bluuebunny/crossref_metadata_2025 huggingface dataset:
High Temperature CMOS Circuits on Silicon Carbide
Authors: Ramsay E. , Breeze James , Clark David T. , Murphy A. , Smith D. , Thompson R. , Wright Sean , Young R. , Horsfall A.
Published: July 2015

This paper presents the characteristics and performance of a range of Silicon Carbide (SiC) CMOS integrated circuits fabricated using a process designed to operate at temperatures of 300°C and above. The properties of Silicon carbide enable both n-channel and p-channel MOSFETS to operate at temperatures above 400°C [1] and we are developing a CMOS process to exploit this capability [4]. The operation of these transistors and other integrated circuit elements such as resistors and contacts is presented across a temperature range of room temperature to +400°C. We have designed and fabricated a wide range of test and demonstrator circuits. A set of six simple logic parts, such as a quad NAND and NOR gates, have been stressed at 300°C for extended times and performance results such as propagation delay drive levels, threshold levels and current consumption versus stress time are presented. Other circuit implementations, with increased logic complexity, such as a pulse width modulator, a configurable timer and others have also been designed, fabricated and tested. The low leakage characteristics of SiC has allowed the implementation of a very low leakage analogue multiplexer showing less than 0.5uA channel leakage at 400°C. Another circuit implemented in SiC CMOS demonstrates the ability to drive SiC power switching devices. The ability of CMOS to provide an active pull up and active pull down current can provide the charging and discharging current required to drive a power MOSFET switch in less than 100ns. Being implemented in CMOS, the gate drive buffer benefits from having no direct current path from the power rails, except during switching events. This lowers the driver power dissipation. By including multiple current paths through independently switched transistors, the gate drive buffer circuit can provide a high switching current and then a lower sustaining current as required to minimize power dissipation when driving a bipolar switch.
Study of the Stability of 4H-SiC Detectors by Thermal Neutron Irradiation
Authors: Issa Fatima , Ottaviani Laurent , Vervisch Vanessa , Szalkai Dora , Vermeeren Ludo , Lyoussi A. , Kuznetsov Andrej , Lazar Mihai , Klix Axel , Palais Olivier , Ferone R. , Hallén Anders
Published: July 2015

Two types of 4H-SiC semiconductor detectors (D1 and D2) are realized based on ion implantation of 10B inside the aluminum metallic contact. The first detector shows a high leakage current after 10B implantation and low signal to noise ratio. However, improvements concerning the implantation parameters led to lower leakage current and thus to higher signal to noise ratio. Moreover such detectors show their stability under different thermal neutron fluxes showing the reproducible features of the pulse height spectra and same electrical behaviour before and after irradiation.
Full SiC DCDC-Converter with a Power Density of more than 100kW/dm3
Authors: Kreutzer Otto , März Martin , Nakata Hideki
Published: July 2015

This Paper describes a non-isolated bidirectional full SiC 800V 200kW DCDC-converter power stage for electric and hybrid vehicles that reaches a power density of more than 100 kW/dm3 at a switching frequency of 200 kHz. The high power density is achieved by the use of SiC-MOSFETs sintered on custom made Si3N4 DCB-substrates controlled by custom made extremely flat drivers and a resulting very low inductive DC-link connection. All passive components like inductors and capacitor boards are custom made in order to keep all parasitic effects as low as possible. The power is subdivided on six interleaved phases to reduce the required capacitor ripple current capability.
Design and Characterization of 500 °C Schmitt Trigger in 4H-SiC
Authors: Kargarrazi Saleh , Lanni Luigia , Zetterling Carl Mikael
Published: July 2015

Two versions of Schmitt trigger, an emitter-coupled and an operational amplifier (opamp)-based, are implemented in 4H-SiC bipolar technology and tested up to 500 °C. The former benefits the simplicity, smaller footprint, and fewer number of devices, whereas the latter provides better promise for high temperature applications, thanks to its more stable temperature characteristics. In addition, the measurements in the range 25 °C - 500 °C, shows that the opamp-based version provides negative and positive slew rates of 4.8 V/µs and 8.3 V/µs, ~8 and ~3 times higher than that of the emitter-coupled version, which are 1.7 V/µs and 1 V/µs.
Improved Planar MOS Barrier Schottky (PMBS) Rectifier with High-k Dielectrics
Authors: Song Qing Wen , Zhang Yu Ming , Tang Xiao Yan , Wang Yu Hu , Yuan Hao , Zhang Yi Men
Published: July 2015

In this paper, an improved planar MOS barrier Schottky (PMBS) rectifier is proposed which utilizes the PECVD deposited high-k semi-insulating polycrystalline silicon (SIPOS) as the MOS area gate dielectrics for the first time. By adopting the high-k SIPOS as the MOS gate dielectrics, the peak electric field at the interface betwwen dielectrics layer and SiC can be significantly relieved and the device reliability can obviously enhanced without considerable degradation of on-state characteristics. With the optimized the thickness of the SIPOS film, the breakdown voltage (BV) of 1500V for the fabricated device was achieved, which is approximately corresponds to 85% of the theoretical parallel plane breakdown voltage value calculated from the used epilayer structure. And the specific on-state resistance (RSP-ON) is about 4.2mΩ•cm2. The corresponding figure-of-merit of VB2/ RSP-ON for the proposed device is 535.7MW/cm2.
Nanoscale Dynamic Mechanical Analysis on Heat-Resistant Silsesquioxane Nanocomposite for Power-Device Packaging
Authors: Nagao Shijo , Fujisawa Naoki , Sugioka Takuo , Ogawa Satoshi , Fujibayashi Teruhisa , Wada Takaaki , Sugahara Tohru , Suganuma Katsuaki
Published: July 2015

