bluuebunny/crossref_metadata_2025 huggingface dataset:
Notices on Method of Thickness Evaluation of TiN Layers on Magnesium Alloys
Authors: Golabczak Marcin , Konstantynowicz Andrzej
Published: April 2010

Widely used in mechanics is the method of surface parameters investigation by indentation of some kind of penetrator into test surfaces and registration of the indentation/load dependence through the whole test duration. A small ball made of hardened steel or diamond pyramid, so-called Berkovich pyramid, is used for penetration. An actuator performing the indentation process is used for displacement enforcement as well as for load measurement. Mainly two types of devices are in use: based on piezoelectric effect or purely electromagnetic LVDT. Knowledge about the penetrator tip is essential for the proper evaluation of the measured parameters and knowledge about the actuation method is also desired for better identification of the whole system parameters when using DSP type algorithms at the stage of experimental data elaboration. In this paper we deal with some kind of DSP elaboration of the experimental data. Our attitude is based on successive digital filtration applied to the experimental data as well as to the intermediate stages of calculation, especially for compliance estimation. Different digital filters have been developed and applied to the experimental data. Some conclusions have been taken out due to the precision of the layer thickness estimation based on data obtained by indentation of the investigated surface with a Berkovich pyramid driven by a piezoelectric actuator. The Boussinesq/Sneddon theory has been used as the basis of our analysis. Titanium azide layers imposed on a magnesium alloy have been tested using PVD method. Obtained results especially due to the hardness/indentation plot allow evaluating the layer thickness, which should be also compared with thickness values evaluated by other methods.
Numerical Simulation of Heat Losses between a Partition Plate and the Wall of the Head of a Plastic Heat Exchanger
Authors: Osorio Rita Aguilar , Cliffe Keith
Published: April 2010

For this research it was considered that the heat exchanger was affected by leakage in the head across the partition plate and the wall between the tube passes. Leakage was a problem in the plastic shell and tube heat exchanger, because it was difficult to seal the partition plate to the head of the exchanger. The material used for manufacturing the heat exchanger was polyvinylidene fluoride, PVDF. In order to predict the amount of flow leaking through the clearances of the tube passes, a numerical simulation was carried out using the computational Fluid Dynamics CFD Fluent Software. To obtain the percentage of the heat loss across the 4 tube passes, different clearance sizes between the partition plate and the wall of the head of the exchanger were analysed. For the smaller clearance size of 0.2 mm the heat transfer coefficient was reduced up to 15%. These results suggest that the flow mass bypassing the head between tube passes affect the results of the heat transfer coefficient and confirm the experimental observation, that its performance was affected by leakage between tube passes. This research served as an extension of the preliminary plastic heat exchanger design.
Silicon Dioxide as a Boundary for Oxygen Outdiffusion from CZ-Si
Authors: Barcz Adam
Published: April 2010

Oxygen out-diffusion from CZ-Si or in-diffusion into FZ Si was studied with Secondary Ion Mass Spectrometry. For anneals up to 1200oC , the value of 16O concentration Csurf that develops at the semiconductor surface in bare wafers with ~2 nm thick natural oxide was found to be comparable to that in thermally oxidized wafers with 260 nm thick SiO2. Beyond this temperature, at 1280oC, Csurf in non-oxidised sample appears 5 times lower that in the oxidised one. This means that the spontaneous oxide becomes permeable to the oxygen species and no longer constitutes a barrier preventing the oxygen atoms from direct out-diffusion into the ambient. The effect becomes more pronounced when the specimens were heated to 1150oC in a chamber evacuated to ~ 10-7 Torr. The resultant bare Cz-Si and, to even greater extent, FZ Si with previously in-diffused oxygen exhibited deep oxygen depletion, 10x below the respective values for annealing under atmospheric pressure. Undoubtedly, it is the removal of residual oxides by sublimation that enables oxygen atoms to freely out-diffuse into vacuum.
Cu Ti Formation in Nb Ti/Cu Superconducting Strand Monitored by In Situ Techniques
Authors: Pong Ian , Scheuerlein Christian , Senatore Carmine , Thilly Ludovic , Di Michiel Marco , Gerardin Alexandre , Hopkins Simon C. , Oberli Luc-Rene , Geandier Guillaume , Glowacki Bartek A. , Bottura Luca
Published: April 2010

In order to investigate the high temperature exposure effect on Nb Ti/Cu superconducting strands, as might be encountered in joining by soldering and in cabling annealing, X-ray diffraction and resistometry measurements were performed in situ during heat treatment, and complemented by conventional metallography, mechanical tests and superconducting properties measurements. Changes of the Nb Ti nanostructure at temperatures above 300°C are manifested in the degradation of critical current in an applied external magnetic field, although degradation at self field was insignificant up to 400°C for several minutes. Above 500°C, the formation of various Cu Ti intermetallic compounds, due to Ti diffusion from Nb Ti into Cu, is detected by in situ XRD albeit not resolvable by SEM-EDS. There is a ductile to brittle transition near 600°C, and liquid formation is observed below 900°C. The formation of Cu Ti causes a delayed reduction of the residual resistivity ratio (RRR) and adversely affects the deformation behaviour of the strands.
Hydrogen Diffusivity and Hydride Formation in Rich-Zirconium Alloys Used in Nuclear Reactors
Authors: Silva K.R.F. , dos Santos Dílson Silva , Ribeiro A.F. , Almeida L.H.
Published: April 2010

