bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of the Growth Conditions on the Crystal Quality in Solution Growth of SiC Using Cr Solvent without Molten Si
Authors: Suzuki Koki , Hyun Koang Yong , Taishi Toshinori
Published: June 2018

We have succeeded in solution growth of SiC from Cr solvent without Si using ceramic SiC as the SiC source. The effect of the growth conditions, such as the liquid height in the crucible, on the crystal quality in solution growth of SiC from Cr solvent was investigated. For a liquid height in the crucible of up to 10 mm, the growth rate increases with increasing liquid height and the SiC crystals are a single polytype, while the growth rate decreases and the crystals are polycrystalline for a liquid height above 10 mm. In the former case, the balance between dissolution and transportation of the solute are comparable. The latter case is expected to be transportation limited because transportation of free C and Si atoms is inhibited by excrescent crystals in solution and the increase in the distance for solute transportation. In addition, a higher growth temperature leads to growth of only 4H-SiC.
Investigation of Forward Voltage Degradation due to Process-Induced Defects in 4H-SiC MOSFET
Authors: Konishi Kumiko , Fujita Ryusei , Mori Yuki , Shima Akio
Published: June 2018

We investigated process induced defects at various ion implantation conditions, and evaluated forward voltage degradation of body diode in 3.3 kV SiC MOSFET. First, by using photoluminescence (PL) observation, we evaluated the formation level of Basal Plane Dislocations (BPD) induced by Al implantation and anneal process with various Al implantation dose. Second, 3.3 kV double-diffused SiC MOSFETs were fabricated and forward current stress tests were performed to body diodes in SiC MOSFETs. Then, electrical characteristics of SiC MOSFETs before and after the stress test were measured, and expanded Stacking faults (SFs) in SiC epitaxial layer after the stress test were observed by PL imaging method. These results indicate that low dose or high temperature Al implantation conditions can suppress the formation of BPDs, and SiC MOSFETs fabricated using optimized Al implantation conditions show high reliability under current stress test.
Low Temperature Ni-Al Ohmic Contacts to p-Type 4H-SiC Using Semi-Salicide Processing
Authors: Ekström Mattias , Hou Shuo Ben , Elahipanah Hossein , Salemi Arash , Östling Mikael , Zetterling Carl Mikael
Published: June 2018

Most semiconductor devices require low-resistance ohmic contact to p-type doped regions. In this work, we present a semi-salicide process that forms low-resistance contacts (~10-4 Ω cm2) to epitaxially grown p-type (>5×1018 cm-3) 4H-SiC at temperatures as low as 600 °C using rapid thermal processing (RTP). The first step is to self-align the nickel silicide (Ni2Si) at 600 °C. The second step is to deposit aluminium on top of the silicide, pattern it and then perform a second annealing step in the range 500 °C to 700 °C.
Dislocation Behavior in Bulk Crystals Grown by TSSG Method
Authors: Seki Kazuaki , Kusunoki Kazuhiko , Kishida Yutaka , Kaido Hiroshi , Moriguchi Koji , Kado Motohisa , Daikoku Hironori , Shirai Takayuki , Akita Mitustoshi , Seki Akinori , Saito Hiroaki , Harada Shunta , Ujihara Toru
Published: June 2018

The dislocation behavior during bulk crystal growth on the 4H-SiC (000-1) C-face using the solution method was investigated. A 2 inch wafer with a 4° off angle was fabricated from a bulk crystal grown by the TSSG method, and the dislocations in the crystal were evaluated using synchrotron X-ray topography and TEM observation. From the topograph images, it was found that the TSD density remarkably decreased as the growth progressed. Furthermore, the TEM observation suggested that TSD decreases as the threading dislocations convert to in-plane defects toward the center of the crystal. Conventionally, it was considered that conversion of threading dislocations hardly occurs in solution growth on the C-face. However, it is thought that this phenomenon was not observable because the conversion efficiency is remarkably low. We speculate that dislocations may be transformed by suddenly making macrosteps during bulk growth.
Effect of Design Variations and N2O Annealing on 1.7kV 4H-SiC Diodes
Authors: Sharma Yogesh K. , Jiang Hua Ping , Zheng C. , Dai X. , Deviny Ian
Published: June 2018

In this work we have studied the influence of design and process variations on electrical performance of 1.7 kV 4H-SiC Schottky diodes. Diodes with two variations in their active region design namely, stripe design and segment design, were fabricated in this study. Field Limiting Rings (FLRs) or Junction Termination Extension (JTE) were used as edge termination design to achieve a blocking voltage of 1.7 kV. In addition to these designs an extra processing step of nitrous oxide (N2O) annealing was performed on some of the diodes. The study has shown that there is no extra beneficial effect of nitrous oxide annealing on device characteristics.
Experimental Determination of Carbon Solubility in Si0.56Cr0.4M0.04 (M = Transition Metal) Solvents for Solution Growth of SiC
Authors: Hyun Koang Yong , Taishi Toshinori , Suzuki Koki , Teshima Katsuya
Published: June 2018

Si0.56Cr0.4M0.04 (M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Rh, and Pd) solvents were investigated to identify new multi-component materials in which carbon is highly soluble, because solubility is a key parameter in solution growth of SiC. The solubility of carbon in Si0.56Cr0.4Co0.04 was 8.37 at%, the highest value among the tested multi-component materials. This is about 2.5 times the solubility of carbon in Si0.6Cr0.4. These results show that addition of a small amount of a transition metal enhanced the solubility of carbon in Si0.6Cr0.4. This technique for determining carbon solubility is effective for investigating crystal growth using solvents with several components, for which complex thermodynamic calculations are necessary.
Carrier Lifetimes in 4H-SiC Epitaxial Layers on the C-Face Enhanced by Carbon Implantation
Authors: Kushibe Mitsuhiro , Nishio Johji , Iijima Ryosuke , Miyasaka Akira , Asamizu Hirokuni , Kitai Hidenori , Kosugi Ryoji , Harada Shinsuke , Kojima Kazutoshi
Published: June 2018