Heat-resistance of novel mold compound made of silsesquioxane nanocomposite with silica fillers is demonstrated in a TO247 package of SiC SBD. The test specimens are exposed to thermal cycling between -50°C and 250°C, and the thermal damage of the mold are precisely evaluated by using nanoscale dynamical mechanical analysis based on nanoindentation technology. The results reveal that the excellent heat-resistance is brought by the miscibility between the thermosetting nanocomposite and silica fillers.
RHEED Study of Epitaxial Graphene on Conductive and Semi-Insulating 6H-SiC (0001) Substrates
Authors: Kotousova Irina S. , Lebedev Sergey P. , Lebedev Alexander A.
Published: July 2015

The technique of reflection high-energy electron diffraction (RHEED) has been applied to study the graphene growth on conductive and semi-insulating 6H-SiC (0001) substrates using two RHEED devices. It was found the oriented growth of graphene on the conductive wafer and both oriented as disordered graphene growth on semi-insulating wafer due to the partial formation of polycrystalline component in nanocarbon film. It was shown that the appearance of the graphene polycrystalline phase was caused by the lower perfection structure of the surface of the semi-insulating substrate as compared to the conductive substrate.
Raman Spectra and Strain Uniformity of Epitaxial Graphene Grown on SiC(0001)
Authors: Hu Yan Fei , Guo Hui , Zhang Yu Ming , Zhang Yi Men
Published: July 2015

Large-area epitaxial graphene formed on C-face SiC has been investigated by Raman Spectroscopy and SEM (scanning electron microscopy). Local Raman spectra showed a large homogeneous area of high quality epitaxial FLG (few layer graphene) has been fabricated on C-face SiC. Our work reveals unexpectedly the shift in Raman peak position across the samples resulting from the inhomogeneity in the strains and impurities of the graphene films, which we exhibit to be correlated with physical topography by combining Raman spectroscopy with scanning electron microscopy (SEM)
Assessment of SiC Crystal Chemistry during the PVT Growth Process: Coupled Numerical Modeling and Thermodynamics Approach
Authors: Ariyawong Kanaparin , Chatillon Christian , Blanquet Elisabeth , Dedulle Jean Marc , Chaussende Didier
Published: July 2015

Numerical simulation appeared till now as the only tool able to describe the SiC growth by PVT process, while the chemistry of the Si-C system and its coupling to mass transfer were not considered in a satisfactory way. To assess the chemistry of SiC crystal, the coupling of numerical and thermodynamic calculations computed by FEM, and by treating SiC as a solid solution, respectively, is presented. This enables the possibilities to control the activity of each component in SiC crystal during the growth. The link between growth conditions and SiC crystal chemistry could be one of the key issues to link the growth and the occurrence of cubic or hexagonal polytypes.
Influence of Diamond CVD Growth Conditions and Interlayer Material on Diamond/GaN Interface
Authors: Izak Tibor , Babchenko Oleg , Jirásek Vít , Vanko Gabriel , Vojs Marián , Kromka Alexander
Published: July 2015

In this study we present the diamond deposition on AlGaN/GaN substrates focusing on the quality of the diamond/GaN interface. The growth of diamond films was performed using microwave chemical vapour deposition system in different gas mixtures: standard CH4/H2 (at low and high ratio of CH4 to H2) and addition of CO2 to CH4/H2 gas chemistry. The diamond films were grown directly on GaN films either without or with thin interlayer. As interlayer, 100 nm thick Si3N4 was used. Surprisingly, in the case of standard CH4/H2 gas mixture, no diamond film was observed on the GaN with SiN interlayer, while adding of CO2 resulted in diamond film formation of both samples with and without SiN interlayer. Moreover, adding of CO2 led to higher growth rate. The morphology of diamond films and the quality of the diamond/GaN interface was investigated from the cross-section images by scanning electron microscopy and the chemical character (i.e. sp3 versus sp2 carbon bonds) was measured by Raman spectroscopy.
Electrical Properties of Graphene Contacts to AlGaN/GaN Heterostructures
Authors: Fisichella Gabriele , Greco Giuseppe , Roccaforte Fabrizio , Giannazzo Filippo
Published: July 2015

A nanoscale electrical characterization of graphene (Gr) contacts to AlxGa1-xN/GaN heterostructures has been carried out using conductive atomic force microscopy. The impact of the AlGaN microstructure on the current transport at Gr/AlGaN interface was evaluated considering two Al0.25Ga0.75N/GaN heterostructures with very different quality in terms of surface roughness and defectivity, i.e. a uniform and defect-free sample and a sample with a high density of V-defects, that locally cause a reduction of the AlGaN thickness. Rectifying contacts were found on the bare (Gr-free) AlGaN surfaces of both samples, but with a more inhomogeneous and lower Schottky barrier height (ΦB≈0.6 eV) in the presence of V-defects with respect to the case of the uniform AlGaN (ΦB≈0.9 eV). Very different electrical behaviour was observed for Gr on the two AlGaN samples, i.e. a low barrier height Schottky contact (ΦB≈0.4 eV) for the uniform AlGaN and an Ohmic contact for the defective AlGaN. Both Schottky and ohmic Gr/AlGaN contacts exhibit an excellent lateral uniformity, that can be ascribed to an averaging effect of the Gr electrode over the AlGaN interfacial inhomogeneities.
Quasistatic Magnetic Properties and Dynamic Hysteretic Losses in (La,Sr)MnO3 Nanoparticles Fabricated by Different Technological Routes
Authors: Tovstolytkin Alexander I. , Solopan S.O. , Kalita V.M. , Ryabchenko S.M. , Belous Anatolii G.
Published: July 2015