Hydrogen gas permeation tests were performed on two Nb-modified Zr alloys used in the nuclear industry. The influence of the microstructure on hydrogen diffusivity in each alloy is discussed and a mechanism of hydride formation is presented. The hydrogen binding energy for different trap sites was calculated in the M5 alloy as well as hydrogen diffusivity value in the Zirlo alloy at 300oC, D = 2.5 x 10-13 m2/s.
Modeling of Turbulent Flow and Heat Transfer in Graphitic Foams
Authors: Cepek J. , Straatman Anthony G.
Published: April 2010

We describe a study conducted to examine the influence of turbulence on the flow and heat transfer in graphitic foams. In this study, a Large Eddy Simulation (LES) model was used to characterize turbulence in the momentum and energy balances, and calculations were done to produce transient results of the velocity and temperature fields inside the spherical pores of the foam. The LES simulations enable excellent insight into the pore-level heat transfer mechanisms for the spherical void shape, and show that the heat transfer increases by a factor of 4.7 for an order of magnitude increase in the Reynolds number.
Hydrogen Absorption/Desorption in Nanostructured Fe- and Ti-Doped Mg2Ni Alloys
Authors: Atías Adrián Isabel C. , Deorsola Fabio A. , Ortigoza-Villalba G.A. , DeBenedetti Bruno , Baricco Marcello
Published: April 2010

Nanostructured Mg2Ni, Fe-doped and Ti-doped Mg2Ni alloys for hydrogen storage applications have been produced by means of Mechanically Activated Self-propagating High temperature Synthesis (MASHS). Different molar compositions of Fe and Ti (0.1; 0.3 and 0.5) have been studied in order to determine their influence in the hydrogen sorption properties. Different Mg-Ni based alloys have been tested in order to study their hydrogen sorption behavior. The hydrogenation was carried out in a Pressflow Gas Controller. Subsequently, the dehydrogenation process was conducted by means of a Differential Scanning Calorimetry (DSC) equipped with an H2 detector of the purged gas. The MASHS method has been demonstrated to be effective for the obtainment of nanostructured pure and doped Mg2Ni intermetallics. In addition, the materials produced showed hydrogen storage capacities superior to 4wt%, especially in the case of Fe-doped Mg2Ni and a slight reduction of desorption temperature was reached with Ti-doped Mg2Ni. Finally, the activation energy of the dehydrogenation process was evaluated and Ti-doped sample exhibited the lower activation energy value. Obtained results are promising for technological applications of Mg-based alloys.
Peculiarities of the Electron-Phonon Interaction in Graphite Containing Metallic Intercalated Layers
Authors: Feher Alexander , Feodosyev S.B. , Gospodarev I.A. , Grishaev V.I. , Kravchenko K.V. , Manzhelii E.V. , Syrkin Eugenyi
Published: April 2010

The calculation of the local density of electronic states of graphene with vacancies, using the method of Jacobi matrix, was performed. It was shown that for atoms in the sublattice with a vacancy the local density of electronic states conserves the Dirac singularity, similarly as in an ideal graphene. A quasi-Dirac singularity was observed also in the phonon spectra of graphite for the atom displacements in the direction perpendicular to layers. Changes of phonon spectra of graphite intercalated with various metals were analyzed. On the basis of our results and using the BCS theory and Eliashberg equation we proposed what dynamic properties an intercalated graphite system should show to obtain an increased Tc.
Experimental and Analytical Investigation of Ammonia Absorption into Ammonia-Water Solution: Estimated Interface Concentration
Authors: Mustafa Hatem
Published: April 2010

Ammonia absorption process of ammonia vapor into ammonia water solution has been investigated experimentally, by inserting superheated ammonia vapor into a test cell containing a stagnant pool of ammonia water solution of several ammonia mass fractions, Ci. Before commencing the experiment, the pressure in the test cell corresponds to the equilibrium vapor of the ammonia-water system at room temperature. When the valve is opened, mechanical equilibrium is established quickly and the ammonia vapor diffuses into ammonia solution [1]. The difference between the initial pressure in the vapor cylinder and the initial pressure in the test cell ΔPi is found to have a major influence not only on the absorption rate but also on the estimated interface concentration. The interface concentration Cint of the cases ΔPi = 50 and 100 kPa exhibits a similar tendency, Cint decreases rapidly compared to other initial pressures ΔPi = 150 and 200 kPa. On the other hand, the interface concentration Cint of the cases ΔPi = 250 and 300 kPa are increasing within about 50 sec, then are hardly changing with time. They behave almost in a similar way as of Cint = 0.27 kg/kg. A correlation which gives the total absorbed mass of ammonia as a function of the initial concentration, the initial pressure difference and time is derived. In addition, the absorbed mass at no pressure difference could be estimated from the absorbed mass at initial pressure difference.
Reaction Diffusion in Pb Free Solder-Cu System
Authors: Taguchi O. , Lee C.G. , Park D.Y. , Shin G.S. , Suzuki Shigeru , Nakamura Ryusuke
Published: April 2010

