bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effects of Unsteadiness and Compressibility on the Interaction Between Hub Leakage and Mainstream Flows in HP Turbines
Authors: Popovic´ I. , Hodson H. P. , Janke E. , Wolf T.
Published: May 2012

This paper investigates the effects of compressibility and unsteadiness due to the relative blade row motion and their importance in the interaction between hub leakage (purge) and mainstream flows. First, the challenges associated with the blade redesign for low-speed testing are described. The effects of Mach number are then addressed by analyzing the experiments in the low-speed linear cascade equipped with the secondary airflow system and computations performed on the low- and high-speed blade profiles. These results indicate that the compressibility does not significantly affect the interaction between the leakage and mainstream flows despite a number of compromises made during the design of the low-speed blade. This was due to the fact that the leakage-mainstream interaction takes place upstream of the blade throat where the local Mach numbers are still relatively low. The analysis is then extended to the equivalent full-stage unsteady computations. The periodic unsteadiness resulting from the relative motion of the upstream vanes appreciably affected the way in which the leakage flow is injected and the rotor flowfield in general. However, the time-average flowfield was still found to be dominated by the rotor blade’s potential field. For the present test arrangement, the unsteady effects were not very detrimental, and caused less than a 10% increase in the losses due to the leakage injection relative to the steady calculations.
Discussion About the Practice of Using a Heated Surface in Film Cooling Studies
Authors: Zhao Lei , Wang Ting
Published: May 2012

It is found in many film-cooling experiments and computational analyses that a heated surface is employed to simulate the actual film-cooling condition with a cooling jet and a hot main flow. Considering that the dominant energy passage in turbine airfoil film cooling is always from the hot combustion gas flowing into the airfoil, employing a heated surface to simulate the actual film cooling condition does not provide the correct physics of the heat flow under an actual film cooling condition, and therefore, the results are questionable. The objective of this paper is to investigate the consequent results associated with the practice of employing a heated surface by comparing its result with actual conditions including a conjugate metal wall and internal cooling via a series of computational simulations. When the surface is heated, in some conditions, negative film cooling effectiveness can be found as a result of a higher surface temperature than the main gas stream temperature. This is unrealistic for an operational turbine system. The heated wall acts as an active heat source; as a result, the concept of using the adiabatic wall temperature (Taw) as the driving temperature potential is no longer valid because an artificially created competing heat source is added into the system, and the heat transfer mechanism on the airfoil is not solely determined by Taw. Heating the surface to simulate the film cooling boundary condition, although it does not provide correct physics, can provide the heat transfer coefficient value within 10–15% of the value calculated from the correct boundary conditions. Using a heated surface is only correct under one condition: when all the conditions are reversed, i.e. with a hot jet and cold main gas flow. The practice of using a jet flow with the same temperature of the hot gas (isoenergetic jet) to obtain the film heat transfer coefficient will result in about 20–25% discrepancy from the cooling jet case. The uniformly cooled wall cases fair better than heated cases because it provides correct physics in most part of the surface.
Evaluation of CFD Predictions Using Thermal Field Measurements on a Simulated Film Cooled Turbine Blade Leading Edge
Authors: Mathew Sibi , Ravelli Silvia , Bogard David G.
Published: May 2012

Computational Fluid Dynamics (CFD) predictions of film cooling performance for gas turbine airfoils are an important part of the design process for turbine cooling. Typically, industry relies on the approach based on Reynolds Averaged Navier Stokes equations, together with a two-equation turbulence model. The Realizable k-ε (RKE) model and the Shear Stress Transport k-ω (SST) model are recognized as the most reliable. Their accuracy is generally assessed by comparing to experimentally measured adiabatic effectiveness. In this study, the performances of the RKE and SST models were evaluated by comparing predicted and measured thermal fields in a turbine blade leading edge with three rows of cooling holes, positioned along the stagnation line and at ±25°. Predictions and measurements were done with high thermal conductivity models which simulated the conjugate heat transfer effects between the coolant flow and the solid. Particular attention was placed on the thermal fields along the stagnation line, and immediately downstream of the off-stagnation line row of holes. Conventional evaluations in terms of adiabatic effectiveness were also carried out. Predictions of coolant flows at the stagnation line were significantly different when using the two different turbulence models. For a blowing ratio of M = 2.0, the predictions with the SST model showed coolant jet separation at the stagnation line, while the RKE predictions showed no separation. Experimental measurements showed that there was coolant jet separation at the stagnation line, but the actual thermal fields obtained from experimental measurements were significantly different from that predicted by either turbulence model. Similar results were seen for predicted and measured thermal fields downstream of the off-stagnation row of holes.
Influence of the Different Design Parameters to the Centrifugal Compressor Tip Clearance Loss
Authors: Turunen-Saaresti Teemu , Jaatinen Ahti
Published: May 2012

In this paper the effect of the tip clearance was studied with six different centrifugal compressors and data available in literature. The changes in the overall performance of the compressor stage were examined. The aim was to study the influence of the different design parameters to the tip clearance loss. It was evident by the previous studies that the sensitivity of the centrifugal compressor to the tip clearance loss varies with different designs. However, for the designer it is important to know the effect of the tip clearance loss in order to initially evaluate the quality of different designs. Analysis of the data demonstrated that no clear correlation between the sensitivity of the tip clearance loss and the specific speed, the diffusion ratio, the blade number and the ratio of blade heights exists.
Optimization of a 3-Stage Booster: Part 2—The Parametric 3D Blade Geometry Modeling Tool
Authors: Siddappaji Kiran , Turner Mark G. , Dey Soumitr , Park Kevin , Merchant Ali
Published: May 2012