Structural and magnetic characteristics of (La,Sr)MnO3 nanoparticles synthesized by different methods have been studied in the work. The specific loss power which is released on the exposure of an ensemble of synthesized particles to alternating magnetic field was calculated and measured experimentally. The contributions to the specific loss power resulted from different heating mechanisms have been discussed. The directions to enhance the heating efficiency of various kinds of magnetic nanoparticles are outlined
Synthesis of Iron Oxide Nanoparticles by Different Methods and Study of their Properties
Authors: Yelenich O.V. , Solopan S.O. , Kolodiazhnyi T.V. , Greneche Jean Marc , Belous Anatolii G.
Published: July 2015

In this work, iron oxide nanoparticles have been synthesized by precipitation in diethylene glycol, by cryochemical synthesis, in microemulsions using surfactants Triton X-100, Brij-35 and CTAB. Comparative spectroscopic, thermal, X-ray diffraction, 57Fe zero-field Mössbauer and magnetic studies of the synthesized nanoparticles have been carried out. Magnetic fluids prepared from synthesized nanopowders have been characterized by calorimetric measurements of specific loss power (SLP).
Synthesis, Characterization and Electrochemical Properties of Mesoporous Maghemite γ-Fe2O3
Authors: Kotsyubynsky Volodymyr , Ostafiychuk Bogdan , Moklyak Volodymyr , Hrubiak Andrii
Published: July 2015

Mesoporous maghemite γ-Fe2O3 was obtained by thermal decomposition of iron citrate xerogel hydrate. The influence of precursor molar concentration and calcination temperature on the material phase composition, morphology, crystalline and magnetic microstructure, surface condition and optical properties was studied. The model of mesoporous γ-Fe2O3 formation is proposed. Obtained maghemite was tested as cathode material for lithium power sources. Increase of lithium power sources specific capacity and energy with the samples specific surface area enlarging is determined. Two kinetic processes are observed during discharge processes: lithium accumulation at the cathode material/electrolyte interface and diffusion of lithium ions into the material crystal structure. The diffusion coefficients of lithium in the cathode material on the different stages of discharge process are calculated.
Preparation and Properties of Nanocomposites of Silicon Oxide in Porous Silicon
Authors: Olenych Ihor , Tsizh Bohdan , Monastyrskii Lubomyr , Aksimentyeva Olena , Sokolovskii Bohdan
Published: July 2015

The composition of the surface and electrical properties of silicon oxide nanocomposites of porous silicon were investigated by FTIR spectroscopy in the range of 400 – 4000 cm-1and by impedance spectroscopy in the frequency range of 25 Hz – 1 MHz. It was revealed the different dispersion of electrical capacitance in different frequency bands and the complex relaxation processes that affect the electrical transport properties of nanocomposites. The correlations between the IR absorption spectra of silicon oxide composites and processes of charge transfer was defined. On the basis of analysis of spectra of thermal stimulated depolarization it was shown that oxidation of the surface of porous silicon nanocrystals gives rise to changing the density of states in different energy ranges.
Synthesis, Characterization and EPR Investigation of γ-Induced Defects of Nanoparticles of (MI, CO3)-Containing Apatites (MI – Na, K)
Authors: Strutynska Nataliia , Slobodyanik Nikolai , Malyshenko Anna , Zatovsky Igor , Vorona Igor , Prylutskyy Yuriy , Prymak Oleg , Baran Nikolai , Ishchenko Stanislav , Nosenko Valentyna
Published: July 2015

The nanoparticles of (Na, CO3)- and (K, CO3)-containing Calcium phosphates have been prepared by a wet precipitation method in aqueous media. The influence of nature of alkaline metal and of samples composition on particles size and peculiars of their thermal transformation have been studied using such physical-chemical methods as FTIR, XRD, SEM and TPM MS analysis. Chemical composition of powders have been determined by ICP analysis and the degree of substitution of Calcium atoms by alkaline metals depends on CO32-/PO43- molar ratio in initial solutions. The differences in the formation of γ-induced defects in (Na, CO3)- and (K, CO3)-containing apatites have been found using EPR spectroscopy.
Study of Temperature Behavior of Luminescence Emission of LaVO4 and La1-xEuxVO4 Powders
Authors: Chukova Oksana , Nedilko Sergiy G. , Nedilko Sergiy A. , Voitenko Tetiana , Gomenyuk Olga , Sheludko Vadym
Published: July 2015

The La1‑xEuxVO4 powders were synthesized by co-precipitation method. Emission spectra of the LaEuVO4 and La1‑xEuxVO4 powders consist of wide non-structural bands of the matrix emission and narrow spectral lines caused by inner f-f electron transitions in the Eu3+ ions, respectively. The both types of emission were studied within 8 – 300 K temperature range. Decomposition of spectra of the wide matrix emission on three bands has been carried out and temperature dependencies for each band were studied. Temperature behavior of the Eu3+ emission was investigated for lines assigned to different Eu3+ centres. Obtained dependencies are analyzed and discussed using proposed schemes of transitions in the VO43- groups and structure of the nearest surrounding of the Eu3+ emission centres.
Luminescence of ZnMoO4 Crystals Developed for the LUMINEU Double Beta Decay Experiment
Authors: Degoda V.Ya. , Danevich F.A. , Coron N. , Ivanov I.M. , Kogut Ya.P. , Makarov E.P. , de Marcillac P. , Nasonov S.G. , Torres L. , Tretyak V.I. , Shlegel V.N. , Vasiliev Ya.V. , Velazquez M. , Zhdankov V.N.
Published: July 2015