Reaction diffusion in liquid Pb free solder- and solid Pb free solder- pure Cu systems has been investigated in the temperature range between 397 K and 563 K. The Pb free solder of which composition is 95.7 mass% Sn, 2.8 mass% Ag, 1.0 mass% Bi and 0.5 mass% Cu and 99.99 mass% oxygen free Cu has been used. In the liquid Pb free solder-pure Cu system, as soon as the solder melted down, an intermetallic compound phase formed preferentially, and grew with increasing diffusion time. Only the phase exists in the experimental time up to 120 seconds. The layer thickness of the phase obeyed the parabolic law. On the other hand, in the solid Pb free solder-pure Cu system two intermetallic compounds  phase and ’ phase form and grew with increasing diffusion time, although the  phase forms after an incubation time at low temperature. The layer thickness of these intermetallic compounds obeyed the parabolic law. The growth rate of ’ phase is greater than that of the  phase. The growth kinetics of the intermetallic compounds and the diffusion behavior in the ’ phase have been investigated.
Numerical Analysis of Heat and Mass Transfer in an Annular Porous Adsorber for Solar Cooling System
Authors: Allouache Nadia , Bennacer Rachid , Chikh Salahs , Al Mers A.
Published: April 2010

The present study deals with a solid adsorption refrigerator analysis using activated carbon/methanol pair. It is a contribution to technology development of solar cooling systems. The main objective consists to analyse the heat and mass transfer in an annular porous adsorber that is the most important component of the system. The porous medium is contained in the annular space and the adsorber is heated by solar energy. A general model equation is used for modelling the transient heat and mass transfer. Effects of the key parameters on the adsorbed quantity, the coefficient of performance, and thus on the system performance are analysed and discussed.
A Study of Porosity Influence on Thermal Diffusivity of Aluminium Foam by Experimental Analysis and Numerical Simulation
Authors: Adamčíková A. , Taraba B. , Kováčik J.
Published: April 2010

Aluminium foam is a unique material possessing very high thermal diffusivity due to high thermal conductivity of the cell walls accompanied with rather low overall thermal conductivity, controlled via porosity [1]. There is a presumption of increasing influence at thermal diffusivity of aluminium foam by decreasing porosity, following the presented results (e.g. by using the transient plane source method [2]) and relation between thermal diffusivity and density. Thermal diffusivity of aluminium foam considering various porosity and various compositions of precursors were observed. The Aluminium foam was prepared by the powder metallurgy route, also well known as the ALULIGHT process, and various densities were achieved by changing of parameters (temperature, time) of foaming. The following types of foamable precursors were used: AlMg1Si0.6, AlSi10, as blowing agent was used 0.8 wt. % of TiH2.The thermal diffusivity of particular precursors by the flash method was measured. Specific heat capacities of samples with different density were measured by a calorimeter for various temperatures. The coefficient of thermal conductivity as a function of temperature was calculated by heat transient experiment data and numerical simulation consequently as an inverse heat transfer task. The problem was solved by the finite element method using the engineering-scientific program code ANSYS. The results depend on the thermal diffusivity, on the porosity and the type of precursor. Despite that aluminium foam is considered as a type of composite, thermophysical properties could be calculated upon known volume of aluminium alloy and air in the pores However there is a presumption that this rule cannot be used in case of porous materials. Values obtained by the mentioned methodology shown a significant influence on the porosity and the thermal diffusivity of the aluminium foam.
Ion Nitriding of CoCrMo Alloys
Authors: Kaya Beril , Yılmaz Suleyman , Ergun Celaletdin
Published: April 2010

Medical grade cast CoCrMo alloy (F75) was ion nitrided under different process parameters including time (2, 9 hr) and temperature (600, 800 0C) at a gas mixture of 80%N2–20%H2. The nitrided surfaces were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). MicroVickers hardness tests were done on the cross sections of the nitrided specimens to investigate the hardness profile. The significant effects of nitriding temperature and time on the microstructure and hardness value of nitrided surface layers were displayed.
Microsegregation Induced Inhomogeneity of Coarsening of γ’ Precipitates in a Nickel-Based Single Crystal Superalloy
Authors: Gebura Marek , Lapin Juraj
Published: April 2010

Microsegregation induced inhomogeneity of the coarsening of cuboidal γ’(Ni3(Al,Ti)) precipitates was studied in a single crystal nickel-based superalloy CMSX-4 at temperatures ranging from 850 to 1000 °C and for an ageing time up to 5000 h. Experimental results showed a significant statistical difference in the size of the γ’ precipitates between the dendrites and interdendritic region. The achieved results are analyzed and discussed from the point of chemical heterogeneity, activation energy for coarsening, time exponent, effective diffusion coefficient and γ/γ’ interfacial energy which control coarsening kinetics of the cuboidal γ’ precipitates within the dendrites and interdendritic region.
Thermal Expansion of Advanced Materials for High Temperature Fusion Application
Authors: Dvorák Tomáš , Kavecký Štefan , Štefánik Pavol
Published: April 2010

In this paper, two different technologies for preparation of the composite are presented: vacuum diffusion bonding and gas pressure infiltration. Samples contained different volume fractions of tungsten fibres (10%, 50% and 78%) that were arranged in unidirectional, cross-ply and circular architecture. The coefficient of thermal expansion (CTE) of Cu/W MMC samples was measured in the longitudinal and transverse direction to the fibre orientation and it strongly depended on arrangement of reinforcing phase and direction of measurement. For the unidirectional material the CTE was 4 - 6 ppm.K-1 and 11-12 ppm.K-1 in directions parallel and transverse to the fibre orientation, respectively.
Samples in a shape of a ring contained reinforcement that was wounded around the sample centre (circumferential winding) or was cut-out from the Cu/W MMC plate. In the second case, the reinforced fibres had the woven arrangement. The CTE of ring measured in radial direction showed values from 5 ppm.K-1 to 20 ppm.K-1 for composites containing 72 and 10 vol. % of W-fibres, respectively.
Thermal Stability of Al2O3 Coated Low Transition Temperature Glass
Authors: Ma Kung Jeng , Chien His Hsin , Vattikuti S. Prabhakar , Kuo Chien Huang , Huo Cheng Bang , Chao Choung Lii
Published: April 2010

