bluuebunny/crossref_metadata_2025 huggingface dataset:
Growth of Heavily Indium Doped Si Crystals by Co-Doping of Neutral Impurity Carbon or Germanium
Authors: Inoue Kaihei , Tokumoto Yuki , Kutsukake Kentaro , Ohno Yutaka , Yonenaga Ichiro
Published: March 2012

Czochralski Growth of Si Crystals Heavily Doped with in Impurity and Co-Doped with Electrically Neutral Impurity C or Ge Was Conducted in Order to Investigate the Solubility and Ionization Ratio of in in Si for Utilizing in Advanced ULSI and PV Devices. The Carrier Concentrations in the Grown in-Doped and (In+C) and (In+Ge) Co-Doped Crystals Were in a Range of 3.5~6.5 × 1016 Cm-3, much Lower than the Total Concentration of in Impurity due to the Low Ionization Ratio. Sufficient Increase of Carrier Concentrations by Co-Doping of C or Ge Impurity Was Not Detected for their Low Concentrations in the Grown Crystals Investigated.
Nd3+ Doped LiCaAIF6 Single Crystal for Scintillator Application
Authors: Yanagida Takayuki , Futami Yoshisuke , Kawaguchi Noriaki , Pejchal Jan , Fujimoto Yutaka , Kurosawa Shunsuke , Yokota Yuui , Yoshikawa Akira
Published: March 2012

ααΑαNd3+ 0.5% Doped Single Crystal LiCaAlF6 Scintillator Was Grown by the Micro-Pulling down (µ-PD) Method. Powder X-Ray Diffraction Analysis Was Done and the Grown Crystal Was a Single Phase LiCaAlF6. it Was Cut and Polished to the Physical Dimension of 1 × 2 × 7 mm3. in Transmittance Spectrum, Nd3+ 5d-4f Absorption Observed at 175 Nm and the Transmittance Became 80% at Wavelength Longer than 180 Nm. Excited by 160 Nm, Nd3+ 5d-4f Emission Appeared at 180 Nm. X-Ray Induced Radio-Luminescence Spectrum Showed the Similar Feature with the Photoluminescence One. when Coupled with PMT and Irradiated by 241Am α-Ray, the Absolute Light Yield Resulted 100 Ph/5.5 Mev α.
Optical and Scintillation Properties of Eu-Doped Calcium Orthoborate
Authors: Fujimoto Yutaka , Futami Yoshisuke , Yanagida Takayuki , Kurosawa Shunsuke , Kawaguchi N. , Fukuda K. , Totsuka D. , Yoshikawa Akira
Published: March 2012

Single Crystals of Eu-Doped Calcium Orthoborate Have Been Grown by Micro-Pulling (μ-PD) Technique with Radio Frequency Heating System, and its Transmittance, Photoluminescence and Radiation Responses Were Investigated. In Transmittance Spectra, Eu-Doped Crystal Showed Broad Absorption Band around 200-450 nm, which Is due to the Complex of Charge Transfer (CT) Transition and 4f-4f Transition of Eu3+. Intense Eu2+5f-4f and Eu3+4f-4f Emission Peaks Were Observed when Excited to 265 nm and 385 nm, and the Calculated Decay Times Were 230 ns and 1.5 ms, Respectively.241Am 5.5 Mev α-Ray Excited Radioluminescence Spectra Indicated both Eu2+5f-4f and EuSuperscript text3+ 4f-4f Emission Peaks.
Study on Phase Diagram of Ca3NbGa3Si2O14 Piezoelectric Material by Differential Thermal Analysis and X-Ray Diffraction Measurement
Authors: Futami Yoshisuke , Yokota Yuui , Sato Masato , Tota Kazushige , Pejchal Jan , Yanagida Takayuki , Onodera Ko , Yoshikawa Akira
Published: March 2012

Ca3NbGa3Si2O14 (CNGS) Is One of the Langasite-Type Crystals and it Is Known as a Piezoelectric Material. We Have Successfully Grown the Shaped CNGS Crystal Using Micro-Pulling-down (μ-PD) Method with Shape Control. However, the Impurity Phases such as Ca-Nb-O Related Compounds Were Detected in the Grown Crystals. The Creation of the Impurity Phases Is Related to Difference in Stoichiometric and Congruent Compositions. Therefore, the Detailed Investigation of Phase Diagram on CNGS Was Carried Out to Prevent the Impurity Phases Creation. It Follows from the TG-DTA Measurements that the Melting Point Systematically Changed with the Ca/Ga Ratio in the Ca3-xNbGa3+xSi2O14±δ Cmpositions. The CNGS Phase with Ca/Ga = 1.02 Indicated the Maximum Melting Point which Suggests that the Stoichiometric Composition of CNGS Is Different in the Congruent Composition. Furthermore, in the DTA Measurements the Peaks of Impurity Phases Were Detected around 1550 °C for the CNGS Sample with Ca/Ga = 1.02.
Effect of Precursor Supply on (100) and (001) Orientations of α-Al2O3 Film Prepared by Laser CVD
Authors: Hokuto Kadokura , Ito Akihiko , Kimura Teiichi , Goto Takashi
Published: March 2012

Α-Al2O3 Films Were Prepared by Laser Chemical Vapor Deposition and the Effects of Precursor Evaporation Temperature (Tvap) and Oxygen Gas Flow Rate (FRo) on Phase and Orientation of Al2o3 Films Were Investigated. at Tvap = 413 K, (100)-Oriented α-Al2O3 and θ-Al2O3 Were Codeposited. the Amount of θ-Al2O3 Increased with Increasing FRo. at Tvap = 433–443 K, α-Al2O3 Films Showed a (001) Orientation. (100)- and (001)-Oriented α-Al2O3 Films Had a Rectangular- and Hexagonal-Shaped Grains, Respectively, and Showed a Columnar in Cross Section. Grain Size of (100)- and (001)-Oriented α-Al2O3 Films Decreased from 10 to 2 μm with Increasing FRo from 0.085 to 0.85 Pa m3 s−1. Deposition Rate Increased from 100 to 300 μm h−1 with Increasing Tvap from 413 to 443 K.
Orientation and Morphology of LiCoO2 Prepared by Chemical Vapor Deposition on Al2O3 Single Crystal
Authors: Katsui Hirokazu , Yuji Yamashita , Goto Takashi
Published: March 2012