Scintillation efficiency of ZnMoO4 crystals is one of the main characteristics for application in cryogenic double beta decay experiments. Luminescence of ZnMoO4 crystals developed from deeply purified molybdenum under X-ray irradiation of different doses was studied in the temperature interval from 1.4 K to 295 K. Emission spectra, dependence of luminescence intensity on dose and temperature, phosphorescence and thermally stimulated luminescence were investigated. Two emission bands were identified: recombination luminescence at ~ 600 nm and exciton luminescence at ~ 500 nm. We have found that concentration of shallow traps in the material is much greater than the concentration of deep traps. Furthermore only shallow traps absorb a small part of the luminescence and cause the low scintillation efficiency of the sample.
Evolution of I-V Characteristics and Photo Effects of Heterojunction LBMO/ZnO Prepared by IBS
Authors: Mori Toshiki , Yokura Miyoshi , Matsui Masahito , Reddy S. Lakshmi , Reji Philip , John Rita , Nishikawa Hiroaki , Iwata Nobuyuki , Nakamura Yoshinobu , Kaneko Satoru , Endo Tamio
Published: July 2015

The hetero p-n junctions of LBMO/ZnO were fabricated by ion beam sputtering. The sample shows clear temperature-dependent rectifying current (I)-voltage (V) characteristics, and junction resistance vs temperature curve is reflected by the CMR nature based on DEC model. The sample shows two-step switching, then theI-Vis composed of very-low-resistance (VLR), low-resistance (LR) and high-resistance (HR) regions. The wholeI-Vbehavior is changed by measurement running current. The switching is caused by the spot current, and the original VLR is restored when the current is reduced. The mechanism of switching is proposed in terms of the percolation paths composed of metallic FM-grains. Photo illumination effect on theI-Vwas investigated. The currents are increased in VLR and HR regions by the illumination. Two origins are possible, electronic process due to hole injection, and phase process. The percolation path might be reinforced by the light.
Complex Impedance Analyses of Ba1-xLi0.5xBi0.5xTiO3 Solid Solution PTCR Ceramics
Authors: Plutenko Tatiana , V'yunov Oleg , Plutenko Dmytro , Belous Anatolii , Makovec Darko
Published: July 2015

Conditions for the formation of (1-x)BaTiO3–xLi0.5Bi0.5TiO3 (0 ≤ x ≤0.6) solid solutions with positive temperature coefficient of resistance (PTCR) effect were studied. Solid solutions were prepared by solid state reaction technique. Samples were sintered under reducing atmosphere N2/H2 in the temperature range 1200–1450 °C with subsequent oxidation in air. The phase composition was investigated by X-ray powder diffraction method. It was found that samples of (1-x)BaTiO3–xLi0.5Bi0.5TiO3 (0 ≤ x ≤0.6) solid solutions at room temperature exhibit perovskite structure. Unit cell parameters of unstable at the room temperature compound Li0.5Bi0.5TiO3 were determined by extrapolation of concentration dependence of the unit cell parameters in the (1-x)BaTiO3–xLi0.5Bi0.5TiO3 system. It was shown that minimum value of resistivity ρmin rises with increase in x value. Complex impedance method shown that ceramic grains of (1-x)BaTiO3–xLi0.5Bi0.5TiO3 materials consist of three areas with different electrical properties. Boundary and outerlayer region of grains make the main contribution to the PTCR effect in lithium-containing solid solutions. It was shown that magnitude of the potential barrier's decreases with increasing x.
Substituted Bi-2212 and Bi-2223 HTSC
Authors: Shcherban Oleg , Gladyshevskii Roman E. , Giannini Enrico , Dhallé Marc
Published: July 2015

Formation of bismuth-based high-Tc superconducting ceramics 2212 and 2223 with partial replacement of Bi by p-elements of group III (Ga, In, Tl), IV (Ge, Sn, Pb), or V (Sb) was studied. XRPD, DTA/TG, SEM/EDX, SQUID, and VSM were used for phase identification, structural analysis, grain morphology studies, chemical analysis and magnetic measurements.
Phase Composition and Catalytic Activity of Nanostructured Materials Based on Solid Component of Welding Aerosol
Authors: Rakitskaya Tatyana L. , Truba Alla S. , Ennan A.A. , Kiro S.A. , Volkova V.Ya.
Published: July 2015

The comparison of the phase compositions and catalytic properties of the solid components of welding aerosol (SCWAs) obtained as a result of metal welding by two types of electrodes, ANO-4 and TsL‑11 was made. Their phase compositions were investigated by X-ray diffraction phase analysis, IR spectroscopy, and pH-metry. The catalytic properties of SCWAs were studied in the low-temperature reaction of ozone decomposition. Both SCWA samples were found to purify the ozone-air mixtures (OAM) from ozone at its concentration of 1 mg/m3 to the levels below the maximum permissible concentration (MPCO3) however the protective time of SCWA-ANO-4 (50 h) was higher than that of SCWA-TsL-11 (3 h) because of the differences in their compositions
Photomagnetic Medium as Weak Magnetic Field Sensor
Authors: Tychko Oleksandr
Published: July 2015

Photoinduced nucleation in an external magnetic field is investigated. A possibility of a week magnetic field strength measurement is showed.
Structural Behaviour of EuCoO3 and Mixed Cobaltites-Ferrites EuCo1−xFexO3
Authors: Pekinchak Olia , Vasylechko Leonid , Berezovets Vasyl , Prots Yurii
Published: July 2015