Carrier lifetime in low carrier concentration 4H-SiC epitaxial layers grown on the C-face was enhanced by using carbon implantation and post annealing. The measured carrier lifetime increased with the thickness of the epitaxial layer and was 11.4 µs for the 150 µm thick epitaxial layer. The internal carrier lifetime was estimated as 21 µs from the dependence of the measured carrier lifetime on the epitaxial layer thickness. This value is almost comparable to the reported values of the internal carrier lifetime for the layers grown on the Si-face.
Analysis of 3-Dimensional 4H-SiC MOS Capacitors Grown by Atomic Layer Deposition of Al2O3
Authors: Idris Muhammad I. , Wright Nick G. , Horsfall Alton B.
Published: June 2018

3-Dimensional 4H-SiC metal-oxide-semiconductor capacitors have been fabricated to determine the effect of the sidewall on the characteristics of 3-Dimentional gate structures. Al2O3 deposited by Atomic Layer Deposition (ALD) was used as the gate dielectric layer on the trench structure. The 3-D MOS capacitors exhibit increasing accumulation capacitance with excellent linearity as the sidewall area increases, indicating that ALD results in a highly conformal dielectric film. The capacitance – voltage characteristics also show evidence of a second flatband voltage, located at a higher bias than that seen for purely planar devices on the same sample. We also observe that the oxide capacitance of planar and 3-D MOS capacitors increases with temperature. Finally, we have found that the 3-D MOS capacitor has a weaker temperature dependence of flatband voltage in comparison to the conventional planar MOS capacitor due to the incorporation of the (1120) plane in the sidewall.
Near Breakdown Voltage Optical Beam Induced Current (OBIC) on 4H-SiC Bipolar Diode
Authors: Planson Dominique , Asllani Besar , Hamad Hassan , Locatelli Marie Laure , Arvinte Roxana , Raynaud Christophe , Bevilacqua Pascal , Phung Luong Viet
Published: June 2018

This paper presents OBIC measurements performed at near breakdown voltage on two devices with different JTE doses. Overcurrent has been measured either at the JTE periphery or at the P+ border. Such overcurrent is present due to the electric field enhancement near the breakdown voltage. This hypothesis is proved by the electroluminescence. TCAD simulation of two different JTE doses yielded similar results to the OBIC measurements.
Effect of High Energy Electron Irradiation on Electrical and Noise Properties of 4H-SiC Schottky Diodes
Authors: Lebedev Alexander A. , Kozlovski Vitalii V. , Levinshtein Michael E. , Rumyantsev S.L. , Palmour John W.
Published: June 2018

Electron irradiation of high voltage Ni/4H-SiC Schottky diodes with the dose Φ=(0.2-7)×1016cm-2 led to increase in the base resistance, appearance of slow relaxation processes at extremely small currents, and increase of the low frequency noise. On exponential part of the current-voltage characteristics and on linear part of current-voltage characteristics in non-irradiated samples, low frequency noise always has the form of the 1/f noise. On linear part of the current-voltage characteristics in irradiated diodes the generation recombination (GR) noise predominates. Temperature dependences of the base resistivity and character of GR noise indicate that mainly Z1/2 center contributes to the change in the parameters of irradiated samples. Capture cross section of this level, obtained from noise measurements, is within the range (8×10-16-2×10-15) cm2 and only weakly depends on temperature.
A High Current Gain 4H-SiC BJT of Novel Epitaxial Passivation Structure
Authors: Zhang You Run , Wang Wen , Li Ming Ye , Guo Fei , Li Jun Tao , Li Xuan
Published: June 2018

This paper proposes a novel high-gain 4H-SiC BJT structure with a p-type epitaxial layer on top of the extrinsic base layer. The current gain of the novel structure is improved by 140% compared with the conventional one by the simulator tool with the number of reasonable interface traps, which could be ascribed to the epitaxial layer to reduce the surface recombination in the extrinsic base. The process to fabricate this structure is also proposed in the paper.
Impact of Embedding Schottky Barrier Diodes into 3.3 kV and 6.5 kV SiC MOSFETs
Authors: Kawahara Koutarou , Hino Shiro , Sadamatsu Koji , Nakao Yukiyasu , Iwamatsu Toshiaki , Nakata Shuhei , Tomohisa Shingo , Yamakawa Satoshi
Published: June 2018

External Schottky barrier diodes (SBDs) used as free-wheel diodes should be larger in higher voltage devices to avoid bipolar degradation consequent on current conduction of body diodes in SiC MOSFETs. By embedding an external SBD into an SiC MOSFET, we achieved compact 3.3 kV and 6.5 kV SiC MOSFETs that are free from bipolar degradation. The active area of the 3.3 kV/6.5 kV samples is only about a half/quarter of the total active area of a conventional MOSFET and a coupled external SBD.
Short-Circuit Robustness of SiC Trench MOSFETs
Authors: Green Ronald , Urciuoli Damian , Lelis Aivars J.
Published: June 2018

