bluuebunny/crossref_metadata_2025 huggingface dataset:
Spin-Coated La0.8Sr0.2Ga0.8Mg0.2O3-δ Electrolyte on Infiltrated Anodes for Biogas Utilization
Authors: Salehi Zahra , Basoli Francesco , Luisetto Igor , Licoccia S. , di Bartolomeo Elisabetta
Published: October 2014

Dense micrometric La0.8Sr0.2Ga0.8Mg0.2O3-δ (LSGM) films were deposited by spin-coating on porous LSGM scaffolds characterized by an homogeneous pore structure. Porous anodes were infiltrated with aqueous nickel nitrate solutions, dried and fired at 700 °C. Homogeneous metal coating with proper interconnections was observed by SEM, chemical stability was confirmed by XRD. Fuel cell tests and electrochemical impedance spectroscopy (EIS) were performed and discussed.
Composite Anode Catalysts Based on PtRu and Metal Oxide Nanoparticles for DMFCs
Authors: Sebastián David , Baglio Vincenzo , d'Urso Claudia , Stassi Alessandro , Aricò A.S.
Published: October 2014

A composite anode was investigated with the aim of enhancing the performance of direct methanol fuel cells (DMFCs). Fine iridium oxide nanoparticles were synthesized by a sulfite complex method. These IrO2 nanoparticles were mixed by sonication with a 50% PtRu/C catalyst prepared by the same procedure, considered as benchmark anode catalyst. A significantly higher performance was recorded for the composite electrode compared to the bare one based only on PtRu/C. The results confirm that the electrocatalytic activity is related to the characteristics of water displacement of the additive, evidencing that a multifunctional catalyst can operate better than PtRu for methanol oxidation since this multi-step process requires different functionalities to speed up the reaction rate.
Plasma Chemical Reactor for Hydrogen Production
Authors: Essiptchouk Alexei M. , Filho Gilberto Petraconi
Published: October 2014

The process of carbon dioxide reforming of hydrocarbon feedstock (like natural gas, coal, petroleum coke, residual oil, glycerine, etc) for hydrogen production has attracted great attention from both environmental and industrial perspectives. The plasma chemical reactor for study the CO2 reforming of hydrocarbon gaseous feedstock is presented. The reactor consists of a DC plasma torch coupled to a compact quenching chamber. The linear plasma torch operates with a reverse vortex flow and hollow blind-end cathode for enhancing the thermal efficiency and enthalpy of the plasma jet. The quenching chamber consists of a set of refrigerated discs equipped with flow turbulent flow generator. Estimated quenching rates are up to 107-108 K/s. Electrical and thermal characteristics of the plasma-chemical reactor torch as well as the energy efficiency of the process are presented.
Adsorption Materials Development for the Separation of Actinides and Specific Fission Products from High Level Waste
Authors: Wei Yue Zhou , Ning Shun Yan , Wang Qi Long , Chen Zi , Wu Yan , Liu Rui Qin , Mimura Hitoshi
Published: October 2014

The long-term radiotoxicity of high level liquid waste (HLLW) generated in spent nuclear fuel reprocessing is governed by the content of several long-lived minor actinides (MA) and some specific fission product nuclides. To efficiently separate MA (Am, Cm) and some FPs such as Cs and Sr from the HLLW, we have been studying an advanced aqueous partitioning process, which uses selective adsorption as separation method. In this work, we prepared different types of porous silica-based organic/inorganic adsorbents with fast diffusion kinetics, improved chemical stability and low pressure drop in a packed column. So they are advantageously applicable to efficient separation of the MA and specific FP elements from HLLW. Adsorption and separation behaviors of the MA and some FP elements such as Cs and Sr were studied. Small scale separation tests using simulated and genuine nuclear waste solutions were carried out and the obtained results indicate that the proposed separation method based on selective adsorption is essentially feasible.
Progress at ANSTO on a Synroc Plant for Intermediate-Level Waste from Reactor Production of 99Mo
Authors: Vance Eric R. , Moricca S.A. , Stewart M.W.A.
Published: October 2014

Intermediate level waste from ANSTO’s expanded 99Mo production plant will consist of ~5000L/year of 6M NaOH + 1.4 NaAlO2 + fission products. Detailed engineering is being carried out on a synroc plant to immobilise this waste in a glass-ceramic, with completion scheduled for 2016. The liquid waste will be mixed with precursors and dried before being calcined in a reducing atmosphere to control fission product volatility. The calcine will be transferred to 30L metal cans which will be hot isostatically pressed at 1000°C/30MPa for 2h, then cooled to room temperature and stored preparatory to final disposal. Laboratory scale waste form material will pass 90°C PCT tests. In addition, legacy intermediate level uranyl nitrate-based liquid waste from 99Mo production at ANSTO between the 1980s and 2005 via irradiation of UO2 targets will also be immobilised by the same process to form a Synroc-type waste form. Some examples illustrating the wide applicability of hot isostatic pressing to consolidate nuclear waste forms will be given showing the advantages for particular wastes, notably high waste loadings and the absence of off-gas in the high temperature consolidation step. The immobilisation of a variety of low-level liquid and solid wastes from 99Mo production will also be discussed.
Study on the Creep and Fatigue Properties of CLAM Steel
Authors: Zhao Yan Yun , Liu Shao Jun , Li Chun Jing , Zhong Bo Yu , Xu Gang , Huang Qun Ying , Wu Yi Can
Published: October 2014