A parametric approach for blade geometry design has been developed to obtain 3D blade models. The geometry of the blade is defined by a basic set of parameters that are first obtained from an axisymmetric solver. These parameters include the leading edge meridional coordinates, flow angles, axial chord, and the meridional coordinates of streamlines. Other parameters such as thickness to chord ratio need to be defined. Using these parameters the 2D airfoils are created and are stacked radially using one of the many multiple options that define the stacking axes from several additional parameters. The tool produces the desired number of 2D sections in a normalized coordinate system. Each blade section is then transformed to a 3D Cartesian coordinate system. Using Unigraphics-NX (CAD package), these sections are lofted and a 3D blade model is obtained. Parametric update of the spline points defining the 3D blade sections results in new blade shapes without going directly back into the CAD system. The importing of the geometry into a CFD solver, and a finite element solver to determine mode shapes and stresses is demonstrated. Full details of the blade procedure is presented for a 3-Stage Booster design. This parametric approach for defining blade geometry and how it lays a groundwork for a high-fidelity optimization procedure is described.
Prediction of Turbomachinery Aeroelastic Behavior From a Set of Representative Modes
Authors: Mayorca Mari´a A. , Vogt Damian M. , Ma˚rtensson Hans , Fransson Torsten H.
Published: May 2012

A method is proposed for the determination of the aeroelastic behavior of a system responding to mode-shapes different to the tuned in-vacuo ones, due to mistuning, mode family interaction or any other source of mode-shape perturbation. The method is based on the generation of a data base of unsteady aerodynamic forces arising from the motion of arbitrary modes and uses Least Square approximations for the prediction of any responding mode. The use of a reduced order technique allows for mistuning analyses and is also applied for the selection of a limited number of arbitrary modes. The application on a transonic compressor blade shows that the method captures well the aeroelastic properties in a wide frequency range. A discussion of the influence of the mode-shapes and frequency on the final stability response is also provided.
Evaluation of Commercial Alumina-Forming Austenitic Foil for Advanced Recuperators
Authors: Pint Bruce A. , Brady Michael P. , Yamamoto Yukinori , Unocic Kinga A. , Matthews Wendy J.
Published: May 2012

A corrosion- and creep-resistant austenitic stainless steel has been developed for advanced recuperator applications. This fully austenitic alloy is optimized for creep strength while allowing the formation of a chemically-stable external alumina scale at temperatures up to 900°C. An alumina scale eliminates long-term problems with the formation of volatile Cr oxy-hydroxides in the presence of water vapor in exhaust gas. The first batch of commercially fabricated foil was produced with a composition selected from prior laboratory creep and oxidation results. The results for ∼80 and ∼105μm thick foil are compared to the prior laboratory-fabricated foils and other commercial candidates. Results from initial creep testing at 750°C show comparable creep strength to other commercial Fe-base foil candidates. Laboratory exposures in humid air at 650°–800°C have shown excellent oxidation resistance for this composition. Similar oxidation resistance was observed for sheet specimens of the first set of alloys exposed in a modified 65kW microturbine for up to 6,000h.
Gas Turbine Inlet Filtration System Life Cycle Cost Analysis
Authors: Wilcox Melissa , Brun Klaus
Published: May 2012

Gas turbine inlet filtration systems play an important role in the operation and life of gas turbines. There are many factors that must be considered when selecting and installing a new filtration system or upgrading an existing system. The filter engineer must consider the efficiency of the filtration system, particles sizes to be filtered, the maintenance necessary over the life of the filtration system, acceptable pressure losses across the filtration system, required availability and reliability of the gas turbine, and how the filtration system affects this, washing schemes for the turbine, and the initial cost of any new filtration systems or upgrades. A life cycle cost analysis provides a fairly straightforward method to analyze the lifetime costs of inlet filtration systems, and it provides a method to directly compare different filter system options. This paper reviews the components of a gas turbine inlet filtration system life cycle cost analysis and discusses how each factor can be quantified as a lifetime cost. In addition, an example analysis, which is used to select a filtration system for a new gas turbine installation, is presented.
Inlet Guide Vane Failure: Aero-Mechanical and System Control Interaction Effect
Authors: Duong Loc Q. , Hu Charlene X. , Thayalakhandan Nagamany
Published: May 2012

The APU, a gas turbine engine is designed to provide the aircraft with electrical power and pneumatic air both on the ground and in-flight conditions. The variable inlet guide vane (VIGV) system is used to regulate the air flow to the load compressor. The vane motions are controlled by an actuator and associated linkage. Common failure mechanisms of the VIGV such as cracking, corrosion of vanes, have been reported. This paper discusses a particular mode of failure which involves the aero-mechanical and control feedback interaction. The failure phenomenon is characterized by sector and ring gear tooth non-uniform wear, jamming of sector gears, actuator resonance, actuator fluid contamination and subsequent engine shutdown. Solution to failure mode is also discussed.
Design and Analysis of a New Accessory Gearbox Housing for a Gas Turbine Engine
Authors: Das Partha S.
Published: May 2012

