microscopies, as well as XRD measurements (Bruker D8 Discover). SEM and TEM observations of composite cross-section microstructure showed that the presence of ultrasounds considerably reduces the particles agglomeration and enables a uniform distribution of particles in the Ni-W matrix. The electron diffraction pattern analysis revealed that the composite metallic matrix consists of an α-Ni(W) solid solution. The matrix was characterized by quasifibrous, nanocrystalline grains of an average size about 10 nm.
Secondary Electron Detector with the Unipotential Lens Structure for Variable Pressure/Environmental SEM
Authors: Słówko Witold , Krysztof Michał
Published: March 2012

To extend capabilities of classic instruments toward the VP/E technique, authors designed the vacuum-detector system in the form of a simple attachment, which can be mounted to a classic SEM, without changes in its original structure. The main part of the system is the vacuum and detection head, combining the intermediate chamber and electron detectors of chosen kinds. Authors investigate the SE detector showing the unipotential lens structure to find optimum solution for a wide range of gas pressures from high vacuum to pressures exceeding 10 mbar.
TEM Study of Quasicrystals in Al-Mn-Fe Melt-Spun Ribbon
Authors: Stan Katarzyna , Lityńska-Dobrzyńska Lidia , Dutkiewicz Jan , Rogal Lukasz , Janus Anna Maria
Published: March 2012

Microstructure of rapidly solidified Al91Mn7Fe2 (at.%) alloy was investigated using SEM and TEM techniques. Quasicrystalline particles of different shapes and sizes embedded in the aluminium matrix were observed. Quasilattice constant was calculated as 0.461 Å. Additionally orientation relationships between matrix and quasicrystals particles were found based on electron diffraction patterns and high resolution images, such that: five-fold axis lie along [011] or [001] axes of the α-Al crystallographic direction.
Electron Microscopy Investigation of Ageing Behavior in a Cu–Ni–Si Alloy
Authors: Dymek Stanisław , Kwaśniewski Paweł , Blicharski Marek , Knych Tadeusz
Published: March 2012

The investigated material was a commercial CW111A (CuNi2Si) copper alloy containing nominally 1.6–2.5 wt% Ni and 0.4–0.8 wt% Si. The thermo-mechanical treatment consisted of three-stage forging beginning at 900°C and immediate quenching followed by ageing at 500°C for 5 hours bringing about a balance of strength and electrical conductivity suitable for application of the alloy as electrical connectors. The main strengthening phase in the CW111C (CuNi2Si) copper alloy is the β-Ni3Si phase.
Alloying the near Surface Layer of Stainless Steel with Rare Earth Elements (REE) Using High Intensity Pulsed Plasma Beams (HIPPB)
Authors: Sartowska Bożena , Piekoszewski Jerzy , Waliś Lech , Barlak Marek , Calliari Irene , Brunelli Katya , Senatorski Jan , Starosta Wojciech
Published: March 2012

Addition of some active elements such as yttrium, cerium, lanthanum and other rare earths elements (REE) to austenitic stainless steels helps to improve their high temperature oxidation resistance and tribological properties. The high intensity plasma pulses were used to introduce Ce and La into AISI 316L austenitic stainless steel. The plasma pulses contained both ions/atoms of Ce-La and those of the working gas. The pulse energy densities were sufficient to melt the near surface layer of the steel and introduce those elements into the surface layer. Scanning electron microscopy (SEM) as well as energy dispersion spectroscopy (EDS) was used during each one part of surface characterisation. Obtained results allowed us to make decision about directions of modified material successive investigations.
Characterization of Precipitation Process in T24 Steel after Long–Term Ageing
Authors: Golański Grzegorz , Kępa Joanna , Wieczorek Paweł , Prusik Krystian
Published: March 2012

