bluuebunny/crossref_metadata_2025 huggingface dataset:
Low Aspect Ratio Turbines
Authors: Ohlsson Gunnar O.
Published: January 2012

Four different axial, impulse turbines with extremely low aspect ratios (between 0.07 and 0.70) were tested over wide ranges of pressure and speed ratios. The influence on mass rate of flow and efficiency of Reynolds number and axial distance between stator and rotor is given. Stator and rotor efficiency, Mach number, and flow angles, as well as other quantities, are obtained by means of a wheel with axial outlet. Semiempirical formulas are given for turbine efficiency, stator efficiency, and rotor efficiency as functions of aspect ratio.
Supersonic Turbines
Authors: Ohlsson Gunnar O.
Published: January 2012

The design of supersonic turbine nozzles and rotors is discussed and a series of four supersonic turbine nozzles, which is believed to be of a new type, was built and tested. The ratio A/A* between the outlet flow area and the throat area varied between 3.64 and 1. Four axial turbines with these nozzles and with the same rotor were tested over wide ranges of pressure and speed ratios. These turbines were of impulse type. The influence on mass rate of flow and efficiency of Reynolds number and axial distance between stator and rotor is given. Stator and rotor efficiency, Mach numbers, and flow angles, as well as other flow quantities, are obtained by means of a wheel with axial outlet.
Hydrogen Damage in Power Boilers
Authors: Partridge Everett P.
Published: January 2012

In an effort to state what is known and not known about hydrogen damage to steel in power boilers, this paper summarizes the varied conditions under which it has developed in 27 plants since 1938 and reviews pertinent research on the influence of chemical, mechanical, and metallurgical factors in producing this type of brittle failure. Hydrogen damage has occurred in many different locations in boilers of a great variety of designs operating at pressures from 450 to 2700 psi. It has been found only in the steel underlying local areas of corrosion, where hydrogen would have been produced at a greater rate than elsewhere. Metal temperatures in the range from 600 to 950 F suffice. Pure iron containing only 42 ppm of carbon is not damaged by hydrogen. Low-carbon steel is damaged less rapidly when the iron carbide has been spheroidized by prior heat-treatment, or when the oxygen content of the steel is relatively high. Low-alloy steels containing about 3 percent of chromium and small amounts of such elements as molybdenum, vanadium, and tungsten are highly resistant. Cold work increases the rate of damage by hydrogen.
Embrittlement in One of Four Boilers
Authors: Finnegan T. J.
Published: January 2012

This paper raises the question as to why one of four identical boilers, operating under the same conditions, should develop problems of hydrogen embrittlement while the others do not. The boilers are all in the Niagara Mohawk Power Corporation system.
Hydrogen Damage in a 1250-Psi Boiler
Authors: Galloway E. E.
Published: January 2012

This paper covers the case history of hydrogen damage in a relatively low-pressure boiler (1250 psi). Two failures are discussed, as well as the pertinent facts concerning boiler operation, chemical treatment, and cleaning.
A Case History of Hydrogen Damage
Authors: Simon D. E.
Published: January 2012

This history outlines the occurrence of hydrogen damage in a central station boiler and the steps taken to prevent its recurrence. The case covers a period of six years of operation and is fully documented with analytical and metallographic data.
Measurement of the Total Transmittance of Rock Salt Samples
Authors: DeCorso S. M. , Coltman J. W.
Published: January 2012

Values of total transmittance were obtained for several rock salt specimens in the natural state ranging from 0.122 to 1.90 in. in length, for black-body radiation in the region of 1475 deg F. The results are seen to fit a previously obtained theoretical formulation for transmittance of light through a diffuse screen. As a result the reflectance of a rock salt slab may be calculated, and the reflectance for an infinitely thick slab is given.
Heat-Transfer and Flow-Friction Characteristics of Skewed-Passage and Glass-Ceramic Heat-Transfer Surfaces
Authors: Howard C. P.
Published: January 2012

Experimental results for convective heat-transfer and flow-friction characteristics of three skewed-passage and four glass-ceramic compact heat-exchanger surfaces are presented which should be of practical use, particularly in the design of gas-turbine regenerators. The heat-transfer data were obtained by the transient technique.
Solar Thermionic Generators for Space Power
Authors: Brosens Pierre J.
Published: January 2012

All solar space power systems are subject to the condition that the amount of solar energy available in space depends on the collector-sun distance, which generally differs among missions and which may change markedly during the course of any one mission. Thus the design problem exists of how to tailor the system so as to best use the available solar flux. Furthermore, particularly in the case of thermionic systems, it is difficult to change arbitrarily the size of the system. It is therefore of interest to find the system size which can best fit a variety of missions without need for alterations which increase cost and decrease reliability. An approach to handle this design problem is presented, and numerical examples are given based on the data obtained from tests on the hardware prototype of a solar thermionic generator.
Formation of SO3 in a Noncatalytic Combustor
Authors: Barrett Richard E. , Hummell John D. , Reid William T.
Published: January 2012

The major contributor to corrosion and deposits in boilers and gas turbines has been recognized as the reaction of sulfur oxides, especially SO3, in the combustion gas with furnace elements. One way to minimize these reactions is to reduce the quantity of SO3 formed. Factors affecting SO3 formation have been studied in a noncatalytic laboratory combustor, and results of the investigation show that SO3 in the combustion gas can be reduced by: (a) Reducing excess air, (b) burning fuel with a lower sulfur content, (c) preventing air leakage into the combustion system, and (d) covering catalytic surfaces, such as superheater tubes, with less catalytic protective coatings. Some experiments showed that iron-oxide coatings, which built up on iron surfaces, were highly catalytic for the production of SO3 under boiler-furnace-simulated conditions.
Vanadium Pentoxide Deposition From Combustion Gases
Authors: Hedley A. B. , Brown T. D. , Shuttleworth A.
Published: January 2012