There are growing varieties of glasses available on the market for the manufacture of molded optical lenses. A glass with a low transition temperature (Tg) has the advantage of extending the service life of molding dies. However, most of the low Tg glasses have a high content of alkali metal oxides and tend to induce severe glass sticking problems. This has made the molding process of these kinds of glasses very difficult indeed. The low Tg glasses normally demonstrate poor chemical durability and scratch resistance. As a result, the yields of fabricating the glass-preforms are frequently rather low. This research tried depositing a very thin layer of aluminum oxide on various glass-preforms by a water based sol-gel process. A high temperature glass wetting experiment was carried out to investigate the high temperature interfacial reaction between the coated glass gobs and stainless steel substrate.
It was found that when the uncoated glass-preforms were brought into contact with stainless steel, the contact angle decreased with increasing heating temperature and duration. Owing to the severe interfacial chemical reaction, the originally transparent glass gradually turned translucent. In the case of Al2O3 coated glass-preforms, the variation of the contact angles was very limited, which presented no sticking and no wetting behavior. No reaction products could be detected on the contact area after the wetting test. The optical transmission of those lenses molded from the coated glass-preforms exhibited no or very little changes after the molding process.
Thermal Diffusivity of Traditional and Innovative Sheet Steels
Authors: Campagnoli Elena , Matteis Paolo , Mortarino Giovanni M.M. , Scavino Giorgio
Published: April 2010

The low carbon steels, used for the production of car bodies by deep drawing, are gradually substituted by high strength steels for vehicle weight reduction. The drawn car body components are joined by welding and the welded points undergo a reduction of the local tensile strength.
In developing an accurate welding process model, able to optimized process parameters and to predict the final local microstructure, a significant improvement can be given by the knowledge of the welded steels thermal diffusivity at different temperatures.
The laser-flash method has been used to compare the thermal diffusivity of two traditional deep drawing steels, two high strength steels already in common usage, i.e. a Dual Phase (DP) steel and a TRansformation Induced Plasticity (TRIP) steel, and one experimental high-Mn austenitic TWIP (Twinning Induced Plasticity) steel.
The low carbon steels, at low temperatures, have a thermal diffusivity that is 4-5 times larger than the TWIP steel. Their thermal diffusivity decreases by increasing temperature while the TWIP steel shows an opposite behaviour, albeit with a lesser slope, so that above 700°C the TWIP thermal diffusivity is larger. The different behaviour of the TWIP steel in respect to the ferritic deep drawing steels arises from its non ferro-magnetic austenitic structure. The DP and TRIP steels show intermediate values, their diffusivity being lower than that of the traditional deep drawing steels; this latter fact probably arises from their higher alloy content and more complex microstructure.
Characterization of Electrolytically Deposited CdSe on Ti Substrates
Authors: Argyropoulos T.G. , Novakovic Jelica , Athanassopoulou M.D. , Vassiliou P. , Mergos J.A. , Dervos C.T.
Published: April 2010

Electrolytical deposition of CdSe on Ti substrates from CdSO4 - SeO2 solutions is investigated. The effect of the bath temperature was investigated and how it affects the CdSe deposits. According to the XRD spectra, the obtained CdSe films exhibit the cubic zinc-blende structure that remains unaffected by vacuum heat treatment (650°C). The surface morphology of the films differs significantly with bath solution temperatures. When Au contacts are used, the Ti/CdSe/Au structure may exhibit rectifying properties depending on the temperature during the electrodeposition. High temperature baths make the deposits to obtain ohmic properties.
The Effect of Al2O3 and Li2O on the Anatase to Rutile Phase Transformation
Authors: Athanassopoulou M.D. , Argyropoulos T.G. , Paparoupas G.T. , Mergos J.A. , Dervos C.T.
Published: April 2010

The utilization of Al2O3 and Li2O as dopants that promote the anatase-to-rutile (A-R) phase transition in TiO2 nanoparticles during calcinations is studied. X-Ray Diffraction and SEM techniques were employed for the evaluation of phase transformation and particle size coarsening in pure TiO2, TiO2-Al2O3 and TiO2-Li2O mixtures. For the Li-Ti-O pseudobinary systems some complex oxides may be formed during phase transformation that occurs at significantly lower temperatures compared to pure TiO2 or TiO2-Al2O3 mixtures. Al2O3 doping in TiO2 only increases the anatase-to-rutile transition rate once the phase transformation has been initiated.
Pulse Electrolysis for the Production of Hard Ni/TiO2-ZrO2 Composite Coatings
Authors: Kollia C. , Deligkiozi I. , Dardavila M.M.
Published: April 2010

The electrolytic codeposition has drawn interest as an alternative method for the preparation of metal matrix composite electrocoatings with improved properties. Moreover, the application of a current periodically varied by time during electrodeposition, i.e. pulse current (p.c.), instead of the commonly used direct current (d.c.), has been proved to lead to the preparation of surfaces with well-defined properties. In this work, Ni/TiO2-ZrO2 composite electrocoatings were produced under direct and pulse current conditions. The synergetic action of both the pulse application and the simultaneous codeposition of the two different types of particles on the structure, the morphological characteristics and the microhardness of the composite electrocoatings, were studied. Concerning their mechanical behaviour, it was found that the Ni/TiO2-ZrO2 deposits prepared by pulse electrolysis are characterized by Vickers microhardness threefold harder than the d.c. ones.
Effect of Processing Parameters on the Structural and Mechanical Properties of Micro Arc Oxidized Aluminium Alloy
Authors: Ozkara Isa Metin , Baydogan Murat
Published: April 2010

