bluuebunny/crossref_metadata_2025 huggingface dataset:
Multilayered Fiber-Reinforced Oxide Composites Produced by Lamination of Thermoplastic Prepregs
Authors: Guglielmi Paula O. , Blaese Diego , Hablitzel Murilo , Nunes Gabriel , Lauth Victor R. , Garcia Daniel , Al-Qureshi Hazim A. , Hotza Dachamir , Janssen Rolf
Published: October 2014

For advanced ceramic composites, affordable manufacturing is still the most essential shortcoming with respect to successful commercial use. This holds particularly for components made out of composites with complex hierarchical structures and high demands of mechanical performance and reliability at the same time, e.g. fiber-reinforced ceramic matrix composites (FRCMCs). Therefore, a new processing route is presented here, which is based on the lamination of thermoplastic prepregs. This route allows not only affordable manufacturing, but also advanced mechanical reliability. Powder metallurgy techniques are combined here with concepts from the prepreg technology in a route consisting of the following steps (a) manufacturing of 2 D prepregs using commercial fiber fabrics which are infiltrated with compounds of ceramic particles embedded in an organic matrix, (b) followed by respective stacking and joining, (c) burn out of the organic matrix and (d) sintering to consolidate the matrix. Composites consisting of a porous Al2O3/ZrO2 matrix, reinforced by 8 layers of NextelTM 610 fiber fabric exhibit a bending strength of ~440 MPa, with graceful failure behavior, e.g. a stepwise stress reduction after peak nominal stress. The fracture of these composites is controlled by a series of interfacial delamination events, which enhance energy dissipation during failure.
Effect of Different Form of Carbon Addition on the Wear Behaviour of Copper Based Composites
Authors: Chmielewski Marcin , Pietrzak Katarzyna , Dutkiewicz Jan , Piekoszewski Witold , Michalczewski Remigiusz
Published: October 2014

Copper-carbon composites are very promising functional materials used as electrical contact devices due to their high electrical conductivity, thermal conductivity and excellent wear resistance. In the present study the influence of carbon forms (including carbon nanotubes, graphite nanopowder and graphene) on the properties of copper matrix composites was examined. The composites were fabricated using the powder metallurgy method. The optimal parameters of the hot-pressing process in vacuum were fixed as follows: the temperature of 525°C, the pressure of 600 MPa and the time of 10 min. The wear tests were performed in dry conditions using an SRV (Schwingungs Reibung und Verschleiss) friction and wear tester in a reciprocating motion. The friction and wear behaviour of copper with 3 vol.% of carbon were investigated. Scanning electron microscopy (SEM) was used to analyse the worn surfaces and debris, and finally the wear mechanism was discussed.
Corrosion of Polymer-Derived Ceramics in Hydrofluoric Acid and Sodium Salts
Authors: Jothi Sudagar , Ravindran Sujith , Kumar Ravi
Published: October 2014

Corrosion behavior of polymer-derived ceramics (PDCs) was investigated in aqueous hydrofluoric acid (HF) and sodium salts (NaCl or Na2SO4). Two oxides (SiCO and SiCNO-(Hf)) and two non-oxide PDCs (SiCN and SiCN-(B)) were examined in this study. The HF acid corroded the oxide PDCs, whereas non-oxide PDCs resisted acid corrosion. Nevertheless, the degradation is slow in some cases to extend the engineering ceramic materials lifespans. The PDCs composites were hot corroded by NaCl or Na2SO4. The Na-salt attacked the PDCs, producing corrosion layers. The cross-sectional X-ray elemental analysis and microstructure surveillance exhibited that the corroded layers comprised of distinct regions. The corrosion mechanism is discussed in line with the experimental discoveries.
Glass-Based Photonic Crystals: From Fabrication to Applications
Authors: Chiappini Andrea , Chiasera A. , Armellini Cristina , Carpentiero Alessandro , Lukowiak Anna , Mazzola Maurizio , Normani Simone , Ristic Davor , Valligatla Sreeramulu , Vasilchenko Iustyna , Varas Stefano , Righini G.C. , Ferrari Maurizio
Published: October 2014

We report on the fabrication and on the assessment of the properties of two glass-based photonic crystals (PhCs) obtained using alternative approaches such as rf-sputtering and sol-gel techniques. (i) By means of rf-sputtering a one-dimensional dielectric photonic crystal constituted by an Er3+-doped SiO2 active layer inserted between two Bragg reflectors consisting of 10 pairs of SiO2∕TiO2 layers has been realized. Near infrared transmittance spectra evidenced the presence of a stop band from 1500 to 2000 nm with a cavity resonance centered at 1749 nm. Intensity enhancement and narrowing of the emission band of Er3+ ions, due to the cavity effect have been observed and a cavity quality factor of 890 has been achieved. (ii) Through chemical route a 3D colloidal crystal based on polystyrene (PS) nanoparticles (NPs) embedded in elastomeric matrix has been realized. In the specific has been shown that the structure can produce a variation of its color applying different organic solvents that can be also easily observed by the naked eye. Optical measurements have evidenced a red shift of the diffraction peak as a function of the solvents applied. This feature has been exploited in order to create a sensitive material showing high sensitivity and reversibility of the signal change.
Luminescence Intensity Enhancement of Copper Doped Hydronium Alunite Synthesized under Hydrothermal Conditions Using Sulfates Solution
Authors: Kuroki Yuichiro , Hatsuse Takashi , Okamoto Tomoichiro , Takata Masasuke
Published: October 2014