China Low Activation Martensitic (CLAM) steel has been chosen as the structural material for China ITER Test Blanket Module (TBM). Creep-rupture and fatigue damage caused by high temperature and pulse stresses are two key issues for the final application of CLAM steel in China ITER TBM. In this paper, the research and development progress of the creep and fatigue behaviors of CLAM steel were presented. These results showed that CLAM steel possessed good high temperature mechanical properties.
A Microfluidic-Assisted Fabrication of Size-Controlled Porose CeO2 Microspheres as an Analog Production of Nuclear Fuel Beads
Authors: Li Xiang , Yang Ya Ting , Fu Cao Fei , Huang Qun Ying , Sheng Liu Si , Chang Zhen Qi , Serra Christophe C.
Published: October 2014

Porosity-controlled nuclear fuel microsphere is an essential material of fabricating minor actinide-bearing dispersion-type nuclear fuel with the infiltration processes. In this paper, monodisperse and size-controlled spherical oxide nuclear fuel particles with size range of 20μm to 800μm were fabricated by means of microfluidic technology combined with sol-gel process using cerium as a surrogate for plutonium. The porous CeO2 beads with the density range of 25% to 93% T.D. were successfully prepared by the addition of polyethylene glycol 6000 used as a porogen to the feed broth. The uniform U3O8 beads were also prepared at the same experimental conditions as CeO2 beads prepared, which shows the feasibility of the method for fabricating size-controlled monodisperse nuclear fuel beads.
Selective Decontamination and Stable Solidification of Cs-Insoluble Ferrocyanide by Zeolites
Authors: Mimura Hitoshi , Ikarashi Yuki , Ishizaki Eiji , Matsukura Minoru
Published: October 2014

Large amounts of high-activity-level water (HALW) were generated from the nuclear accident in Fukushima NPP-1 caused by the Great East Japan Earthquake. At present, the cold shutdown is completed by cooling system, while large amounts of HALW (> 300,000m3) and secondary solid wastes such as insoluble ferrocyanide sludge adsorbing 137Cs are still stored. For the stable solidification of Cs-insoluble ferrocyanides, the press/sintering method was developed by mixing zeolites. In this method, the excellent abilities of zeolites such as Cs adsorbability, gas trapping and self-sintering abilities were used for the stable solidification; zeolites are effective for the stable solidification of Cs-insoluble ferrocyanides as a solidification matrix. Cs adsorbed insoluble ferrocyanides tend to release all Cs at higher temperature above 1,000°C, while the immobilization ratio of Cs about 100% was maintained by sintering the mixtures of Cs-insoluble ferrocyanide and zeolite. The advantages of sintered products are large volume reduction of 30-50%, no effect of NaCl on Cs immobilization and low leachability of Cs, indicating the excellent solidification properties of sintered products of insoluble ferrocyanide and zeolite. This method can be applied to the stable solidification of the secondary solid wastes such as insoluble ferrocyanide sludge in Fukushima NPP-1.
Thermionic and Photon-Enhanced Emission from CVD Diamond: Influence of Nanostructure, Doping, and Substrate
Authors: Sun Tian Yin , Koeck Franz A.M. , Nemanich Robert J.
Published: October 2014

Thermionic electron emitters based on doped diamond films have shown significant emission at less than 500°C. Results have established that it is necessary to control the electron affinity, doping levels and concentration, and band bending, and these properties have been achieved with engineered multilayered structures with controlled morphology, doping and substrate. Recently, visible light photo-electron emission has been demonstrated using the same diamond film emitters. This report presents a spectroscopic and surface electron microscopy study of photo-and thermionic emission from nitrogen doped diamond films with controlled morphology on metal substrates. Electron emission spectra were recorded to 500°C, while illuminated with sub diamond band gap light. Significant photo-induced emission was observed with an efficiency greater than metal photo cathodes.
Thermal Conductivity Measurement of a Sb2Te3 Phase Change Nanowire
Authors: Saci Abdelhak , Battaglia Jean Luc , Kusiak Andrzej , De Indrayush , Fallica Roberto , Longo Massimo
Published: October 2014

In this work we present the measurements of thermal conductivity of nanowire Sb2Te3 phase change. These measurements are made using a thermal scanning probe microscopy (SThM) operating in regime modulated type 3ω. The spatial resolution of the probe is of the order of 100 nm. The measurement of amplitude and phase are used to identify unknown radius of contact between the nanowire and the sensor parameters, the contact resistance at the interface probe and nanowire and the thermal conductivity of the nanowire. An identification method is used which minimizes the difference between the measured values and those from a simulated model of heat transfer in the materials. This model uses a matched model heat transfer in the probe
Superconductivity at Tc = 36.5 K in Na-Substituted SrFe2As2 Single Crystals
Authors: Shlyk Larysa , Bischoff Markus , Rose Eva , Niewa Rainer
Published: October 2014

We report superconductivity, which is achieved in Sr1-xNaxFe2As2 at Tc = 36.5 K for x = 0.47. Single crystals of Na-substituted SrFe2As2 up to 2 × 2 mm2 were grown from NaF flux. The superconducting transition temperature with a narrow width less than 2 K, confirmed by both magnetic and resistivity measurements, indicates the high quality of our samples. The upper critical fields (0) = 87 T and (0) = 217.5 T are extremely high. The anisotropy ratio γ ~ 2.5 is close to that of other hole-or electron-doped 122 phases but lower than γ ~ 4.3 – 5 of phases from the 1111 series and much lower than γ ~ 7 – 10 of superconducting cuprates. Magnetic relaxation measurements, which are consistent with the collective pinning model, reveal that the flux-creep rate in Na substituted 122 SrFe2As2 is smaller than in 1111 type iron pnictides.
Critical Current Density and Pinning Energy of Partial Melted Sm-Based Superconductor
Authors: Imao Hiroya
Published: October 2014