The micro arc oxidation process (MAO) was applied to a 2024 ingot aluminium alloy by an AC MAO equipment using an alkali based electrolyte. The processing parameters of the process were positive and negative voltage pulse durations. Structural and morphological characterization of the coating were made by a scanning electron microscope (SEM), an X-ray diffractometer (XRD), a surface profilometer and a thickness gage operating according to the Eddy current principle. Cross sectional hardness of the coatings was measured, and reciprocating wear and immersion corrosion tests were performed. XRD analysis showed that an oxide layer comprising - and -Al2O3 phases was produced on the surface, whose thickness and surface roughness varied by the processing parameters applied. Wear and corrosion resistance of the original alloy significantly improved upon the MAO process. Variation of hardness, wear and corrosion resistance with respect to the processing parameters was discussed based on the experimental data obtained.
Conjugate Heat and Mass Transfer in Metal Foams: A Numerical Study for Heat Exchangers Design
Authors: Hugo Jean Michel , Brun Emmanuel , Topin Frédéric , Vicente Jérôme
Published: April 2010

This numerical study focuses on the determination of macroscopic (effective) properties from pore scale calculation. These results will be applied to heat exchangers design. The computational domain -representative of heat exchanger section- is a parallelepiped filled with metallic foam, heated on one face and crossed by a forced fluid flow. Conjugate heat transfer and fluid flow are computed using finite volume approach on the actual solid matrix and pore space topology obtained from X-ray tomograms. Calculated heat transfer coefficient and flow law parameters are in good agreement with literature data. An active foam length is defined and measured in order to provide optimal design characteristic for foamed heat exchanger.
Numerical Simulation Study for the Effect of the Strength and the Direction of a Static Magnetic Field on the Transient Double-Diffusive Flow in Liquid Phase during an Alloy Solidification
Authors: Mechighel Farid , Pateyron Bernard , Kadja Mahfoud , El Ganaoui Mohammed , Dost S.
Published: April 2010

A numerical simulation study has been carried out to examine the effect of a static magnetic field on the solidification process of an alloy. A mathematical model, based on the continuum model, was developed for the computation of a transient double-diffusive fluid flow under Lorentz body force. The model includes conservation of mass and momentum, heat, species and electrical charge balance equations. The simulation domain was selected as a cavity filled with a metallic alloy and differentially heated, which may be taken as a Bridgman model domain used in the crystal growth process. The solution is carried out by using a Finite Volume Method. Study of the direction and the intensity of the applied magnetic field effects on stabilizing the double diffusive flow field were also carried out. Simulation results indicate that the use of a static, magnetic field in this growth setup is effective in suppressing natural convection in the solution.
Molecular Dynamics Simulation of the Buckling Behavior of Boron Nitride Nanotubes under Uniaxial Compressive Loading
Authors: Ebrahimi-Nejad S. , Shokuhfar Ali , Zare-Shahabadi A.
Published: April 2010

Boron Nitride nanotubes (BNNTs) together with carbon nanotubes (CNTs) have attracted the wide attention of the scientific community and have been considered as promising materials due to their unique structural and physical properties. In this paper, the behavior of BNNTs of different diameters under compressive loading has been studied through molecular dynamic (MD) simulations. We have used a Lennard-Jones pair potential to characterize the interactions between non-bonded atoms and harmonic potentials for bond stretching and bond angle vibrations. Results of the MD simulations determine the critical buckling loads of the BNNTs of various diameters under uniaxial compression, and indicate that for the simulated BNNTs of length L = 6 nm, the critical buckling loads increase by increasing the nanotube diameters.
Heat Transfer of Mineral-Filled Polypropylene Foams
Authors: Antunes Marcelo , Realinho Vera , Martínez Antonio B. , Solórzano E. , Rodríguez-Pérez Miguel A. , Velasco Jose Ignacio
Published: April 2010

The thermal conductivity of unfilled polypropylene foams produced using different foaming processes has previously been demonstrated to be mainly affected by the foam’s bulk density [1]. The influence of adding inorganic particles is now studied, with the thermal conductivity of the mineral-filled PP foams being determined using the Transient Plane Source Method (TPS). To this end, two different fillers were used. The incorporation of high amounts (50 and 70 wt.%) of magnesium hydroxide resulted in considerably higher thermally conductive foamed materials, with interesting thermal anisotropies being observed for the higher expansion ratio foams. On the contrary, adding montmorillonite (MMT) nanoparticles did not considerably alter the thermal conductivity of the foams, their value being mainly affected by the relative density.
Virus-Specific Cytotoxic CD4+ T Cells for the Treatment of EBV-Related Tumors
Authors: Merlo Anna , Turrini Riccardo , Bobisse Sara , Zamarchi Rita , Alaggio Rita , Dolcetti Riccardo , Mautner Josef , Zanovello Paola , Amadori Alberto , Rosato Antonio
Published: April 2010