An investigation into the robustness of 1200-V/80-mΩ commercial trench-gate MOSFETs reveals that the critical energy for failure during short-circuit operation is reached in shorter times in comparison to similarly rated planar DMOSFETs under similar stress conditions. This critical energy for trench devices was estimated to be between 615 mJ to 660 mJ depending on the gate-drive voltage. These values are considerably smaller when compared to DMOSFETs from the same manufacturer. In comparison to planar designs, trench devices can have lower losses, and manufactured with much smaller chip size for the same device rating. As a result, higher power density, improved efficiency, lower chip costs, and higher yields for trench designs are possible, but these enhancements are offset by a reduction in short-circuit capability. The critical short-circuit time for a 600-V bus voltage is shown to be dependent on gate-drive voltage magnitude, with higher gate voltages leading to increased peak short-circuit current, higher power dissipation, and reduced short-circuit capability.
99.9% BPD Free 4H-SiC Epitaxial Layer with Precisely Controlled Doping upon 3 x 150 mm Hot-Wall CVD
Authors: Wada Keiji , Terao Takemi , Itoh Hironori , Hori Tsutomu , Doi Hideyuki , Furumai Masaki , Tanabe Tatsuya
Published: June 2018

Epitaxial growth of 4H-SiC on 150 mm wafers has been investigated using experimental results and numerical simulations toward the goal of BPDs reduction and doping uniformity control in the epitaxial layer. We have reported analyses of the temperature distribution dependence of the doping uniformity and BPDs propagations on the 3 x 150 mm multi-wafer CVD epitaxial growth. By optimizing epitaxial growth conditions, we have demonstrated an excellent doping and thickness uniformity and a 99.9% BPD free region, simultaneously.
3300V SiC DMOSFETs Fabricated in High-Volume 150 mm CMOS Fab
Authors: Powell Blake , Matocha Kevin , Chowdhury Sauvik , Hundley Chris
Published: June 2018

We fabricated 3300V Silicon Carbide (SiC) DMOSFETs on 150mm substrates in a high volume automotive qualified Si CMOS foundry. In this paper we will show that JFET optimization can yield noticeable improvements in on-state performance without exceeding acceptable gate oxide electric fields. For the optimized design, breakdown voltages (BV) in excess of 3900V are observed along with a specific on resistance of 13.5mOhm-cm2 at room temperature and 30mOhm-cm2 at 150°C.
Shielded Gate SiC Trench Power MOSFET with Ultra-Low Switching Loss
Authors: Li Xuan , Tong Xing , Huang Alex Q. , Qiu Shi , She Xu , Deng Xiao Сhuan , Zhang Bo
Published: June 2018

A shielded gate trench silicon carbide (SiC) metal oxide semiconductor field effect transistor (SG-TMOS) is proposed and investigated by simulation in this paper. The impact of shielded gate design in SG-TMOS on Miller charge (Qgd) as well as conduction resistance (Ron) are comprehensively discussed, showing a tradeoff between Qgd and Ron. Furthermore, the Huang’s Figure of Merit (HFOM) of the SG-TMOS with reasonable design of SG is reduced more than 20%, compared with the conventional trench MOSFET (C-TMOS). Therefore, the proposed SG-TMOS is a competitive next generation device structure for ultra-high switching speed SiC MOSFET.
An Experimental Demonstration of Short Circuit Protection of SiC Devices
Authors: Aeloiza Eddy , Kadavelugu Arun , Cairoli Pietro , Rodrigues Rostan
Published: June 2018

An experimental demonstration of an effective short circuit protection scheme for SiC MOSFETs is presented in this paper. Measurements of the static characteristics of the SiC device before and after the short circuit events were obtained to evince that the device remained in good health. An ultra-fast short circuit protection scheme is implemented given the observed lower short-circuit withstand of present SiC devices. It is shown that the integrity of the SiC device was protected after one-hundred short circuit events.
30 kV Pulse Diode Stack Based on 4H-SiC
Authors: Ilyin Vladimir A. , Afanasyev Alexey V. , Demin Yuri S. , Ivanov Boris V. , Kardo-Sysoev Alexey F. , Luchinin Victor V. , Reshanov Sergey A. , Schöner Adolf , Sergushichev K.A. , Smirnov A.A.
Published: June 2018

The paper reports on the studies of static and dynamic characteristics of 30 kV diode stacks based on 4H-SiC drift step recovery diodes (DSRDs). It was found that the optimal performance in terms of blocking voltage and switching speed can be achieved with 2 kV DSRD dies. Fifteen 2 kV DSRD dies were connected in series and sealed with molding compound. The stacks were dynamically tested in a special oscillator circuit. Repetitive voltage pulses of 30.5 kV with the leading edge of 1.6 ns were demonstrated.
Experimental Demonstration on Ultra High Voltage and High Speed 4H-SiC DSRD with Smaller Numbers of Die Stacks for Pulse Power
Authors: Goto Taiga , Iwamuro Noriyuki , Tokuchi Akira , Naito Takashi , Fukuda Kenji , Iwamuro Noriyuki
Published: June 2018

This paper presents the experimental results of static and dynamic characteristics of the newly developed 14 kV 4H-SiC high-speed drift step recovery diode (DSRD) for pulse power applications for the first time. The feature of the diode structure is to be designed based upon the p+/p-/n+ structure and is to make an additional extremely low doping and thin n-drift layer between the p-drift layer and n+ substrate. This device successfully exhibits higher breakdown voltage of 14kV and high-speed voltage pulse in a range of a few nanoseconds, simultaneously.
Performance and Reliability Requirements for the Application of SiC Power MOSFET in Electrified Vehicle Drive Systems
Authors: Su Ming , Chen Ching Chi
Published: June 2018