The relationship between critical current density (Jc) and pinning energy (Up) in partial melted superconductors was investigated. The partial melted Sm-Ba-Cu-O superconducting bulks were composed of SmBa2Cu3Ox (Sm-123) superconductor and Sm2BaCuOy (Sm-211) insulator. The pinning force and the pinning energy of the superconductor were measured by a system combining an electronic balance and permanent magnet. The pinning energy and the Jc of the samples were influenced by crystalline orientation. The Jc of the samples depends on the pinning energy. However, in the partial melting process, changes in retention temperature altered the Jc values but had little effect on the value of the pinning energy. The results indicated that Jc was influenced by the dispersion of the insulator acting as a pinning center with in the superconducting bulks.
Critical Current of Bi-2212 Single Crystal by Doping Oxides as a Pinning Center
Authors: Agou Takuya , Imao Hiroya
Published: October 2014

It is necessary to formpinning centers in superconductors to allow the flow of large currents throughthe specimens. To clarify the properties of pinning centers, it is preferableto investigate single crystals. In this study, heat treatment was used to dopevarious oxides into Bi2Sr2CaCu2Ox(Bi-2212) single crystals prepared by self-flux methods and the criticalcurrent (Ic) was measured. The oxides used in this study were Al2O3and the rare earth oxides Er2O3and Nd2O3. At 77K, Nd2O3and Er2O3 are magnetic, whereas Al2O3is nonmagnetic. The Ic of the samples were measured as a current per width of 1cm (Ics). The resulting Ics of the Bi-2212 single crystal was 2.8A/cm and thatof the Al2O3 doped Bi-2212 sample was 4.5A/cm. Comparedwith these samples, doping the other rare earth oxides gave Ics values inexcess 10A/cm. The results indicated that the doping oxides were effective inoperating as pinning centers in the samples. We assumed the current path in asingle crystal, and calculated the Ics by superconducting current simulation.The results indicated that the oxides permeated from a crystal surface in aporous shape. The oxides increase the current which flow in the Cu-O2planes that are parallel to the a-b plane.
Fabrication of MgB2 Bulk Magnets with High Critical Currents
Authors: Muralidhar Miryala , Inoue Kazuo , Koblischka Michael R. , Murakami Masato
Published: October 2014

We report on the fabrication and characterization of disk-shaped bulk MgB2 superconductors with high performance as superconducting bulk magnets. Several samples of diameters 20 mm, 30 mm and 40 mm were fabricated using a solid state reaction in pure Ar atmosphere at 775°C for 3h. The magnetization measurements confirmed that all the samples exhibited a sharp superconducting transition with Tc(onset) at around 38.5 K. The samples showed respective critical current density (Jc) values of 176 kA cm-2 and 55 kA cm-2 at 20 K in self field and 1T. The Jc values increased further to 250 kA cm-2 and 100 kA cm-2 with decreasing temperature down to 10 K. MgB2 samples 20 mm and 30 mm in diameter and 7 mm in thickness exhibited trapped field values of 1.15 T and 1.3 T at 25 K, respectively. Microstructural observations with scanning electron microscopy (SEM) revealed that the samples are highly porous. And hence, continuing development of large-sized bulk MgB2 with higher density will lead to promising industrial applications.
Improvement of Performance of Paper Transistor Using Carbon-Nanotube-Composite Paper and its Application to Logic Circuit
Authors: Hamana Yoshiki , Oya Takahide
Published: October 2014

We propose development of an advanced type of "paper transistor" by using carbon-nanotube (CNT) composite papers (CNTCPs) and aim to apply our paper transistors to the construction of logic circuits. It is known that CNTs have many functions such as high electrical and thermal conductivities and metallic and semiconducting properties. Our CNTCP, which has various functions held by CNTs despite being paper, can be fabricated easily by scooping up and drying materials from a mixture of CNT and pulp (paper materials) dispersions. The CNTs have metallic or semiconducting properties, so metallic and semiconducting CNTCPs can be fabricated. By preparing such CNTCPs and normal paper as an insulator, we can produce the paper transistor. In previous work, we confirmed our prototype paper transistor could operate as a p-type transistor. However, the sample had problems, e.g., the internal resistance was rather high. In this study, we aim to overcome the problems by using a novel method for making the CNTCP. As the result of experiments, we succeeded in obtaining new paper transistors with better performance in comparison with the previous one. Moreover, we succeeded in finding a potential use as an n-type paper transistor by using an n-type doping material for semiconducting CNTCPs.
Development of Carbon-Nanotube Composite Thread and its Application to "Thread Transistor"
Authors: Yoshida Masatoshi , Oya Takahide
Published: October 2014