The T24 steel belongs to a new group of bainitic steels introduced currently to the power industry. Higher requirements connected with applying higher steam parameters in power units are the reason why the low-alloy steels used so far can no longer be applied. Therefore, new T24 steel has been developed in Europe on the basis of 10CrMo9-10 (10H2M) steel, which has been used in the power industry for many years, as a result of modification in its chemical composition. This modification consisted in introducing additions and microadditions of titanium, vanadium, boron and nitrogen into the base steel. As a result of the modification the new-found T24 steel is characterized by higher mechanical properties in comparison with the base steel, which allows to use the steel for tight shields in the new supercritical power units. The material for research was low-alloy bainitic T24 steel. Samples for examination were taken from a pipe section of the following size: outside diameter 44.5mm, wall thickness 7mm. Samples were isothermally aged in the air atmosphere, at the temperature of 580°C and at times up to 12 000 hours. Changes in the microstructure were observed and recorded by means of high-resolution electron microscope, JOEL JEM 3010. Identification of the precipitates was made using carbon extraction replicas and thin foils with the SAED method. The aim of research was the analysis of precipitation processes. They are extremely important in the context of long-term service and maintaining strength parameters above the minimum level. The tests were performed on T24 steel for the as-received condition (after heat treatment) and after 12 000 hours of ageing at the temperature of 580°C. The research made it possible to determine the morphology of precipitates. It also allowed to establish the sequence of precipitation process for the examined steel.
TEM Characterization of a 7042 Aluminum FSW Joint
Authors: Kopyściański Mateusz , Dymek Stanislaw , Hamilton Carter
Published: March 2012

This research characterizes the changes in microstructure that occur in friction stir welded extrusions of a novel 7042 aluminum alloy. Due to the presence of scandium the base material preserved the deformation microstructure with elongated grains and fairly high dislocation density. The temperature increase with simultaneous severe plastic deformation occurring during friction stir welding induced significant changes in the microstructure within the weld and its vicinity. The weld center (stir zone) was composed of fine equiaxed grains with residual dislocations and a modest density of small precipitates compared to the neighbouring thermomechanically and heat affected zones where the density of small precipitates was much higher.
Martensitic Transformation in Ti50Ni25Cu25 Shape Memory Alloy Studied by EBSD
Authors: Goryczka Tomasz , Lelątko Józef
Published: March 2012

Presented work summarizes studies done on the course of the martensitic transformation in the Ti50Ni25Cu25 alloy. Studies were carried out using scanning electron microscopy JEM 6480 equipped with an electron back scattered detector (EBSD) as well as a heating attachment. As-received ribbon was mainly amorphous. At the free side of the ribbon some fine randomly oriented crystalline grains were formed. During heating followed by cooling the reversible martensitic transformation occurred with sequence: B2↔B19. The crystallographic correlation between the B2 phase and the B19 martensite were confirmed. It allowed finding transformation matrix between both phases.
Wurtzite-to Amorphous-to Cubic Phase Transition of GaN1-XAsx Alloys with Increasing as Content
Authors: Liliental-Weber Zuzanna , dos Reis R. , Levander A. , Yu Kin M. , Walukiewicz Wladek , Novikov S.V. , Foxon C.T.
Published: March 2012

This paper describes Transmission Electron Microscopy studies of the structural changes of GaN1-xAsx alloys grown by Molecular Beam Epitaxy at low temperatures on Al2O3 substrate. We found that by lowering the growth temperature increasing amount of As can be incorporated in GaN1-xAsx forming a single phase alloy. For the low As content a columnar growth of wurtzite structure is observed but for increasing As in the range of 0.170.75 the layer becomes amorphous. Increase in Ga flux at low growth temperature (about 200°C) leads to columnar alloys with As content >75% with a cubic structure. In addition to the structural changes monotonic change of the band gap is also observed with the As content in the alloy. The amorphous alloy is stable up to annealing at temperatures not higher than 600°C. Annealing at higher temperature leads to phase separation of GaAs:N and GaN:As confirmed by Z-contrast electron microscopy.
Nonplasmacytoid, High IFN-α–Producing, Bone Marrow Dendritic Cells
Authors: O’Keeffe Meredith , Fancke Ben , Suter Mark , Ramm Georg , Clark Joan , Wu Li , Hochrein Hubertus
Published: March 2012