In the past 20 years, SiC has gone through rapid development as a next-generation power semiconductor and the automotive market is considered one of its key potential application areas. Recently SiC power MOSFETs became commercially available from multiple manufacturers, attracting significant interest in the automotive industry for their benefits in the electric drivetrain system, including higher energy efficiency and opportunities of component weight and size reduction. Optimistic prediction of technology adoption in hybrid electric vehicles (HEV) also helped create a momentum for semiconductor suppliers to engage in the demonstration of SiC power modules for the traction inverter application. However, the performance expectations and reliability requirements of SiC-based power control units remain challenging for the cost-sensitive market. This paper will discuss the status and outlook of electrified powertrain systems, and outline the requirements for wide implementation of SiC power MOSFETs.
Graphene/SiC Functionalization for Blood Type Sensing Applications
Authors: Lebedev Sergey P. , Usikov Alexander , Novikov Sergey , Shabunina Evgeniya I. , Shmidt Natalia M. , Barash Iosif , Roenkov Alexander D. , Lebedev Alexander A. , Makarov Yuri
Published: June 2018

Functionalization of graphene/SiC dies by nitro-phenyl and its reduction to phenyl-amine is discussed. The graphene films were formed on a SiC substrate by the substrate surface thermal decomposition at 1800-2000°C. The functionalizing procedure included a two-step electrochemical process monitored by cyclic voltammetry and the die resistance. Functionalized graphene/SiC dies with applied antibody were blood sensitive and can be potentially applied to identify promptly types of the blood.
Electrical Characterization of the Operational Amplifier Consisting of 4H-SiC MOSFETs after Gamma Irradiation
Authors: Masunaga Masahiro , Sato Shintaroh , Kuwana Ryoh , Hara Isao , Shima Akio
Published: June 2018

The operational amplifier (op-amp) with high gamma irradiation capability of over 30 kGy have been fabricated by 4H-SiC MOSFETs for measuring instruments which are installed in nuclear power plants. The chip size was 0.7 mm x 1.0 mm, and they consisted of five n-channel MOSFETs and three p-channel MOSFETs on the same die. The output waveform after having irradiated 50 kGy at a rate of 60 Gy/hr was amplified without distortion. On the other hand, the offset voltage became unstable when gamma integral dose was beyond 30 kGy and it at 50 kGy increased to +7.2 mV. For reduction of gamma irradiation influence, we proposed the MOSFETs structure which has field plate (FP) electrodes connected to isolation layer electrically. We indicated that the proposal device had the potential of gamma irradiation capability of 100 kGy experimentally.
Magnetic Field Sensing with 4H SiC Diodes: N vs P Implantation
Authors: Cochrane Corey J. , Kraus Hannes , Neudeck Philip G. , Spry David J. , Waskiewicz Ryan J. , Ashton James , Lenahan Patrick M.
Published: June 2018

We explore the magnetic sensing capabilities of two 4H-SiC n+p diodes fabricated by NASA Glenn which only differ in the implanted ion species, nitrogen and phosphorus, and the implant activation annealing time. We use low-and high-field electrically detected magnetic resonance (EDMR) to investigate the defect structure used to sense magnetic fields as well as to evaluate the sensitivity. In addition, we expose these devices to high energy electron radiation to evaluate the defect sensing capability in a harsh radiation environment. The results from this work will allow us to tailor our processing methods to design a more optimal 4H-SiC pn diode for magnetic field sensing in harsh environments.
X-Ray Imaging of Formation and Growth of Spheroidal Graphite in Ductile Cast Iron
Authors: Yasuda Hideyuki , Sugiyama A. , Kiattisaksri C. , Morishita Kohei , Nagira Tomoya , Yoshiya Masato , Uesugi Kentaro , Takeuchi Akihisa
Published: June 2018

Time-resolved and in-situ observations using synchrotron radiation X-rays were performed to observe solidification of cast iron (CE=4.5, 0.02mass%Mg). Morphology of graphite particles was influenced by specimen holder material. In the Al2O3 holder, graphite particles were spheroidal at the beginning and then deviated from the spheroidal shape. In addition, the coupled eutectic solidification of austenite and graphite occurred at the final stage. In contrast, the divorced eutectic solidification, in which graphite particles and austenite dendrites independently grew, was selected until the end of solidification in MgO holder. Spheroidal graphite particles were engulfed by austenite. Consequently, typical microstructure observed in ductile cast iron was reproduced in the in-situ observation. The results suggested that oxygen potential, which was determined by Al2O3 or MgO (specimen holder) in the observations, could be an important factor for the selection of eutectic growth mode and graphite morphology.
Analysis of Nuclei in a Heavy-Section Nodular Iron Casting
Authors: Celis Mayerling Martinez , Domengès Bernadette , Hug Eric , Lacaze Jacques
Published: June 2018

The microstructure of heavy section nodular graphite cast irons often presents a bimodal distribution of nodule size associated with so-called primary and secondary graphite nucleation. It has been found that the nuclei in both types of nodules consist mainly in magnesium sulphide. However, nuclei in primary nodules contain some traces of calcium and are thus related with the inoculation treatment. On the contrary, nuclei in secondary nodules do not contain any element that could be associated to inoculation. It is suggested they form in the late stage of the eutectic reaction as a result of microsegregation build-up in magnesium and sulphur.
Effect of Cooling Rate and Aluminium Addition on Graphite Growth during Solidification and Graphitization
Authors: Bourdie Jacques , Bruneseaux Fabien , de Parseval Philippe , Gouy Sophie , Laffont Lydia , Lacaze Jacques
Published: June 2018