Accessory Gearbox (AGB) Housing is one of the most critical components of a gas turbine engine that lies between the core engine & the aircraft. The function of the AGB Housing is to provide support for the gear drive assembly that transfers power from the engine to the engine accessories and to the power takeoff drive for the aircraft accessories. The housing also functions as an oil tight container and passageway for lubrication. In addition, the AGB housing provides mount points to attach engine/aircraft support accessories, including the engine mount points to the aircraft. The complexity in predicting AGB housing behavior under the gear loading, engine loading and engine induced vibration is one of the main challenges of designing a new gearbox with minimum weight. To address these issues, the current paper presents for the first time the design-analysis of a new lightweight AGB housing for a turboshaft engine, based on the following three major requirements: i) gear bearing pads strength & stiffness capability, ii) AGB mount pads (for accessories and for engine) load carrying capability, and, iii) vibratory response (mainly high cycle fatigue (HCF) response) of the AGB housing. A 3-D Finite Element Analysis (FEA) model of the AGB housing was developed using the proposed initial design. Various design modifications, involving several interrelated, iterative steps, were then carried out by adjusting and modifying the housing wall thickness, placement & sizes of internal ribs and external gussets, including additional geometric modifications to satisfy the design objectives. The result is a robust, lightweight AGB housing design, eliminating the need for some of the required testing for the qualification of the new gearbox, indicating a significant cost savings. This paper also discusses in detail the methodology for the gear bearing pad strength/stiffness calculation, the FEA modeling techniques for the application of mount loads and gear bearing loads under operating & flight maneuver conditions, and, a methodology for addressing a combined HCF & LCF (Low Cycle Fatigue) response of the housing.
Secondary Flow Structures and Losses in a Radial Turbine Nozzle
Authors: Natkaniec Christoph K. , Kammeyer Jasper , Seume Joerg R.
Published: May 2012

An analysis of secondary flow structures and losses in a variable-vane radial turbine geometry is provided based on CFD. A complete turbine stage of a commercial vehicle turbocharger is modeled, including the entire 360° rotor and stator, in order to account for the circumferential non-uniformity of the flow. The full-stage model consists of approximately 12,500,000 nodes. The stator domain accounts for the endwall clearance on the hub side of the nozzle vanes. As an additional feature typical for variable turbine geometries, cylindrical shaft seals at the stator vane axis at hub and shroud as well as four circumferentially equidistant spacers are modeled. These geometrical details allow a more realistic simulation of the stator domain. In an analysis using fields of helicity and Q-Criterion, the present features are found to induce additional secondary vortices in the stator, in addition to the inflow and horse shoe vortices found by previous investigators. A detailed analysis of the secondary flow structures in this realistic stator shows that the spacers contribute 33% to the overall stator losses.
Optimization of an Axial Turbine Stage for Aerodynamic Inlet Blockage
Authors: Arabnia Mohammad , Sivashanmugam Vadivel K. , Ghaly Wahid
Published: May 2012

This paper presents a practical and effective optimization approach to minimize 3D-related flow losses associated with high aerodynamic inlet blockage by re-stacking the turbine rotor blades. This approach is applied to redesign the rotor of a low speed subsonic single-stage turbine that was designed and tested in DLR, Germany. The optimization is performed at the design point and the objective is to minimize the rotor pressure loss coefficient as well as the maximum von Mises stress while keeping the same design point mass flow rate, and keeping or increasing the rotor blade first natural frequency. A Multi-Objective Genetic Algorithm (MOGA) is coupled with a Response Surface Approximation (RSA) of the Artificial Neural Network (ANN) type. A relatively small set of high fidelity 3D flow simulations and structure analysis are obtained using ANSYS Workbench Mechanical. That set is used to train and to test the ANN models. The stacking line is parametrically represented using a quadratic rational Bezier curve (QRBC). The QRBC parameters are directly related to the design variables, namely the rotor lean and sweep angles and the bowing parameters. Moreover, it results in eliminating infeasible shapes and in reducing the number of design variables to a minimum while providing a wide design space for the blade shape. The aero-structural optimization of the E/TU-3 turbine proved successful, the rotor pressure loss coefficient was reduced by 9.8% and the maximum von Mises stress was reduced by 36.7%. This improvement was accomplished with as low as four design variables, and is attributed to the reduction of 3D-related aerodynamic losses and the redistribution of stresses from the hub trailing edge region to the suction side maximum thickness area. The proposed parametrization is a promising one for 3D blade shape optimization involving several disciplines with a relatively small number of design variables.
Parametric Study of Bump Foil Gas Bearings for Industrial Applications
Authors: De Santiago Oscar , San Andres Luis
Published: May 2012

