bluuebunny/crossref_metadata_2025 huggingface dataset:
A Binary Gas Composition Sensor to Measure Impermeable Wall Concentration in Film Cooling Experiments
Authors: Seffal R. , Schwarz S. G. , Walker S. J.
Published: March 2015

A binary gas composition sensor has been developed to measure impermeable wall effectiveness with the foreign gas injection technique. The sampled gas is drawn at a controlled flow rate over a platinum hot wire connected to an anemometer circuit. A change in composition of the gas flowing over the wire results in a change in the heat loss to the gas and, hence, the anemometer output voltage. The sensitivity of a prototype sensor with a 6.1 mm platinum hot wire length has been found to be 0.278 V/% helium at a mass concentration of 2% He.

The sensor has been tested in a film cooling experiment in which an air-helium mixture (helium mass concentration 2%) was injected through a slot along a flat surface. A series of sensors placed downstream of the injection slot measured the foreign gas wall concentrations. The effectiveness results deduced from the anemometer output voltages compare very well to those of classical film cooling experiments in the literature.

The use of the binary gas composition sensor in film cooling experiments has the advantage of simulating adiabatic walls without the disadvantages of the inability to reduce the effectiveness data during the film cooling test and the requirement of an expensive gas chromatograph.
The Quasi-Three Dimensional Design Method for Steam Turbines With Curvilinear Leaned and Twisted Stator Blades
Authors: Wang Zhongqi , Liu Fengjun
Published: March 2015

A quasi–three dimensional calculating method for steam turbines with curvilinear leaned and twisted stator blades is given in this paper. A 300 MW steam turbine throughflow designs of the last stages with conventional twisted and curvilinear leaned–twisted blades are calculated respectively. Results of the calculation show that the present method is an improvement on the traditional prediction method and a practical method in the engineering design for steam turbines.
Flexible Manufacturing of Aircraft Engine Parts
Authors: Hassan Dssama M. , Jenkins Douglas M.
Published: March 2015

GE Aircraft Engines, a major supplier of jet engines for commercial and military aircraft, has developed a fully integrated manufacturing facility to produce aircraft engine components in flexible manufacturing cells. This paper discusses many aspects of the implementation including process technologies, material handling, software control system architecture, socio-technical systems and lessons learned. Emphasis is placed on the appropriate use of automation in a flexible manufacturing system.
Digital Control Retrofit of an Industrial Gas Turbine
Authors: Metzger Alan , Kness Tena
Published: March 2015

As worldwide power requirements increase, power generation facilities must begin to think more closely about the reliability of existing units. In order to enhance plant capability, many power producers are considering control upgrades to aging equipment as an alternative to adding new machinery.

This paper details an advanced digital control system coupled with a progressive valving scheme and a unique man-machine interface that features the following:

(1) increased unit reliability due to the replacement of the pneumatic control system with a state-of-the-art, digital controller and an electro-hydraulic fuel valve,

(2) cooler, more predictable start-ups achieved by removing the relay sequencer and substituting an advanced software-driven sequencer,

(3) an intuitive, color graphics operator control station that offers trending, archiving, and rapid configuration.

The scope of this paper will describe this system as it applies to a Westinghouse 191G gas turbine. This unit is located at a peaking facility in Astoria, New York. The control retrofit was successfully completed in June 1991.
Balance of Moments for Hypersonic Vehicles
Authors: Kremer Frans G. J.
Published: March 2015

Ramjet engines propelling hypersonic flight vehicles will be highly integrated into the vehicle, resulting in strong interactions between the vehicle and the engine. An assessment of these interactions in relation to the flight mission is made by simple but adequate modeling of the flight vehicle aerodynamics and the engine performance. Especially moments associated with the propulsion system are of interest.