Even using high inoculation levels, mottled structures are often obtained when casting Mg-treated cast irons in thin wall parts. For full graphitization of the cast components, this calls for a subsequent heat-treatment which is generally achieved in the austenite field. The aim of this work was investigating the impact of the process and the cooling rate on the graphite structure for two different casting conditions. The influence of the cooling rate on graphite degeneracy due to the presence of impurity was also investigated considering low-level additions of aluminium. Extensive metallographic investigation has been carried out from which it is concluded that the internal graphite structure is the same for the two studied cooling conditions. Accordingly, the growth mechanism of graphite should be the same when it precipitates from liquid, during eutectic reaction or else solid-state graphitization. Finally, microanalyses suggest magnesium and aluminium do not interact in the same way with graphite during its growth.
Correlation between Solidification Time and Cooling Rate, Microstructure and Tensile Strength of a Low Alloyed Grey Cast Iron
Authors: Schmidt Pål
Published: June 2018

Despite more than hundred years of research the quantitative relation between microstructure and tensile strength of pearlitic grey irons is not fully understood. Relations found in literature mainly consist of formulas based on regression analysis of chemical composition and wall thickness. Microstructural features like size and shape of the graphite as well as pearlite fineness are seldom included in these equations. In this paper is presented an experimental correlation between microstructure and tensile strength for a low alloyed grey iron including the influence of course of solidification, pearlite hardness and graphite size and shape. The experimental material consists of two six-cylinder engine blocks which were gravity cast in horizontally parted green sand moulds. The alloy is similar to EN-GJL-200 but with addition of Cr. Measured values of hardness and tensile strength have been correlated to simulated values of solidification time and cooling rate at pearlite transformation with excellent agreement. It was also possible to confirm these findings by observation of the tensile test bar fracture surfaces. The main conclusions are: - Tensile strength is mainly dependent on solidification time and the related graphite flake size. - Hardness is mainly dependent on pearlite transformation rate and the related pearlite fineness.
Understanding the Machinability of Austempered Ductile Iron (ADI)
Authors: Handayani Dika , Voigt Robert C. , Hayrynen Kathy
Published: June 2018

Guidelines for production milling, turning and drilling of the standard grades of austempered ductile irons (ADI) have been established. Electron Backscatter Diffraction (EBSD) characterization has clearly shown that severe plastic deformation in the machining-affected-zone, ahead of and beneath the cutting tool, will cause strain-induced martensitic transformation of the austenite in the ausferrite structure that inhibits machinability. This phenomenon is particularly of concern during finish machining where small depths of cut are strongly influenced by surface martensite from prior machining passes.
Ductile Cast Iron with High Toughness at Low Temperatures
Authors: Duwe Stephanie , Tonn Babette
Published: June 2018

High life expectancy of cast components and good material performance at dynamic load are a prerequisite to cater for future trends in wind energy generators. To remain competitive in this ever evolving sector challenges reside in alloy development. In this work fractional factorial design has been applied to ferritic ductile iron with varying contents of silicon (1.6‑2 wt%), nickel (0‑1 wt%), cobalt (0‑3 wt%) and copper (0‑0.2 wt%). The minimum criteria the new alloy should meet were a minimum yield strength of 240 MPa and an impact work of minimal 8 J at a temperature of -20 °C for wall thicknesses of 60‑200 mm. To obtain these mechanical properties thick-walled castings with additional insulation were produced to achieve a higher thermic module. They provided the material for test specimens to perform static tensile tests, Charpy impact tests at varying temperatures and a microstructure analysis. With these results, a sweet spot plot has been created. That way, an optimum alloy composition could be found and has been proven by validation experiment.The optimum alloy for thick-walled castings is composed of Si = 1.6 wt%, Cu = 0.2 wt%, Ni = 0 wt% and Co = 0 wt%. It offers an enhancement in yield strength and acceptable impact work at low temperatures for massive castings in as cast state. The heat treated, full ferritic material could even improve these results.
Mathematical Characterization of the Tensile Deformation Curve of Cast Iron Materials
Authors: Svensson Ingvar L. , Salomonsson Kent
Published: June 2018

The manufacturing process gives cast iron castings properties which are dependent on component design, metallurgy and casting method. Factors as local wall thickness influences the coarseness and type of microstructure and the material will have local properties depending on the local metallurgical and thermal history. The stress/strain behaviour of cast products at load are typically performed by using a tensile test machine.
Crystallography of Growth Blocks in Spheroidal Graphite
Authors: Brodu Etienne , Bouzy Emmanuel , Fundenberger Jean Jacques , Beausir Benoit , Laffont Lydia , Lacaze Jacques
Published: June 2018

A better understanding of spheroidal graphite growth is expected in a near future thanks to widespread use of transmission electron microscopy. However, common transmission electron microscopy is quite time consuming and new indexing techniques are being developed, among them is transmission Kikuchi diffraction in a scanning electron microscope, a recent technique derived from electron backscatter diffraction. In the present work, on-axis transmission Kikuchi diffraction in scanning electron microscope, completed by transmission electron microscopy, was used with the objective of producing new observations on the microstructure of spheroidal graphite. This study shows that disorientations between blocks and sectors in spheroidal graphite are quite large in the early growth stage, which may be indicative of a competition process selecting the best orientations for achieving radial growth along thecdirection of graphite.
Comparison of Sn-Sb and Sn-Ag-Cu-Ni-Ge Alloys Using Tensile Properties of Miniature Size Specimens
Authors: Kobayashi Tatsuya , Yokoi Masaki , Kobayashi Kyosuke , Mitsui Kohei , Shohji Ikuo
Published: June 2018