Gas bearings are an appealing technology for rotor support due to their inherent characteristic of oil-free operation. Elimination of lubricant brings also the possibility of designing the bearings for operation within the flow path of thermal machines and even using the process gas as working fluid for the bearing. Among several gas bearing technologies, foil bearings are the most common ones currently found in applications such as small compressors for aircraft pressurization, microturbines, and other small turbomachinery. Broad application of foil gas bearings to date is precluded due to their limited load capacity. Presently, scaling up of foil bearings requires expensive testing due to limitation of validated computational models of the fluid flow in the bearing coupled to the mechanical behavior of the metal foil and underlying corrugated structure. Recent work in this area shows that calibrated models are now available in the open literature and it is possible to predict more accurately the performance of the bearings at non-conventional sizes. The objective of this work is to present a study of the most relevant parameters of foil bearings affecting their static and dynamic performance and aimed at scaling them up for industrial applications currently not considered for them. The paper presents a calibration of the computational model to previous tests by independent researchers and discusses simple rules for scaling up the bearing components. Finally, the paper presents a feasibility study of application of foil gas bearings to a generic centrifugal compressor for industrial use.
Understanding the Twin Scroll Turbine: Flow Similarity
Authors: Brinkert Nils , Sumser Siegfried , Schulz Achmed , Weber Siegfried , Fieweger Klaus , Bauer Hans-Jo¨rg
Published: May 2012

The current study investigates the flow conditions of a twin scroll asymmetric turbine. This is motivated by the operating conditions of the turbine at a heavy-duty reciprocating internal combustion engine with exhaust gas recirculation. The flow conditions of the turbine at the engine can be described best with the turbine scroll interaction map. Standard hot gas measurements of a turbocharger turbine are presented and discussed. Due to the strong interaction of the turbine scrolls, further hot gas measurements are performed at partial admission conditions. The turbine inlet conditions are analysed experimentally, in order to characterize the turbine performance. The turbine scroll pressure ratio is varied, leading to unequal twin turbine admission conditions. The flow behaviour is analysed regarding its ability for further extrapolation. Beyond scroll pressure ratio variations, unequal temperature admission conditions were studied. A way of characterizing the representative turbine inlet temperature, regarding the reduced turbine speed, is presented. The different scroll parameter ratios are evaluated regarding their capability of describing flow similarity under different unequal turbine admission conditions. In this content, turbine scroll Mach number ratio, velocity ratio and mass flow ratio are assessed. Furthermore, a generic representation of the turbine flow conditions at the engine is presented, based on standard turbine performance maps.
The Influence of Blade Properties on the Forced Response of Mistuned Bladed Disks
Authors: Hohl Andreas , Kriegesmann Benedikt , Wallaschek Jo¨rg , Panning Lars
Published: May 2012

In turbomachinery applications bladed disks are subjected to high dynamic loads due to fluctuating gas forces. Dynamic excitation can result in high vibration amplitudes which can lead to high cycle fatigue (HCF) failures. Herein, the blades are almost identical but differ due to wear or small manufacturing tolerances. Especially, after regeneration and repair procedures the properties of the blades can differ with a high variance. These deviations of the blade properties can lead to a localization of the vibrational energy in single blades and even higher risk of HCF. A recently developed substructure model with a combination of the Hurty transformation or Component Mode Synthesis (CMS) and the so called Wave Based Substructuring (WBS) is used to obtain a Reduced Order Model (ROM) with a reasonable low number of degrees of freedom. The CMS of the disk can be calculated with one cyclic disk segment of the underlying finite element model. The WBS is used to describe the numerous coupling degrees of freedom between the disk and the blades with a truncated set of waves. The orthogonal waves are derived by a Singular Value Decomposition or a QR decomposition from the coupling nodes normal modes calculated by a cyclic modal analysis of the full structure. The blade eigenvalues of the clamped blade can be mistuned individually under consideration of the variance as well as the correlation between the different eigenvalues of the blades. Monte-Carlo-Simulations are performed to calculate the effect of these parameters on the forced response of a mistuned bladed disk for blade dominated modes. Furthermore, Monte-Carlo-Simulations and a constraint optimization approach is used to calculate the worst and best case blade patterns for specific blade patterns and blade patterns with distributed blade properties.
Large Eddy Simulation of a Hot, High Speed Coflowing Jet
Authors: Eastwood Simon , Tucker Paul G. , Xia Hao
Published: May 2012

Computations are made of a short cowl coflowing jet nozzle with a bypass ratio 8 : 1. The core flow is heated, making the inlet conditions reminiscent of those for a real engine. A large eddy resolving approach is used with a 12 × 106 cell mesh. Since the code being used tends towards being dissipative the sub-grid scale (SGS) model is abandoned giving what can be termed Numerical Large Eddy Simulation (NLES). To overcome near wall modelling problems a hybrid NLES-RANS (Reynolds Averaged Navier-Stokes) related method is used. For y+ ≤ 60 a k–l model is used. Blending between the two regions makes use of the differential Hamilton-Jabobi (HJ) equation, an extension of the eikonal equation. Results show encouraging agreement with existing measurements of other workers. The eikonal equation is also used for acoustic ray tracing to explore the effect of the mean flow on acoustic ray trajectories, thus yielding a coherent solution strategy.
Testing of Full Speed No Load Operating Conditions in a Subscale Steam Turbine Test Vehicle
Authors: Basirico John , Zhou Bin , Mujezinovic Amir , Starodubtsev Yuri , Frolov Boris
Published: May 2012