The rate of deposition of vanadium pentoxide vapor from combustion gases produced by burning a liquid fuel (kerosene with added vanadium ethyl hexoate) under controlled mixing-history conditions has been shown to agree with the following theoretical mass transfer equation when considering cooled tubes in a transverse gas stream: m=0.8B(Sc)2/3(Pr)1/3(μρ)1/2VD1/2 Theoretical and experimental evidence indicates the existence of a “dew point” at a deposition surface temperature of about 670 C. In addition, it would appear that, for the mechanism of deposition under consideration, an “induction” or “immunity” period before the onset of deposition does not exist. Experimental evidence also shows that the rate of deposition was not affected by changes in the excess air level within the range 25 to 1 percent.
Operating and Maintenance Experience With Pump-Turbines in the U. S., Italy, and Japan
Authors: Rheingans W. J.
Published: January 2012

This paper presents operating and maintenance data on eighteen reversible pump-turbines in six different plants. Starting and stopping times and procedures for both pumping and generating cycles are detailed for most of the units. Operating records at one of the plants indicate a combined overall efficiency of 68.59 percent and an estimated combined pump-turbine unit efficiency of 74 percent. Cavitation and other maintenance problems for all the units are discussed in detail.
On a Wave Phenomenon in Turbines
Authors: Owczarek J. A.
Published: January 2012

The paper deals with the theoretical analysis and experimental verification of a periodic wave phenomenon occurring in running turbine stages, which until now was not recognized. This wave phenomenon can be responsible for failure of turbine blades and for loss in efficiency of turbomachines. Being periodic, it can produce a blade vibration stimulus which, in general, does not have an integral number of cycles per revolution. It consists of concentrated pressure waves (pressure pulses) which, when the conditions are favorable, are generated on the leading edges of the moving turbine blades, propagate toward the suction sides of the nozzles, are reflected back toward the turbine wheel, collide with the leading edges of the turbine blades, and are again reflected toward the nozzles. For a given turbine stage, depending on the ratio of the number of nozzles to the number of blades, on the edge-to-edge distance between the nozzles and the blades, on the nozzle angle and shape, and on the Mach number of the flow, there exist certain speed ranges (or, in the constant-speed turbines having variable inlet conditions to the stage, certain speed ratio, W/V0, ranges) in which these waves may exist. The equations derived in this paper indicate that the ratio of the number of nozzles to the number of blades should become an important new parameter in the design of turbine stages free of the wave-produced vibration stimulus at the natural frequency of the blades. A comparison is made of the blade stimulus frequencies predicted by the method described in this paper and of the stimulus frequencies measured by the NACA on a J47 turbojet engine. Very good agreement exists between the observed and predicted stimulus frequencies. A direct observation of the reflecting waves (pressure pulses), made on a water-table model of a turbine stage, is also reported in this paper.
THE SLIP AND INDUCED MAGNETIC FIELD EFFECTS ON THE PERISTALTIC TRANSPORT WITH HEAT AND MASS TRANSFER
Authors: HAYAT T. , NOREEN S. , ALSAEDI A.
Published: January 2012

In this attempt, simultaneous effects of slip condition and an induced magnetic field on the peristaltic flow of viscous fluid in an asymmetric channel is investigated. The whole analysis have been carried out in the presence of heat and mass transfer characteristics. The resulting mathematical model is solved by exploiting the boundary conditions derived from physical point of view. The expressions of the desired flow quantities of interest are derived and discussed. A comparison with no-slip condition is shown.
DIFFERENTIAL CALCULUS ON THE LOGARITHMIC EXTENSION OF THE QUANTUM 3D SPACE AND WEYL ALGEBRA
Authors: OZAVSAR MUTTALIP , YESILOT GURSEL
Published: January 2012

Noncommutative derivative operators acting on the quantum 3D space in the sense of Manin are introduced. Furthermore, the quantum 3D space is extended by the series expansion of the logarithm of the grouplike generator in the quantum 3D space. We give its differential calculus and the corresponding Weyl algebra. We also obtain algebra of Cartan–Maurer forms on this extension and the corresponding Lie algebra of vector fields. All noncommutative results are found to reduce to those of the standard commutative algebra when the deformation parameter of the quantum 3D space is set to one.
ON THE GEOMETRY OF SIEGEL–JACOBI DOMAINS
Authors: BERCEANU S. , GHEORGHE A.
Published: January 2012

We study the holomorphic unitary representations of the Jacobi group based on Siegel–Jacobi domains. Explicit polynomial orthonormal bases of the Fock spaces based on the Siegel–Jacobi disk are obtained. The scalar holomorphic discrete series of the Jacobi group for the Siegel–Jacobi disk is constructed and polynomial orthonormal bases of the representation spaces are given.
ON HIGHER DERIVATIVES AS CONSTRAINTS IN FIELD THEORY: A GEOMETRIC PERSPECTIVE
Authors: VITAGLIANO L.
Published: January 2012