Tensile properties of Sn-5Sb (mass%) and Sn-3.5Ag-0.5Cu-0.07Ni-0.01Ge (mass%) were investigated using miniature size specimens and obtained results were compared. Tensile strength of both alloys increase with increasing the strain rate and decrease with increasing the temperature. Although similar dependency to the temperature is observed in 0.1% proof stress, the effect of the strain rate on it is obscure. The tensile strength and the 0.1% proof stress of Sn-3.5Ag-0.5Cu-0.07Ni-0.01Ge are higher than those of Sn-5Sb. The elongation of Sn-5Sb is relatively stable at the range from 0.4 to 0.6. The elongation of Sn-3.5Ag-0.5Cu-0.07Ni-0.01Ge which is approximately 0.3, is inferior to that of Sn-5Sb. On the basis of investigation of stress exponent, n, it was clarified that dispersion strengthening by Ag3Sn particulates in Sn-3.5Ag-0.5Cu-0.07Ni-0.01Ge is effective to prevent the degradation of creep resistance compared with Sn-5Sb that is strengthened by solid-solution of Sb in β-Sn phases and dispersion of SbSn compounds.
Atti Sociali
Authors: Italiana Società Entomologica
Published: June 2018

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Segnalazioni faunistiche italiane
Authors: V.V. A.A.
Published: June 2018

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Segnalazioni Faunistiche Italiane
Authors: V.V. A.A.
Published: June 2018

Platydema violaceum (Fabricius, 1790) (Coleoptera Tenebrionidae)Semanotus russicus (Fabricius, 1776) (Coleoptera Cerambycidae)Graptostethus servus (Fabricius, 1787) (Hemiptera Lygaeidae)
Terzo contributo alla conoscenza di Oreonebria (Nebriorites) gagates (Bonelli, 1810): una sintesi (Coleoptera Carabidae)
Authors: Bisio Luigi
Published: June 2018

Viene descritta l’ecologia di Oreonebria (Nebriorites) gagates (Bonelli, 1810). La specie vive principalmente nelle fenditure tra grandi blocchi di roccia di paleofrane o di antiche morene. La sua presenza all’interno di questi litosuoli è probabilmente da mettere in relazione alle sue peculiari esigenze ecologiche che la portano a ricercare biotopi caratterizzati da fattori abiotici costanti con umidità elevata e basse temperature. Viene anche descritta la metodologia utilizzata per la ricerca della specie in questi substrati: essa si basa sull’uso di trappole costituite da bottiglie innescate con aceto di vino (addizionato con acido salicilico a scopo conservante) che devono essere collocate, per quanto possibile, nelle zone più profonde all’interno delle fessure, appoggiate in posizione inclinata sulla superficie dei blocchi di roccia. Viene inoltre fornita un’analisi della sua corologia lungo il versante italiano delle Alpi Occidentali: O. gagates è diffusa dalla Valle Po (Alpi Cozie) alla Valle Anzasca (Alpi Pennine). Infine, sono riassunte le diverse opinioni sulla tassonomia e sulla sistematica della specie espresse da diversi autori e sono elencati i caratteri diagnostici (morfologia e chetotassi del pronoto, morfologia dell’edeago) che, secondo Coulon (1994), permetterebbero di distinguere la ssp. veronicae dalla ssp. nominale. sulla base di questi caratteri, lungo il versante italiano la sottospecie nominale pare vivere nelle Alpi Cozie, mentre nelle Graie sembra presente la ssp. veronicae. Purtroppo, però, i pochi esemplari disponibili non permettono al momento di verificare la costanza di tali caratteri e di confermare la sua effettiva validità.
Diagnostic utility of endobronchial ultrasound features in differentiating malignant and benign lymph nodes
Authors: Agrawal Sumita P. , Ish Pranav , Goel Akhil Dhanesh , Gupta Nitesh , Chakrabarti Shibdas , Bhattacharya Dipak , Sen Manas Kamal , Suri Jagdish Chander
Published: June 2018

Endobronchial ultrasound (EBUS) features have been shown to be useful in predicting etiology of enlarged malignant lymph nodes. However, there is dearth of evidence especially from developing countries. We assessed the EBUS characteristics across various mediastinal and hilar lymphadenopathies. In this prospective study, all patients with mediastinal and hilar lymphadenopathy on CT Chest and who were planned for EBUS-FNA (Fine Needle Aspiration) were included. EBUS features of lymph nodes studied were shape, size, margins, echogenicity, central hilar structure (CHS), coagulation necrosis sign and colour power doppler index (CPDI). These were scored and compared between benign and malignant lymphadenopathies. A total of 86 lymph nodes in 46 patients were prospectively studied of which 23 (26.7%) were malignant, 27 (31.3%) tuberculosis and 36 (41.8%) sarcoidosis. There was significant difference between malignant and benign lymph nodes in terms of CHS [central hilar structutre] (p=0.011), margins (p=0.036) and coagulation necrosis sign (p<0.001). On comparison of features of malignancy and tuberculosis, there were significant differences in margins (p=0.016) and coagulation necrosis sign (p 0.001). However, when malignancy and sarcoidosis was compared, there were differences in echogenicity (p=0.002), CHS (p=0.009) and coagulation necrosis sign (p<0.001). Only coagulation necrosis sign was found to be highly consistent with malignant lymph nodes. The other features cannot be used to distinguish malignant from benign lymph nodes, especially in a developing country like India where tuberculosis is a common cause of mediastinal lymphadenopathy.
Actual and Perceived Questions Asked by Preceptors with and Without the Use of Bug-in-Ear Technology
Authors: Nottingham Sara L.
Published: June 2018

Context:

Questioning is an instructional strategy used by preceptors to assess knowledge and improve clinical reasoning in students. Preceptors face challenges asking high-level questions, and bug-in-ear (BIE) technology may be one way to address these challenges.

Objective:

Assess the cognitive level of questions asked by preceptors with and without the use of BIE technology.