Plasmacytoid dendritic cells (pDC) are the producers of type I IFNs in response to TLR9 ligands. However, we have found that when bone marrow is depleted of pDC, the IFN-α produced in response to TLR9 ligands is not fully removed. We assign the source of this non-pDC IFN-α as a newly described DC type. It displays the high IFN-α producing activity of pDC but to a more limited range of viruses. Unlike pDC, the novel DC display high T cell stimulation capacity. Moreover, unlike mouse pDC, they are matured with GM-CSF and are less prone to apoptosis upon activation stimuli, including viruses. We propose that these DC constitute a novel bone marrow inflammatory DC type, ideally geared to linking innate and adaptive immune responses in bone marrow via their potent IFN-α production and high T cell stimulatory capacity.
The Fusion Protein of IFN-α and Apolipoprotein A-I Crosses the Blood–Brain Barrier by a Saturable Transport Mechanism
Authors: Fioravanti Jessica , Medina-Echeverz José , Ardaiz Nuria , Gomar Celia , Parra-Guillén Zinnia P. , Prieto Jesús , Berraondo Pedro
Published: March 2012

IFN-α is widely used for the treatment of chronic viral hepatitis and malignancies. However, systemic IFN-α treatment causes severe neuropsychiatric complications in humans, including depression, anxiety, and cognitive impairments. We have previously reported that the fusion protein formed by IFN-α and apolipoprotein A-I (IA) circulates bound to high-density lipoproteins (HDLs) and exhibits liver targeting, increased half-life, enhanced immunostimulatory activity, and reduced cytotoxicity. As the transport of HDLs across the blood–brain barrier is a highly complex and regulated process, in this study, we examine the effects of IA on the brain. Determination of IFN-α in brain and serum after hydrodynamic administration of different doses of a plasmid encoding IFN-α or IA showed that IA penetrated into the brain by a saturable transport mechanism. Thus, at high serum levels of the transgenes, the induction of IFN-sensitive genes and the number of phospho-STAT1+ cell nuclei in the brain were substantially higher with IFN-α than with IA. This was associated with attenuation of neurodepression in mice given IA, as manifested by shorter immobility time in the tail suspension test. However, when given low doses of rIFN-α or the same antiviral units of HDLs containing IA, the induction of IFN-stimulated genes in the brain was significantly greater with the latter. In conclusion, IA crosses the blood–brain barrier not by diffusion, as is the case of IFN-α, but by a facilitated saturable transport mechanism. Thus, linkage to apolipoprotein A-I may serve to modulate the effects of IFN-α on the CNS.
Complement Component C1q Regulates Macrophage Expression of Mer Tyrosine Kinase To Promote Clearance of Apoptotic Cells
Authors: Galvan Manuel D. , Foreman Deborah B. , Zeng Erliang , Tan John C. , Bohlson Suzanne S.
Published: March 2012

Failure to efficiently clear apoptotic cells is linked to defects in development and the onset of autoimmunity. Complement component C1q is required for efficient engulfment of apoptotic cells in mice and humans; however, the molecular mechanisms leading to C1q-dependent engulfment are not fully understood. In this study, we used primary mouse macrophages to identify and characterize a novel molecular mechanism for macrophage-mediated C1q-dependent engulfment of apoptotic cells. We found that macrophage activation with C1q resulted in cycloheximide-sensitive enhanced engulfment, indicating a requirement for de novo protein synthesis. To investigate the cycloheximide-sensitive pathway, C1q-elicited macrophage transcripts were identified by microarray. C1q triggered the expression of Mer tyrosine kinase (Mer) and the Mer ligand growth arrest-specific 6: a receptor–ligand pair that mediates clearance of apoptotic cells. Full-length native C1q, and not the collagen-like tail or heat-denatured protein, stimulated Mer expression. This novel pathway is specific to C1q because mannose-binding lectin, a related collectin, failed to upregulate Mer expression and function. Soluble Mer-Fc fusion protein inhibited C1q-dependent engulfment of apoptotic cells, indicating a requirement for Mer. Moreover, Mer-deficient macrophages failed to respond to C1q with enhanced engulfment. Our results suggest that C1q elicits a macrophage phenotype specifically tailored for apoptotic cell clearance, and these data are consistent with the established requirement for C1q in prevention of autoimmunity.
Early Induction of CCL7 Downstream of TLR9 Signaling Promotes the Development of Robust Immunity to Cryptococcal Infection
Authors: Qiu Yafeng , Zeltzer Stuart , Zhang Yanmei , Wang Fuyuan , Chen Gwo-Hsiao , Dayrit Jeremy , Murdock Benjamin J. , Bhan Urvashi , Toews Galen B. , Osterholzer John J. , Standiford Theodore J. , Olszewski Michal A.
Published: March 2012