Lithium Cobaltate (LiCoO2) Films Were Prepared on the (001), (110), (110) and (112) Planes of Al2O3 Single Crystals Substrates by Metal Organic Chemical Vapor Deposition, and the Phases, Orientated Textures and Surface Morphologies Were Examined. (001)-Oriented LiCoO2 Films Were Obtained on (001) and (110) Al2O3 Substrates, while (018)- and (104)-Oriented LiCoO2 Films Were Grown on (110) and (112) Al2O3 Substrate. Triangular and Elongated Rectangular Faceted Structures Were Directionally Aligned, and (001)- and (018)-Oriented Grains Were Epitaxially Grown on (001) and (110) Al2O3 Substrates. Randomly Arranged Polygonal Faceted Structures Were Observed in the (001)-Oriented Licoo2 Film on (110) Al2O3 Substrate, while Locally Inhomogeneous Grains Were Observed in the (104)-Oriented LiCoO2 Film on (1_,12) Al2O3 Substrate.
Charging and Discharging Phenomena in Organic Photoconductors Observed Using Electron Holography
Authors: Takahashi K. , Murakami Y. , Shindo Daisuke
Published: March 2012

The Phenomenon of Laser-Induced Discharging in an Organic Photoconductor Sample Was Directly Observed Using Electron Holography and Sophisticated Techniques for In Situ Observations. Mechanical Friction Was Used to Induce Negative Tribocharges on the Surface of the Photoconductor Sample. the Observation of Equipotential Contour Lines (i.e., the Electric Potential Distribution) outside the Specimen Revealed that the Amount of Tribocharges Was Reduced by the Laser Exposure. Computer Simulations of the Equipotential Lines Provided Useful Information for Evaluating the Quantity of Tribocharges.
Effect of Heating Rate on the Synthesis and Sintering of Ternary Carbide Zr2Al3C4 through Spark Plasma Sintering
Authors: Zhang Lian Meng , Guo Qi Long , Li Jun Guo , Shen Qiang
Published: March 2012

The Nearly Full Dense Zr2Al3C4 Ceramic Was Successfully Fabricated at 1800 °C for 10 min under a Uniaxial Load of 20 MPa in Vacuum by the Spark Plasma Sintering Process, Using a Mixture of Zr, Al and Graphite Powders as Raw Materials. The Reaction Route of Synthesis as Well as the Sintering Conditions of the SPS Technique Were Discussed Based on X-Ray Diffraction Results. The Results Showed that the Heating Rate Can Largely Affect the Loss and Aggregation of Molten Al. Moreover, the Contents of Al4O4C and the Elevated Sintering Temperature Were Beneficial for the Synthesis of Zr2Al3C4 Ceramic. The Microstructures of the Samples Were Observed by Scanning Electron Microscopy, Showing that the as-Synthesized Zr2Al3C4 Has an Anisotropic Microstructure Consisting of Elongated Grains. Compared to the Hot-Pressing, the Starting Temperature for the Formation of Zr3Al3C5 and Al4O4C Phases Was Rather Low. It Indicates that the SPS Technique Can Rapidly Synthesize Zr2Al3C4 from the Zr/Al/C Powders in a Relatively Low Temperature Range. The Mechanical Properties of the Sintered Materials Were Also Investigated, Including the Hardness of 11.66±0.34 GPa, and Fracture Toughness of 4.0 ± 0.4 MPa×m1/2.
Emission Characteristics of Copper Ionic Lines from the 3d95s-3d94p Transition in a Low-Pressure Laser-Induced Plasma
Authors: Zhang Lei , Shunsuke Kashiwakura , Wagatsuma Kazuaki
Published: March 2012

The Emission Characteristic of Copper Ionic Lines Requiring Large Excitation Energies Was Investigated in Low-Pressure Laser-Induced Plasma Spectroscopy (LP-LIPS), when Argon Was Employed as Plasma Gas. The Excited Mechanism of the Ironic Lines Whose Electron Transitions Were Assigned to the 3d95s-3d94p Configuration Was Understood from the Time-Resolved Spectra of Copper. The Emission Intensity of the Copper Emission Lines, Measured in a Time-Resolved Mode, Was Extremely Dependent on the Kind of Copper Lines and the Upper Energy. Generally, their Emission Intensities Dramatically Decreased with the Duration Time, along with the Recombination as Well as the De-Excitation of Copper Ions Requiring Larger Kinetics Energy which Mainly Were Produced in a Hot Breakdown Plasma. The Emission Behavior Excited from the 3d95s-3d94p Transition, such as the Cu II 254.4 nm and the Cu II 276.9 nm Lines, Was Generally Similar to that from 3d94p-3d94s Transition, although their Excitation Energies Were Different. This Effect Would Result from a Common and Dominant Ionization /excitation Mechanism, which Was Collision Energy Transfer from Energetic Particles such as Fast Electrons.
Optical Conductivity of Rattling Phonons in Type-I Clathrates Ba8Ga16Ge30 and Ba8Ga16Sn30
Authors: Iwamoto K. , Mori T. , Kushibiki S. , Honda H. , Matsumoto H. , Suekuni K. , Avila M.A. , Takabatake T. , Toyota N.
Published: March 2012