Design:

Mixed methods.

Setting:

Seven clinical education sites affiliated with 3 Commission on Accreditation of Athletic Training Education–accredited undergraduate athletic training programs.

Patients or Other Participants:

A total of 13 athletic training students and 8 preceptors.

Main Outcome Measure(s):

Preceptor-student interactions were observed and audio recorded for 2 days without and 2 days with the availability of BIE technology. Cognitive levels of questions were analyzed using the Question Classification Framework and a 2 (Intervention) × 3 (Question Type) analysis of variance. Interviews were conducted to obtain participants' experiences with and perceptions of questioning and BIE technology. Interviews were analyzed by 2 individuals using an inductive coding process. Trustworthiness was established with member-checking, multiple-analyst triangulation, and data-source triangulation.

Results:

Preceptors asked 1044 questions, including 46.94% low-level (n = 557), 2.38% high-level (n = 24), and 50.69% other (n = 463), such as yes/no questions, during 149 hours of observation. Preceptors asked more questions during the control sessions than when they used BIE technology (39.1 ± 31.7 versus 26.1 ± 20.4 questions; F1,7 = 6.3; P = .04), although participants perceived the opposite. Two themes emerged from the interview data: (1) Preceptors use questioning to develop clinical reasoning in students, and (2) BIE technology facilitates low-level questioning.

Conclusions:

Although preceptors primarily asked low-level and basic recall questions of their students during clinical education, participants described the use of strategic sequencing of questions to facilitate clinical reasoning. Preceptors should be encouraged to ask more high-level questions and sequence them to target higher cognitive processing. Bug-in-ear technology was not effective at facilitating effective questioning in clinical education.
Body dysmorphic disorder: A diagnostic challenge in adolescence
Authors: Thungana Yanga , Moxley Karis , Lachman Anusha
Published: June 2018

Body dysmorphic disorder (BDD) is a chronic and disabling condition that is characterised by distressing preoccupations with perceived defects in one’s own appearance, which might be slight or not observable to others. It is considered to be an obsessive–compulsive spectrum disorder and is associated with depression, feelings of shame and poor quality of life. It is primarily a disorder of childhood or adolescent onset, and sub-clinical BDD symptoms begin, on average, several years before an individual’s symptoms meet full criteria for the disorder. Here we report the case of an adolescent admitted to an inpatient psychiatric unit for treatment of psychotic symptoms that were poorly responsive to standard treatments. This challenging case of BDD in an adolescent highlights the various comorbidities of the disorder, as well as the difficulties associated with BDD diagnosis.
Earthworm avoidance behavior to antimicrobial sulfadiazine on tropical artificial soil
Authors: Candello Fernando Pena , Guimarães José Roberto , Nour Edson Aparecido Abdul
Published: June 2018

Veterinary pharmaceuticals can reach the soil via animal excretions and cause impacts on aquatic and terrestrial ecosystems. In this work, we employed a standardized avoidance behavior test to assess the sublethal effects of antimicrobial sulfadiazine on the earthworm Eisenia andrei. Cultivation of red worms was based on an alternative substrate made of mostly household vegetable wastes and dry leaves. The bioassays were performed with tropical artificial soil spiked with the tests substance at five different concentrations ranging from 0.01 to 100 mg sulfadiazine kg-1. The outcome resulted in avoidance response of 30% (maximum) and a nonlinear concentration-response curve, differing from classical pollutant responses and correlating with those asymmetric responses over the environment caused by some rare xenobiotics. Avoidance tests were validated with reference substance, resulting in an EC50-48h of 819 mg boric acid kg-1 (628-1066 mg boric acid kg-1 95% confidence interval). We concluded that the avoidance test with E. andrei is useful as a standardized tool for a rapid ecotoxicological screening of soil.
Arctic warming induced by the Laurentide Ice Sheet topography
Authors: Liakka Johan , Lofverstrom Marcus
Published: June 2018

Abstract. It is well known that ice sheet–climate feedbacks are essential for
realistically simulating the spatiotemporal evolution of continental ice
sheets over glacial–interglacial cycles. However, many of these feedbacks
are dependent on the ice sheet thickness, which is poorly constrained by
proxy data records. For example, height estimates of the Laurentide Ice Sheet
(LIS) topography at the Last Glacial Maximum (LGM; ∼ 21 000 years ago)
vary by more than 1 km among different ice sheet reconstructions. In order
to better constrain the LIS elevation it is therefore important to understand
how the mean climate is influenced by elevation discrepancies of this
magnitude. Here we use an atmospheric circulation model coupled to a
slab-ocean model to analyze the LGM surface temperature response to a broad
range of LIS elevations (from 0 to over 4 km). We find that raising the LIS
topography induces a widespread surface warming in the Arctic region,
amounting to approximately 1.5 ∘C per km of elevation increase, or
about 6.5 ∘C for the highest LIS. The warming is attributed to an
increased poleward energy flux by atmospheric stationary waves, amplified by
surface albedo and water vapor feedbacks, which account for about two-thirds
of the total temperature response. These results suggest a strong feedback
between continental-scale ice sheets and the Arctic temperatures that may
help constrain LIS elevation estimates for the LGM and explain differences in
ice distribution between the LGM and earlier glacial periods.
Additional detail in aggregate integrated land-use models via simulating developer pro forma thinking
Authors: Johnson Jerry , Frkonja Jeff , Todd Maribeth , Yee Dennis
Published: June 2018