A novel phosphor, copper doped hydronium alunite ((H3O)Al3(SO4)2(OH)6:Cu), exhibiting a blue photoluminescence peak at a wavelength of 420 nm was successfully synthesized from aluminum and copper sulfates solution under hydrothermal condition (240 °C, 60 min). The measurement of XRD revealed that the obtained products were single phase with a crystal structure of (H3O)Al3(SO4)2(OH)6. Luminescence intensity of (H3O)Al3(SO4)2(OH)6:Cu synthesized from sulfates solution was 6.2 times higher than that from an aluminum nitrate solution mixed with an elemental sulfur and a copper nitrate solution. The increase of luminescence intensity was resulted from an improvement of the crystallinity of (H3O)Al3(SO4)2(OH)6.
Characterization of Aerogels – Challenges and Prospects
Authors: Reichenauer Gudrun
Published: October 2014

Aerogels are porous materials with potential applications in fields ranging from thermal insulation, catalyst support, filters, electrical storage, components in optical devices, mechanical damping all the way to drug release. However, careful reliable characterization is the base for both, understanding of fundamental structure - property relationships as well as a directed development of materials and composites for specific applications. The review therefore addressed severe problem upon aerogel characterization that have been identified in the past and presents reliable non-destructive alternatives and novel methods that can be applied for the characterization of aerogels as well as their gel precursors.
Porous Clay Ceramic for Environmental Technologies
Authors: Švinka Ruta , Svinka Visvaldis , Dabare Liga , Lescinskis Oskars
Published: October 2014

In the present work porous clay ceramic pellets (porosity ≤ 30 %) are investigated for the wastewater purification technologies. Calcareous and non-calcareous illite containing clays with different content of fine clay fraction (particle size ≤ 0.005 mm) are used. Sawdust in amount of 3 wt% for the increasing of porosity and surface area is used. Non-calcareous clays are also used for the production of ceramic materials with porosity ≥ 50 %. Pores are formed in result of chemical reaction in clay suspension of aluminium paste with water. After sintering of dry samples the sorption ability of covalent (iodine) and ionic (ammonia) compounds are determined. Sorption ability depends on many factors such as chemical composition of clay, sintering temperature, pore size distribution in the ceramic materials, surface area, pH of water after immersion of pellets and adsorbable substances.
Solar Reflectance of Glazed Tiles
Authors: Sugiyama Toyohiko , Kakiuchida Hiroshi , Kusumoto Keiji , Ohashi Masayoshi
Published: October 2014

Exterior wall tiles with high solar reflectance are effective in mitigating heat-island phenomenon. Such walls have also the potential to decrease the warming up of building interiors in mid-summer. For the purpose of increasing the solar reflectance of wall tiles, several kinds of glazes were prepared to measure their visible and infra-red spectral reflectance by the spectrophotometer. The incident angle of sunlight on vertical exterior wall is larger than 70 degrees at midday of the summer season in Japan. The reflectance theoretically increases with the increase of incident angle. It is important to examine the reflectance against the sunlight with varied incident angles. The practical solar reflectance of glazed tiles is calculated by measuring the hemi-spherical integrated spectral reflectance with an oblique incident light. The glazed tiles having layered structure were also prepared and their spectral reflectance was investigated.
Preparation of Exfoliated Melamine Modified Mica/Polyamide-6 Nanocomposite and its Properties
Authors: Oyama Shoichi , Tamura Kenji , Kitazawa Takafumi , Minagawa Kazumi , Yamagishi Akihiko
Published: October 2014

The Expandable Mica was Modified with a Melamine Hydrochloride Salt at 60°C for Three Hours. the Resulting Melamine-Modified Mica (MME) was Melt-Kneaded with Polyamide 6 (PA6) Using a Twin-Screw Kneader at 250°C. the Addition of MME to the PA6 Matrix Resulted in a Finer Dispersion, as Evidenced by the Disappearance of the (001) Reflections in the XRD Patterns and TEM Image. the Tensile Modulus of MME/PA Nanocomposite (including 4.1 Mass % Mica) Increased by Approximately 1.8 Times Compared with that of the Neat PA6, which can be Attributed to the Increasing of the Exfoliated Silicate Platelets and the Dominating of the γ Crystalline Form in the Nanocomposites.
Mechanical Performances and Corrosion Resistance of Reinforced Fly Ash Geopolymer Mortars
Authors: Natali Maria Elia , Manzi Stefania , Carabba Lorenza , Chiavari Cristina , Bignozzi Maria Chiara , Abbottoni Marco , Balbo Andrea , Monticelli Cecilia
Published: October 2014

The growing focus on issues related to the control of CO2 emissions, energy conservation and waste recycling pushes the construction industry to tackle the challenge of sustainable development. The production of ordinary Portland cement (OPC), main product of the sector, is one of the most polluting in terms of CO2 emissions, thus finding alternative binder is becoming an urgent matter. Geopolymers are largely investigated for this purpose, but studies concerning the durability of reinforced conglomerates prepared with alkali activated binders are only few. The present work aims at investigating the durability performances of steel reinforced geopolymer mortar samples based on carbon fly ash in comparison with OPC mortar. The effect of different Na2O/SiO2 molar ratios in the geopolymer mixes is evaluated in terms of mechanical and microstructural properties as well as corrosion resistance in a chloride rich environment. The obtained results show that under the same severe environmental conditions more limited chloride amounts penetrate in reinforced fly-ash geopolymers where a better corrosion behaviour is also detected up to a week of exposure for samples with a nominal Na2O/SiO2 molar ratio equal to 0.12 and 0.14. Instead, the corrosion resistance is quite similar to that of reinforced OPC mortar when a period of three months is considered.
Development of a Subscale Hydrogen Generator Unit for SOFC as APU for Naval Applications
Authors: Recupero Vincenzo , Pino Lidia , Vita Antonio , Italiano Cristina , Fabiano Concetto , Laganà Massimo
Published: October 2014