We investigated mechanisms by which TLR9 signaling promoted the development of the protective response to Cryptococcus neoformans in mice with cryptococcal pneumonia. The afferent (week 1) and efferent (week 3) phase immune parameters were analyzed in the infected wild-type (TLR9+/+) and TLR-deficient (TLR9−/−) mice. TLR9 deletion diminished 1) accumulation and activation of CD11b+ dendritic cells (DCs), 2) the induction of IFN-γ and CCR2 chemokines CCL7, CCL12, but not CCL2, at week 1, and 3) pulmonary accumulation and activation of the major effector cells CD4+ and CD8+ T cells, CD11b+ lung DCs, and exudate macrophages at week 3. The significance of CCL7 induction downstream of TLR9 signaling was investigated by determining whether CCL7 reconstitution would improve immunological parameters in C. neoformans-infected TLR9−/− mice. Early reconstitution with CCL7 1) improved accumulation and activation of CD11b+ DCs at week 1, 2) restored early IFN-γ production in the lungs, and 3) restored the accumulation of major effector cell subsets. CCL7 administration abolished the difference in lung fungal burdens between TLR9+/+ and TLR9−/− mice at week 3; however, significant reduction of fungal burdens between PBS- and CCL7-treated mice has not been observed, suggesting that additional mechanism(s) apart from early CCL7 induction contribute to optimal fungal clearance in TLR9+/+ mice. Collectively, we show that TLR9 signaling during the afferent phase contributes to the development of protective immunity by promoting the early induction of CCL7 and IFN-γ and the subsequent early recruitment and activation of DCs and additional effector cells in mice with cryptococcal pneumonia.
CD27 Stimulation Promotes the Frequency of IL-7 Receptor-Expressing Memory Precursors and Prevents IL-12–Mediated Loss of CD8+ T Cell Memory in the Absence of CD4+ T Cell Help
Authors: Dong Han , Franklin Nathan A. , Roberts Drew J. , Yagita Hideo , Glennie Martin J. , Bullock Timothy N. J.
Published: March 2012

Fully functional CD8+ T cell memory is highly dependent upon CD4+ T cell support. CD4+ T cells play a critical role in inducing the expression of CD70, the ligand for CD27, on dendritic cells. In this study, we demonstrate that CD27 stimulation during primary CD8+ T cell responses regulates the ability to mount secondary CD8+ T cell responses. CD27 stimulation during vaccinia and dendritic cell immunization controls the expression of the IL-7R (CD127), which has been shown to be necessary for memory CD8+ T cell survival. Furthermore, CD27 stimulation during primary CD8+ T cell responses to vaccinia virus restrained the late expression on memory precursor cells of cytokine receptors that support terminal differentiation. The formation of CD8+ T cell memory precursors and secondary CD8+ T cell responses was restored in the absence of CD27 costimulation when endogenous IL-12 was not available. Similarly, the lesion in CD8+ T cell memory that occurs in the absence of CD4+ T cells did not occur in mice lacking IL-12. These data indicate that CD4+ T cell help and, by extension, CD27 stimulation support CD8+ T cell memory by modulating the expression of cytokine receptors that influence the differentiation and survival of memory CD8+ T cells.
Cutting Edge: Protein Phosphatase 2A Confers Susceptibility to Autoimmune Disease through an IL-17–Dependent Mechanism
Authors: Crispín José C. , Apostolidis Sokratis A. , Rosetti Florencia , Keszei Marton , Wang Ninghai , Terhorst Cox , Mayadas Tanya N. , Tsokos George C.
Published: March 2012