We propose development of a novel functional thread that contains carbon nanotubes (CNTs), i.e., a CNT-composite thread (CNTCT), and of a "thread transistor." The CNT is expected to be a next-generation material because it has a lot of useful characters, e.g., it can have both metallic and semiconducting characteristics. Thread is flexible and an everyday material. In our study, we succeeded in developing the CNTCT easily by dipping thread in CNT dispersion like dyeing. Here, we also developed and demonstrated a novel type of field-effect transistor (FET), i.e., the thread transistor. To do this, we prepared a metallic (M) and a semiconducting (S) CNTCT. The S-CNTCT was coated with a non-conductive paint as an insulating layer for simplicity. To construct the thread transistor, we tensed the S-CNTCT that plays the role of a channel for the FET and tied the M-CNTCT around the S-CNTCT as a gate electrode. The source and drain electrodes can also be materialized by tying the M-CNTCTs. As a result of measurement, a drain-to-source current could be measured on the order of micro-amperes. Moreover, the current could be controlled by the gate voltage.
The Influence of the Exterior Surface on Grain Boundary Mobility Measurements
Authors: Novick-Cohen Amy , Zigelman Anna , Vilenkin Arkady
Published: October 2014

Polycrystalline materials typically contain a very large number of grains whose surrounding grain boundaries evolve over time to reducethe overall energy of the microstructure. The evolution of the microstructure is influencedby the motion of the exterior surface since the grain boundaries couple to the exterior surface of the specimen; these effects can be appreciable especially in thin specimens. We model these effects using the classical framework of Mullins, in whichgrain boundaries move by mean curvature motion, Vn =A κ, and the exterior surface evolves by surface diffusion, Vn = -BΔs κ. Here Vn and κ denote the normal velocity and the mean curvature of the respective evolving surfaces, and Δs is the surface Laplacian. A classical way to determine A, the ``reduced mobility," is to make measurements based on the half-loop bicrystalline geometry. In this geometry one of the two grains, which embedded within the other, recedes at a roughly constant rate which can provide an estimate for A. In this note, we report on findings concerning the effects of the exterior surface on grain boundary motion and mobility measurements in the context of the half-loop bicrystalline geometry. We assume that the ratio of grain boundary energy to the exterior surface energy is small, and suitable assumptions are made of the specimen aspect ratio.
Protonic SOFCs Using Perovskite-Type Conductors
Authors: Yugami Hiroo , Kato Hisashi , Iguchi Fumitada
Published: October 2014

High temperature solid oxide fuel cells (SOFCs) have high efficiency and low emissions and contribute to the saving of the fossil fuel and the decreasing of the CO2 emission bringing about the global warning. As concerned about the development of electrolytes, oxide-ion conductors alternative to yttria-stabilized zirconia (YSZ) such as doped CeO2, Sc-SZ and perovskite-type oxides (LaGaO3) etc. have been reported to apply to the intermediate temperature SOFCs (IT-SOFCs).Some of perovskite-type oxides shows high proton conductivity at high temperature and are expected to the electrolyte materials for IT-SOFCs. In this paper we have investigated review the mixed electrical conductivity and the optical absorption spectrum of OH(D)-vibration of LaScO3.We also evaluated its applicability to the electrolyte material for IT-SOFCs by testing the SOFC performance of Pt/LaScO3/Pt single cell configuration.
Extraction of Filament Properties in Resistive Random Access Memory (ReRAM) Consisting of Binary-Transition-Metal-Oxides
Authors: Moriyama Takumi , Koishi Ryosuke , Kimura Kouhei , Kishida Satoru , Kinoshita Kentaro
Published: October 2014

Which parameter dominantly decides the value of time required to reset ReRAM (treset) among possible parameters, the value of a low resistance (RL), voltage to induce reset (Vreset), and temperature to induce reset (Treset) Although to answer this question is important to achieve faster resistive switching, detailed correlations between the parameters are still unclear. In this paper, we extracted treset, Vreset, RL and Treset at the same time by combining two electrical measurements. As a result, we found a clear correlation between Vreset, RL, and Treset, meaning that each parameter can not be controlled independently. Tresetincreases not only with increasing Vresetbut also with increasing RL, which suggests the necessity of introducing ununiformly-shaped filamens and resistive switching takes place at the narrowing part of the filament.
Resistive Switching Behavior in Undoped α-Fe2O3 Film with a Low Resistivity
Authors: Ogawa Yukiko , Sutou Yuji , Ando Daisuke , Koike Junichi
Published: October 2014

The resistive switching behavior of a low resistive p-type α-Fe2O3 thin film sandwiched between Fe bottom electrode and top electrodes of various materials (Fe, Ni and TiN) was studied by current-voltage measurements. When TiN was used for top electrode of memory cell, the reversible resistive switching behavior was observed for over 100 cycles. From impedance measurement, it was suggested that the resistive switching behavior in the TiN/p-type α-Fe2O3/Fe device is attributed to the change of the contact resistance in the interface between TiN and α-Fe2O3 layers.
Soft Conductive Polymer Dry Electrodes for High-Quality and Comfortable ECG/EEG Measurements
Authors: Chen Yun Hsuan , Op de Beeck Maaike , Vanderheyden Luc , Vanstreels Kris , Vandormael Herman , van Hoof Chris
Published: October 2014