This paper covers the current activities at the CNR-ITAE aimed to developing a diesel steam reforming (SR) Hydrogen Generator based unit, dedicated to a Solid Oxide Fuel Cell (SOFC) in a power range until 1 kWe, to support auxiliary power units (APUs) for naval applications. The unit will is able to convert n-dodecane, as a diesel surrogate, with a nominal syngas production of 0.5 Nm3/h and a maximum hydrogen production of 1.5 Nm3/h.
Hydrogen Technologies and Applications: Safety
Authors: Ruiz Patricia , Jiménez Cristina , Llorca Marta , Vega Lourdes F.
Published: October 2014

The H2TRUST is a Coordination and Support Action by a team of European FCH industry leaders to foster a smooth and well managed transition to a full scale commercialization of FCH applications in Europe and, to aid the process by which all industry stakeholders are informed, prepared and confident from a safety perspective. Safety is considered in all hydrogen applications: production, storage, distribution, mobility, vehicles, non-vehicles and residential power generation.Here we will present the data collection from a set of hydrogen stakeholders, recognized experts in this field, consumers and incident response bodies associated with the fuel cells and hydrogen industries. These results will be disseminated by creating an online website with all the information collected. Best practices and methodology are going to be prepared in order to improve the hydrogen safety knowledge of the society.
Copper Doped Lanthanum Strontium Ferrite as Cathode for La0.8Sr0.2Ga0.8Mg0.2O3
Authors: Zurlo Francesca , di Bartolomeo Elisabetta , d’Epifanio A. , Felice Valeria , Natali Sora Isabella , Licoccia S.
Published: October 2014

A “cobalt free” cathode material with stoichiometric composition La0.8Sr0.2Fe0.8Cu0.2O3 (LSFCu) was specifically developed for La0.8Sr0.2Ga0.8Mg0.2O3 (LSGM) electrolyte. The chemical stability with LSGM electrolyte was investigated by structural and morphological analysis. The electrochemical properties of LSFCu dense pellets were investigated in the temperature range 600–750°C by electrochemical impedance spectroscopy (EIS). LSFCu/LSGM/LSFCu symmetrical cells were prepared and Area Specific Resistance (ASR) values, directly depending on the rate limiting step of the oxygen reduction reaction, were evaluated. Fuel cells were prepared using LSFCu as cathode material on LSGM pellet and electrochemical tests were performed and compared to similar fuel cells prepared by using commercial La0.6Sr0.4Fe0.8Co0.2O3(LSFCo). The maximum current density and power density recorded for LSFCu and LSFCo were comparable demonstrating that Cu can be used as substitutes Co.
A Millimeter Scale Reactor Integrated PEM Fuel Cell Energy System with an On-Board Hydrogen Production, Storage and Regulation Unit for Autonomous Small Scale Applications
Authors: Balakrishnan Arvind , Mueller Claas , Reinecke H.
Published: October 2014

We present a millimeter scale reactor integrated PEM fuel cell energy source with an onboard hydrogen production reactor (realized by alkaline chemical hydride), and passive hydrogen buffering unit (realized by metal hydride) of hydrogen. A stacked system of reactor-hydrogen buffer-PEM fuel cell is demonstrated. The system is driven by the hydrolysis of the alkaline chemical hydride (NaOH+NaBH4) in the presence of micro porous catalyst layer (platinum catalyst (Ni-Pt)). The produced hydrogen gas from the reactor is buffered through the hydrogen buffer (Palladium metal hydride) and gets distributed (due to the pressure difference) onto the anode of the PEM fuel cell. The operational behaviour of the complete system is investigated with the hydrogen produced from the alkaline chemical hydride and pure hydrogen gas. Long term voltage measurements under a defined electrical load of the alkaline chemical hydride driven system was measured. The increase in time for the hydrogen production observed in the long term voltage measurement is anticipated to the degradation of the Ni-Pt catalyst. The system is “self-buffering” in nature so any change in electrical load can be handled during system operation.
Relating Electrochemistry of New Organic Materials for Batteries and Fundamental Understanding through DFT Calculations
Authors: Frayret Christine , Tomerini Daniele , Gatti Carlo , Danten Yann , Becuwe Matthieu , Dolhem Franck , Poizot Philippe
Published: October 2014

We present DFT investigations on the redox properties of quinone based precursors exhibiting growing interest from the electrochemists community due to their potential application as electrodes for new battery devices, with lower ecological footprint. A screening of various substituents is undertaken with the aim of providing guidelines to the experimentalists towards most promising candidates. A comparison of the effect of aromaticity extension is provided through the comparison of 1,4-benzo-/naphtho-/anthra-quinone and 9,10-anthraquinone backbones. Additionally, this work allowed the establishment of a ranking and quantitative assessment of substituents with respect to both increase and decrease of the redox voltage (useful for positive and negative electrodes, respectively) by considering such functionalizing groups for the monosubstitution of the 1,4-benzoquinone. Our computational work elucidates important fundamental relationships between redox voltage and local chemical bonding features, which may serve to the comprehension and design of new organic electrodes.
Influence of Magnetic Field of Super High Frequency on Hysteretic Properties of Soft Magnetic Microwires
Authors: Chizhik Alexander , Gonzalez Julian , Zhukov Arkadi , Stupakiewicz Andrzej , Maziewski Andrzej
Published: October 2014