Although adoptive immunotherapy with CD8+ CTL is providing clinically relevant results against EBV-driven malignancies, the effector role of CD4+ T cells has been poorly investigated. We addressed this issue in a lymphoblastoid cell line-induced mouse model of posttransplant lymphoproliferative disease (PTLD) by comparing the therapeutic efficacy of EBV-specific CD4+ and CD8+ T cell lines upon adoptive transfer. CD4+ T cells disclosed a long-lasting and stronger proliferative potential than CD8+ T cells, had a similar activation and differentiation marker profile, efficiently killed their targets in a MHC class II-restricted manner, and displayed a lytic machinery comparable to that of cognate CD8+ T cells. A detailed analysis of Ag specificity revealed that CD4+ T cells potentially target EBV early lytic cycle proteins. Nonetheless, when assessed for the relative therapeutic impact after in vivo transfer, CD4+ T cells showed a reduced activity compared with the CD8+ CTL counterpart. This feature was apparently due to a strong and selective downmodulation of MHC class II expression on the tumor cells surface, a phenomenon that could be reverted by the demethylating agent 5-aza-2′-deoxycytidine, thus leading to restoration of lymphoblastoid cell line recognition and killing by CD4+ T cells, as well as to a more pronounced therapeutic activity. Conversely, immunohistochemical analysis disclosed that HLA-II expression is fully retained in human PTLD samples. Our data indicate that EBV-specific cytotoxic CD4+ T cells are therapeutic in mice bearing PTLD-like tumors, even in the absence of CD8+ T cells. These findings pave the way to use cultures of pure CD4+ T cells in immunotherapeutic approaches for EBV-related malignancies.
T Cell Pathways Involving CTLA4 Contribute To a Model of Acute Lung Injury
Authors: Nakajima Takeshi , Suarez Carlos Jose , Lin Ko-Wei , Jen Kai Yu , Schnitzer Jan E. , Makani Samir S. , Parker Nathan , Perkins David L. , Finn Patricia W.
Published: April 2010

Acute lung injury (ALI) is a frequent pulmonary complication in critically ill patients. We characterized a murine model of LPS-induced ALI, focusing on Th cells. Following LPS administration, bronchoalveolar lavage lymphocytes, neutrophils, IL-6, TNF-α, and albumin were increased. Analysis of LPS-induced T cells revealed increased Th cell-associated cytokines (IL-17A, -17F, and -22), as well as increased expression of CD69 (a cell activation marker), Foxp3, and CTLA4 in CD4+ T cells. Administration of anti-CTLA4 Ab decreased LPS-induced bronchoalveolar lavage albumin and IL-17A, while increasing CD4+Foxp3+ cell number and Foxp3 expression in CD4+Foxp3+ cells. These data suggest that pulmonary LPS administration promotes CD4+ T cells and that T cell pathways involving CTLA4 contribute to ALI.
Suppression of TLR2-Induced IL-12, Reactive Oxygen Species, and Inducible Nitric Oxide Synthase Expression byMycobacterium tuberculosisAntigens Expressed inside Macrophages during the Course of Infection
Authors: Gupta Deepti , Sharma Sachin , Singhal Jhalak , Satsangi Akash T. , Antony Cecil , Natarajan Krishnamurthy
Published: April 2010

We report the enrichment of and immune responses mediated by genes expressed by Mycobacterium tuberculosis inside macrophages as a function of time. Results indicate that M. tuberculosis expresses different genes at different times postinfection. Genes expressed early (day 1) following infection enhance M. tuberculosis-mediated activation of dendritic cells (DCs), whereas genes expressed later (day 5) in the infection prevent DC activation. However, all genes downmodulated MHC class I and II expression on infected macrophages, thus compromising their ability to interact with Ag-specific T cells. Day-1 and -5 genes downmodulated proinflammatory cytokine production from DCs, thus impairing signal 3 during DC–T cell cognate interactions. Consequently, T cells activated by Ag-experienced DCs secreted low levels of IFN-γ and IL-17 but maintained high IL-10 secretion, thus inducing suppressor responses. Further characterization revealed that day-1 and -5 genes increased TLR2-induced expression of suppressors of cytokine signaling 1 from DCs and downmodulated IL-12 expression. In addition, day-1 and -5 genes prevented the generation of reactive oxygen species in DCs. In contrast, although day-5 genes increased TLR2-mediated suppressors of cytokine signaling 1 expression in macrophages, day-1 genes downmodulated the expression of inducible NO synthase 2. Similar downregulation of immune responses was observed upon exogenous stimulation with day-1 or -5 Ags. Finally, day-1 and -5 genes promoted enhanced survival of M. tuberculosis inside DCs and macrophages. These results indicate that M. tuberculosis genes, expressed inside infected macrophages as a function of time, collectively suppress protective immune responses by using multiple and complementary mechanisms.
Herc5 Attenuates Influenza A Virus by Catalyzing ISGylation of Viral NS1 Protein
Authors: Tang YuJie , Zhong Gongxun , Zhu Lianhui , Liu Xing , Shan Yufei , Feng Huapeng , Bu ZhiGao , Chen Hualan , Wang Chen
Published: April 2010

Ubiquitin-like protein ISG15, which is robustly induced by IFN or virus, is implicated to inhibit influenza A virus (IAV) in vivo. But the underlying mechanism still remains largely unknown. In this study, we report that Herc5 could catalyze conjugation of ISG15 onto IAV-NS1 protein, the critical virulence factor of IAV. This modification produces two more species, respectively mapped to IAV-NS1 at lysine 20, 41, 217, 219, and 108, 110, and 126. The ISGylated IAV-NS1 fails to form homodimers and inhibits relevant antiviral processes. Knockdown of Herc5 or ISG15 could partially alleviate IFN-β–induced antiviral activities against IAV, whereas ectopic expression of the Herc5-mediated ISGylation system could distinctly potentiate IFN-β–induced antiviral effects against IAV. Notably, IAV-NS1s of H5N1 avian IAVs display less ISGylation species than that of IAV-PR8/34 (human H1N1). Consistently, IAV-PR8/34 mutants deprived of IAV-NS1’s ISGylation exhibit augmented viral propagation and virulence in both cultured cells and mice. Our study reports the first microbial target of ISGylation and uncovers the direct antiviral function and mechanism of this novel modification.
Mural Nodules of Clear Cell Carcinoma in a Mucinous Borderline Tumor of the Ovary: A Case Report
Authors: Allende Daniela S. , Drake Richard D. , Chen Longwen
Published: April 2010