The contribution of individual molecular aberrations to the pathogenesis of systemic lupus erythematosus (SLE), an autoimmune disease that affects multiple organs, is often difficult to evaluate because of the presence of abundant confounding factors. To assess the effect of increased expression of the phosphatase protein phosphatase 2A (PP2A) in T cells, as recorded in SLE patients, we generated a transgenic mouse that overexpresses the PP2Ac subunit in T cells. The transgenic mouse displays a heightened susceptibility to immune-mediated glomerulonephritis in the absence of other immune defects. CD4+ T cells produce increased amounts of IL-17 while the number of neutrophils in the peripheral blood is increased. IL-17 neutralization abrogated the development of glomerulonephritis. We conclude that increased PP2Ac expression participates in SLE pathogenesis by promoting inflammation through unchecked IL-17 production and facilitating the development of end-organ damage.
The impact of erosion on the classification of Mollisols in Iowa
Authors: Fenton Thomas E.
Published: March 2012

Fenton, T. E. 2012. The impact of erosion on the classification of Mollisols in Iowa. Can. J. Soil Sci. 92: 413–418. The fertile black soils in the Great Plains and Western States of the United States are dark brown Chernozems in the Canadian system of soil taxonomy and Mollisols, when a mollic epipedon is present, according to the United States soil taxonomy. Other primary criteria are organic carbon content, color, structure, and thickness of the mollic epipedon. Accelerated erosion can affect all of these properties and is especially critical for soils that have slope gradients of more than 2%. Accelerated erosion and erosion phases are recognized in field mapping based on the amount of A horizon remaining but criteria provided in the Soil Taxonomy guidelines conflict with procedures outlined in the Soil Survey Field Manual and result in a dichotomy between the classification system and field mapping practices. Soil map unit data for the five most extensive Mollisol soil series in Iowa that have multiple phases of slope and erosion were summarized and variations between the taxonomic and survey principles were identified. Eroded units comprise 26 to 77% of the total mapped area of the series studied and do not qualify as Mollisols under the taxonomic system. However, under the principle of following the genetic thread to classify soils, the taxonomic system should be modified to accommodate the eroded units that have the same genetic pathway as their uneroded counterparts. This could be accomplished by placing primary emphasis on the organic carbon content and waiving the color requirement for eroded soil map units.
Soil chemical and biological properties affected by 21-year application of composted manure with chemical fertilizers in a Chinese Mollisol
Authors: Li X. H. , Han X. Z. , Li H. B. , Song C. , Yan J. , Liang Y.
Published: March 2012