Wet gel electrodes are widely used for ECG/EEG monitoring, their low impedance results in high-quality signals. But they have important drawbacks too, such as time-consuming electrode set-up for EEG followed by a painful removal, skin irritation by the gel and signal degradation due to gel drying. Hence various dry electrode types are investigated, such as hard metal electrodes with low impedance but limited patient comfort/safety. We focus on flexible conductive polymer-based electrodes to combine low impedance, user comfort and safety. The composition of the conductive polymers is optimized to improve various properties such as conductivity, which directly affects signal quality and sensitivity to motion artifacts, and mechanical properties of the electrodes, important with respect to patient comfort. Electrode impedance and ECG/EEG signal recordings are evaluated using various polymer compositions and compared to wet gel electrode results. Additive optimization to improve processability of the conductive formulations is performed by dedicated flow studies, and will result in a high electrode fabrication yield. Very promising results are obtained regarding impedance, EEG/ECG signal quality and user comfort.
Effect of Titanium Dioxide Nanoparticles on Mechanical and Thermal Properties of Poly(Lactic Acid) and Poly(Butylene Succinate) Blends
Authors: Buasri Achanai , Buranasing Gridtapas , Piemjaiswang Ratchanon , Yousatit Satit , Loryuenyong Vorrada
Published: October 2014

Poly (lactic acid) (PLA) blended with poly (butylene succinate) (PBS) were prepared by using twin screw extruder and injection molding machine at various contents of PBS from 0-15 wt%. The surface of titanium dioxide (TiO2) nanoparticles was treated using aminopropyl trimethoxy silane (ATS) order to disperse them into the biopolymer blends. The mechanical and thermal properties of PLA/PBS/TiO2 nanocomposites were investigated over a range of filler content 0-5 wt%. All samples with a wide range of TiO2 addition exhibit the translucency. The surface morphology showed that the addition of PBS at 10 wt% was miscible with PLA while the other contents of PBS exhibited phase separation in the blends. Additionally, a uniform dispersion of filler in the matrix existed when the nanoparticles content was less than 3 wt%. The surface treated nanoparticles played an important role in mechanical and thermal properties of the nanocomposites because of its well dispersion and strong interfacial interaction between the nanoparticles and PLA/PBS matrix.
Electrochemical Detection of Bacteria Using Graphene Oxide Electrodeposited on Titanium Implants
Authors: Sirivisoot Sirinrath , Parcharoen Yardnapar , Webster Thomas J.
Published: October 2014

Graphene oxide was electrodeposited on titanium (Ti-GO) and anodized titanium (ATi-GO) as label-free sensors for the detection of challenging living organisms, specifically Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The graphene modification contributed to two sets of oxidation-reduction peaks in cyclic voltammograms (CVs) of bacteria growth on the electrode surfaces (ATi-GO) that resulted in increasing direct electron transfer and stimulating excretion of mediating molecules for higher electron transfer between electrodes and bacteria. Additionally, similar wave patterns of CVs were found when E. coli or S. aureus were grown and electrocatalyzed on ATi-GO. The results suggest that bacteria on titanium implant surfaces could be easily detected by using mediatorless ATi-GO sensors electrochemically. These finding open another interesting method in using ATi-GO as in situ electrochemical sensors for label-free, close to real-time detection of bacteria infection in orthopedic implants.
Mechanical Behavior of Alumina Toughened Zirconia Nanocomposites with Different Alumina Additions
Authors: Díaz Luis Antonio , Rivera Sergio , Fernández Adolfo , Okunkova Anna , Vladimirov Yu.G. , Torrecillas San Millan Ramon
Published: October 2014

ZrO2 and Al2O3 are monolithic ceramics used today in a wide variety of structural components. However, both materials present important drawbacks for some specific applications. In the case of Al2O3, its moderate strength (500 MPa) and toughness (4 MPa.√m) makes it unsuitable for high loading conditions. On the other hand, ZrO2 presents higher strength and toughness values (900 MPa and 6 MPa.√m) than Al2O3 but it is a material limited in its long-term behaviour due to its bad response to hydrothermal ageing and a pronounced tendency for subcritical crack growth. Due to this fact, ceramic nanocomposites made of Al2O3 and ZrO2 (ATZ and ZTA) have been developed in the last years in order to overcome the main drawbacks of the monolithic materials as they can combine the properties of both, strong and tough materials, simultaneously, with null ageing and even higher biocompatibility. In this work, several amounts of Al2O3 disperse phase (15, 35 and 50 vol %) were added to one ZrO2 matrix (CeO2 - 10 mol %) in order to see their effect on the mechanical properties, subcritical crack propagation and long-term reliability.
On-Body Chemo/Bio-Sensing - Opportunities and Challenges
Authors: Matzeu Giusy , Fay Cormac , O’Quigley Conor , Orpen Dylan , Coleman Simon , Kavanagh Andrew , Diamond Dermot
Published: October 2014

In recent years, there has been significant progress in a number of sensing technologies related to on-body measurements, such as platforms for monitoring respiration, heart rate, location and movement. In these cases, the sensing element (s) are based on highly effective transducers that are increasingly integrated into garments such that they are becoming innocuous to the user. In contrast, the area of on-body chemical sensing remains highly under-developed. In this paper, we will address the significant challenges that are inhibiting the practical realisation of reliable chemical sensors and biosensors capable of generating accurate data in real time.
Strain Evaluation and Fracture Properties of Hetero-Epitaxial Single Crystal 3C-SiC Squared Membrane
Authors: Anzalone Ruggero , D'Arrigo Giuseppe , Camarda Massimo , Piluso Nicolo’ , La Via Francesco
Published: October 2014