Normal 0 21 false false false MicrosoftInternetExplorer4 The influence of super high frequency (SHF) circular magnetic field on magnetization reversal in the Co-rich glass covered microwire has been investigated. The study has been performed by magneto-optical Kerr effect (MOKE) technique. It was found that the presence of the SHF field causes the change of the re-magnetization mechanism – the rotation of the magnetization is observed instead of domain walls motion. Also the hysteresis loop has an asymmetric shape that confirms the co-existence of the stable and meta-stable helical magnetic states in the surface of microwires. /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tabla normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;}
The Effect of Compacting Pressure on Power Loss in a SMC
Authors: Ślusarek Barbara , Szczygłowski Jan , Chwastek Krzysztof , Jankowski Bartosz
Published: October 2014

The paper considers the effects of compacting pressure and the working parameters (maximum flux density, excitation frequency) on power loss dissipated in a soft magnetic composite core. The effects may be efficiently described with simple power laws . The description has been verified using commercial SMC cores. The proposed dependencies are in a good agreement with experiment.
Effect of Temperature on Phase Transition of Ni-Co Oxide and its Application on Optoelectronics
Authors: Tsai Shu Yi , Fung Kuan Zong , Wei Chao Nan , Bor Hui Yun
Published: October 2014

Ni-Co thin films were prepared on glass substrate by RF magnetron sputtering technique. Post-deposition annealing of Ni-Co film in oxygen atmosphere was found to improve film structure and electrical characteristics. The correlation between annealing conditions and the physical structure of the films was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-Vis-NIR spectrophotometer. The lowest resistivity was observed after annealing a sputter-deposited Ni-Co film at 600 °C for 5h. The transmittance showed more than 85% in the infrared range. The preferred annealing condition has been found to improve Ni-Co film characteristics for transparent conducting material applications.Keywords: Ni-Co film, annealing, phase transition
Activity and Durability of PEFCs Alloy Core-Shell Catalysts: Role of Surface Oxidation
Authors: Ramos-Sanchez Guadalupe , Godínez-Salomón Fernando , Solorza-Feria Omar , Balbuena Perla
Published: October 2014

Low temperature fuel cells are one of the most promising systems for the transformation of fuels into electricity in an efficient, silent, and environmentally friendly manner. In this paper we show the advances accomplished in the synthesis and a theoretical-experimental analysis of the changes induced by the Ni@Pt structure and the presence of the almost unavoidable NiO species. The synthesis of core-shell nanoparticles is described and then physical and electrochemical characterizations confirm the presence of core-shell nanoparticles with a high electrochemical activity towards the Oxygen Reduction Reaction. Periodic density functional theory calculations are used to analyze the shift in the oxidation potential for Pt, Ni@Pt and NiO@Pt with different number of layers in the shell. The changes in the electrochemical activity towards oxygen reduction are evaluated by allowing oxygen to adsorb on the surface of the nanoparticle and alloys. It is found that only the first and second layers of Pt are being affected by the presence of the Ni or NiO core.
Direct Methanol Fuel Cell Stack Design and Test in the Framework of DURAMET Project
Authors: Barbera Orazio , Stassi Alessandro , Sebastián David , Baglio Vincenzo , Aricò Antonino S.
Published: October 2014

Direct methanol fuel cell stacks, with different architectures have been developed. A fuel cell planar stack, operating in passive mode, has been designed for portable application. The device consists of 10 cells, with nominal power of 1.00 – 2.42 W, single cell active area of 4.85 cm2, nominal current of 1.00 A, at room pressure and temperature. Two printed circuit boards have been chosen to clamp and support the MEA and to electrically connect the active areas via conductive pathways. To investigate the stack performance, 4 different boards with different feeding holes shape have been designed. For high temperature operation purpose, a device with “stacked” configuration has been designed and manufactured. Operating parameters are: nominal power of 150W, single cell active area of 100 cm2, nominal current of 25 A, cell number of 10. Promising results have been obtained both for APU and portable applications.
Optimization of Hydrogen Production by Co-Culture of Clostridium beijerinckii and Rhodobacter sphaeroides Bacteria
Authors: Zagrodnik Roman
Published: October 2014

The biological methods of hydrogen generation have attracted a significant interest recently. In this work the hybrid system applying both dark fermentation bacteria in co-culture was tested. Objective of this work was to investigate the optimization of different parameters on co-culture of Clostridium beijerinckii DSM-791 and Rhodobacter sphaeroides O.U.001. The effect of glucose concentration (1–5 g/L), temperature and initial pH (6,5–7,5) was analyzed. Moreover the influence of organic nitrogen sources were tested for their capacity to support hydrogen production (yeast extract, peptone, glutamic acid). Fermentations were conducted in batch tests with glucose as sole substrate. Hydrogen production in mixed culture was compared with pure cultures. The process was greatly affected by pH and light/dark bacteria ratio. Liquid metabolites, namely acetic and butyric acids, from the dark fermentation step were the source of organic carbon for photosynthetic bacteria. This increased the hydrogen yield in comparison to single-step dark fermentation to over 4 mol H2/mol glucose. Obtained results showed that combination of photo and dark fermentation may increase hydrogen production and conversion efficiency of complex substrates or wastewaters.
Review of the Development of the Proposed Yucca Mountain Geologic Repository
Authors: Sanders Charlotta E.
Published: October 2014