Crystal structure of the mixed cobaltites-ferrites EuCo1−xFexO3, obtained by solid state reaction in air at 1573 K, has been studied by means of X-ray powder diffraction technique. It was found that all samples synthesized adopt orthorhombic perovskite structure. Obtained values of structural parameters indicate formation of continuous solid solution in the EuCoO3−EuFeO3 system. Thermal behaviour of the EuCoO3 structure has been investigated in the temperature range of 298–1173 K by means of in situ high-resolution powder diffraction technique applying synchrotron radiation. Strong anomalies in the lattice expansion have been detected between 580 K and 800 K, which are evidently connected with the transitions of Co3+ ions to the higher spin states and further metal-insulator transition occurred in EuCoO3 at about 600 K.
Structural Behaviour of Solid Solution in the SmAlO3−TbAlO3 System
Authors: Ohon Natalja , Vasylechko Leonid , Prots Yurii , Schmidt Marcus , Syvorotka I.I.
Published: July 2015

Phase and structural behaviour in the SmAlO3–TbAlO3system has been studied in a whole concentration range by means of laboratory X-ray diffraction,in situhigh temperature synchrotron powder diffraction and differential thermal analysis. Formation of the continuous solid solution Sm1−xTbxAlO3with the orthorhombic perovskite structure (space groupPbnm) has been established. Peculiarity of the investigated system is lattice parameter crossovers resulted in the existence of three regions with different relations of the lattice parameters. Based on the results obtained, as well as an available literature data for the “pure” SmAlO3and TbAlO3, a phase diagram of the pseudo-binary SmAlO3–TbAlO3system has been constructed.
Synthesis, Luminescence and Electronic Band Structure of Al(PO3)3 Crystals
Authors: Boyko Volodymyr , Nedilko S.G. , Hizhnyi Yuriy , Chornii Vitalii , Terebilenko Kateryna , Zatovsky Igor , Gomenyuk Olga , Sheludko Vadym
Published: July 2015

The crystals of aluminium metaphosphate Al(PO3)3 are synthesized by flux method. The photoluminescence properties of Al(PO3)3 are studied under the vacuum ultra violet (VUV) synchrotron excitations. The electronic structure of Al(PO3)3 crystal is calculated by the full-potential linear-augmented-plane-wave (FLAPW) method. The photoluminescence (PL) emission spectra of of aluminium metaphosphate reveal emission bands in the ultraviolet-blue and in the yellow-red spectral regions. Obtained results point to an active role of the electronic states of phosphate groups in the processes of intrinsic luminescence in Al(PO3)3 crystals.
Li+-Doping-Induced Changes of Phase Composition in Electrodeposited Manganese(IV) Oxide Materials
Authors: Sokolsky Georgii V. , Ivanov Sergii V. , Boldyrev Eudgene I. , Ivanova Natalya D. , Lobunets Tatyana F.
Published: July 2015

The impact of Li+dopant-ions in fluorine-containing electrolytes on electrodeposited manganese (IV) oxide material was under investigation in this paper. The dependence of phase composition of this material at Li+-concentration range in the electrolyte below the stoichiometric content of lithium in hollandite A2Mn8O16(Mn:Li ≈ 4:1) was established. The hollandite phase stabilization as a template effect caused by Li+-ions is gradually reduced with the Li+concentration growth from 0.025 to 0.15mol∙L-1LiOH concentration range. The hollandite content sharply drops at close to the stoichiometric Mn:Li ratio for the hollandite phase. In contrary, the concentration of cation-deficient ε-MnO2becomes significant. Thus, the template effect of Li+cations at electrolytic doping from fluorine-containing electrolytes consists of stabilization of the hollandite tunnels at longer distance with the size of coherent scattering regions of this phase more than of about 20—50 Å comparing with undoped materials. It is supposed that Li+-ions presence makes tunnel space unavailable unlike water molecules or ammonium cations. Therefore, to realise molecular sieves based on manganese (IV) oxides the availability of tunnels should be taken into account.
Recrystallization Behaviour of Plane Strain Deformed Al-Mn-Mg-Sc-Zr Alloy
Authors: Miszczyk Magdalena M. , Paul Henryk
Published: July 2015

Early stages of recrystallization were observed for the Al-Mn-Mg-Zr(Sc) aluminium alloy containing a fine second phase particles. The samples were plane strain compressed to 40%, 60% and 83% and then annealed. The processes of the recovery and the nucleation of new grains were analysed with the use of scanning electron microscopy equipped with a high resolution electron backscattered diffraction facility. The deformed alloy contained a structure of flat grains situated parallel to the compression plane. After annealing, the structure coarsened. However, the growth of the new grains was strongly hindered by the presence of particles, and the elongated shape of the deformed grains was conserved up to the later stages of recrystallization. In the case ofthe samples deformed up to 40%, the structure was transformed by the mechanism of continuous recrystallization, whereas, in the case of the samples deformed up to 60% or 83%, both mechanisms- of continuous and discontinuous recrystallization - were valid. A particular role in the rise of thenuclei and the structure spheroidization is attributed to the thermally activated migration of the low-angle grain boundaries and the movement of the dislocations stored inside the cells. This leads to an increase of the misorientation angles across the pre-existing low-angle boundaries.
Application of Scanning Electron Microscopy and EDS Microanalysis for Microstructural Investigation of Hypoeutectoid Steel
Authors: Rożniata Edyta , Zasada Dariusz
Published: July 2015

The results of a microstructure, energy dispersive X-ray spectroscopy (EDS) analysis and hardness investigations of the hypoeutectoid steels with 1% Ni, imitating by its chemical composition toughening steels, are presented in the paper. According to PN-EN 10027 standard this steel should have a symbol 37NiMo4-3.The kinetic of phase transformation of undercooled austenite of investigated steel was presented on CCT diagram (continuous cooling transformation). The CCT diagram of tested steel is characterized in that the curves of beginning of the diffusion transitions form a letter "C" and are not separated from bainitic transformation by the stability range of the undercooled austenite.The EDS analysis performed for the selected cooling rates did not reveal any changes in the distribution of alloying elements of hypoeutectoid 37NiMo4-3 steel. However, these studies, from the point of view of the effect of alloying elements (acting jointly) are only the preliminary assessment analysis (beginning) of the impact of the chemical composition gradient in micro-scale in iron-based alloys.
Microstructural Investigations of Cracks in Turbine Wheels in Car Engine Turbochargers
Authors: Krawiec Sebastian , Krawczyk Łukasz
Published: July 2015