We formalize geometrically the idea that the (de Donder) Hamiltonian formulation of a higher derivative Lagrangian field theory can be constructed understanding the latter as a first derivative theory subjected to constraints.
MOLECULAR TEMPLATES FOR CONTROLLING AND ORDERING ORGANIC MOLECULES ON SOLID SURFACES
Authors: ZHANG XU , LI SHAN-SHAN , CHEN TING , WANG DONG , WAN LI-JUN
Published: January 2012

Molecular templates are effective for inducing the formation of functional organic molecular structures on solid surfaces. Various surface nanopatterns as molecular templates were developed by self-assembly and molecular engineering. These molecular templates were used and led to the formation of ordered assembly of alien species into designed two-dimensional matrices targeting at future applications. Both molecular template and so-fabricated nanopatterned assembly were clearly observed by scanning tunneling microscopy (STM). This paper summarizes some recent results on molecular templates for controlling and ordering organic molecules on solid surfaces mainly from our group. Several typical molecular templates and the consequent nanofabrication of ordered assemblies are described, including template design and fabrication, molecule ordering and patterning with the template as well as the possible application of these systems.
Numerical Simulation of Laser Induced Weakly Ionized Helium Plasma Process by Lattice Boltzmann Method
Authors: Zhang Xiaobo , Deguchi Yoshihiro , Liu Jiping
Published: January 2012

Generation process of laser induced weakly ionized helium plasma is simulated using the lattice Boltzmann method (LBM). Maxwell equations, which are used to model the propagation of laser, are calculated by the finite difference time domain (FDTD) method. Employing coefficients of distribution functions, processes of multi-photon ionization, electron impact ionization and three-body recombination are included in Boltzmann equations. Using D2Q9 model in LBM, number densities of particles in plasma can be obtained after solving Boltzmann equations. For the energy transformation in plasma, the finite volume method (FVM) is applied to calculate the macroscopic energy equations directly coming from the continuous Boltzmann equations. Interaction between laser and plasma as well as laser induced weakly ionized plasma are demonstrate to validate the hybrid model.
Electrical Properties of Cr–N Films Deposited by Sputtering: Application to Cryogenic Temperature Sensors
Authors: Satoh Kazuo , Kakehi Yoshiharu , Uno Mayumi , Sakurai Yoshiaki , Yotsuya Tsutom , Ishida Takekazu
Published: January 2012

The electrical properties of chrome nitride (Cr–N) films have been investigated for application to cryogenic temperature sensors. The films were deposited on silica substrates by RF magnetron sputtering under various total pressures without substrate heating. The electrical resistivity at room temperature increased from 1.4×10-3–1.7×10-3 to 3.4×10-3–4.0×10-3 Ω cm as the total pressure increased. X-ray diffraction measurements revealed that the crystallinity was improved in the high-total-pressure region. The temperature dependence of the electrical resistivity for Cr–N films exhibited semiconducting behavior. The slope of the electrical resistivity versus temperature increased with increasing total pressure. When a magnetic field was applied parallel to the current direction, the change in magnetoresistance at 3.7 K for Cr–N films was less than 1% in the range of 0 to 10 T. The results indicated that temperature sensors made of Cr–N films are available in high magnetic fields.
Observation of Phenomena After Pulsed Laser Irradiation of Solid with Optical Wave Microphone
Authors: Mitsugi Fumiaki , Ikegami Tomoaki , Nakamiya Toshiyuki , Sonoda Yoshito
Published: January 2012

Pulsed laser irradiation of a solid has been used in plasma processing. The refractive index change of the medium is one of the important factors to understand phenomena after laser irradiation. An optical wave microphone, which is based on Fraunhofer diffraction, was applied as a novel method to detect the refractive index change of air after laser irradiation of a solid. In this paper, the theory and fundamental properties of the optical wave microphone are introduced. We report the results of optical wave microphone measurement for the refractive index change of air after pulsed laser irradiation of silicon. The effect of the energy density of the pulsed laser on the measurement was discussed.
Deposition of Cluster-Free B-doped Hydrogenated Amorphous Silicon Films Using SiH4+B10H14 Multi-Hollow Discharge Plasma Chemical Vapor Deposition
Authors: Koga Kazunori , Nakahara Kenta , Kim Yeon-Won , Matsunaga Takeaki , Yamashita Daisuke , Matsuzaki Hidefumi , Uchida Giichiro , Kamataki Kunihiro , Itagaki Naho , Shiratani Masaharu
Published: January 2012

We have deposited cluster-free B-doped hydrogenated amorphous silicon (a-Si:H) films using a SiH4+B10H14 multi-hollow discharge plasma chemical vapor deposition (CVD) method. We have studied the dependence of the deposition rate, band gap, and conductivity of the films on the gas flow rate ratio R=[B10H14]/[SiH4]. The deposition rate for SiH4+B10H14 plasmas is 2–3 times as high as that for pure SiH4 plasmas. Optical emission spectroscopy (OES) measurements indicate that SiH3 radical generation rate remains nearly constant regardless of R. These results suggest that B
x
H
y
radicals enhance the surface reaction probability and/or sticking probability of SiH3, being the predominant deposition precursor. Cluster-free B-doped a-Si:H films have a wide band-gap energy of 1.8–2.0 eV and a conductivity as high as 5.0×10-6 S/cm. These results demonstrate that cluster-free B-doped a-Si:H films deposited using SiH4+B10H14 multi-hollow discharge plasma CVD are promising as a p-layer of pin a-Si:H solar cells.
Gallium Nitride Film Growth Using a Plasma Based Migration Enhanced Afterglow Chemical Vapor Deposition System
Authors: Butcher K. Scott A. , Kemp Brad W. , Hristov Ilian B. , Terziyska Penka , Binsted Peter W. , Alexandrov Dimiter
Published: January 2012