Mural nodules of ovarian mucinous borderline tumors are rare. In this study, we report a case of mural nodules of clear cell carcinoma in an intestinal type mucinous borderline tumor of the ovary. The patient was a 54-years-old woman presented with back and pelvic pain for 3 months. A right-sided multiloculated ovarian mass approximately 20 cm was identified on the CT scan. CA-125 was moderately elevated. She underwent total abdominal hysterectomy with bilateral salpingo-oophorectomy and bilateral pelvic and para-aortic lymphadenectomy. Grossly, the right ovarian mass showed a multiloculated cystic mass with mucinous fluid. There were papillations in the internal surface and two mural nodules were seen. Microscopic examination revealed that the cystic mass was an intestinal type borderline mucinous tumor. The mural nodules showed a classic histology of clear cell carcinoma with tubulocystic and papillary growth patterns. This is an extremely rare case of mural nodules of clear cell carcinoma arising in a mucinous borderline tumor.
Environmental control of open‐ocean phytoplankton groups: Now and in the future
Authors: Boyd Philip W. , Strzepek Robert , Fu Feixue , Hutchins David A.
Published: April 2010

Climate change will alter concurrently many environmental factors that exert control over oceanic phytoplankton. Recent laboratory culture work, shipboard experiments, and field surveys reveal many remaining unknowns about the bottom‐up controls for five globally important algal groups. Increasing uncertainties exist, respectively, for picocyanobacteria, diatoms, Phaeocystis spp., N2‐fixing cyanobacteria, and coccolithophores. This missing information about current environmental controls will hinder progress in modeling how these phytoplankton will be influenced by climate change. A review of conceptual approaches used to elucidate the relationship between environmental controls and phytoplankton dominance, from Margalef's mandala to functional traits, uncovered limitations regarding their application to climate‐change scenarios. For example, these previous approaches have insufficient scope or dimensions to take into account the confounding effects of synergistic and antagonistic interactions of multiple environmental change variables. A new approach is needed that considers all of the different environmental properties altered by climate change and their interactions while at the same time permitting a subset of the most significant controls for a specific phytoplankton group to be isolated and evaluated in factorial matrix perturbation experiments. We advocate three new interlinked approaches, including environmental clusters that incorporate all factors (temperature, CO2, light, nutrients, and trace metals), which both exert control over present‐day floristics and will be altered by climate change. By carefully linking a holistic conceptual approach to a reductionist experimental design, the future responses of open‐ocean phytoplankton groups to a complex, rapidly changing environment can be better predicted.
The Case Study: Bringing Real‐World Experience Into the Teacher Preparation Program
Authors: JURCHAN JOANN , MORANO TODD A.
Published: April 2010

This article documents our efforts to design and implement a transformational opportunity for teacher credential candidates prior to their student teaching. Through the Case Study Project, candidates participated in an intensive one‐on‐one teaching and learning experience with a K‐12 English language learner (ELL) in classroom settings. In addition to the tutoring experience, the project required candidates to gather and analyze student language proficiency data for instructional design, report school and district ELL policies and support services, and collect information on state and federal regulations regarding ELL instruction and programs. As a result, candidates reported that they were better prepared to meet the educational and emotional needs of ELLs. Some of the categories in which candidates reported significant professional growth were developing a greater understanding of self as teacher, developing a greater awareness of the learner and the learning process, and realizing the importance of maintaining the integrity of the content—not reducing the level of complexity.
Message Boards: A Springboard to Literacy for Prekindergarten English Language Learners (and Others, Too)
Authors: MARTINEZ GILDA , LASTER BARBARA P. , CONTE BETTY
Published: April 2010

Message boards provide an opportunity for students, teachers, and parents to write (or draw) about a story from their lives on a large or small chalkboard. Oral language is then used to describe the written message during a structured circle time. (It is a variation of the traditional show‐and‐tell except that the focus is on the communication of stories through conversations and writing rather than explanations about possessions.) A teacher in a prekindergarten classroom in Florida, in the United States, has been using message boards over the past 10 years. In collaboration with this teacher, researchers decided to examine the effectiveness of message boards on the literacy progress of the English language learners (as well as the few native‐English‐speaking students) in her classroom. Through this qualitative study, this teacher and her students were observed and interviewed, and documentation of the message boards was collected and carefully examined to determine what student achievement, if any, was evident. The results indicate that language and literacy growth was noted through the use of message boards.
Granular activated carbon adsorption process for removing trichloroethylene from groundwater
Authors: Huang Liuya , Yang Zhidong , Li Bingjing , Hu Juan , Zhang Wei , Ying Wei‐Chi
Published: April 2010