It can be said that the nuclear community neglected the issue of final storage of nuclear waste in the first era of nuclear power production, with many nations not looking at this topic until some years into its program. This is a matter that must not be neglected now during the ‘renaissance’ of nuclear if nuclear energy is to have a part on the stage of the play in world energy supplies. In 1982, the United States (U.S.) Congress passed the Nuclear Waste Policy Act (NWPA), which outlines the screening process for selecting a national site for used nuclear fuel and high-level radioactive waste storage. This paper describes the U.S. nuclear waste policy dilemma and its impact on the selection and development of the nation's first long-term geologic repository for over 70,000 metric tons of used nuclear fuel and high-level radioactive waste. In 1987, the U.S. Congress designated Yucca Mountain, which can be described as the "most studied real estate on the planet", as the repository site to be characterized. However, due to political pressures, the fate and realization of the Yucca Mountain repository is uncertain.
Characterization of SiC Ceramic Tube Prepared by the Combined CVI and CVD Process
Authors: Park Ji Yeon , Kim Dae Jong , Kim Weon Ju
Published: October 2014

SiCf/SiC composites are one of the candidates for high temperature structural applications because of their high strength and corrosion resistance under severe conditions and stability under neutron irradiation [1~3]. A silicon carbide fuel cladding for the light water cooled reactors (LWRs) may allow a number of advances, including: the increased safety margins under transients and accident scenarios, such as loss of coolant accident; the improved resource utilization via a higher burn-up beyond the present limit of 62 GWd/MTU; and improved waste management [3~5]. Some components of SiCf/SiC composite will be applied as tubular geometry for the high-temperature core parts. The proposed design of an advanced LWR fuel cladding, referred to as Triplex, consists of three layers: an inner SiC monolith, a central SiCf/SiC composite, and an outer dense SiC evrionmental barrier coating. The inner SiC layer provides the strength and hermeticity to contain fission products. The SiCf/SiC composite layer fabricated by the CVI process provides a pseudo-ductile failure mode. The outer SiC thin coating layer protects against corrosion [5]. The chemical vapor deposition (CVD) technique is an effective approach for the fabrication of SiCf/SiC composite and coated SiC monolith [6]. To increase the homogeneity of the microstructure and the deposition rate of a SiC tube, the process parameters should be optimized and modified.
Fabrication and Chemical Durability of Ceramic Technetium-Based Pyrochlores and Perovskites as Potential Waste Forms
Authors: Hartmann Thomas , Alaniz-Ortez Izua J.
Published: October 2014

Technetium-99 is a key radioisotope from a nuclear waste perspective because of its long half-life (t1/2= 2.13x105 years) and its abundance in used nuclear fuel. As such, it is targeted in separation strategies such as UREX+, for isolation and encapsulation in solid waste forms for final disposal in a nuclear repository. We report here results regarding the incorporation of Tc-99 into ternary oxides of different structure types: pyrochlore (Nd2Tc2O7), perovskite (SrTcO3), and layered perovskite (Sr2TcO4). The objective was to determine synthesis conditions of these ceramic waste forms to immobilize Tc-99 as Tc (IV) and to harvest crystallographic, thermophysical and hydrodynamic data. The fabricated ceramic technetates exhibit good crystallinity and lattice parameters and atomic coordinates could be refined with high accuracies. Thermophysical properties of the oxides, such as the critical temperature (Tc) for superconductivity, were analyzed using AC magnetic susceptibility measurements. In our efforts to compare hydrodynamic properties of the ceramic waste forms with those to Tc-bearing borosilicate glass, we applied the standard test method ASTM C1220-10. Hereby matrix corrosion and Tc-leaching of Tc-99 containing LAWE4 type borosilicate glass and ceramic specimens were compared by static leaching experiments.
A New Matrix for Conditioning Chloride Salt Wastes from the Electrorefining of Spent Nuclear Fuel
Authors: de Angelis Giorgio , Capone Mauro , Fedeli Carlo , Marzo Giuseppe A. , Mariani Mario , Macerata Elena , Giola Marco
Published: October 2014

A novel method proposed by Korea Atomic Energy Research Institute has been applied to the treatment of chloride salt wastes coming from electrorefining of spent nuclear fuel, which allows to separate uranium from fission products. It is based on a matrix, SAP (SiO2-Al2O3-P2O5), synthesized by a conventional sol-gel process, able to stabilize the volatile salt wastes due to the formation of metalaluminosilicates, metalaluminophosphates and metalphosphates. With this method a higher disposal efficiency and a lower waste volume can be obtained. Eutectic melt LiCl-KCl (59-41 mol%) has been used to simulate the waste salt. The composite SAP has been prepared by using tetraethyl ortosilicate (TEOS), aluminum chloride (AlCl3.6H2O) and phosphoric acid (H3PO4) as sources of Si, Al, and P, respectively. All reagents were dissolved in EtOH/H2O and the mixture, tightly sealed, was placed in an electric oven at 70 C. After a gelling/ageing for 3 days, the transparent hydrogels were dried at 110 C for 3 days and then thermally treated at 600 C for 2 hours. The final product (SAP) was reacted with metal chlorides at increasing temperatures for 20 hours inside an Argon-atmosphere glove-box, after mixing them at a SAP/metal chloride mixing ratio of 2. The obtained products have been characterized by means of density measurements, scanning electron microscopy, thermal analysis, as well as by XRD, FTIR and Raman spectra. Financial support from the Nuclear Fission Safety Program of the European Union (project SACSESS, contract FP7-CP-2012-323282) is gratefully acknowledged.
Research of Diamond-Like Carbon Film Deposited by Double Pulsed Lasers
Authors: Cheng Yong , Wang Shu Yun , Lu Yi Min , Huang Guo Jun , Guo Yan Long , Liu Xu , Sun Bin
Published: October 2014