We Review Our Dynamical Property Measurements of Rattling Phonons in Type-I Clathrate Compounds, the Quasi-on-Center Ba8Ga16Ge30 (BGG) and Off-Center Ba8Ga16Sn30 (BGS), Using a Terahertz Time-Domain Spectrometer. The Lowest-Lying Vibrational Modes of Rattling Ba Ions in the Oversized Cage Show Anomalous Temperature Dependence in their Spectra. For BGG, the Temperature Dependence Is Mostly Consistent with a Local Anharmonic Potential Approximation that Predicts Softening towards Low Temperature. On the other Hand, for BGS, a Single Broad Peak of Off-Center Rattling Phonons Splits into Two Subpeaks below 120 K, and, with Further Lowering Temperature, the Spectra Show Anomalous Broadening. While the Splitting Can Be Understood by the Double Well Potential, the Linewidth Broadening Must Be Attributed to some Relevant Interactions with such Excitations as Acoustic Phonons and Doped Carriers.
Features of the Mackay Clusters with and without a Center Atom in Al Based Approximants of Icosahedral Quasicrystals
Authors: Suzuki Shota , Simura Rayko , Sugiyama Kazumasa
Published: March 2012

The Packing Features of Mackay and Pseudo Mackay Clusters in Al Based Approximants to Icosahedral Phases Are Surveyed. The Cubic Approximants of α-AlMnSi, AlReSi, and α-(Al,Si)CuFe Indicate Typical Mackay Clusters Composed by the Dense Icosahedral Shell Packing. On the other Hand, the Cubic Approximants of α-Alcuru and α-(Al,Si)CuFe and the Non-Cubic Approximants of Ir9Al28, χ-AlPdRe, and R-AlPdCo Shows so-Called Pseudo Mackay Clusters in which the Icosahedral Packing Feature Is Disappeared at their First Shells. The Distorted First Shells Represent a Variation of Pseudo Mackay Clusters, which Could Be Classified into Three Subgroups Based on the Symmetry.
Computer Simulation Model for Multi-Size Spherical Particles Reinforced Composite Materials
Authors: Chen Zhuo , Huang Zhi Xiong , Dou Rong Yang , Dai Jing , Shi Min Xian , Ji Jia You
Published: March 2012

In this Research a Method for Computer Simulation Model of Composite Materials, which Are Reinforced by Multi-Size Particles, Is Introduced. All Particles Are Embedded in the Matrix Randomly. Composite of Different Particle Volume Fraction Were Simulated and Visualized. Statistic Results Shows that the Particles Disperse Distribution Are Uniform which Could Be Used in the Further Study of Composite.
Densification and Microstructure of Monolithic TiN and TiB2 Fabricated by Spark Plasma Sintering
Authors: Kitiwan Mettaya , Ito Akihiko , Goto Takashi
Published: March 2012

Sintering Behavior of Monolithic TiN and TiB2 Was Investigated Using Spark Plasma Sintering (SPS) at Temperatures between 1673 and 2573 K. Relative Density of TiN Was Increased from 82.3 to 96.7% while that of TiB2 Increased from 70.1 to 92.8% with Increasing Temperature. At Temperatures between 1673 and 2273 K, TiB2 Was More Difficult to Consolidate Compare to TiN. At 2473 K, TiB2 Densified Rapidly to 92.8%.
Phase Transformation and Densification of hBN-TiN Composites Fabrication by Spark Plasma Sintering
Authors: Kitiwan Mettaya , Ito Akihiko , Goto Takashi
Published: March 2012

hBN-TiN Binary Composite Was Fabricated Using Spark Plasma Sintering (SPS) at Temperatures between 1973 and 2273 K. With Increasing TiN Content from 10 to 90 Vol%, the Relative Density Increased from 75.7 to 96.4%. The Maximum Relative Density of 96.4% Was Achieved in the hBN-TiN Containing 90 Vol%TiN Sintered at 2273 K. hBN and TiN Was Stably Coexisted at 1973 K without TiB2 Formation.
Formation of Mo2S3 Layers on the Surface of Graphitic Platelets
Authors: Koroteev V.O. , Okotrub A.V. , Shubin Y.V. , Bulusheva L.G.
Published: March 2012

The Powder Mixture of Thermally Exfoliated Graphite (TEG) and Amorphous Molybdenum (VI) Sulfide MoS3Has Been Annealed in Vacuum at 723, 1073, and 1273 K. The Obtained Samples Were Examined Using Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), and Raman Spectroscopy. XRD and Raman Spectroscopy Detected that the Main Product of MoS3Annealing Is MoS2Nanoparticles. TEM Images Showed the Formation of a Continuous Coating on the Surface of TEG Platelets at 1273 K and Fourier Analysis of the High Resolution TEM Image Revealed that this Coating Corresponds to the Mo2S3Layers.
Foaming of CNTs/PMMA Nanocomposite with Supercritical Carbon Dioxide
Authors: Xiong Yuan Lu , Shen Qiang , Yuan Huan , Chen Fei , Luo Guo Qiang
Published: March 2012

The CNTs/PMMA Nanocomposite Foams Are a Kind of Novel Multifunctional Foams which Have a Potential Application for Lightweight Conductive and EMI Shielding Materials. In this Work, the CNTs/PMMA Nanocomposite Foams with Different CNTs Contents from 1wt.% to 10wt.% Were Prepared at a Temperature Range of 50-140 °C with Supercritical Carbon Dioxide as Blowing Agent. The Results Suggest that the Fully Heterogeneous Nucleation Is Achieved due to the Contribution of Well-Dispersed CNTs in PMMA. The CNTs/PMMA Nanocomposite Foams Exhibit a Uniform Cell Distribution, and the Cell Density Is Two Orders of Magnitude Higher than that of PMMA Foams. The Cell Size and Cell Density of CNTs/PMMA Nanocomposite Foams Could Be Controlled by Adjusting the Foaming Process and CNTs Contents. It Is Also Suggested that the Foaming Process Plays an Important Role on the Cell Structure Rather than that of CNTs Content when it Is Higher than 1wt.%.
Mechanical Properties of Silicon Nitride Porous Ceramics with Bimodal Porosity
Authors: Chen Fei , Shen Qiang , Zhang Lian Meng
Published: March 2012