The following paper explores the development the bulge test technique combined with the micro-Raman analysis and a refined load-deflection model for high quality 3C-SiC squared-membranes. By the minimization of the total elastic energy, starting from the isotropic relation between the stress tensor and the strain tensor, it is possible to calculate the relationship between the maximum deflection and the applied pressure, in both regime of small and large deflection. From the measured breaking pressure through the refined model it is possible to evaluate the breaking strain of the membrane. Furthermore, the relationship between the measured shift of Raman Transverse Optical (TO) phonon modes and the total residual strain (Δa/a) within the epitaxial 3C-SiC layer was found.
Impact of Design on Electrical Characteristics of 3.5 kV 4H-SiC JBS Diode
Authors: Brosselard Pierre , Chevalier Florian , Proux Benjamin , Thierry-Jebali Nicolas , Bevilacqua Pascal , Tournier Dominique , Planson Dominique , Grosset Gregory , Dupuy Lionel
Published: October 2014

This work reports on the fabrication and electrical characterization of 3 different diodes. The first one is a Schottky diode with a single 50 mm P+ ring between the edge termination and the active area. The two other diodes are JBS with a 3 mm P+ strips separated by 4 mm and 8 mm respectively. The breakdown voltage ranges from 2.7kV up to 3.7kV depending on the P+/N area. The 3 different diodes exhibit a similar on-resistance versus the temperature behavior. Moreover, no contribution of the bipolar conduction is observed and no degradation has been observed when a forward stress is performed in forward mode and also in reverse.
Impact of Fabrication Process on Electrical Properties and on Interfacial Density of States in 4H-SiC n-MOSFETs Studied by Hall Effect
Authors: Ortiz Guillermo , Mortet Vincent , Strenger Chrisitan , Uhnevionak Viktoryia , Burenkov Alexander , Bauer Anton J. , Pichler Peter , Cristiano Fuccio , Bedel-Pereira Eléna
Published: October 2014

In this work, electrical properties of lateral n-channel MOSFETs implanted with differentnitrogen doses in the channel region were measured by Hall-effect technique at 300K. A mobility improvement with increasing nitrogen implantation doses is observed. Interface trap density (Dit) was determined from the experimentally measured Hall carrier density. Our results show a high Dit near and within the conduction band that does not change significantly when the nitrogen implantation dose is increased, despite observed mobility improvement.
Stable Phosphorus Passivated SiO2/4H-SiC Interface Using Thin Oxides
Authors: Sharma Yogesh K. , Ahyi A.C. , Issacs-Smith Tamara , Jennings M.R. , Thomas S.M. , Mawby Philip  Andrew , Dhar Sarit , Williams John R.
Published: October 2014

The NO (nitric oxide) passivation process for 4H-SiC MOSFETs (silicon carbide metal-oxide-semiconductor filed effect transistors) effectively reduces the interface trap density and increases the inversion channel mobility from less that 10 to around 35cm2/V.s, only 5% of the bulk mobility. Recent results on the phosphorous passivation of the SiO2/4H-SiC interface have shown that it improves the mobility to about 90 cm2/V.s. Phosphorous passivation converts oxide (SiO2) into phosphosilicate glass (PSG) which is a polar material and results in device instabilities under abias-temperature stress (BTS) measurements. To limit the polarization effect, a new thin PSG process has been developed. The interface trap density of 4H-SiC-MOS capacitors using this process is as low as 3x1011cm-2 eV-1. BTS results on MOSFETs have shown that the thin PSG devices are as stable as NO passivated devices with mobility around 80 cm2/V.s.
SiC NWs Grown on Silicon Substrate Using Fe as Catalyst
Authors: Lagonegro Paola , Bosi Matteo , Attolini Giovanni , Negri Marco , Dhanabalan Sathish Chander , Rossi Francesca , Boschi Francesco , Lupo P.P. , Besagni Tullo , Salviati Giancarlo
Published: October 2014

We report on the synthesis of SiC nanowires (NWs) using iron as catalyst. The NWs were grown on silicon substrate by vapour-liquid-solid (VLS) mechanism with propane and silane as precursors, both 3% diluted in hydrogen, and hydrogen as carrier gas. The growth temperature was 1250°C, to reach the eutectic values of the Si-Fe alloy and to permit the VLS mechanism. The as-grown SiC nanowires were characterized by scanning and transmission electron microscopy. The nanowires are from 30 to 100 nm in diameter and several μm in length, with <111> growth direction.
Raman Investigation of Heavily Al Doped 4H-SiC Layers Grown by CVD
Authors: Kwasnicki Pawel , Arvinte Roxana , Peyre Hervé , Zielinski Marcin , Konczewicz Leszek , Contreras Sylvie , Camassel Jean , Juillaguet Sandrine
Published: October 2014

In this work, we focus on heavily aluminum (Al) doped 4H-SiC samples. We compare the effect of the Al concentration and Hall carrier concentration on the Raman spectra in a large frequency range. The Al concentration measured by Secondary Ion Mass Spectrometry ranged from 2×1016 to 8.4×1019 cm-3 while the electrical measurement give a carrier concentration up to 5×1019 Al×cm-3. On the Raman spectra, three different frequency domains have been analysed: i) at high frequency where we consider the change in longitudinal optical phonon-plasmon coupled mode; ii°) at low frequency where we consider the continuum of electronic transitions and iii°) finally, considering the Fano interference effect between the continuum of electronic transitions and the Folded Transverse Acoustic phonon modes. This analysis is applied to comment a Raman spectra mapping collected on a 4H-SiC 2 inch wafer.
Improvement of the Specific Contact Resistance on P-Type 4H-SiC by Using a Highly P-Typed Doped 4H-SiC Layer Selectively Grown by VLS Transport
Authors: Thierry-Jebali Nicolas , Vo-Ha Arthur , Carole Davy , Lazar Mihai , Ferro Gabriel , Peyre Hervé , Contreras Sylvie , Brosselard Pierre
Published: October 2014