During the operation of a power plant, a steam turbine may experience operation at full speed with little or no load (FSNL). Such an operation can take place when power demand is low or during start-up. At such an operation turbine buckets, in particular last stage buckets (LSB), can experience high stimulus coming from unsteady loading due to the flow instability. In those conditions LSBs consume energy rather than produce it. In some cases stimulus can create high alternating stresses in the LSB. As such, operation at those conditions is a particular concern in bucket aeromechanical design. To properly simulate FSNL operation in a stand alone low-pressure (LP) subscale turbine test facility, an external drive motor is normally required due to the unavailability of high and intermediate-pressure sections that would drive the LP turbine at very low load. This work shows that such a simulation can be achieved in the absence of an external drive by running the LP test turbine at higher exhaust pressure and higher mass flow. In those conditions LP exit flow velocity (VAN) similar to an actual FSNL operation will be achieved. This work shows that achieving prototypical VAN is sufficient to simulate operation at FSNL. Measurement data of the test show correlations between bucket alternating stress and turbine operating parameters such as VAN and exhaust pressure. This demonstrates that bucket responses equal or greater than those which would occur in actual FSNL conditions can be tested in a lab setup, In other words, testing at a given combination of VAN and exhaust pressure provides a limiting bucket response case for an operation at the same VAN but lower exhaust pressure. Further, numerical simulations using computational fluid dynamics were performed to prove that steam flow parameters and bucket structural mechanics characteristics in a subscale test turbine are fully representative of its full-scale counterpart, even at low flow or FSNL operating conditions, where broad spectrum of steam stimuli and bucket responses are expected.
Analyses of Temperature Distribution on Steam Turbine Last Stage Low Pressure Buckets at Low Flow Operations
Authors: Filippenko Victor , Frolov Boris , Chernobrovkin Andrey , Zhou Bin , Mujezinovic´ Amir , Slepski Jon
Published: May 2012

Steam turbine power plant operations during start up and during operation at high exhaust pressure have the potential to result in an extremely low steam flow through the Low Pressure (LP) turbine. This inevitably leads to windage and results in significant temperature increases in the Last Stage Buckets (LSBs). High steam temperature can also initiate potential thermo-mechanical failure of the LSBs. Temperature prediction for a wide range of operational regimes imposes a significant challenge to modern LSB design. Extensive numerical and experimental investigations on an LP section steam turbine with LSBs of different lengths at typical low flow operation conditions have been conducted with the primary focus on LSB temperature prediction. A Low Pressure Development Turbine (LPDT) test rig was used to help develop and validate Computational Fluid Dynamic (CFD) based temperature prediction methodologies, which later were applied to predict operational temperatures for multiple LP section configurations under development. This article presents some important results of LPDT test measurements as well as CFD predictions of LP turbine flow structures and temperature distributions in last stage buckets.
Enhanced light extraction of GaN-based light emitting diodes via simultaneous ITO texturing and n-GaN nanorod formation using Al2O3 powder
Authors: Kim Seung Hwan , Sun Woo Young , Yang Gye Mo , Song Young Ho , Jeon Seong Ran
Published: May 2012

The authors have fabricated the surface-textured GaN based light emitting diodes (LEDs) by incorporating a transparent powder onto an indium tin oxide (ITO) surface and exposed n-GaN surface to improve the light extraction efficiency by decreasing the total internal reflection and by achieving an angular randomization of the photons. The ITO surface and exposed n-GaN surface was simultaneously textured using a method known as natural lithography. The Al2O3 powders were coated onto the LED surface as a random mask for dry etching. After packaging, the light output powers of the LEDs with the textured ITO layer and with nanorods at n-GaN were enhanced about ∼ 11 and 15 %, respectively, compared with that of the conventional LED. Also, the light output power of the LED with both the textured ITO layer and the formed n-GaN nanorods increased by ∼ 24% compared with that of the conventional LED.
Quasistatic and dynamic mechanical properties of Al–Si–Cu structural films in uniaxial tension
Authors: Fujii Masayuki , Namazu Takahiro , Fujii Hiroki , Masunishi Kei , Tomizawa Yasushi , Inoue Shozo
Published: May 2012

In this article, the quasistatic and dynamic tensile properties of aluminum–silicon–copper (Al–Si–Cu) alloy films are described. The films were deposited by sputtering onto thermally oxidized Si wafers, and then half of the wafers were heat treated at 623 K in nitrogen gas for 1 h. Specially developed environment-controlled uniaxial tensile test equipment was used to carry out the quasistatic tensile test, stress relaxation test, and cyclic loading test at temperatures ranging from room temperature (RT) to 573 K in high vacuum, and the influence of annealing on the mechanical characteristics was investigated. The Young’s modulus did not show annealing dependency. The mean value was 65 GPa at RT, and gradually decreased with increasing test temperature. The yield stresses of nonannealed and annealed films were 168.5 and 129.6 MPa, respectively, which also decreased with temperature rise. In stress relaxation test results, creep exponents in respective films were obtained from curve fitting using the Norton law, which indicated that creep deformation was restricted by annealing. The cyclic loading test was performed under stress- and displacement-amplitude-constant modes. The stress-amplitude-constant mode test provided creep deformation acceleration to failure, whereas the displacement-amplitude-constant mode test showed a gradual drop of stress amplitude. The stress-amplitude change was compared with stress relaxation curves; consequently, the creep deformation was dominant to the degradation of Al–Si–Cu films subjected to cycling loading with constant displacement amplitude.
Charge transport and relaxation in hydrogenated barium titanate films and their potential for integrated supercapacitors
Authors: El Kamel Fadhel , Gonon Patrice
Published: May 2012