Gallium nitride layers were grown by a new migration enhanced epitaxy technique called MEAglow. Initial experiments were performed to characterize the plasma source used and to examine the surfaces of thin samples grown by the technique. Atomic force microscopy (AFM) results show root mean square (RMS) surface roughness values of less than 1 nm for samples grown at 650 °C, this is commensurate with Ga-face material grown directly on nitrided sapphire substrates.
Effect of Growth Temperature on Structural Quality of InAlN Layer Lattice Matched to GaN Grown by Metal Organic Chemical Vapor Deposition
Authors: Ichikawa Junki , Sakai Yusuke , Chen Zhitao , Fujita Kazuhisa , Egawa Takashi
Published: January 2012

The authors report the effect of growth temperature on the structural quality of an InAlN layer lattice matched to GaN. InAlN/GaN structures were grown on a sapphire substrate using a low-temperature-grown GaN buffer layer. The X-ray diffraction and Atomic force microscopy results indicate that the quality of the InAlN layer is strongly affected by the three-dimensionally grown surface morphology, depending on the growth temperature. The lattice matching of InAlN to GaN with a flat surface and a smooth interface are obtained at temperatures of 790–800 °C. The Schottky diode fabricated on InAlN grown at 800 °C shows high-quality characteristics with the leakage current as low as 2.3 ×10-9 A at -5 V, corresponding to a current density of 1.2 ×10-6 A/cm2 and 6.2 ×10-8 A at -10 V.
Nonphosphor White Light Emitting Diodes by Mixed-Source Hydride Vapor Phase Epitaxy
Authors: Lee Gang Seok , Jeon Hunsoo , Jung Se-Gyo , Bae Seon Min , Shin Min Jung , Kim Kyoung Hwa , Yi Sam Nyung , Yang Min , Ahn Hyung Soo , Yu Young-Moon , Kim Suck-Whan , Ha Hong-Ju , Sawaki Nobuhiko
Published: January 2012

In this paper, we approached a novel fabrication for non phosphor white light emitting diodes (LEDs) by the growth of AlGaN/InAlGaN double-hetero structures using by mixed-source hydride vapor phase epitaxy (HVPE) system with multi-sliding boat. It is unique crystal growth technology different from conventional HVPE and metal organic chemical vapor deposition (MOCVD) system using mixed metal source of aluminum, indium and gallium. The characterization of non phosphor white LEDs was examined by photoluminescence (PL) and electroluminescence (EL). The results of EL were found green and yellow emissions as spectrum peaks near 500, 550, and 610 nm definitely. The CIE chromaticity coordinates of white LEDs was measured at injection current 30 mA. Our results are nearly positions; atx= 0.28 andy= 0.31. Even though the LED needs more improved in optical properties, we demonstrated achieving phosphor-free solid-state white lighting.
Design and Fabrication of AlN/GaN Heterostructures for Intersubband Technology
Authors: Ive Tommy , Berland Kristian , Stattin Martin , Fälth Fredrik , Hyldgaard Per , Larsson Anders , Andersson Thorvald G.
Published: January 2012

We have used models based on the effective-mass approximation and Schrödinger–Poisson to design AlN/GaN multiple quantum well structures for intersubband transitions between two or three energy levels. The structures were realized by molecular beam epitaxy and the surface morphology and structural quality were investigated. We also investigated GaN waveguides that were fabricated using standard cleanroom techniques. Our work is focused on the various challenges associated to the fabrication of quantum cascade lasers based on group III–nitrides. These challenges are discussed in the light of our results.
Growth Characteristics of Carbon Nanotubes on Oxidized Catalyst under Low-Pressure Condition
Authors: Sawaguchi Daiki , Sato Hideki , Hata Koichi , Miyake Hideto , Iida Kazuo , Hiramatsu Kazumasa
Published: January 2012

Low-pressure alcohol catalytic chemical vapor deposition (LP-ACCVD), which is an ACCVD method at a lower pressure (<1 Pa) than that in the conventional method, has been attracting much interest because it enables the low-temperature growth of single-wall carbon nanotubes (CNTs). However, the growth rate of CNTs by LP-ACCVD is markedly low owing to its low growth pressure. To alleviate this problem, we have examined the influence of the catalyst preparation and CVD conditions on the properties of CNTs grown by LP-ACCVD. It has been found that the oxidation of catalyst enhances the growth of CNTs by LP-ACCVD. Furthermore, the low flow rate of the ethanol enhances the growth yield of CNTs at lower growth temperature, which is understood to be the result of sufficient gas heating on the substrate.
Hardfacing of Bulk Nanophase Coatings
Authors: Reisgen Uwe , Balashov Boris , Stein Lars , Geffers Christoph
Published: January 2012

This paper discusses the production of iron-based nanophase hardfaced coatings by means of common arc welding methods. The key is the exact, close-to-eutectic composition of the newly developed alloys. In combination with a precise control of the dilution of the base metal, this results in an eutectic composition of the coating, which allows the in-situ generation of nanoscale hardphases during solidification. The applied cooling rates are only of secondary importance. The self-organizing nanophase structures within the hardfaced coatings show phase dimensions of approximately 100–300 nm. The generation of nanoscale structures in hardfaced coatings allows the improvement of mechanical properties, wear resistance and corrosion resistance. The article further demonstrates a potential application for these types of hardfaced coatings in the field of cutting edges.
White Photoluminescence from Carbon-Incorporated Silica Fabricated from Rice Husk
Authors: Ishikawa Yukari , Kawasaki Shinji , Ishi Yosuke , Sato Koji , Matsumura Akihiro
Published: January 2012