This work reports on the improvement of ohmic contacts made on heavily p-type doped 4H-SiC epitaxial layer selectively grown by Vapor-Liquid-Solid (VLS) transport. Even before any annealing process, the contact is ohmic. This behavior can be explained by the high doping level of the VLS layer (Al concentration > 1020 cm-3) as characterized by SIMS profiling. Upon variation of annealing temperatures, a minimum value of the Specific Contact Resistance (SCR) down to 1.3x10-6 Ω.cm2 has been obtained for both 500 °C and 800 °C annealing temperature. However, a large variation of the SCR was observed for a same process condition. This variation is mainly attributed to a variation of the Schottky Barrier Height.
Interface Shape: A Possible Cause of Polytypes Destabilization during Seeded Sublimation Growth of 15R-SiC
Authors: Tsavdaris Nikolaos , Ariyawong Kanaparin , Sarigiannidou Eirini , Dedulle Jean Marc , Chaix-Pluchery Odette , Chaussende Didier
Published: October 2014

We report on the stabilization of 15R Silicon Carbide (15R-SiC) grown by seeded sublimation method. It was found that polytype transitions are directly related to the occurrence of facets on the grown crystals. Once a foreign polytype is formed, its propagation is governed mainly by the interface shape of the crystal and its evolution during growth. A concave crystal shape enhances the expansion of foreign polytypes, usually formed at the periphery of the crystal. Then, foreign polytypes can either overlap the original polytypes (constant concave crystal shape) or form inclusions (change to convex crystal shape). On the contrary, an initially slightly convex interface repels foreign polytypes towards the edge of the crystal. The optimization of the growth interface shape can be a key issue towards the stabilization of bulk 15R-SiC crystals.
Aneurysmal Bone Cyst of the Calcaneus
Authors: Kaplanoğlu Veysel , Ciliz Deniz Sözmen , Kaplanoğlu Hatice , Elverici Eda
Published: October 2014

Aneurysmal bone cysts (ABCs) are benign, non-neoplastic, expansile, vascular, locally destructive lesions. The lesion may arise de novo (65%) or secondarily (35%) in pre-existing benign or malignant lesions (giant cell tumor, osteoblastoma, chondroblastoma, angioma, and others). The calcaneus is a rare localization for ABC, comprising only 1.6% of the cases. In this paper, we present a case of a female patient with a 3-month history of heel pain that got worse and was accompanied by swelling and difficulty in walking. The magnetic resonance images of the postero-lateral calcaneus showed a contrast-enhanced cystic lesion located in the medullary cavity; exophytic portion of the tumor extended into the soft tissue causing distinctive cortical thinning. Heterogeneous hyperintense septae formations and blood level components were also detected. After correlation with pathology results, the lesion was diagnosed as an ABC. Since an ABC of the calcaneus is a rarely seen phenomenon, we present the radiologic findings in this case and a review of the literature.
The Coming Swarm
Authors: Sauter Molly
Published: October 2014

What is Hacktivism?

In The Coming Swarm, rising star Molly Sauter examines the history, development, theory, and practice of distributed denial of service actions as a tactic of political activism. The internet is a vital arena of communication, self expression, and interpersonal organizing. When there is a message to convey, words to get out, or people to unify, many will turn to the internet as a theater for that activity. As familiar and widely accepted activist tools-petitions, fundraisers, mass letter-writing, call-in campaigns and others-find equivalent practices in the online space, is there also room for the tactics of disruption and civil disobedience that are equally familiar from the realm of street marches, occupations, and sit-ins? With a historically grounded analysis, and a focus on early deployments of activist DDOS as well as modern instances to trace its development over time, The Coming Swarm uses activist DDOS actions as the foundation of a larger analysis of the practice of disruptive civil disobedience on the internet.
Parametrization of convective transport in the boundary layer and its impact on the representation of diurnal cycle of wind and dust emissions
Authors: Hourdin F. , Gueye M. , Diallo B. , Dufresne J.-L. , Menut L. , Marticoréna B. , Siour G. , Guichard F.
Published: October 2014

Abstract. We investigate the impact of the representation of the boundary layer transport in a climate model on the representation of the near surface wind and dust emission, with a focus on the Sahel/Sahara region. We show that the combination of vertical turbulent diffusion with a representation of the thermal cells of the convective boundary layer by a mass flux scheme leads to a more realistic representation of the diurnal cycle of wind in spring, with a maximum near surface wind in the morning. This maximum occurs when the thermal plumes reach the low level jet that forms during the night at a few hundred meters above surface. The horizontal momentum in the jet is transported downward to the surface by compensating subsidences around thermal plumes in typically less than one hour. This leads to a rapid increase of wind speed at surface and therefore of dust emissions owing to the strong non linearity of emission laws. The numerical experiments are performed with a zoomed and nudged configuration of the LMDZ general circulation model, coupled to the emission module of the CHIMERE Chemistry Transport Model, in which winds are relaxed toward that of the ERAI reanalyzes. The new set of parameterizations leads to a strong improvement of the representation of the diurnal cycle of wind when compared to a previous version of LMDZ as well as to the reanalyzes used for nudging themselves. It also reinforces dust emissions in better agreement with observations, but the aerosol optical thickness is still significantly underestimated.
Sources and contributions of wood smoke during winter in London: assessing local and regional influences
Authors: Crilley L. R. , Bloss W. J. , Yin J. , Beddows D. C. S. , Harrison R. M. , Allan J. D. , Young D. E. , Flynn M. , Williams P. , Zotter P. , H. Prevot A. S. , Heal M. R. , Barlow J. F. , Halios C. H. , Lee J. D. , Szidat S. , Mohr C.
Published: October 2014