The turbine wheel is the most affected element in passenger car turbochargers. In order to meet the requirements for the high temperature corrosion, vibrations and the mechanical resistance in the oxidizing environment of the exhaust gases, the turbine wheel is produced from polycrystalline nickel based superalloys, Inconel 713C in the as-cast condition. In this work the methods and results of turbine wheel failure analysis are presented. For this type of research, correlative microscopy, light microscope Axio Imager Z2m (LM), scanning electron microscope Zeiss Ultra Plus with field emission (FESEM) equipped with EDX detector and stereoscopic microscope were used. The results of this work suggest that the Inconel 713C turbine wheel was damaged by two factors: fatigue cracking at low frequencies and grain boundaries oxidation.
Application of Peltier Cooling Device in a Variable-Pressure SEM
Authors: Wassilkowska Anna , Woźniakiewicz Teresa
Published: July 2015

In environmental monitoring and water protection one has to deal with various hydrated specimens, and therefore, there is a need for scanning electron microscopes which are suited for hydrated specimens. Wet specimens can be observed in a hydrated state using a commercial Peltier cooling holder for conventional microscopes. However, the optimization of the time of observation for the sample needs to be determined by carrying out experiments in advance for specifically determining the optimal observation time. The temperature-pressure conditions also require optimization to obtain good quality images of amoeba and fungi. Further studies are required to establish whether the same imaging conditions would be possible to replicate closely the observation on other biological specimens.
Application of Electron Microscopy to Investigation of Corrosion of Mg-Al Alloys in Various Electrolyte Solutions
Authors: Chmiela Bartosz , Mościcki Adrian , Sozańska Maria
Published: July 2015

The Mg-Al alloys are the best-known and most commonly used magnesium alloys (especially AZ91 alloy). However, the AZ91 alloy offers insufficient corrosion resistance. Many investigations show that hydrogen is the main corrosive factor appearing during chemical reactions between magnesium and water in electrolyte solution. The main intermetallic phase in the AZ91alloy is the Mg17Al12 (β phase), which is a hydrogen trap. During corrosion, magnesium hydride forms inside the β phase, and this phase is brittle fractured when the inner stress caused by hydrogen pressure and expansion stress due to the formation of magnesium hydride is higher thanthe fracture strength. We examined the corrosion behaviour of AZ91 and AE44 magnesium alloysin 0.1M Na2SO4 solution and 3.5% NaCl solution. We analysed two Mg-Al alloys in order todetermine the various effects of hydrogen on these materials.
Microstructural Features of Cu-Zn Single Crystals Deformed at Elevated Temperature
Authors: Grzegorczyk Barbara , Ozgowicz Wojciech , Kalinowska-Ozgowicz Elżbieta , Kowalski Aleksander
Published: July 2015

Copper alloys are characterized by high plasticity and good resistance to corrosion. They are applied in electrical industry, telecommunication, in transport and machine building, particularly in the production of elements for deep drawing. The scope of investigation enclosed production of testing single crystals, determination of their crystallographic orientation, deformation of selected single crystals by compression in a temperature range from 20 °C to 400 °C, applying strain rate from 10-5 s-1 to 10-1 s-1 as well as microstructure observations. Typical plastic strain effects were observed in the microstructures of studied single crystals in the form of parallel and intersecting lines and slip bands with locally intensified density in different areas of cross section of examined specimen and the deflection bands with slightly marked slip lines in the primary system.
The Effect of Additions of Zn and Zr on the Microstructure and Texture of Cast and Wrought Mg Alloys with Different Content of Ca
Authors: Boczkal Sonia , Lech-Grega Marzena , Żelechowski Janusz
Published: July 2015

The microstructure of magnesium alloys containing 1% and 2.5% Mg, as well as the addition of 6% Zn and 0.6% Zr was examined in as-cast and as-extruded condition. After the casting process, the presence of Mg2Ca and Ca2Mg6Zn3 phases was determined by means of the scanning electron microscopy (SEM) and X-ray diffractometry (XRD). The microstructure of MgCa0.8Zn6.1Zr0.6 and MgCa2.8Zn6.1Zr0.6 alloys after the extrusion process revealed an impact of Zr addition on grain refinement. The electron backscatter diffraction (EBSD) analysis showed that, among all the tested alloys, the smallest grain size was found in the MgCa2.8Zn6.1Zr0.6 alloy and the mean grain diameter amounted to about 4 mm. The analysis of texture has indicated that the lattice planes most often parallel to the cross-sections of the examined magnesium rods are the crystal lattice planes (1 0-1 0).
Electron Microscopy Characterization of Friction Stir Welded 5083-H111 and 7075-T651 Aluminum Alloys
Authors: Kalemba Izabela , Kopyściański Mateusz
Published: July 2015