Hydrogenated barium titanate films show enhancement of the double-layer capacitance and therefore can be employed as electrolytes in the all-solid-state supercapacitors. This behavior was attributed to the accumulation of protons at the metal–electrolyte interface over a Debye length (capacitive double layer). Electrical measurements were carried out on hydrogenated layers (BaTiO3:H) and trilayer stack (BaTiO3/BaTiO3:H/BaTiO3) to study the active defects at the origin of the conduction mechanisms.
Syndecan 4 Regulates FGFR1 Signaling in Endothelial Cells by Directing Macropinocytosis
Authors: Elfenbein Arye , Lanahan Anthony , Zhou Theresa X. , Yamasaki Alisa , Tkachenko Eugene , Matsuda Michiyuki , Simons Michael
Published: May 2012

Macropinocytosis controls the kinetics of endothelial signaling initiated by a fibroblast growth factor receptor.
An ATP-Site On-Off Switch That Restricts Phosphatase Accessibility of Akt
Authors: Lin Kui , Lin Jie , Wu Wen-I , Ballard Joshua , Lee Brian B. , Gloor Susan L. , Vigers Guy P. A. , Morales Tony H. , Friedman Lori S. , Skelton Nicholas , Brandhuber Barbara J.
Published: May 2012

ATP and ATP-competitive inhibitors prevent dephosphorylation of the kinase Akt.
Effect of Coadministration of Vancomycin and BMP-2 on Cocultured Staphylococcus aureus and W-20-17 Mouse Bone Marrow Stromal Cells
In Vitro
Authors: Nguyen A. H. , Kim S. , Maloney W. J. , Wenke J. C. , Yang Y.
Published: May 2012

In this study, we aimed to establish an
in vitro
bacterium/bone cell coculture model system and to use this model for dose dependence studies of dual administration of antibiotics and growth factors
in vitro
. We examined the effect of single or dual administration of the antibiotic vancomycin (VAN) at 0 to 16 μg/ml and bone morphogenetic protein-2 (BMP-2) at 0 or 100 ng/ml on both methicillin-sensitive
Staphylococcus aureus
and mouse bone marrow stromal cells (W-20-17) under both mono- and coculture conditions. Cell metabolic activity, Live/Dead staining, double-stranded DNA (dsDNA) amounts, and alkaline phosphatase activity were measured to assess cell viability, proliferation, and differentiation. An interleukin-6 (IL-6) enzyme-linked immunosorbent assay (ELISA) kit was used to test the bone cell inflammation response in the presence of bacteria. Our results suggest that, when delivered together in coculture, VAN and BMP-2 maintain their primary functions as an antibiotic and a growth factor, respectively. Most interestingly, this dual-delivery type of approach has shown itself to be effective at lower concentrations of VAN than those required for an approach relying strictly on the antibiotic. It may be that BMP-2 enhances cell proliferation and differentiation before the cells become infected. In coculture, a dosage of VAN higher than that used for treatment in monoculture may be necessary to effectively inhibit growth of
Staphylococcus aureus
. This could mean that the coculture environment may be limiting the efficacy of VAN, possibly by way of bacterial invasion of the bone cells. This report of a coculture study demonstrates a potential beneficial effect of the coadministration of antibiotics and growth factors compared to treatment with antibiotic alone.
Pharmacokinetics of Intraperitoneal and Intravenous Fosfomycin in Automated Peritoneal Dialysis Patients without Peritonitis
Authors: Tobudic Selma , Matzneller Peter , Stoiser Brigitte , Wenisch Judith Maria , Zeitlinger Markus , Vychytil Andreas , Jaeger Walter , Boehmdorfer Michaela , Reznicek Gottfried , Burgmann Heinz
Published: May 2012

Blood and dialysate concentrations of fosfomycin were determined after intravenous and intraperitoneal application of 4 mg/liter in patients undergoing automated peritoneal dialysis. Maximum serum concentrations after intravenous (287.75 ± 86.34 mg/liter) and intraperitoneal (205.78 ± 66.78 mg/liter) administration were comparable. Ratios of intraperitoneal to systemic exposure were 1.12 (intraperitoneal administration) and 0.22 (intravenous administration), indicating good systemic exposure after intraperitoneal application but limited penetration of fosfomycin into the peritoneal fluid after the intravenous dose.
Multiplex PCR To Identify Macrolide Resistance Determinants in Mannheimia haemolytica and Pasteurella multocida
Authors: Rose Simon , Desmolaize Benoit , Jaju Puneet , Wilhelm Cornelia , Warrass Ralf , Douthwaite Stephen
Published: May 2012