In this Paper, Silicon Nitride Porous Ceramics with Hierarchical Porosity Were Prepared Using Pressureless Sintering and their Mechanical Properties as a Function of Porosity and Pore Size Were Analyzed. In these Porous Ceramics, Macro-Pores with the Pore Size of 0.1 µm Were Formed by the Continuous Reaction of ZrP2O7 at ~250 °C and Macro-Cellular Pores with the Pore Size of 10~30μm Were Formed by the Burnout of Starch at ~550 °C or the Sublimation of Naphthalene at 80 °C. The Flexural Strength Decreased from 105 MPa to 6 MPa with the Porosity Increased from 35% to 65%. The Obtained Results Showed that the Flexural Strength Was Fit for the Equation of σ=σ0exp(-bP), where σ0 Is the Bending Strength of Nonporous Body of the same Material, P Is the Porosity and b Is the Factor Determines by Pore Structure. The Difference of Pore Size Was Determined by the Different Value of b and the Value of b Increased with the Increasing of Pore Size. Macro-Pores with the Pore Size of 0.1 µm Referred to a b Value of 4.3 and Macro-Cellular Pores with the Pore Size of 10 μm and 30 μm Referred to a b Value of 5.1 and 6.0 Respectively.
Investigation of a Tb-Doped HfO2 Single Crystal Grown by a Skull Melting Method
Authors: Kurosawa Shunsuke , Futami Yoshisuke , Kochurikhin Vladimir V. , Borik Mikhail A. , Yokota Yuui , Yanagida Takayuki , Yoshikawa Akira
Published: March 2012

HfO2 Has High Effective Atomic Number and No Radioactive-Isotope as the Background Source, and it Can Be the Candidate for the High-Stopping Scintillator Instead of Lu2SiO5:Ce Scintillator Used in Medical Imaging, Astronomy and etc. However, HfO2 Has an Extremely High Melting Point of 2774 °C, and it Is Difficult to Grow the Crystal from the Melt Using Crucible, as there Is No Suitable Metals, which Can Survive around that Temperature. Thus, Czochralski, Bridgman, and Micro-Pulling down Method Cannot Be Applied. Therefore we Investigated Optical Properties of a 17-mol% b-Doped (Stabilized) HfO2 Crystal Grown by the Skull Melting Method, and this Crystal Had a High Refractive Index of 2.5 at 550 nm, and the Maximum Emission Peak at ~550 nm from 5D4 Excited States of Tb3+. In Addition, we Found the Radiation Reaction of the Crystal Irradiated with Alpha and Gamma Rays Measuring with a Photomultiplier.
New Fe-B-P-Cu Nanocrystalline Soft Magnetic Alloys with High Js Combined with Low Coercivity Hc
Authors: Zhang Ze Qiang , Sharma Parmanand , Makino Akihiro
Published: March 2012

Fe-Si-B Amorphous Alloys with Less than 80 at% Fe Are now in Practical Use due to their Excellent Magnetic Softness (Low Coercivity Hc) Combined with Rather High Saturation Magnetic Polarization (Js) which Basically Owing to the Lack of Intrinsic Magnetic Anisotropy and the High Fe Content, Respectively. In Order to Obtain High Js, High Fe Content Is Required. However, Alloys with High Fe Content Exceeding the Limit Usually Have the as-Quenched Structure Consisting of Coarse α-Fe Grains in the Amorphous Matrix, which Results in Inferior Magnetic Softness. We Have Developed a New Fe85.2B10P4Cu0.8 Nanocrystalline Soft Magnetic Alloy Ribbon (with 5 mm in Width and about 20 µm in Thickness) Made from Industrial Raw Materials in Air Atmosphere. The as-Quenched Structure of Fe85.2B10P4Cu0.8 Alloy Has Heterogeneous Amorphous Structure (a Large Amount of Extremely Small α-Fe Clusters in Addition to Amorphous Phase). Homogeneous Nanocrystalline Structure Composed of α-Fe Grains with a Size ~19 nm Was Realized by Crystallizing the Hetero-Amorphous Alloy. The Nanocrystalline Alloy Exhibit High Js ~ 1.83 T (Comparable to the Commercial Fe-3.5 Mass% Si Steel) and Extremely Low Hc ~ 6.0 A/m. Additionally the Alloy Has a Large Economical and Industrial Advantage of Lower Material Cost and Good Reproductivity, which Has a High Potential for the Power Applications.
Micromechanical Modeling of the Effective Viscoelastic Response of Polyamide-6-Based Nanocomposites Reinforced with Modified and Unmodified Montmorillonite Clay
Authors: Anoukou K. , Zaïri Fahmi , Naït-Abdelaziz M. , Zaoui Ali , Gloaguen J.M.
Published: March 2012

A micromechanics-based approach using a self-consistent scheme based on the double-inclusion model is adopted to develop a pertinent model for describing the viscoelastic response of polymer/clay nanocomposites. The relationship between the intercalated nanostructure and the effective nanocomposite stiffness is constructed using an equivalent stiffness method in which the clay stacks are replaced by homogeneous nanoparticles with predetermined equivalent anisotropic stiffness. The capabilities of the proposed micromechanics-based model are checked by comparing with the experimental viscoelastic (glassy to rubbery) response of two polyamide-6-based nanocomposite systems reinforced with a modified montmorillonite clay (Cloisite 30B) and an unmodified sodium montmorillonite clay (Cloisite Na+), favoring, respectively, exfoliation and intercalation states.
Nanostructured Thermoset Composites Containing Conductive TiO2 Nanoparticles
Authors: Gutierrez Junkal , Tercjak Agnieszka , Mondragon Iñaki
Published: March 2012