Batch adsorption capacity experiments and continuous flow breakthrough experiments were conducted to compare the effectiveness of seven granular activated carbons (GACs) in removing trichloroethylene (TCE) from groundwater. The order of GACs' adsorptive capacities for TCE was the same as their phenol numbers (indicator for <1 nm micropores). A small amount of methanol (0.05% v/v) did not affect the pure water TCE capacities, which were notably reduced by the small organic constituents of tap water. The breakthrough results show low utilization of the available adsorptive capacity due to both slow mass transport and the need to achieve a high degree of TCE removal, and that the serial bed mode of treatment is cost effective because a very high capacity utilization can be attained. The low‐cost, environmental friendly bamboo GAC is attractive as its competitive TCE capacity was readily used in actual treatment because of its favorable pore structure. © 2010 American Institute of Chemical Engineers AIChE J, 2011
Vaporization enthalpy and cluster species in gas phase of 1,1,3,3‐tetramethylguanidinium‐based ionic liquids from computer simulations
Authors: Yu Guangren , Chen Xiaochun , Asumana Charles , Zhang Suojiang , Liu Xiaomin , Zhou Guohui
Published: April 2010

In this work, the study on the volatility of ionic liquids is focused on the 1,1,3,3‐tetramethylguanidinium‐based ionic liquids. Vaporization enthalpy and cluster species in gas phase for 1,1,3,3‐tetramethylguanidinium lactate ([tmgH][L]), 1,1,3,3‐tetramethylguanidinium trifluoroacetate ([tmgH][T]), and 1,1,3,3‐tetramethylguanidinium formate ([tmgH][F]), are investigated by using molecular dynamic simulation and ab initio calculation, respectively. Results from the molecular dynamic simulations show that the interionic interactions of coulombic electrostatic and Van der Waals forces are the main factors for deciding the volatility. In addition, owing to the change of molecular conformations from the liquid phase to the gas phase, intraionic bond, angle, and torsion interactions also give remarkable contributions. From the ab initio calculations, in the gas phase, an interionic proton transfer easily occurs in the ion pairs of these guanidinium‐based ionic liquids, and the ion pairs are finally transformed into more thermodynamically stable neutral molecule dimers (this is different from some imidazolium‐based ILs where ion pair can stably exist in gas phase). The transfer energy barriers are very low (typically, less than 2 kJ mol−1). However, the existence of a third charged ion ([tmgH]+, [L]−, [T]−, or [F]−) or neutral molecule (tmg, HL, HT, or HF), will stabilize the ion pairs and prevent the transfer of proton. Finally, the stable trimers are then formed. The tetramers are also stable species. Ab initio results explain why they exist as ions in the liquid state. © 2010 American Institute of Chemical Engineers AIChE J, 2011
Genotype–phenotype correlation in eight new patients with a deletion encompassing 2q31.1
Authors: Mitter Diana , Chiaie Barbara Delle , Lüdecke Hermann‐Josef , Gillessen‐Kaesbach Gabriele , Bohring Axel , Kohlhase Jürgen , Caliebe Almuth , Siebert Reiner , Roepke Albrecht , Ramos‐Arroyo Maria A. , Nieva Beatriz , Menten Björn , Loeys Bart , Mortier Geert , Wieczorek Dagmar
Published: April 2010

Microdeletions of the 2q31.1 region are rare. We present the clinical and molecular findings of eight previously unreported patients with overlapping deletions in 2q31.1. The patients have a variable clinical phenotype and present with developmental delay (7/8), growth retardation (5/8), seizures (2/8) and a craniofacial dysmorphism consisting of microcephaly (4/8), short palpebral fissures (7/8), broad eyebrows with lateral flare (7/8), low‐set ears with thickened helices and lobules (5/8), and micrognathia (6/8). Additional congenital anomalies were noted, including limb abnormalities (8/8), heart defects (3/8), genital anomalies (3/8), and craniosynostosis (1/8). Six of these microdeletions, ranging in size from 1.24 to 8.35 Mb, were identified by array CGH, one larger deletion (19.7 Mb) was detected by conventional karyotyping and further characterized by array CGH analysis. The smallest region of overlap in all eight patients spans at most 88 kb and includes only the WIPF1 gene. This gene codes for the WAS/WASL interacting protein family member 1. The patients described here do not present with clinical signs of the Wiskott–Aldrich syndrome and the deletion of this single gene does not allow explaining the phenotype in our patients. It is likely that the deletion of different but overlapping sets of genes from 2q31 is responsible for the clinical variability in these patients. To further dissect the complex phenotype associated with deletions in 2q31, additional patients with overlapping phenotypes should be examined with array CGH. This should help to link particular phenotypes to specific genes, and add to our understanding of the underlying developmental processes. © 2010 Wiley‐Liss, Inc.
Wolf–Hirschhorn syndrome with improvement of renal function
Authors: Ferrara P. , Del Bufalo F. , Nicoletti A. , Romano V. , Gatto A. , Leoni C. , Zampino G.
Published: April 2010

Wolf–Hirschhorn syndrome (WHS) is a chromosomal disorder characterized by partial deletion of the short arm of chromosome 4. We describe a girl with a de novo unbalanced traslocation t(4;7)(p16.2;p22), associated with a mild version of a classical WHS phenotype. She did not present major urinary tract abnormalities but had parenchymal hyperechogenicity at renal ultrasound at the birth with normal renal scintigraphy. She had also a reduction of GFR with elevated levels of blood urea nitrogen and serum potassium until the age of 6 months. We followed the patient with periodic clinical examination and laboratory and radiological investigations and observed at the age of 5 years a normal renal ultrasound without parenchymal hyperechogenicity. © 2010 Wiley‐Liss, Inc.