In the research of Diamond-like carbon (DLC) Film deposited by pulsed laser, method of double pulsed laser deposition was presented. Ti:Sapphire (800nm, 120fs) laser and KrF (248nm, 20ns) laser were used orderly to ablate graphite target. Through controlling parameters of two laser beams, double-layer DLC film was deposited on silicon substrate. The hardness and inner-stress of the DLC film changed gradually from substrate to atmosphere-interface. Nanoindentation measurement system and fourier transfer infrared spectrograph were used to hardness and transmittance of the film. Meanwhile, adhesive tape, 9.8N rubber, NaOH liquor and boiling water were used to compare the adhesion and environment adaptability of double layer or monolayer DLC film samples qualitatively. Results showed that DLC film deposited by double beam pulsed laser not only had high transmittance and hardness, but also kept well and had no phenomenon of peeling off after the tests including dipped in boiled water, etc. Compared to DLC films deposited by single pulsed laser, the chemical and thermal inertness of the double-layer DLC film deposited by double pulsed lasers was much better.
Thermal Properties of In-Sb-Te Thin Films for Phase Change Memory Application
Authors: Nguyen Huu Tan , Kusiak Andrzej , Battaglia Jean Luc , Gaborieau Cecile , Anguy Yanick , Fallica Roberto , Wiemer Claudia , Lamperti Alessio , Longo Massimo
Published: October 2014

Phase change memories (PCM) are typically based on compounds of the Ge-Sb-Te (GST) ternary system. Nevertheless, a major drawback of PCM devices based on GST is the low crystallization temperature, which prevents the fulfillment of automotive-level or military-grade requirements (125°C continuous operation). To overcome this limitation, alloys belonging to the In-Sb-Te (IST) system have been proposed, which have demonstrated high crystallization temperature, and fast switching. Thermal properties of the chalcogenide alloy and of its interfaces within the PCM cell are key parameters versus the programming current, reliability and optimized scaling of PCM devices. The Modulated Photothermal Radiometry (MPTR) technique was implemented to measure the thermal conductivity of IST thin films as well as the thermal boundary resistance at the interface with other surrounding materials (a metal and a dielectric). The experiment was carried out in situ from room temperature up to 550°C in order to investigate the intrinsic thermal properties at different temperatures and the significant structural rearrangement upon the phase transition. Two different stoichiometries for the IST ternary alloy were deposited by Metal Organic Chemical Vapor Deposition (MOCVD) on a Si substrate covered with thermal SiO2 and then capped with a Platinum layer that acts as an optical and thermal transducer. Additional data from Raman and XRD lead to complementary analysis.
Integration of STT-MRAMs for Embedded Cache Memories
Authors: Sugii Toshihiro , Iba Yoshihisa , Aoki Masaki , Noshiro Hideyuki , Tsunoda Kouji , Hatada Akiyoshi , Nakabayashi Masaaki , Yamazaki Yuuichi , Takahashi Atsushi , Yoshida Chikako
Published: October 2014

We report the current status of our development of spin-transfer torque magnetic RAMs (STT-MRAMs) and their integration with the back-end-of-line (BEOL) process to replace conventional embedded SRAM cache memories. Our MRAM technology features a top-pinned, perpendicular magnetic tunnel junction (MTJ) and a highly reliable MTJ for a cache memory. We could obtain a higher density cache memory than that with conventional SRAMs with our STT-MRAMs, and leakage free characteristics, as well as unlimited write and read cycling times and 10-year time-dependent dielectric breakdown (TDDB) characteristics. They were integrated into Cu interconnects with 300 mm facilities. We also discuss variations in MTJ pattern sizes that are very important for memory applications from the viewpoint of high density embedded cache memories.
Role of Mg-B-O Nanostructural Inhomogenities on the Performance of Superconducting MgB2
Authors: Prikhna Tetiana , Eisterer Michael , Gawalek Wolfgang , Sokolovsky Vladimir , Kozyrev Artem , Moshchil Viktor , Weber Harald W. , Dub Sergey , Chaud Xavier , Kovylaev Valeriy , Sverdun Vladimir , Karpets Myroslav , Basyuk Tetyana , Sergienko Nina , Serbenyuk Tatiana
Published: October 2014

Auger and SEM studies show that with increasing of MgB2 manufacturing temperature from 600÷800 °C to 1050÷1100 °C the Mg-B-O nanolayers which are present in the MgB2 matrix transform into distinct dispersed Mg-B-O inclusions. On the other hand the sizes of inclusions of higher magnesium borides (MgBx, x=7 ÷ 25) which are also present in the MgB2 matrix. The tendency is observed in a wide range of synthesis pressures (0.1 MPa-2 GPa). The described structural transformations are accompanied by an increase in critical current density, jc, in low and medium magnetic fields and by transition from the grainboundary to the point pinning. The Ti addition results in a further increase in jc due to: Ti promotes the formation of higher magnesium boride inclusions and localization (or segregation) of oxygen in MgB2 matrix, and, hence, facilitates the formation of a homogeneous MgB2 matrix with lower oxygen content, but with an increased number of Mg-B-O and MgBx pinning centers. At low synthesis temperature Ti absorbs hydrogen forming titanium hydrides, thus preventing the formation of MgH2 and provides the material densification. The positive effect of Ti addition is connected with the high ability of Ti to absorb hydrogen, oxygen, and magnesium. The results of the critical current and AC loss study by transformer method using rings from MgB2 are discussed.
New Measurements of the Transition to the Normal State Induced by High Current Densities in High-Tc Superconductor Microbridges under Thermal Smallness Conditions
Authors: Doval J.M. , Maza J. , Torron C. , Veira J.A. , Tello M. , Vidal Felix
Published: October 2014