Novel transparent multiphase nanostructured thermosetting composites with different block copolymer and sol-gel contents have been developed. Morphology of designed systems has been investigated by atomic force microscopy (AFM). Electrostatic force microscopy (EFM) has been used in order to study the conductive properties of prepared hybrid inorganic/organic nanostructured thermosetting systems. Moreover taking into account the optical properties of TiO2 nanoparticles UV-vis measurements indicate that TiO2 nanoparticles clearly enhance the UV-shielding efficiency of the inorganic/organic nanostructured thermosetting systems without losing high-visible light transparency.
Silsesquioxanes as Modifying Agents of Methylvinylsilicone Rubber
Authors: Strąkowska Anna , Kosmalska Anna , Zaborski Marian
Published: March 2012

The idea and methods of methylvinylsilicone rubber modification are present. Polyhedral oligomeric silsesquioxanes (POSS) functionalized by vinyl-, carboxyl or amino-organic groups were used with the goal of modifying the rubber matrix. Additionally, oxazoline derivative and itaconic acid were used as the coupling agents. Generally, the process of modification contributed to increasing of rubber-filler interactions, however the useful properties of composites depended on a kind of active groups and way of modifications. It has been shown how grafting of POSS molecules to silicone backbone affects the cross-link density, rheometrical and mechanical properties, hysteresis and relaxation rates of the methylvinylsilicone rubber vulcanizates. Moreover, both the presence of silsesquioxanes and the way of composites preparing affect the improvement of filler dispersion degree in the rubber matrix, as indicated by SEM images. The most significant effect was observed for vinylisobutyl-POSS grafting to the silicone backbone which resulted in the considerably improved mechanical properties of the resulting network.
Electrical and Mechanical Properties of Ethylene Vinyl Acetate Based Composites
Authors: Czaniková Klaudia , Špitalský Zdenko , Krupa Igor , Omastová Mária
Published: March 2012

In this study various composites based on the commercial ethylene vinyl acetate polymer matrix and multiwalled carbon nanotubes were prepared by casting from solution in the form of thick films. The degree of dispergation of carbon nanotubes in the polymer matrix was examined by scanning electron microscopy. Electrical conductivity and mechanical properties of those composites were investigated. It was observed that the electrical conductivity of composites increases with an increase of multiwalled carbon nanotubes content. The mechanical properties of composites were only slightly changed when compared with properties of neat ethylene vinyl acetate matrix.
Design of High Thermal Conductivity Particle Filled Polymer Using Effective Thermal Conductivity Models
Authors: Garnier B. , Danes F.
Published: March 2012

The context of this work is the enhancement of the thermal conductivity of polymer by adding conductive particles. It will be shown how we can use effective thermal conductivity models to investigate effect of various factors such as the volume fraction of filler, matrix thermal conductivity, thermal contact resistance, and inner diameter for hollow particles. Analytical models for lower bounds and finite element models will be discussed. It is shown that one can get some insights from effective thermal conductivity models for the tailoring of conductive composite, therefore reducing the amount of experimental work.
Incorporation of Organomodified Layered Silicates and Silica in Thermoplastic Elastomers in Order to Improve Tear Strength
Authors: Jaudouin Olivier , Robin Jean Jacques , Perrin Didier , Sonnier Rodolphe , Ienny Patrick , Léger Romain , Lopez-Cuesta José Marie
Published: March 2012

Organomodified layered silicates and silicas have been incorporated in thermoplastic elastomers such as styrene-ethylene-butylene-styrene copolymers (SEBS) and polyurethanes (PU) in order to improve mechanical properties - especially tear strength. The organically modified layered silicates used were Cloisite® 30B, a montmorillonite modified with a ternary ammonium salt with hydroxyls as end groups and Nanofil®2 which is organically modified by long chains of hydrocarbon and benzyl groups. Sepiolite, a natural clay with fibrous morphology was also used. The silicas incorporated are Aerosil 300, hydrophilic fumed silica and Aerosil R202, hydrophobic fumed silica. nanoparticles are incorporated between 1 and 5 weight percent. A compatibilizer SEBS grafted with maleic anhydride has been incorporated in some of the formulations for a better dispersion of some of the nanoparticles. Different ways of incorporation have been investigated. For SEBS formulations, melt blends of SEBS pellets and clays have been prepared with an internal mixer and then films have been casted. For polyurethanes, solvent blending of polyols and clays were carried out in a vessel and then, compression molding of the blend with diisocyanates was made to synthesize polyurethanes. Materials have been compared on the basis of normalized tear test and sequenced tensile test. Mechanical parameters, as stabilization ratio (Mullins effect) and viscoelastic ratio, have been defined by integration of the stress-strain curves obtained. An interesting improvement of tear strength was observed for modified materials.
Development of Bio-Composites Based of Polymer Matrix and Keratin Fibers: Contribution to Poultry Biomass Recycling
Authors: Salhi Ahmed , Kaci Salah , Boudenne Abderrahim
Published: March 2012

Processing of the poultry feather biomass into useful products presents interesting opportunities of recycling agricultural waste material. According to a chemical process developed in our laboratory, poultry feathers were converted into wool, fibers or powder so as to meet several applications in many fields. Due to of their unique structure and to their physical properties, a suitable molding technique was performed in order to produce composite samples highly filled. The concentration range was varied from 10 to 50% by weight with an increase of 10, because of practical reasons. The morphological, thermophysical and mechanical investigations of polyester matrix filled with several concentrations of the keratin fibers show interesting results.
Multiscale Finite Element Modelling of Gallery Failure in Epoxy-Clay Nanocomposites
Authors: Pisano C. , Priolo Pierluigi , Figiel Łukasz
Published: March 2012