The bacterial pathogens
Mannheimia haemolytica
and
Pasteurella multocida
are major etiological agents in respiratory tract infections of cattle. Although these infections can generally be successfully treated with veterinary macrolide antibiotics, a few recent isolates have shown resistance to these drugs. Macrolide resistance in members of the family
Pasteurellaceae
is conferred by combinations of at least three genes:
erm
(42), which encodes a monomethyltransferase and confers a type I MLS
B
(macrolide, lincosamide, and streptogramin B) phenotype;
msr
(E), which encodes a macrolide efflux pump; and
mph
(E), which encodes a macrolide-inactivating phosphotransferase. Here, we describe a multiplex PCR assay that detects the presence of
erm
(42),
msr
(E), and
mph
(E) and differentiates between these genes. In addition, the assay distinguishes
P. multocida
from
M. haemolytica
by amplifying distinctive fragments of the 23S rRNA (
rrl
) genes. One
rrl
fragment acts as a general indicator of gammaproteobacterial species and confirms whether the PCR assay has functioned as intended on strains that are negative for
erm
(42),
msr
(E), and
mph
(E). The multiplex system has been tested on more than 40 selected isolates of
P. multocida
and
M. haemolytica
and correlated with MICs for the veterinary macrolides tulathromycin and tilmicosin, and the newer compounds gamithromycin and tildipirosin. The multiplex PCR system gives a rapid and robustly accurate determination of macrolide resistance genotypes and bacterial genus, matching results from microbiological methods and whole-genome sequencing.
Pharmacodynamic Evaluation of the Activity of Antibiotics against Hemin- and Menadione-Dependent Small-Colony Variants of Staphylococcus aureus in Models of Extracellular (Broth) and Intracellular (THP-1 Monocytes) Infections
Authors: Garcia L. G. , Lemaire S. , Kahl B. C. , Becker K. , Proctor R. A. , Denis O. , Tulkens P. M. , Van Bambeke F.
Published: May 2012

Staphylococcus aureus
small-colony variants (SCVs) persist intracellularly, which may contribute to persistence/recurrence of infections and antibiotic failure. We have studied the intracellular fate of
menD
and
hemB
mutants (corresponding to menadione- and hemin-dependent SCVs, respectively) of the COL methicillin-resistant
S. aureus
(MRSA) strain and the antibiotic pharmacodynamic profile against extracellular (broth) and intracellular (human THP-1 monocytes) bacteria. Compared to the parental strain, SCVs showed slower extracellular growth (restored upon medium supplementation with menadione or hemin), reduced phagocytosis, and, for the
menD
SCV, lower intracellular counts at 24 h postinfection. Against extracellular bacteria, daptomycin, gentamicin, rifampin, moxifloxacin, and oritavancin showed similar profiles of activity against all strains, with a static effect obtained at concentrations close to their MICs and complete eradication as maximal effect. In contrast, vancomycin was not bactericidal against SCVs. Against intracellular bacteria, concentration-effect curves fitted sigmoidal regressions for vancomycin, daptomycin, gentamicin, and rifampin (with maximal effects lower than a 2-log decrease in CFU) but biphasic regressions (with a maximal effect greater than a 3-log decrease in CFU) for moxifloxacin and oritavancin, suggesting a dual mode of action against intracellular bacteria. For all antibiotics, these curves were indistinguishable between the strains investigated, except for the
menD
mutant, which systematically showed a lower amplitude of the concentration-effect response, with markedly reduced minimal efficacy (due to slower growth) but no change in maximal efficacy. The data therefore show that the maximal efficacies of antibiotics are similar against normal-phenotype and menadione- and hemin-dependent strains despite their different intracellular fates, with oritavancin, and to some extent moxifloxacin, being the most effective.
Cellobiose-Specific Phosphotransferase System of Klebsiella pneumoniae and Its Importance in Biofilm Formation and Virulence
Authors: Wu Meng-Chuan , Chen Ying-Chun , Lin Tzu-Lung , Hsieh Pei-Fang , Wang Jin-Town
Published: May 2012

Klebsiella pneumoniae
is a Gram-negative bacillus belonging to the family
Enterobacteriaceae
. In the past 20 years,
K. pneumoniae
has become the predominant pathogen causing community-acquired pyogenic liver abscess (PLA). The formation of biofilm facilitates bacterial colonization and has been implicated in reduced susceptibility to the host immune response. To investigate genes related to biofilm formation in a PLA-associated
K. pneumoniae
strain, a transposon mutant library was screened by microtiter plate assay to identify isolates impaired for biofilm formation. One of the mutants was disrupted in
celB
, encoding the putative cellobiose-specific subunit IIC of enzyme II (EIIC) of a carbohydrate phosphotransferase system (PTS). This transmembrane protein is responsible for recognizing and binding specific sugars and transporting them across the cell membrane into the cytoplasm. Deletion and chromosomal complementation of
celB
confirmed, by microtiter plate and slide culture assays, that
celB
was indeed responsible for biofilm formation. Cellobiose-specific PTS activities of deletion mutants grown in LB broth and 0.005% cellobiose minimal medium were markedly lower than that of the wild-type strain grown under the same conditions, thereby confirming the involvement of
celB
in cellobiose transport. In 0.005% cellobiose minimal medium, the
celB
mutant showed a delay in growth compared to the wild-type strain. In a mouse model of intragastric infection, deletion of the
celB
gene increased the survival rate from 12.5% to 87.5%, which suggests that the
celB
deletion mutant also exhibited reduced virulence. Thus, the
celB
locus of
K. pneumonia
e may contribute to biofilm formation and virulence through the metabolism of cellobiose.
Complete Genome Sequence of the European Sheatfish Virus
Authors: Mavian Carla , López-Bueno Alberto , Fernández Somalo María Pilar , Alcamí Antonio , Alejo Alí
Published: May 2012