We address here the superconductivity quenching under an external magnetic field of amplitudes up to 1 T and in the so-called "thermal smallness" condition, when the microbridge width becomes smaller than the thermal diffusion length of both the own superconductor and its refrigerant (the substrate, in the case of thin films), which breaks their thermal dimensional scaling. Our results further support that when the current perturbations have characteristic times in the millisecond range the quenching is due to thermal instabilities associated with regular (nonsingular) flux-flow, and they also suggest how to optimize the refrigeration of practical superconductors.
Liquid Crystal Assisted Selective Separation of Large Graphene Oxide and its Size Dependent Oxygen Reduction Catalytic Effect
Authors: Lee Kyung Eun , Kim Ji Eun , Lim Joon Won , Kim Sang Ouk
Published: October 2014

We introduce a new self-separation of graphene oxide flakes exploiting liquid crystalline phase formation. Moderately concentrated discotic GO aqueous solution spontaneously phase separates into isotropic phase and nematic phase. According to Onsager theory, larger flakes with higher aspect ratio tends to form nematic phase, while smaller flakes remain in isotropic phase. Simple isolation of bottom nematic phase (large graphene oxide; LGO) resulted in the LGO dominant dispersion preparation. We employed this size selection principle to investigate the influence of GO flake size upon the material properties of reduced graphene oxide. The electrical properties of spin cast rGO films are thoroughly investigated in terms of the GO flake sizes in the precursor aqueous dispersions. Interestingly, nitrogen doping in order to inject more electron charge carrier exhibit different behavior following flake size. Therefore, it was experimentally confirmed that quaternary nitrogen doping site acts as the dominant catalytic site in oxygen reduction reaction.
The Possibilities of Graphenes Application in Textronic Devices
Authors: Puchalski Michal , Skrzetuska Ewa , Krucińska Izabella
Published: October 2014

Graphene, because of its exceptional properties such as very good electrical conductance, flexibility and high optical transparency in visible light spectrum, has proved to be an excellent nanomaterial for modern electronic applications. The natural point of view is to use this new nanomaterial for the development of unique textronic devices such as sensory systems for monitoring human body’s vital functions and atmospheric composition. The present review shows the state of art of materials science and possibilities of the smart textiles design with graphene. The most promising applications of graphene for the design of textronic devices are the development of conductive polymer composites (CPC) and the development of inks and pastes for printing conductive tracks on textile materials. The preliminary results of implementation of 2D carbon structure into textronic devices are presented.
Energy Gap Associated to Photocatalytic Activity of MWCNT/TiO2/ZnO Nanocomposites
Authors: da Dalt Silvana , Schorne Pinto Juliano , Sanchez Felipe Antonio Lucca , Alves Annelise Kopp , Pérez Bergmann Carlos
Published: October 2014

Carbon nanotubes (CNT) have been investigated for a wide range of applications. The combination of the CNT structure with semiconductors oxides opens up various application possibilities: water separation for hydrogen generation, degradation of pollutants in aqueous contamination and sewage treatment, photoreduction of CO2 activity in self-cleaning air purification and dyes for solar cells. The junction multi-walled carbon nanotubes with dioxide titanium and zinc oxide (MWCNT-TiO2-ZnO), when used as support, can facilitate a change in electron transfer, increasing the photocatalytic activity. MWCNTs/TiO2/ZnO nanocomposites were prepared by the modified sol-gel method using MWCNTs, titanium (IV) propoxide, commercial TiO2 (P25) as titanium sources, zinc oxide produced in the laboratory by thermal evaporation and commercial ZnO. The composites obtained from the titanium (IV) propoxide were prepared by solution processing followed by thermal treatment at 500° C. The results were associated with the characteristics of the nanocomposites using Raman spectroscopy. The photocatalytic activity on organic dye was associated to energy gap evaluated by diffuse reflectance spectroscopy.
Elucidation of Metal Diffusion Mechanism in Conducting-Bridge Random Access Memory (CB-RAM) Using First-Principle Calculation
Authors: Kinoshita Kentaro , Yamasaki Takahiro , Yura Sho , Ohno Takahisa , Kishida Satoru
Published: October 2014

It is important to specify the Cu diffusion path in the oxide layer of a Cu/oxide/Pt-structured conducting-bridge random access memory (CB-RAM), in terms of both the elucidation of resistive switching mechanism and optimization of memory performance. A first-principle calculation is effective in specifying the Cu diffusion path with atomic resolution. However, reported results of first-principle calculations are based on too simplified model to depict the actual system of CB-RAM. In this paper, a periodic slab model for the first-principle calculation of Cu diffusion process in HfO2-CB-RAM was proposed based on experimental results. Both the most probable Cu diffusion surface and Cu diffusion path were suggested by the first-principles calculations based on the model. It was also suggested that the Cu diffusion path was modified by introducing oxygen vacancy into the Cu diffusion surface.
Macromolecular Crowding: The Next Frontier in Tissue Engineering
Authors: Kumar Pramod , Satyam Abhigyan , Gaspar Diana , Cigognini Daniela , Sanz-Nogués Clara , O’Brien Timothy , Pandit Abhay , Zeugolis Dimitrios
Published: October 2014