A multiscale finite element (FE) methodology is applied to study failure behaviour of an intercalated epoxy-clay nanocomposite. A 2D FE model of the nanocomposite is built to capture nanocomposite morphology and gallery failure mechanism. Intercalated morphology is reconstructed using a random dispersion of clay tactoids within the epoxy matrix, while the galleries are modeled using cohesive zone elements. The nanocomposite response is predicted by numerical homogenization technique. The effects of cohesive law parameters (particularly the fracture energy) and clay volume fraction on the macroscopic behavior of the nanocomposite are investigated. The analysis shows that gallery failure is the main cause of strength reduction of the nanocomposite. Moreover, the strength reduction is found to increase with the clay content, which is in a qualitative agreement with available experimental results.
In Vitro Degradation of β-Tricalcium Phosphate Reinforced Poly(L-Lactic Acid)
Authors: Adamus A. , Jozwiakowska J. , Wach R.A. , Suarez-Sandoval D. , Ruffieux K. , Rosiak J.M.
Published: March 2012

Poly (L-lactic acid) (PLLA) and composite of PLLA with osteoconductiveβ-tricalcium phosphate fine powder (PLLA/TCP) compression moulded specimens were subjected to in vitro biodegradation up one year. Samples were investigated in terms of physical-chemical evaluation after several periods of incubationin simulated body fluid solution. Reduction in PLLA molecular weights occurred during thermal processing of compounding of the polymer with TCP. 3-point bending measurements revealed some decay in the flexural strength and increase in stiffness after incorporation of the inorganic particles into the polymer. Those parameters remained nearly stable during the biodegradation period despite constant drop of polymer molecular weight. Thermal properties of both kinds of samples did not changed significantly, however degree of crystallinity of PLLA matrix was increasing slowly in pure PLLA samples. Despite no mass loss,extent of surface deteriorationincreased steady during the incubation. Current study is intended to develop material for implants, mainly fusion cages targeted for spinal applications.
Influence of Interphase Properties on the Macroscopic Response of Single- and Double-Walled CNT/Epoxy Nanocomposites: A Numerical Study
Authors: Weidt David , Figiel Łukasz , Buggy Martin
Published: March 2012

A concept for improving the impact resistance of carbon fibre reinforced plastic (CFRP) laminates by using a carbon nanotube (CNT)/epoxy surface coating is presented. An initial parametric numerical study shows the effects of interphase properties on the macroscopic stress-strain behaviour of carbon nanotube/epoxy nanocomposites. Finite element (FE) simulations carried out for fully aligned single-walled CNTs (SWCNTs) and double-walled CNTs (DWCNTs) investigated the influence of properties of the polymer/CNT interphase and the interwall phase of DWCNTs. They reveal that a high shear stiffness of the CNT/polymer interphase is essential to take the full advantage of the load-bearing ability of the inner wall of the DWCNT, and thus enhance the mechanical performance of the nanocomposite. Furthermore the interphase shear stress distributions in interwall and CNT/polymer interphase of a DWCNT point out the relationship between CNT/epoxy interphase damage propagation and shear stress in the interwall phase.
Determination of Phase Content in Multiphase Polymers by Solid-State NMR Techniques
Authors: Martínez-Richa Antonio , Silvestri Regan
Published: March 2012

Solid-state nuclear magnetic resonance (NMR) spectroscopy has emerged as a relatively facile technique for the characterization of multi-component polymer systems. In particular, it has emerged to be a useful technique for probing the molecular structure, conformation and dynamics of polymer chains at interfaces between phases in various types of multi-component polymer systems including nanomaterials. The usefulness of solid-state NMR stems from its ability to non-destructively probe not only the bulk of the polymer, but moreover its ability to selectively probe the interface or interphase. As such, the technique has been extensively exploited in the study of multi-component polymer systems. To achieve 13C spectral resolution in the solid-state magic angle spinning (MAS), dipolar decoupling and cross-polarization are applied which enables the study of individual carbon atoms directly with excellent resolution and sensitivity. Some examples of applications of this technique to the study of multiphase aliphatic polyesters are reviewed herein.
Low Frequency Relaxation in Block Copolymers and Nanocomposites
Authors: Santamaria Anton , Fernández Mercedes , Muñoz María Eugenia
Published: March 2012

Results of the loss tangent, tan δ, at low frequencies, obtained for a SEBS copolymer and carbon nanotube (CNT)/polyurethane (PUR) nanocomposites, are analysed. The hindering effect of nanostructures (i.e. ordered domains or nanoparticles) on the motion of polymer chains is revealed by the occurrence of a mechanical relaxation at low frequencies. In the case of SEBS copolymer, the effect of domains orientation and extender oil on a characteristic time associated with the relaxation is investigated. For CNT/PUR nanocomposites, the variation of the frequency at which the relaxation takes place, with CNT concentration and temperature, reveals that the interactions between the nanotubes and the polymer chains are improved with temperature
Investigation of Relaxation Processes in Nanocomposites by Transient Grating Experiments
Authors: Taschin A. , Bartolini P. , Sánchez-Ferrer A. , Mezzenga R. , Mrzel A. , Torre R.
Published: March 2012

We report a comparative study on the photo-elastic and photo-thermal features of two nanocomposites based on MoS2 nanotubes dispersed into two different polyurea elastomeric matrices, which have different crosslinking properties. The time-resolved laser spectroscopic investigation on these nanocomposites by transient grating (TG) experiments has been performed. The relaxation kinetics on a very wide time scale has been measured from nanosecond to hundred of microseconds. The TG data on both pure polymers shows fast acoustic oscillations and a slow thermal decay. No structural relaxation is appearing in the experimental time window. Surprisingly, the presence of nanotubes in both the polymeric matrixes induces intermediate dynamics clearly detected by the TG signal. The features of this unexpected dynamic features recall the structural relaxation typical of glass-formers but its origin is still unclear.
Lyn but Not Fyn Kinase Controls IgG-Mediated Systemic Anaphylaxis
Authors: Falanga Yves T. , Chaimowitz Natalia S. , Charles Nicolas , Finkelman Fred D. , Pullen Nicholas A. , Barbour Suzanne , Dholaria Kevin , Faber Travis , Kolawole Motunrayo , Huang Bernice , Odom Sandra , Rivera Juan , Carlyon Jason , Conrad Daniel H. , Spiegel Sarah , Oskeritzian Carole A. , Ryan John J.
Published: March 2012