White photoluminescence (PL) from thermally treated rice husk is demonstrated. The strongest PL is obtained after oxidation at 400 °C following carbonization at 600 °C. The PL intensity was strong enough to be detected by the naked eye in daylight under the irradiation of 370 nm light from a light-emitting-diode (LED)-type flashlight. Thermal treatment changes rice husk to silicon oxycarbide but the amorphous structure and cell-wall architecture of the plants are maintained. The origin of PL is speculated to be related to some centers or defects in strained silicon oxycarbide.
Evaluation of Misfit Relaxation in α-Ga2O3 Epitaxial Growth on α-Al2O3 Substrate
Authors: Kaneko Kentaro , Kawanowa Hitoshi , Ito Hiroshi , Fujita Shizuo
Published: January 2012

Corundum-structured α-Ga2O3 epitaxial thin films were grown on c-plane α-Al2O3 (sapphire) substrates by a mist chemical vapor deposition method. To reveal the defect structures, the α-Ga2O3 film was observed by high-resolution transmission electron microscopy (TEM). We found that the α-Ga2O3 thin film was in-plane compressive stressed from the α-Al2O3 substrate. Although misfit dislocations were periodically generated at the α-Ga2O3/α-Al2O3 interface owing to the large lattice mismatches between α-Ga2O3 and α-Al2O3, 3.54% (c-axis) and 4.81% (a-axis), most of the misfit dislocations did not thread through the layer. An extra-half plane was {2̄110} consisting only of Ga. Screw dislocations were not confirmed, i.e., the density was under 107 cm-2. The threading dislocation density was 7 ×1010 cm-2.
Process Condition Considered Preparation and Characterization of Plasma Polymerized Methyl Methacrylate Thin Films for Organic Thin Film Transistor Application
Authors: Lee Se-Hyun , Lee Boong-Joo , Lim Young-Taek , Lim Jae-Sung , Lee Sunwoo , Ochiai Shizuyasu , Yi Jun-Sin , Shin Paik-Kyun
Published: January 2012

Plasma polymerized methyl methaclylate (ppMMA) thin films were prepared with various process conditions such as inductively coupled plasma (ICP) power, substrate bias power, working pressure, substrate heating temperature, substrate position, and monomer flow rate. Thickness, surface morphology, dielectric constant, and leakage current of the ppMMA thin films were investigated for application to organic thin film transistor as gate dielectric. Deposition rate of over 8.6 nm/min, dielectric constant of 3.4, and leakage current density of 8.9 ×10-9 A/cm-2 at electric field of 1 MV/cm were achieved for the ppMMA thin film prepared at the optimized process condition: plasma power of RF 100 W; Ar flow rate of 20 sccm; working pressure of 5 mTorr; substrate temperature of 100 °C; substrate position of 100 mm. The ppMMA thin film was then applied to pentacene based organic thin film transistor (OTFT) device fabrication. The OTFT device with 80 nm thick pentacene semiconductor layer showed field effect mobility of 0.144 cm2 V-1 s-1 and threshold voltage of -1.72 V.
Device Analysis of Pt/Ti Gate Si-Metal–Oxide–Semiconductor Field-Effect Transistor Hydrogen Gas Sensors: Unintentional Oxygen Invasion into Ti Layers
Authors: Usagawa Toshiyuki , Kikuchi Yota
Published: January 2012

We have investigated Pt/Ti-gate Si-metal–oxide–semiconductor field-effect transistors (MOSFETs) from the viewpoints of hydrogen gas sensors and also mother devices of Pt–Ti–O-gate Si-metal–insulator–semiconductor field-effect transistor (MISFET) hydrogen gas sensors. The Pt/Ti-gate Si-MOSFETs with uniform coverage of Ti layers over the gate area do not respond to hydrogen gases in general. The observed large variations of threshold voltage V
th and sensing amplitude ΔV
g for the as-processed Pt (15 nm)/Ti (5 nm)-gate Si-MOSFETs originate from the initial unintentional oxygen invasion into the Ti layers at the beginning of phosphorus-doped silicon glass deposition. The air-annealed and succeeding hydrogen post-annealing procedure for Pt (15 nm)/Ti (5 nm)-gate Si-MOSFET hydrogen gas sensors recovers the uniformity of V
th distributions close to that of as-processed Pt (90 nm)/Ti (5 nm)-gate Si-MOSFETs and leads to a large sensing amplitude ΔV
g. We have found a critical V
th, V
thc, at which the response to hydrogen gas exposure begins. We have introduced a percolation model in which the ratio of Ti contact area to the effective Pt contact area over the gate oxides will be reduced to zero in accordance with the increasing dose of oxygen invasion, at a point which probably corresponds to V
thc.
III–Nitride Epitaxy on Atomically Controlled Surface of Sapphire Substrate with Slight Misorientation
Authors: Aida Hideo , Kim Seong-Woo , Sunakawa Kazuhiko , Aota Natsuko , Koyama Koji , Takeuchi Misaichi , Suzuki Toshimasa
Published: January 2012