The microstructural characterization of butt friction stir welds of two different wrought aluminum alloys (work-hardened and heat treated) were studied. The detailed studies on the FSW process of dissimilar Al alloys are limited. In particular, the weld microstructure requires deeper characterization to better understand the phenomena occurring during mixing of dissimilar alloys.The characterization of friction stir welds was performed by scanning electron microscopy (an energy dispersive spectroscopy and an electron backscattered diffraction) and transmission electron microscopy. The dissimilar weld microstructure is complex, resembling a vortex-like structure. The microstructure of weld was highly asymmetrical with regard to the weld centerline. The research revealed a change in grain size in particular areas of the stirred zone. Recrystallization in the stirredzone occurred in particular areas in an irregular manner.
Effects of Heat Treatment on the Phase Evolution, Structural, and Magnetic Properties of Mo-Zn Doped M-Type Hexaferrites
Authors: Mahmood Sami H. , Aloqaily Aynour N. , Maswadeh Yazan , Awadallah Ahmad , Bsoul Ibrahim , Awawdeh Mufeed , Juwhari Hassan
Published: July 2015

In this article we report on the structural and magnetic properties of BaFe12-4xMoxZn3xO19hexaferrites with Mo-Zn substitution for Fe ions. The starting materials were commensurate with the BaM stoichiometry, and the Mo:Zn ratio was 1:3. The powder precursors were prepared by high energy ball milling, and subsequently sintered at temperatures from 1100 to 1300° C. The structural analyses indicated that all samples sintered at 1100° C were dominated by a major M-type hexaferrite phase. The relative abundance of the BaMoO4and Zn-spinel secondary phases increased with increasing the concentration of the substituents, resulting in a decrease of the saturation magnetization from about 67 emu/g (forx= 0.0) to 55 emu/g (forx= 0.3). The coercivity also decreased from 3275 Oe (forx= 0.0) to 900 Oe (forx= 0.3), demonstrating the ability to tune the coercivity to the range useful for magnetic recording by the substitution process. The saturation magnetization improved significantly with sintering atT> 1100° C, and the coercivity decreased significantly, signaling the transformation of the samples to soft magnetic materials. These magnetic changes were due to the high-temperature reaction of the spinel phase with the BaM phase to produce the W-type hexaferrite phase on the one hand, and to the growth of the particles on the other hand. The magnetic phases were further investigated using Mössbauer spectroscopy and thermomagnetic measurements. Our study indicated that the sample withx= 0.2 has the highest saturation magnetization (74 emu/g at sintering temperature of 1300° C) and a tunable coercivity between 2100 Oe and 450 Oe.
Scoring Systems for Outcome Prediction in a Cardiac Surgical Intensive Care Unit: A Comparative Study
Authors: Exarchopoulos Themistocles , Charitidou Efstratia , Dedeilias Panagiotis , Charitos Christos , Routsi Christina
Published: July 2015

Background

Most scoring systems used to predict clinical outcome in critical care were not designed for application in cardiac surgery patients.

Objectives

To compare the predictive ability of the most widely used scoring systems (Acute Physiology and Chronic Health Evaluation [APACHE] II, Simplified Acute Physiology Score [SAPS] II, and Sequential Organ Failure Assessment [SOFA]) and of 2 specialized systems (European System for Cardiac Operative Risk Evaluation [EuroSCORE] II and the cardiac surgery score [CASUS]) for clinical outcome in patients after cardiac surgery.

Methods

Consecutive patients admitted to a cardiac surgical intensive care unit (CSICU) were prospectively studied. Data on the preoperative condition, intraoperative parameters, and postoperative course were collected. EuroSCORE II, CASUS, and scores from 3 general severity-scoring systems (APACHE II, SAPS II, and SOFA) were calculated on the first postoperative day. Clinical outcome was defined as 30-day mortality and in-hospital morbidity.

Results

A total of 150 patients were included. Thirty-day mortality was 6%. CASUS was superior in outcome prediction, both in relation to discrimination (area under curve, 0.89) and calibration (Brier score = 0.043, χ2 = 2.2, P = .89), followed by EuroSCORE II for 30-day mortality (area under curve, 0.87) and SOFA for morbidity (Spearman ρ= 0.37 and 0.35 for the CSICU length of stay and duration of mechanical ventilation, respectively; Wilcoxon W = 367.5, P = .03 for probability of readmission to CSICU).

Conclusions

CASUS can be recommended as the most reliable and beneficial option for benchmarking and risk stratification in cardiac surgery patients.
Sjögren’s syndrome and mean platelet volume
Authors: Tezcan M. E. , Demir Ş. , Sargın M. , Aliustaoğlu M. , Göker B.
Published: July 2015

Not required
Systemic sclerosis sine scleroderma: a case report of anterior uveitis
Authors: Borges T. , Vilaça J. , Ferreira S. , Chora I. , Silva S. , Dias C.
Published: July 2015

Systemic sclerosis (SSc) sine scleroderma (ssSSc) is characterized by the absence of skin involvement, despite other manifestations of systemic sclerosis are present. It is not known whether sSSc represents a forme fruste of limited cutaneous SSc or a distinct entity, but the 2013 American College of Rheumatology/European League Against Rheumatism criteria for the classification of SSc have considered SSc without skin involvement to be a distinct subset. The authors present the case of a 70-year old female that was referred for a consultation for Raynaud’s phenomenon and a chronic anterior uveitis (CAU). She had a history of dysphagia, diffuse pulmonary emphysema and a biopsy-documented fibrosis of the upper lobes, and an idiopathic non-ischemic dilated cardiomyopathy with severe left ventricle systolic dysfunction and left bundle branch block. Anti-nuclear and anti-centromere antibodies were positive, while manometry revealed distal esophageal hypomotility. After establishing the diagnosis of ssSSc and starting immunosuppression, the ocular disease improved, while the lung and heart diseases remained stable. This case underlines that it is very important to suspect SSc when CAU is present and/or skin thickening is absent. To our knowledge, this is the first report of CAU in a patient with ssSSc.
Muscular Christianity in contemporary South Africa: The case of the Mighty Men Conference
Authors: Dube Siphiwe
Published: July 2015