Abstract. Determining the contribution of wood smoke to air pollution in large cities such as London is becoming increasingly important due to the changing nature of domestic heating in urban areas. During winter, biomass burning emissions can exceed the contributions from traffic emissions, and have been identified as a major cause of exceedences of European air quality limits. The aim of this work was to quantify the contribution of biomass burning in London to concentrations of PM2.5 and determine whether local emissions or regional contributions were the main source of biomass smoke. To achieve this, a number of biomass burning chemical tracers were analysed at a site within central London and two sites in surrounding rural areas. Concentrations of levoglucosan, elemental carbon (EC), organic carbon (OC) and K+ were generally well correlated across the three sites. At all the sites, biomass burning was found to be a source of OC and EC, with the largest contribution of EC from traffic emissions, while for OC the dominant fraction likely included contributions from secondary organic aerosols, primary biogenic and cooking sources. Source apportionment of the EC and OC using average source ratios from published data was found to give reasonable estimation of the total carbon from non-fossil and fossil fuel sources based upon comparison with estimates derived from 14C analysis. Black carbon (BC) data from 2 and 7 wavelength Aethalometers were also apportioned into the contributions from biomass burning and traffic, based upon the enhanced absorption of wood smoke at UV wavelengths compared to BC. While the source apportionment of BC using this approach found similar trends to that observed for EC, higher percentage contributions of wood burning to BC were estimated. Based on a wood smoke mass conversion factor for levoglucosan, mean wood smoke mass at the sites was found to range from 0.78–1.0 μg m−3 during the campaign in January–February 2012. Measurements on a 160 m tower in London suggested a similar ratio of brown to black carbon (reflecting wood burning and traffic respectively) in regional and London air. Peaks in the levoglucosan and K+ concentrations were observed to coincide with low ambient temperature, consistent with domestic heating as a major contributing local source in London. Overall, the source of biomass smoke in London was concluded to be a background regional source overlaid by contributions from local domestic burning emissions. This could have implications when considering future emission control strategies during winter and may be the focus of future work in order to better determine the contributing local sources.
Experimental drought induces short-term changes in soil functionality and microbial community structure after fire in a Mediterranean shrubland
Authors: Hinojosa M. B. , Parra A. , Laudicina V. A. , Moreno J. M.
Published: October 2014

Abstract. Fire is a major ecosystem driver, causing significant changes in soil nutrients and microbial community structure and functionality. Post-fire soil dynamics can vary depending on rainfall patterns, although variations in response to drought are poorly known. This is particularly important in areas with poor soils and limited rainfall, like arid and semiarid ones. Furthermore, climate change projections in many such areas anticipate reduced precipitation and longer drought, together with an increase in fire severity. The effects of experimental drought and fire were studied on soils in a Mediterranean Cistus-Erica shrubland in Central Spain. A replicated (n = 4) field experiment was carried out in which four levels of rainfall pattern were implemented by means of a rain-out shelters and irrigation system. The treatments were: environmental control (natural rainfall), historical control (long-term average rainfall, 2 months drought), moderate drought (25% reduction of historical control, 5 months drought) and severe drought (45% reduction, 7 months drought). After one growing season, the plots were burned with high fire intensity, except a set of unburned plots that served as control. Soils were collected seasonally during one year and variables related to soil nutrient availability and microbial community structure and functionality were studied. Burned soils increased nutrient availability (P, N, K) with respect to unburned ones, but drought reduced such an increase in P, while it further increased N and K. Such changes in available soil nutrients were short-lived. Drought caused a further decrease of enzyme activities, carbon mineralization rate and microbial biomass. Fire decreased the relative abundance of fungi and actinomycetes. However, fire and drought caused a further reduction in fungi, with bacteria becoming relatively more abundant. Arguably, increasing drought and fires due to climate change will likely shift soil recovery after fire.
Transferring the concept of minimum energy dissipation from river networks to subsurface flow patterns
Authors: Hergarten S. , Winkler G. , Birk S.
Published: October 2014

Abstract. Principles of optimality provide an interesting alternative to modeling hydrological processes in detail on small scales and have received growing interest in the last years. Inspired by the more than 20 years old concept of minimum energy dissipation in river networks, we present a corresponding theory for subsurface flow in order to obtain a better understanding of preferential flow patterns in the subsurface. The concept describes flow patterns which are optimal in the sense of minimizing the total energy dissipation at a given recharge under the constraint of a given total porosity. Results are illustrated using two examples: two-dimensional flow towards a spring with a radial symmetric distribution of the porosity and dendritic flow patterns. The latter are found to be similar to river networks in their structure and, as a main result, the model predicts a power-law distribution of the spring discharges. In combination with two data sets from the Austrian Alps, this result is used for validating the model. Both data sets reveal power-law-distributed spring discharges with similar scaling exponents. These are, however, slightly larger than the exponent predicted by the model. As a further result, the distributions of the residence times strongly differ between homogeneous porous media and optimized flow patterns, while the mean residence times are similar in both cases.