Anaphylaxis is a rapid, life-threatening hypersensitivity reaction. Until recently, it was mainly attributed to histamine released by mast cells activated by allergen crosslinking (XL) of FcεRI-bound allergen-specific IgE. However, recent reports established that anaphylaxis could also be triggered by basophil, macrophage, and neutrophil secretion of platelet-activating factor subsequent to FcγR stimulation by IgG/Ag complexes. We have investigated the contribution of Fyn and Lyn tyrosine kinases to FcγRIIb and FcγRIII signaling in the context of IgG-mediated passive systemic anaphylaxis (PSA). We found that mast cell IgG XL induced Fyn, Lyn, Akt, Erk, p38, and JNK phosphorylation. Additionally, IgG XL of mast cells, basophils, and macrophages resulted in Fyn- and Lyn-regulated mediator release in vitro. FcγR-mediated activation was enhanced in Lyn-deficient (knockout [KO]) cells, but decreased in Fyn KO cells, compared with wild-type cells. More importantly, Lyn KO mice displayed significantly exacerbated PSA features whereas no change was observed for Fyn KO mice, compared with wild-type littermates. Intriguingly, we establish that mast cells account for most serum histamine in IgG-induced PSA. Taken together, our findings establish pivotal roles for Fyn and Lyn in the regulation of PSA and highlight their unsuspected functions in IgG-mediated pathologies.
Inhibition of Mammalian Target of Rapamycin Augments Lipopolysaccharide-Induced Lung Injury and Apoptosis
Authors: Fielhaber Jill A. , Carroll Scott F. , Dydensborg Anders B. , Shourian Mitra , Triantafillopoulos Alexandra , Harel Sharon , Hussain Sabah N. , Bouchard Maxime , Qureshi Salman T. , Kristof Arnold S.
Published: March 2012

Acute lung injury during bacterial infection is associated with neutrophilic inflammation, epithelial cell apoptosis, and disruption of the alveolar-capillary barrier. TLR4 is required for lung injury in animals exposed to bacterial LPS and initiates proinflammatory responses in part via the transcription factor NF-κB. Ligation of TLR4 also initiates a proapoptotic response by activating IFN-β and STAT1-dependent genes. We recently demonstrated that mammalian target of rapamycin (mTOR), a key controller of cell growth and survival, can physically interact with STAT1 and suppress the induction of STAT1-dependent apoptosis genes. We therefore hypothesized that the mTOR inhibitor rapamycin would increase LPS-induced apoptosis and lung injury in vivo. Rapamycin increased lung injury and cellular apoptosis in C57BL/6J mice exposed to intratracheal LPS for 24 h. Rapamycin also augmented STAT1 activation, and the induction of STAT1-dependent genes that mediate cellular apoptosis (i.e., Fas, caspase-3). LPS-induced lung injury was attenuated in STAT1 knockout mice. In addition, LPS and IFN-β–induced apoptosis was absent in cultured cells lacking STAT1, and, unlike in wild-type cells, a permissive effect of rapamycin was not observed. In contrast to its effect on STAT1, rapamycin inhibited NF-κB activation in vivo and reduced selected markers of inflammation (i.e., neutrophils in the bronchoalveolar lavage fluid, TNF-α). Therefore, although it inhibits NF-κB and neutrophilic inflammation, rapamycin augments LPS-induced lung injury and apoptosis in a mechanism that involves STAT1 and the induction of STAT1-dependent apoptosis genes.
Control of Transplant Tolerance and Intragraft Regulatory T Cell Localization by Myeloid-Derived Suppressor Cells and CCL5
Authors: Dilek Nahzli , Poirier Nicolas , Usal Claire , Martinet Bernard , Blancho Gilles , Vanhove Bernard
Published: March 2012

Myeloid-derived suppressor cells (MDSC) are a heterogeneous population of immature cells that are believed to inhibit immune responses in the contexts of cancer and organ transplantation, in association with regulatory T cells (Treg). However, the way in which MDSC cooperate with Treg remains elusive. In this study, we used DNA microarrays to analyze gene expression in blood-derived MDSC from rat recipients of kidney allografts. We found CCL5 (Rantes), a chemotactic C-C motif 5 chemokine, to be strongly downregulated after treatment with a tolerizing regimen. The amount of CCL5 protein was also lower in the plasma of tolerant recipients, whereas intragraft CCL5 was unchanged. Because CCL5 is chemotactic for Treg, we hypothesized that a gradient of CCL5 between the graft and peripheral blood might contribute to the intragraft localization of Treg in tolerant animals. To test this hypothesis, we treated tolerant rat recipients of kidney allografts with recombinant rat CCL5 to restore normal plasma concentrations. This led to a strong reduction in intragraft Treg monitored by immunohistofluorescence and by quantitative real-time PCR measurement of Foxp3 mRNA. Ultimately, this treatment led to an increase in serum creatinine concentrations and to kidney graft rejection after about a month. The kidney function of syngeneic grafts was not affected by a similar administration of CCL5. These data highlight the contribution of MDSC to the establishment of a graft-to-periphery CCL5 gradient in tolerant kidney allograft recipients, which controls recruitment of Treg to the graft where they likely contribute to maintaining tolerance.
Purinergic Receptors Are Required for HIV-1 Infection of Primary Human Macrophages
Authors: Hazleton Joy E. , Berman Joan W. , Eugenin Eliseo A.
Published: March 2012