Li, X. H., Han, X. Z., Li, H. B., Song, C., Yan, J. and Liang, Y. 2012. Soil chemical and biological properties affected by 21-year application of composted manure with chemical fertilizers in a Chinese Mollisol. Can. J. Soil Sci. 92: 419–428. The effects of 21-yr of application of chemical fertilizers, composted pig manure (CPM) alone, and chemical fertilizers combined with compost on soil chemical and biological properties were investigated. Soil samples (0–20cm) were collected from a long-term fertilization experiment under corn (Zea mays L.) production in 2006, prior to seeding, at the corn tasseling stage and following harvest. Fertilizer treatments were: no fertilizer (CK), nitrogen fertilizer alone (N), N + phosphorus (NP), N + P + potassium (NPK), CPM, N + CPM, N + P + CPM (NP + CPM), and N + P + K + CPM (NPK + CPM). Long-term application of N alone resulted in a reduction of soil pH by 0.38 units and reduced the available P concentration compared with CK. An increase in soil pH was seen with CPM alone and NPK + CPM. Both fertilizers sources, singly and combined, increased the total N and available N concentrations. Total P and total K concentrations were greatest with the NPK + CPM treatment. All fertilizer treatments increased the soil organic carbon (SOC), light fraction organic carbon (LFOC) and microbial biomass carbon (MBC) concentrations significantly (P < 0.05) at the tasseling stage. The NPK + CPM treatment showed the greatest increase in SOC (12%), LFOC (78%) and MBC (44%) concentrations, compared with CK. Soil enzyme activities (invertase, urease, acid and alkaline phosphatases) tended to be greater at tasseling than other sampling dates, with highest enzyme activities in the NPK + CPM treatments. These findings suggest that a long-term application of CPM combined with NPK is an efficient strategy to maintain or increase soil quality in Mollisols for sustainable agriculture.
Effect of soil temperature and moisture on soil test P with different extractants
Authors: Song Chunyu , Zhang Xingyi , Liu Xiaobing , Chen Yuan
Published: March 2012

Song, C., Zhang, X., Liu, X. and Chen, Y. 2012. Effect of soil temperature and moisture on soil test P with different extractants. Can. J. Soil Sci. 92: 537–542. Temperature and moisture are important factors affecting adsorption, transformation and the availability of soil phosphorus (P) to plants. The different temperatures and moisture contents at which soil is sampled might affect the results of soil test P (STP). In order to evaluate the effect of the temperature and moisture, as well as the fertilization level, on the results of soil test P, an incubation study involving three soil temperatures (5, 10, and 20°C), and three soil moisture contents (50, 70, 90% of field water-holding capacity) was conducted with Chinese Mollisols collected from four fertilization treatments in a long-term experiment in northeast China. Four soil P test methods, Mehlich 3, Morgan, Olsen and Bray 1 were used to determine STP after a 42-d incubation. The effect of temperature and moisture on STP varied among soil P tests. Averaged across the four fertilization treatments, the temperature had significant impact on STP, while the responses varied among soil P test methods. Mehlich 3, Morgan and Bray 1 STP decreased and Olsen STP increased with increase in temperature. Effect of soil moisture was only significant for Mehlich 3 P and Olsen P. Soil temperature had greater impact on STP than soil moisture content. The responses of the Olsen method to temperature differed from the other three methods tested. The interaction between soil temperature and soil moisture on soil test P was only significant for Mehlich 3 P. Fertilization level does not affect the STP in as a clear pattern as the temperature and moisture varied for all four methods. Consistent soil sampling conditions, especially the soil temperature, appear to be the first step to achieve a reliable STP for any soil P test.
Client-Centered Approach to Develop a Seating Clinic Satisfaction Questionnaire: A Qualitative Study
Authors: McComas Joan , Kosseim Mylène , Macintosh Diana
Published: March 2012

Objective. The purpose of this study was to develop a program evaluation tool through a client-centered approach. Client satisfaction questionnaires previously developed for service recipients of a pediatric seating clinic have reflected the professionals’ views on what should be asked.

Method. Seven parents and caregivers of recent service recipients of the seating clinic participated in tape-recorded semistructured interviews. They were asked their views on the seating clinic, how the service could be improved, and the quality of the seat received through the clinic.

Results. Data were coded into nine themes related to the process and the product. Using these themes and the vocabulary used by the participants, we developed a satisfaction questionnaire. The validity of the questionnaire was evaluated by requesting feedback on clarity, content, and design from all participants and from a panel of five health professionals.