The importance of the atomically well-controlled surface of sapphire substrate with slight misorientation and ideally minimized surface roughness for III–nitride epitaxy is discussed in detail. An atomically controlled surface of sapphire substrate with slight misorientation angle is modeled and an almost ideal level of atomic surface roughness of sapphire substrate is found to be obtained by a chemical mechanical polishing (CMP) with colloidal silica. Cathodoluminescence (CL) imaging indicated the complete absence of subsurface damage induced by mechanical polishing. GaN and AlN thin films are grown on misoriented sapphire substrate with an atomically controlled surface by the CMP to investigate the misorientation angle of both sapphire and grown GaN and AlN thin films. An interface model is proposed to explain the difference in misorientation angle between sapphire and III–nitride thin films, providing strong evidence of the necessity of atomically controlled surface of sapphire substrate for III–nitride epitaxy.
Copper Filling of Deep Submicrometer Trenches with Ruthenium-Lined Barrier Metal by High-Vacuum Magnetron Sputtering Using Argon Gas with Added Oxygen
Authors: Itoh Masatoshi , Saito Shigeru
Published: January 2012

A fine structure with a ruthenium-lined barrier layer was experimentally fabricated, and copper-filling tests were performed by high-vacuum sputtering using argon gas with added oxygen. As a result, the complete copper filling of all trenches with a width of about 80 nm and an aspect ratio (AR) of four was accomplished with good reproducibility. The experimental results also show that complete copper filling was even possible in the case of trenches with a width of about 30 nm and an AR of nine. The reasons for these results are explained by applying capillary theory from the viewpoint of copper wettability on a ruthenium-lined layer.
Effect of Current on Domain Wall Depinning Field in Co/Ni Nanowire
Authors: Hiramatsu Ryo , Kondou Kouta , Koyama Tomohiro , Yoshimura Yoko , Chiba Daichi , Fukami Shunsuke , Ishiwata Nobuyuki , Ono Teruo
Published: January 2012

We have investigated the effect of dc current on magnetic domain wall (DW) depinning fields in a perpendicularly magnetized Co/Ni nanowire by utilizing the giant magnetoresistance (GMR) effect. It was found that the current assisted (prevented) the domain wall depinning when the electron flow was parallel (antiparallel) to the DW depinning direction. The depinning field was found to exhibit a linear dependence on the dc current density, from which the efficiency of the effective field was estimated to be -1.5×10-14 T m2/A.
PGC-1α Promotes the Growth of ErbB2/Neu–Induced Mammary Tumors by Regulating Nutrient Supply
Authors: Klimcakova Eva , Chénard Valérie , McGuirk Shawn , Germain David , Avizonis Daina , Muller William J. , St-Pierre Julie
Published: January 2012

Cancer cells display an increased reliance on glycolysis despite the presence of sufficient oxygen levels to support mitochondrial functions. In this study, we asked whether ameliorating mitochondrial functions in cancer cells might limit their proliferative capacity. Specifically, we increased mitochondrial metabolism in a murine cellular model of ErbB2/Neu–induced breast cancer by ectopically expressing the transcriptional coactivator peroxisome proliferator–activated receptor γ coactivator 1α (PGC-1α), a master regulator of mitochondrial metabolism. As predicted, ErbB2/Neu cells ectopically expressing PGC-1α displayed an increased level of mitochondrial metabolism and reduced proliferative capacity in vitro, compared with controls. In contrast, ErbB2/Neu cells ectopically expressing PGC-1α formed larger tumors in vivo. These tumors exhibited increased concentrations of glucose and the angiogenic factor VEGF as well as higher expression of ErbB2/Neu compared with controls. We discovered that ErbB2/Neu levels were sensitive to nutrient availability, such that reduced glucose concentrations resulted in diminished ErbB2/Neu protein levels. Therefore, our data indicate that PGC-1α prevents the nutrient-mediated downregulation of ErbB2/Neu in tumors by increasing glucose supply. Mechanistic investigations revealed that the regulation of ErbB2/Neu levels by glucose was mediated by the unfolded protein response (UPR). Incubation of ErbB2/Neu–induced breast cancer cells in limited glucose concentrations or with drugs that activate the UPR led to significant reductions in ErbB2/Neu protein levels. Also, ErbB2/Neu–induced tumors ectopically expressing PGC-1α displayed lowered UPR activation compared with controls. Together, our findings uncover an unexpected link between PGC-1α–mediated nutrient availability, UPR, and ErbB2/Neu levels. Cancer Res; 72(6); 1538–46. ©2012 AACR.
Phase I Dose-Escalation Study of Intravenous Aflibercept in Combination with Docetaxel in Patients with Advanced Solid Tumors
Authors: Isambert Nicolas , Freyer Gilles , Zanetta Sylvie , You Benoît , Fumoleau Pierre , Falandry Claire , Favier Laure , Assadourian Sylvie , Soussan-Lazard Karen , Ziti-Ljajic Samira , Trillet-Lenoir Veronique
Published: January 2012

Purpose: This phase I study cohort investigated aflibercept in combination with docetaxel in patients with advanced solid tumors.

Materials and Methods: Eligible patients had metastatic or nonresectable cancer for which docetaxel was considered appropriate. Patients received intravenous aflibercept (either 2, 4, 5, 6, 7, or 9 mg/kg) with docetaxel (75 mg/m2) on day 1 every 3 weeks until disease progression or unacceptable toxicity. Primary objectives were to evaluate dose-limiting toxicities (DLT) during cycle 1 and to determine the aflibercept recommended phase II trial dose (RP2D) for combination with docetaxel. Pharmacokinetics, tolerability, and antitumor activity were also investigated.