Macrophages play a significant role in HIV infection, viral rebound, and the development of AIDS. However, the function of host proteins in viral replication is incompletely characterized in macrophages. Purinergic receptors P2X and P2Y are major components of the macrophage immune response to pathogens, inflammation, and cellular damage. We demonstrate that these receptors are necessary for HIV infection of primary human macrophages. Inhibition of purinergic receptors results in a significant reduction in HIV replication in macrophages. This inhibition is independent of viral strain and is dose dependent. We also identify that P2X1, P2X7, and P2Y1 receptors are involved in viral replication. We show that P2X1, but not P2X7 or P2Y1, is necessary for HIV entry into macrophages. We demonstrate that interaction of the HIV surface protein gp120 with macrophages stimulates an increase in ATP release. Thus, we propose that HIV’s binding to macrophages triggers a local release of ATP that stimulates purinergic receptors and facilitates HIV entry and subsequent stages of viral replication. Our data implicate a novel role for a family of host proteins in HIV replication in macrophages and suggest new therapeutic targets to reduce the devastating consequences of HIV infection and AIDS.
Requirement for Diverse TCR Specificities Determines Regulatory T Cell Activity in a Mouse Model of Autoimmune Arthritis
Authors: Oh Soyoung , Aitken Malinda , Simons Donald M. , Basehoar Alissa , Garcia Victoria , Kropf Elizabeth , Caton Andrew J.
Published: March 2012

CD4+CD25+Foxp3+ regulatory T cells (Tregs) are required to restrain the immune system from mounting an autoaggressive systemic inflammatory response, but why their activity can prevent (or allow) organ-specific autoimmunity remains poorly understood. We have examined how TCR specificity contributes to Treg activity using a mouse model of spontaneous autoimmune arthritis, in which CD4+ T cells expressing a clonotypic TCR induce disease by an IL-17–dependent mechanism. Administration of polyclonal Tregs suppressed Th17 cell formation and prevented arthritis development; notably, Tregs expressing the clonotypic TCR did not. These clonotypic Tregs exerted Ag-specific suppression of effector CD4+ T cells using the clonotypic TCR in vivo, but failed to mediate bystander suppression and did not prevent Th17 cells using nonclonotypic TCRs from accumulating in joint-draining lymph nodes of arthritic mice. These studies indicate that the availability of Tregs with diverse TCR specificities can be crucial to their activity in autoimmune arthritis.
Resolvin E2 Formation and Impact in Inflammation Resolution
Authors: Oh Sungwhan F. , Dona Maria , Fredman Gabrielle , Krishnamoorthy Sriram , Irimia Daniel , Serhan Charles N.
Published: March 2012

Acute inflammation and its resolution are essential processes for tissue protection and homeostasis. In this context, specialized proresolving mediators derived from polyunsaturated fatty acids are of interest. In this study, we report that resolvin E2 (RvE2) from eicosapentaenoic acid is endogenously produced during self-limited murine peritonitis in both the initiation and resolution phases. RvE2 (1–10 nM) carries potent leukocyte-directed actions that include: 1) regulating chemotaxis of human neutrophils; and 2) enhancing phagocytosis and anti-inflammatory cytokine production. These actions appear to be mediated by leukocyte G-protein–coupled receptors as preparation of labeled RvE2 gave direct evidence for specific binding of radiolabeled RvE2 to neutrophils (Kd 24.7 ± 10.1 nM) and resolvin E1 activation of recombinant G-protein–coupled receptors was assessed. In addition to the murine inflammatory milieu, RvE2 was also identified in plasma from healthy human subjects. RvE2 rapidly downregulated surface expression of human leukocyte integrins in whole blood and dampened responses to platelet-activating factor. Together, these results indicate that RvE2 can stimulate host-protective actions throughout initiation and resolution in the innate inflammatory responses.
Transforming a small business: A learning intervention
Authors: Geldenhuys Dirk J. , Cilliers Frans
Published: March 2012

Orientation: This article reports on a learning intervention in a brokers company with fewer than 50 employees. A rich description of the participants’ experience is provided. Research purpose: The purpose of the study was to explore the use of an experiential learning process during an organisation development (OD) intervention in a small business by means of a case study.Motivation for the study: This study explored the important role of small businesses; the role of management; and, more specifically, organisation development models that were developed for large corporations; as these emphasise the need to study the purpose of organisation development interventions in small businesses.Research design, approach and method: The study reported on in this article was a qualitative case study in a small brokers company with 21 staff members. The data were analysed manually by means of qualitative content analysis.Main findings: The main finding of the research concerned how experiential learning intervention provided a space for participants to start exploring, and gradually changing the dynamics of their small business, by transforming their business into a more formal company.Practical/managerial implications: The primary implication is that experiential learning interventions that are operationalised, from a psychodynamic perspective, can be valuable when consulted by small businesses during their transformation towards becoming more formal companies.Contribution/value-add: This article contributes to the OD literature on small businesses, with fewer than 50 employees, by providing data on how the learning process, that commenced during an experiential learning intervention, assisted a small company to develop its identity towards that of a more formal company.
In support of female leadership in the church: Grappling with the perspective of Setswana men � Shepherding as solution offered
Authors: Sekano Gopolang H. , Masango Maake J.
Published: March 2012

This article addresses the overwhelmingly negative experience and feeling of some men who serve under female leaders in the church. They claim to feel degraded and traumatised by the experience of being led by women. They also claim that their patriarchal culture and religion is defied by such actions and laws of equality that encourage female leadership. They substantiate their views by quoting 1 Corinthians 14:34−35 and 1 Timothy 2:12−14 in addition to a Setswana proverb, �Tsa etelelwa pele ke e namagadi di wela ka lengope� [those who are led by a female leader fall into dongas]. In the light of this situation an intensive study regarding the need for an egalitarian concept and constructive interpretation of Bible passages, Setswana proverbs and idioms regarding the inevitability of female leadership is paramount to people who have an androcentric concept of religion and culture.