Conclusion. A client-centered approach can be used to develop a client satisfaction tool that reflects the needs of the users. Future work will involve testing the tool in the clinical setting.
Migration, Trade and Unemployment
Authors: Heid Benedikt , Larch Mario
Published: March 2012

A source of anxiety of policy makers and the public in general is the detrimental impact of trade and immigration on unemployment. The transitory restrictions for worker migration after the EU enlargements of 2004 and 2007 exemplify the supposed negative effect of immigration on labor markets. This paper aims to identify the effects of immigration alongside trade on unemployment controlling for the high correlation between immigration and goods flows in order to prevent an omitted variable bias. The authors use data from 24 OECD countries over the period from 1997 to 2007 and employ instrumental variables fixed effects and dynamic panel estimators in order to account for unobserved heterogeneity as well as the potential endogeneity of migration flows and the high persistence of unemployment. We find no significant effect of immigration on unemployment on average.
Sensitivity to deliberate sea salt seeding of marine clouds – observations and model simulations
Authors: Alterskjær K. , Kristjánsson J. E. , Seland Ø.
Published: March 2012

Abstract. Sea salt seeding of marine clouds to increase their albedo is a proposed technique to counteract or slow global warming. In this study, we first investigate the susceptibility of marine clouds to sea salt injections, using observational data of cloud droplet number concentration, cloud optical depth, and liquid cloud fraction from the MODIS (Moderate Resolution Imaging Spectroradiometer) instruments on board the Aqua and Terra satellites. We then compare the derived susceptibility function to a corresponding estimate from the Norwegian Earth System Model (NorESM). Results compare well between simulations and observations, showing that stratocumulus regions off the west coast of the major continents along with large regions over the Pacific and the Indian Oceans are susceptible. At low and mid latitudes the signal is dominated by the cloud fraction. We then carry out geo-engineering experiments with a uniform increase over ocean of 10−9 kg m−2 s−1 in emissions of sea salt particles with a dry modal radius of 0.13 μm, an emission strength and areal coverage much greater than proposed in earlier studies. The increased sea salt concentrations and the resulting change in marine cloud properties lead to a globally averaged forcing of −4.8 W m−2 at the top of the atmosphere, more than cancelling the forcing associated with a doubling of CO2 concentrations. The forcing is large in areas found to be sensitive by using the susceptibility function, confirming its usefulness as an indicator of where to inject sea salt for maximum effect. Results also show that the effectiveness of sea salt seeding is reduced because the injected sea salt provides a large surface area for water vapor and gaseous sulphuric acid to condense on, thereby lowering the maximum supersaturation and suppressing the formation and lifetime of sulphate particles. In some areas, our simulations show an overall reduction in the CCN concentration and the number of activated cloud droplets decreases, resulting in a positive forcing.
Global distribution and climate forcing of marine organic aerosol – Part 2: Effects on cloud properties and radiative forcing
Authors: Gantt B. , Xu J. , Meskhidze N. , Zhang Y. , Nenes A. , Ghan S. J. , Liu X. , Easter R. , Zaveri R.
Published: March 2012

Abstract. In the first part of this paper series (Meskhidze et al., 2011), a treatment of marine organic aerosols (including primary organic aerosol, secondary organic aerosols, and methane sulfonate) was implemented into the Community Atmosphere Model version 5 (CAM5) with a 7-mode Modal Aerosol Module. A series of simulations was conducted to quantify the changes in aerosol and cloud condensation nuclei concentrations in the marine boundary layer. In this study, changes in the cloud microphysical properties and radiative forcing resulting from marine organic aerosols are assessed. Model simulations show that the anthropogenic aerosol indirect forcing (AIF) predicted by CAM5 is decreased in absolute magnitude by up to ~0.10 W m−2 (8%) when marine organic aerosols are included. Changes in the AIF from marine organic aerosols are associated with small global increases in low-level in-cloud droplet number concentration and liquid water path of ~1.3 cm−3 (~1.6%) and 0.2 g m−2 (0.5%), respectively. Areas especially sensitive to changes in cloud properties due to marine organic aerosol include the Southern Ocean, North Pacific Ocean, and North Atlantic Ocean, all of which are characterized by high marine organic emission rates. As climate models are particularly sensitive to the background aerosol concentration, this small but non-negligible change in the AIF due to marine organic aerosols provides a notable link for ocean-ecosystem marine low-level cloud interactions and may be a candidate for consideration in future earth system models.