Results: Fifty-four patients (mean age, 56 y) were enrolled. Most had prior chemotherapy (96%) and most (24.1%) had breast cancer. In the dose-escalation phase (n = 34), there were three DLTs: grade 4 neutropenic infection (2 mg/kg), grade 3 dysphonia (7 mg/kg), and grade 2 hypertension (9 mg/kg). An excess of free-over-bound aflibercept was observed at doses of 5 mg/kg or more. The pharmacokinetics of aflibercept and docetaxel were not modified by coadministration. Aflibercept (6 mg/kg) was defined as the RP2D based on DLT and pharmacokinetic data. Overall, the most frequent grade 3/4 adverse events (AE) were neutropenia (85.2%), leukopenia (74.1%), hypertension (18.5%), and stomatitis (16.7%). AEs associated with vascular endothelial growth factor blockade included epistaxis (all grades, 83.3%), proteinuria (68.5%), dysphonia (68.5%), and hypertension (53.7%). Seven patients had partial responses, and 32 patients had stable disease (>3 months in 18 patients).

Conclusion: On the basis of findings from this study, aflibercept (6 mg/kg) was the dose recommended for further clinical development. Clin Cancer Res; 18(6); 1743–50. ©2012 AACR.
Bioinformatical Assistance of Selecting Anti-HIV Therapies: Where Do We Stand?
Authors: Lengauer Thomas
Published: January 2012

In this opinion statement, we give a critical synopsis of the state-of-the-art of bioinformatic HIV resistance analysis and point out what we consider to be challenges and perspectives.
Development and Performance of Conventional HIV-1 Phenotyping (Antivirogram®) and Genotype-Based Calculated Phenotyping Assay (virco®TYPE HIV-1) on Protease and Reverse Transcriptase Genes to Evaluate Drug Resistance
Authors: Pattery Theresa , Verlinden Yvan , De Wolf Hans , Nauwelaers David , Van Baelen Kurt , Van Houtte Margariet , Mc Kenna Paula , Villacian Jorge
Published: January 2012

Objectives: A wide array of monitoring tests is commercially available to gauge HIV-1 disease progression and the overall health status of an HIV-1-infected patient. Viral load tests provide a picture of viral activity, while CD4 cell counts shed light on the immune status and can help physicians to prevent the development of opportunistic infections in patients. On the other hand, genotypic and phenotypic resistance testing and therapeutic drug monitoring help to optimize HIV-1 antiretroviral therapy. Resistance testing is currently recommended within the standard of care guidelines to aid the choice of new drug regimens following treatment failure(s). Methods: Genotypic testing described here is based on the amplification and sequencing of an HIV-1 protease (PR) and reverse transcriptase (RT) region from a patient sample to identify resistance mutations associated with PR and RT inhibitor resistance. A genotypic test takes a week to perform and the results are reported as a list of detected mutations. The virco®TYPE HIV-1 report uses genotypic data to predict phenotypic susceptibility by linear regression modeling that uses a large correlative database of genotype-phenotype pairs. Phenotypic testing measures the ability of the virus to replicate in the presence of a drug and provides a direct measurement of drug susceptibility in vitro. Since phenotypic analysis is laborious and time consuming (28 days), genotypic resistance testing is currently the standard reference method used for HIV-1 resistance testing. However, a phenotypic test is important when a patient harbors virus with complex genetic patterns, or when the mutational resistance profile for a particular drug is not well-characterized. Results and Conclusions: Some of the currently used resistance tests are partially automated enabling laboratories to increase overall efficiency. However, maximum automation and standardization of the process, instruments and software that we have described here can overcome many of the problems encountered with current tests and aims at having a compliant, high-throughput, diagnostic laboratory, which can guarantee sample integrity from sample reception to result reporting. We also describe in detail the development and performance of virco®TYPE HIV-1 (genotype) and Antivirogram® (phenotype) assay on PR and RT genes to evaluate antiretroviral resistance.
How Individual Can Personalized Antiretroviral Treatment Be? Deep Salvage in an HIV-1-Infected Patient
Authors: Jensen Bjoern , Esser Stefan , Kaiser Rolf , Luebke Nadine , Häussinger Dieter
Published: January 2012

We present an HIV-1-infected male (who is now 52 years old) with a multi-drug-resistant virus and discuss the considerations finally leading to an antiretroviral regimen resulting in long-term viral suppression and excellent immunological response in a deep salvage situation. Even in a desperate situation with high-level multi-class resistance, highly individual, personalized antiretroviral regimes can be tailor-made to achieve unexpected improvements in the health status of a patient.
Prediction of Mortality in the First Two Years of Hemodialysis: Results from a Validation Study
Authors: Thijssen Stephan , Usvyat Len , Kotanko Peter
Published: January 2012