Drawing on key aspects of Muscular Christianity identified through this movement’s literature, this article ventures that the major contemporary Evangelical Christian men’s movement in South Africa, the Mighty Men Conference (MMC), draws on and harkens back to the concerns of the Victorian era of Muscular Christianity. Moreover, the article argues that this reversion should be of concern in the context of a post-apartheid and postcolonial South Africa where both women’s rights and human rights (especially encompassing racial equality) now form the core of the country’s identity. In other words, the MMC’s call to men to reclaim their top position is problematic even while it comes from a place of concern regarding the changing role of men in a transitional South African landscape.
Lesions in canine stifle joints due to trochleoplasties as treatment for medial patellar luxation
Authors: Van der Zee Johannes Hans
Published: July 2015

Lesions in canine stifle joints after previous trochleoplasty surgery were documented. Infour clinical cases arthrotomies were performed due to stifle pain after previous trochleardeepening procedures. A small area of hyaline cartilage remained in the groove of the stiflesin cases where previous wedge trochleoplasties had been performed. All of the stifles hadsignificant areas of eburnation on the axial aspect of the medial trochlear ridge. The stifle jointsof a dog that was euthanased due to severe irreversible osteo-arthritis were photographed.The dog had undergone previous surgery for patellar luxation and cranial cruciate ligamentruptures. The trochlear grooves in this dog had almost no visible articular cartilage left.
Aerial surveys conducted along the Garden Route coastline, South Africa, to determine patterns in shore fishing effort
Authors: Smith M. Kyle S. , Kruger Nerina , Murray Taryn S.
Published: July 2015

Coastal environments provide a wide range of leisure opportunities, including recreational fishing. Understanding spatial and temporal fishing patterns is important in ensuring wise management and sustainable use. To provide information on shore angler effort and distribution, randomised aerial surveys of the Garden Route coast between the eastern border of the Tsitsikamma Marine Protected Area and the Kaaimans River mouth in the west were undertaken between December 2008 and November 2009. A total of 15 flights were conducted, with six flights taking place over weekends, two on public holidays and the balance on normal week days. Angler effort was not uniformly distributed along the coastline, and spatial analysis highlighted coastal areas both inside and outside marine protected areas that had increased angler effort. In general, fishing effort was highest around more densely populated areas and concentrated in areas with easy access. Although angler counts were highly variable, the seasonality of shore angling effort showed a slight increase during autumn and winter and angling effort was significantly higher on weekends.Conservation implications: Data obtained during these surveys can assist management with future conservation planning exercises, whilst also guiding daily law enforcement patrols to maximise angler encounters.
Exploring the significance of "Mudra and Bandha" in pelvic floor dysfunction
Authors: Rathore Mrithunjay , Agrawal Sarita , Nayak Prasanta Kumar , Sinha Manisha , Sharma Dhanyesh Kumar , Mitra Subarna
Published: July 2015

Pelvic floor dysfunction (PFD) is commonly associated with the weakness of pelvic floor muscles and the supporting connective tissue structures, which may lead to prolapse of the pelvic organs. There are various researches which have shown the significance of pelvic floor exercise (PFE) on the PFD. The last few years have seen a growing interest in the field of yoga. "Mudra" and "Bandha" are reported as pelvic floor yogic exercises (PFYEs) in the ancient Indian texts. These yogic exercises involve the coordination of breath, maintain the structural integrity of the pelvic floor, and thereby prevent PFD. It is recognized that all the female patients of PFD can be benefited from education on PFYE. So, in this article, we have tried to highlight the significance of PFYE in the preventive and therapeutic aspects of PFD.
Extending Seventh-Order Dissipative Compact Scheme Satisfying Geometric Conservation Law to Large Eddy Simulation on Curvilinear Grids
Authors: Jiang Yi , Mao Meiliang , Deng Xiaogang , Liu Huayong
Published: July 2015

Seventh-order hybrid cell-edge and cell-node dissipative compact scheme (HDCS-E8T7) is extended to a new implicit large eddy simulation named HILES on stretched and curvilinear meshes. Although the conception of HILES is similar to that of monotone integrated LES (MILES), i.e., truncation error of the discretization scheme itself is employed to model the effects of unresolved scales, HDCS-E8T7 is a new high-order finite difference scheme, which can eliminate the surface conservation law (SCL) errors and has inherent dissipation. The capability of HILES is tested by solving several benchmark cases. In the case of flow past a circular cylinder, the solutions of HILES fulfilling the SCL have good agreement with the corresponding experiment data, however, the flowfield is gradually contaminated when the SCL error is enlarged. With the help of fulling the SCL, ability of HILES for handling complex geometry has been enhanced. The numerical solutions of flow over delta wing demonstrate the potential of HILES in simulating turbulent flow on complex configuration.
Bessel Sequences and Its F-Scalability
Authors: Liu Lei , Zheng Xianwei , Yan Jingwen , Niu Xiaodong
Published: July 2015

Frame theory, which contains wavelet analysis and Gabor analysis, has become a powerful tool for many applications of mathematics, engineering and quantum mechanics. The study of extension principles of Bessel sequences to frames is important in frame theory. This paper studies transformations on Bessel sequences to generate frames and Riesz bases in terms of operators and scalability. Some characterizations of operators that mapping Bessel sequences to frames and Riesz bases are given. We introduce the definitions of F-scalable and P-scalable Bessel sequences. F-scalability and P-scalability of Bessel sequences are discussed in this paper, then characterizations of scalings of F-scalable or P-scalable Bessel sequences are established. Finally, a perturbation result on F-scalable Bessel sequences is derived.