Viral diseases are an increasing threat to the thriving aquaculture industry worldwide. An emerging group of fish pathogens is formed by several ranaviruses, which have been isolated at different locations from freshwater and seawater fish species since 1985. We report the complete genome sequence of European sheatfish ranavirus (ESV), the first ranavirus isolated in Europe, which causes high mortality rates in infected sheatfish (
Silurus glanis
) and in other species. Analysis of the genome sequence shows that ESV belongs to the amphibian-like ranaviruses and is closely related to the epizootic hematopoietic necrosis virus (EHNV), a disease agent geographically confined to the Australian continent and notifiable to the World Organization for Animal Health.
The Genome Sequence of a Reassortant Bluetongue Virus Serotype 3 from India
Authors: Maan Narender S. , Maan Sushila , Guimera Marc , Nomikou Kyriaki , Morecroft Elizabeth , Pullinger Gillian , Belaganahalli Manjunatha N. , Mertens Peter P. C.
Published: May 2012

All 10 genome segments (Seg-1 to 10—a total of 19,188 bp) were sequenced from a strain of bluetongue virus serotype 3 (BTV-3) from India (strain IND2003/08). Sequence comparisons showed that nine of the genome segments from this virus group with other eastern topotype strains. Genome Seg-2 and Seg-6 group with eastern BTV-3 strains from Japan. However, Seg-5 (the NS1 gene) from IND2003/08 belongs to a western lineage, demonstrating that IND2003/08 is a reassortant between eastern and western topotype bluetongue viruses. This confirms that western BTV strains have been imported and are circulating within the subcontinent.
Complete Genome Sequence of an Overattenuated Highly Pathogenic Porcine Reproductive and Respiratory Syndrome Virus
Authors: Wu Jiajun , Chen Nanhua , Han Wei , Cao Zhen , Deng Xiaoyu , Wang Lilin , Yu Xiuling , Zhou Zhi , Li Xiangdong , Shi Jishu , Tian Kegong
Published: May 2012

JXA1-P170 is an overattenuated highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) that has been passaged
in vitro
170 times. Vaccination with JXA1-P170 cannot protect pigs against JXA1 challenge. Compared with the parental virus JXA1, JXA1-P170 contains 1 nucleotide (nt) deletion and 113 nt mutations leading to 59 amino acid substitutions. Here we announce the first complete genome sequence of the overattenuated HP-PRRSV.
Assessment of phylogenetic structure in genome size – gene content correlations
Authors: Prasad Vibhu Ranjan , Isler Karin
Published: May 2012

Gene content and gene-coding percentage can be predicted from genome size in newly sequenced organisms. Here, we investigate whether these predictions are influenced by phylogenetic relationships between the involved species. Combining a highly resolved phylogenetic tree with a large compilation of gene content data, our results reveal the presence of significant phylogenetic structure in the correlations between genome size and gene content in both bacteria and eukaryotes. The variation in log(gene content) explained by log(genome size) in combination with phylogeny was found to be 97% in bacteria and 55% in eukaryotes. Further, in bacteria, gene-coding percentages are only significantly correlated to genome size if phylogenetic information is taken into account in the analyses. These findings support the usage of phylogenetic correlation models for gene content predictions.
Snapshots of gene expression in rice: limitations for allelic expression imbalance determination
Authors: Akkinepalli Harika , Ereful Nelzo , Liu Yan , Malabanan Kaye , Howells Rhian , Stamati Konstantina , Powell Wayne , Leung Hei , Greenland Andy , Mackay Ian , Lee David
Published: May 2012

In an initial investigation of differential expression of genes caused by cis-acting regulatory elements in rice, the lack of reproducibility led us to question the basic premise of allelic expression imbalance determination: namely that departures of cDNA expression ratios from those observed in genomic DNA provide unequivocal evidence of cis-acting polymorphisms. This paper describes experiments designed to demonstrate that stochastic variation in low copy number of targets in PCR reactions give variable allelic ratios even when starting with the same copy numbers of the two alleles. These significant departures from an expected 1:1 ratio provide an explanation to the lack of reproducibility observed for our cDNA measurements.
Rye chromosome-specific polymerase chain reaction products developed by primers designed from theEcoO109I recognition site
Authors: Tomita Motonori , Seno Akiyoshi
Published: May 2012

From our analysis of repeat sequences in the rye genome, the presence of multiple restriction sites of EcoO109I (5′–PuGGNCCPy–3′) across the genome has been predicted. By first using primers designed to contain EcoO109I sites in polymerase chain reaction (PCR), polymorphic DNA markers were effectively obtained. A total of 43 types of 10-mer primers containing EcoO109I sites were applied for PCR by using genomic DNA of Secale cereale self-fertile line IR27 and Triticum aestivum ‘Chinese Spring’ (CS) as the template. Twenty two primers detected polymorphisms between wheat and rye, and they were applied for PCR using a series of CS wheat – ‘Imperial’ rye chromosome addition lines as templates. Nine chromosome-specific amplification fragments identified on five chromosomes were collected from gels and hybridized with nylon membrane-transferred PCR products from the wheat–rye chromosome addition lines. The gel blot was only observed between the collected fragments; therefore, these fragments were confirmed to be chromosome-specific. These fragments were sequenced and converted to sequence-tagged site (STS) primers. We therefore introduce a new method for building chromosome-specific DNA markers: (i) multiple polymorphic fragments can be obtained from EcoO109I primers and (ii) the addition of three nucleotides to the EcoO109I site restricts the amplification region to generate chromosome-specific fragments.