This paper describes an enhancement to MetroScope, the land-use model component of an integrated model suite used to answer current- and next-generation policy questions facing Oregon Metro (the Portland regional planning organization) and other public agencies. The enhancement is designed to simulate more-detailed housing developer decision processes within an overall aggregate spatial equilibrium model (SEM) framework via a pro forma paradigm. The paper enumerates the policy questions that motivated the enhancement, discusses the integrated model framework, briefly reviews levels of detail available in existing models as context, and frames potential future research directions for additional decision process detail that would be helpful in the consumer modules of the model and potentially other SEMs currently in use.
La promoción de la cultura de defensa en las universidades españolas: Evaluación de diseño del Programa de Colaboración del Ministerio de Defensa
Authors: Bueno Alberto
Published: June 2018

Este artículo presenta una evaluación de diseño del Programa de Colaboración con las Universidades del Ministerio de Defensa, por ser el instrumento de planificación e implementación de la política pública de promoción de la cultura de defensa en ese ámbito. Desde el enfoque del análisis de políticas públicas, valora su racionalidad, pertinencia, coherencia interna y coherencia externa mediante diversas técnicas analíticas. Con esta investigación se pretende, por un lado, profundizar en el conocimiento de esta política y evaluar la alternativa formulada y, por otro, ofrecer una serie de recomendaciones de política, las cuales podrían ser de utilidad para los decisores públicos en la elaboración del nuevo Plan Director de Cultura de Defensa.
AVALIAÇÃO DE CUSTO-BENEFÍCIO PARA MANUTENÇÃO EM TANQUES DE HIDROCARBONETOS DE TRANSFERÊNCIA E ESTOCAGEM
Authors: Monteiro Aluisio Dos Santos , Monteiro Denise Loyola Silva , De Menezes João Orlando Rodrigues , De Castro Marcello Gonçalves
Published: June 2018

Para instalações de refino de petróleo, os tanques são ativos fundamentais e têm como função possibilitar o armazenamento de produtos intermediário de forma a preservar suas características fundamentais. Este estudo faz correlação com a fase de declínio de alguns poços na Bacia de Campos e suas consequências no parque de refino. Para isto, foi realizado um estudo de caso, com enfoque na viabilidade técnico-econômica para manutenção de tanques de armazenamento de hidrocarboneto. Foram analisados os dados de inspeção e manutenção de equipamentos para dois tanques distintos, bem como os aspectos financeiros a partir da análise da Relação Custo-Benefício e o Valor Presente Líquido (VPL). A análise efetuada nos tanques distintos demonstrou que a substituição do material da tampa superior é uma solução econômica e tecnicamente viável.
MINIMIZATION OF PHENOL AND AMMONIACAL NITROGEN IN REFINERY WASTEWATER EMPLOYING BIOLOGICAL TREATMENT
Authors: Silva M.R. , Coelho M.A.Z. , Araújo O.Q.F.
Published: June 2018

Wastewater from refineries is usually characterized by presence of phenol and
ammoniacal nitrogen. The aim of this work was to search for a refinery wastewater
minimization employing a biological technology to reduce these pollutants.
Experimental data was obtained by treating a synthetic wastewater in a sequencing
batch reactor (SBR) operating on different operational schemes for batch scheduling.
COD, nitrate, ammonia, phosphate and phenol were monitored as well as dissolved
oxygen, pH, level and redox potential through a supervisory control software.
Reductions of 95 % were achieved for different concentrations of NH4
+ and phenol,
providing an effluent acceptable by Brazilian environmental legislation.
EXPERIMENTAL STUDY OF INTERACTION SHALE-FLUID THROUGH IMMERSION TESTS
Authors: Rabe Claudio , Da Fontoura Sérgio Augusto Barreto , Antunes Franklin Dos Santos
Published: June 2018

The present work has as objective the study of the behavior of preserved shale
samples when immersed in aqueous solutions. The obtained results show that the
solutions presented high variations of pH, salinity and electric conductivity, what
indicates ionic migration of salts from the rock to the fluid, and small variations of
Redox potential. Chemical analysis indicate strong migrations of ions from the
rock to the fluid. It can also be observed that the solutions become cloudy, denser
and more viscous. Besides, the samples suffer elevations of its water content,
small variation of its cation exchange capacity and chemical composition, loss of
solid material from superficial disintegration and the development of fractures in
the cores. This work contributes to the understanding of the shale behavior in
presence of drilling fluid water base.
Financial Fragility and Interbank Structure
Authors: Feng Yalan
Published: June 2018

This paper follows Allen and Gale (2000) to model financial contagion as an equilibrium phenomenon. I assume a two-country economy where banks in each country hold interregional claims on other banks to provide insurance against liquidity preference shocks. The results completely replicate Allen-Gale model. To further test the relative robustness of different market structures I test the implication of moral hazard as in Brusco and Castiglionesi (2007). I find that under certain situation, complete and incomplete structures are equally fragile.
Mediastinal neuroendocrine tumour presenting with ECG changes: An unusual ST-Elevation Myocardial Infarction mimic
Authors: Borrie Andrew J. , Pegg Tammy J.
Published: June 2018

A 63-year-old male was referred to the cardiology team with a one month history of progressive chest pain and shortness of breath. This was associated with general decline, weight loss and new heart failure. Emergency Department ECG showed ST elevation throughout the chest leads and blood tests confirmed an elevated troponin. Clinical examination revealed a precordial mass. Bedside echocardiography showed an akinetic anterior wall with infiltration from a mediastinal mass. CT scan demonstrated a large mediastinal mass invading the sternum, ribs and myocardium. Biopsy showed a high grade neuroendocrine tumour of uncertain origin. Despite the need for rapid treatment of ST-Elevation Myocardial Infarction (STEMI), due care needs to be taken to ensure accurate diagnosis.