Background: Chronic hemodialysis (HD) patients experience high rates of mortality. Alerting medical staff of patients at increased risk of death may support clinical decision making. Methods: A large cohort of incident HD patients was used to develop logistic regression models to predict death in the subsequent 6 months (‘derivation cohort’). Predictors were age, gender, race, ethnicity, vascular access type, diabetic status, pre-HD systolic and diastolic blood pressure, pre-HD weight, pre-HD temperature, relative interdialytic weight gain, serum albumin, hemoglobin, phosphorus, serum creatinine, serum sodium, urea reduction ratio, equilibrated normalized protein catabolic rate, and equilibrated dialytic and renal Kt/V. These logistic regression models were then applied to validation cohorts. Predictive performance of the models was described in terms of sensitivity, specificity, and area under receiver-operating characteristic curves (AUC-ROC). Results: A total of 6,838 incident HD patients were followed over 2 years. The derivation cohort initially comprised 4,512 patients. In the validation cohort of initially 2,326 patients, the logistic regression models were able to predict mortality in subsequent 6-month periods with a sensitivity between 58 and 69%, and a specificity of 74–77%; the respective AUC-ROC were 0.67–0.72 (all p < 0.0001). Pre-HD weight and serum albumin levels were consistently significant predictors of mortality in all models. Conclusion: The results indicate that logistic regression models are useful tools in estimating incident HD patients’ probability of death in 6-month intervals for at least up to 2 years after beginning dialysis. Model predictions may be used to alert medical staff to patients at increased risk of death and facilitate timely diagnostic and therapeutic interventions to improve outcomes.
Acute Peritoneal Dialysis Treatment Programs for Countries of the East African Community
Authors: Carter Mary , Kilonzo Kajiru , Odiit Amos , Kalyesubula Robert , Kotanko Peter , Levin Nathan W. , Callegari John
Published: January 2012

The literature abounds with attestations about the lack of treatment programs for kidney injury in developing countries. To date, no sustainable treatment program exists for acute kidney injury (AKI) in many of the 48 countries in the sub-Saharan region of Africa. The Sustainable Kidney Care Foundation, together with industry, universities, and funding organizations, has been working on establishing peritoneal dialysis treatment programs for AKI in East Africa, starting with the countries comprising the East African Community and with a special focus on treating children and women of childbearing age.
Hypertension and Future Cardiovascular Health in Pediatric End-Stage Renal Disease Patients
Authors: Flynn Joseph T.
Published: January 2012

Background: There are now numerous studies that have documented an increased risk of cardiovascular morbidity and mortality in young adults who had childhood-onset end-stage renal disease (ESRD). Since the number of such patients surviving to adulthood is increasing, strategies to reduce this risk are urgently needed. Methods: The various risk factors contributing to adult cardiovascular disease in this population will be reviewed, with an emphasis on hypertension and its control. Data demonstrating the prevalence of hypertension in childhood chronic kidney disease as well as the results of improved blood pressure control in ESRD will also be presented. Conclusions: Hypertension is exceedingly common in pediatric ESRD patients and frequently poorly controlled. Efforts to improve blood pressure control in this patient population could potentially reduce future cardiovascular morbidity and mortality.
Critical Evaluation of Blood Volume Measurements during Hemodialysis
Authors: Dasselaar Judith J. , van der Sande Frank M. , Franssen Casper F.M.
Published: January 2012

Devices that continuously measure relative blood volume (RBV) changes during hemodialysis (HD) are increasingly used for the prevention of dialysis hypotension and fine-tuning of dry weight. However, RBV measurements are subject to various limitations. First, RBV devices provide information on relative blood volume changes but not on absolute blood volume. Since blood volume varies with the hydration status, identical reductions of RBV may result in very different absolute blood volumes at the end of HD. Second, RBV changes underestimate the change of total blood volume due to translocation of lower-hematocrit blood from the microcirculation to the central circulation. Third, changes in posture before and during HD, food intake, exercise, and administration of intravenous fluids may influence the validity of the RBV measurement. Fourth, results obtained by various RBV devices show large interdevice differences. Finally, although a fall in blood volume is an important factor in dialysis hypotension, frank dialysis hypotension only occurs when the cardiovascular compensatory mechanisms can no longer compensate for the reduction in blood volume. Therefore, the dialysis staff should not exclusively focus on RBV, but also search for opportunities in the dialysis prescription to facilitate cardiovascular compensatory mechanisms, e.g. by lowering dialysate temperature. In the opinion of the authors, routine RBV monitoring should be used with caution until the major conceptual and methodological problems that are inherent to the indirect RBV estimation are clarified.
Impact of the Bundled End-Stage Renal Disease Payment System on Patient Care
Authors: Maddux Franklin W.
Published: January 2012

This article provides a perspective on the impact of the bundled end-stage renal disease prospective payment system on patient care. As the first year of the bundle comes to a close, we are beginning to see information about practice pattern changes that have resulted and the impact of those changes on the care of patients with renal disease. This review recognizes the background of the prospective payment system for renal replacement therapy and its evolution to include multiple components, as well as a description of the features of this payment system that are expected to have an impact on the clinical care by nephrologists and dialysis providers. Some of the expected impact on the dosing of erythropoiesis-stimulating agents, consolidation of dialysis providers, and a move toward more measurement are beginning to be seen. This brief summary not only reviews the components of the bundled payment system, but also the anticipated impact and some early information on the response to these predicted findings in the industry.
Natalizumab May Improve Cognition and Mood in Multiple Sclerosis
Authors: Lang C. , Reiss C. , Mäurer M.
Published: January 2012

Immunomodulating therapies may prevent relapses in multiple sclerosis and stabilize neurological status. However, little is known about the influence particularly of newer drugs on cognitive functions. We conducted an open-label prospective study to demonstrate whether natalizumab is apt to improve cognitive functions and mood in 29 patients tested psychometrically while under treatment for 6 months. We found improvements in some measures of attention, memory, mood, and well-being, but no deterioration, although patients suffered from their diseases for more than 10 years and had an EDSS score of 3.5. It is concluded that natalizumab is able to stabilize or improve cognition and mood even in longer-lasting multiple sclerosis.