Tissue engineering by self-assembly hypothesises that optimal repair and regeneration can be achieved best by using the cells’ inherent ability to create organs with proficiency still unmatched by currently available scaffold fabrication technologies. However, the prolonged culture time required to develop an implantable device jeopardises clinical translation and commercialisation of such techniques. Herein, we report that macromolecular crowding, a biophysical in vitro microenvironment modulator, dramatically accelerates extracellular matrix deposition in cultured human corneal, lung and dermal fibroblasts and human bone marrow mesenchymal stem cells. In fact, an almost 5 to 30 fold increase in collagen type I deposition was recorded as early as 48 hours in culture, without any negative effect in cell phenotype and function.
Diopside Glass-Ceramics for Dental and Biomedical Applications
Authors: Almuhamadi Jamila , Karpukhina Natalia , Cattell Mike
Published: October 2014

A series of glass compositions with varying equimolar amounts of Na2O:Al2O3 were designed using Appen factors. High purity batch reagents were ball milled for 30 min and transferred to Pt/Rh crucible and melted in an electric furnace (EHF1700, Lenton, UK) at high temperatures then held for 90 min. The molten glass was poured into a graphite mould, annealed at 50°C below the glass transition temperature for 1h and the remaining glass was quenched into water. Glass frits were crushed and ball milled into powders with different particle sizes. Glass powders (PS<125μm) were heat-treated via two-step heat treatment cycles and air quenched. Experimental glasses and glass-ceramics were characterised using X-Ray Diffraction (XRD), Dilatometry, Scanning Electron Microscopy (SEM) and solid state Nuclear Magnetic Resonance (NMR).
Bioactive and Biocompatible Silica/Pseudowollastonite Aerogels
Authors: Reséndiz-Hernández P.J. , Cortés-Hernández D.A. , Méndez Nonell Juan , Escobedo-Bocardo J.C.
Published: October 2014

Silica aerogels have attracted increasingly more attention due to their extraordinary properties and their existing and potential applications in a wide variety of technological areas. Materials that promote bone-tissue formation at their surface and bond to osseous tissues when implanted are called bioactive, such as pseudowollastonite particles. In this work, the synthesis of aerogels with pseudowollastonite particles was performed. The synthesis involved the preparation of an alcogel by a two step sol-gel route followed by ambient pressure drying. To promote a higher bioactivity the obtained aerogels were then biomimetically treated using simulated body fluids, SBF and 1.5 SBF. A high bioactivity was demonstrated by FT-IR, SEM, EDS, and XRD. The in vitro biocompatibility was assessed by testing cytotoxicity using rat osteoblasts cultures. The results obtained indicate that these materials are highly potential aerogels for bone tissue regeneration.
Characterization and Biocompatibility Evaluation of Hydroxyapatite Doped with Silver and/or Fluorine
Authors: González-Torres Verónica , Méndez-Sánchez Edgar R. , Gaitan-Cepeda Luis A. , Torres-Arellano María E. , Díaz-Trujillo G. César
Published: October 2014

Hydroxyapatite [Ca5(PO4)3(OH)] is a form of calcium phosphate inorganic compound of great importance in the health area because of its presence in bone as in teeth where it provides structural rigidity to the matrix. Hydroxyapatite is often used in the biomaterial area as a primary material for implants that help regenerate tissues. The addition of doping agents may improve the degree of crystallization providing new characteristics to the material without losing its biocompatibility. The present study shows characterization results for a hydroxyapatite biomaterial doped with silver and/or fluorine prepared through combustion method. The mineralogy was determined using X-Ray diffraction identifying the following phases: Ca5(PO4)3OH, Ca2P2O7, Ag3PO4, Ca5(PO4)3F and CaF2; the oxidation state of elements was determined by X-ray photoelectron spectroscopy; the morphological structure was studied by scanning electron microscopy and atomic force microscopy. Biocompatibility tests through intramuscular and subcutaneous implantation were performed in rodents to evaluate inflammatory response at 7, 14 and 30 days.
Natural Polymers as Heat and Moisture Exchange Devices for Medical Applications
Authors: Vazquez Brais , Nicosia Alessia , Belosi Franco , Santachiara Gianni , Monticelli Paolo , Sandri Monica , Savini Elisa , Tampieri Anna
Published: October 2014

In recent decades, Heat and Moisture Exchange (HME) devices have been employed increasingly for short-term use in anaesthesia and long-term use in intensive care units. These devices work as heat exchangers, accumulating the patient’s expired heat and moisture and returning them to the patient during the inhalation phase. Porous matrices obtained from freeze-drying of blends of natural polymers exhibit high open and interconnected porosity and water vapour intake characteristics which make them possible candidates for HME devices. Preliminary tests were conducted on specimens made of gelatine blended with chitosan and treated with a non-toxic cross-linking agent. The tests were carried out in cyclic flow conditions with saturated and dried air. Results show water vapour retention comparable with accepted standards for HME devices.
Development of Novel Mesoporous Silica-Based Bioactive Glass Scaffolds with Drug Delivery Capabilities
Authors: Philippart Anahí , Boccardi Elena , Pontiroli Lucia , Beltrán Ana Maria , Inayat Alexandra , Vitale-Brovarone Chiara , Schwieger Wilhelm , Spiecker Erdmann , Boccaccini Aldo Roberto
Published: October 2014

Novel silica-based bioactive glasses were successfully prepared by the sol-gel method. The optimized glass composition for fabrication of the scaffolds was (in mol.%) 60% SiO2 – 30% CaO - 5% Na2O - 5% P2O5 (60S30C5N5P). This composition was confirmed to develop a thick hydroxycarbonate apatite (HCA) layer in Simulated Body Fluid (SBF) after 7 days, as revealed by Fourier Transform Infrared Spectroscopy (FTIR), indicating the bioactive character of the scaffolds. The mesoporous nature of the glass structure allows the load of tetracycline and a sustained release of the drug in PBS during 7 days was measured.