This paper deals with the pitch moments introduced by the ramjet related forces, which are evaluated by one-dimensional engine performance and by modeling of the inlet and nozzle flow. Furthermore, it discusses the balance of moments for the first stage of a two stage transportation system for an ascent trajectory.
The Qualities of PRENFLO Coal Gas for Use in High-Efficiency Gas Turbines
Authors: Schellberg Wolfgang , Kuske Eberhard
Published: March 2015

Up to now, gas turbines have mainly been built for use with liquid fuels or natural gas. For the new combined cycle system with integrated coal gasification, the quality of the feed gas has to match the requirements of the gas turbine, which is particularly important for high-efficiency gas turbines. The paper describes a combined cycle system with integrated PRENFLO coal gasification and, in particular, the treatment of the gas produced by the gasifier. This power plant concept — a highly integrated plant — is a joint development of Siemens/KWU and Krupp Koppers. Our coal gasification is based on the entrained-flow principle with dry coal dust feeding.
Measurement of Combustion Turbine Non-Recoverable Degradation
Authors: Flashberg Larry S. , Haub Gary L.
Published: March 2015

The combustion turbine industry, especially the cogenerators and independent power producers, would like to commence commercial operations and have the turbine-generators produce steady sources of energy and income streams over the life of the project. Some inexperienced operators have relied on the rated output as a constant over the life of the machine. However, industry experience has shown that combustion turbines have measurable decreases in performance over time. This could cause significant loss of revenues for owners from power sales agreements or cause operators not to be able to achieve the capacity of their machines. Yet, some of this degradation has been recoverable by compressor washing. However, some of this degradation is not recoverable. This paper quantifies extensive experience of non-recoverable measured performance on nine heavy-duty industrial combustion turbines.
Numerical Research on Flows in Nonuniform Cascades
Authors: Qi Feng , Guocai Tang , Chunhua Sheng
Published: March 2015

In this paper, a fast and accurate multi–grid Euler flow solver was used to simulate flows in an uniform cascade under distorted outlet pressure, flows in nonuniform cascades under uniform boundary conditions, and flows in a nonuniform cascade under nonuniform outlet pressure. Results, including the variation of blade load in the uniform cascade under distorted outlet pressure, the propagation of outlet pressure distortion through the cascade, the flow mechanisms in nonuniform cascades, etc, were obtained. Finally a specific nonuniform cascade was designed, where the inlet pressure nonuniformity induced by outlet pressure distortion was greatly weakened through the cascade, which proves it is possible to reduce the propagation of outlet pressure distortion by a specially designed nonuniform cascade.
Prediction of Secondary Losses in Axial Compressors
Authors: Cyrus Václav
Published: March 2015

A large number of both published and own experimental data on secondary losses in straight compressor cascades and compressor blade rows has been reviewed. Published correlations for prediction of secondary losses have been compared to chosen experiments. Two cases of the blade and end-wall design have been investigated-blade with and without tip clearance. On the basis of experimental results, new improved correlations for secondary loss coefficient have been derived. These have been implemented in the program for characteristics computation of axial compressors and an improved agreement between predictions and experiments has been obtained.
A Three-Dimensional Numerical Method for Turbomachinery Blading
Authors: Gu C. W. , Xu J. Z. , Du J. Y.
Published: March 2015

By inversing one of the stream functions and their principal equations in a three–dimensional flow the equations with the second–order partial derivatives of both the coordinate and another stream function are derived. The corresponding boundary conditions are easily specified. Based on these equations and the boundary conditions the convergent solution for turbomachinery blading is obtained. The computational results show that the method is simple and effective.
Powder Metallurgy Repair of Turbine Components
Authors: Ellison K. A. , Lowden P. , Liburdi J.
Published: March 2015

An advanced powder metallurgy repair process called Liburdi Powder Metallurgy (LPM)1 has been developed for the repair, overlay or joining nickel and cobalt-based high temperature alloys. This process involves mechanical cleaning, followed by the application and consolidation of a filler metal powder which has substantially the same composition as the base metal, and produces joints with mechanical properties similar to those of the parent material.

While previous activated braze or “wide-gap” repair processes have been limited to clearances of approximately 1 mm, the LPM technique has the ability to bridge larger gaps of over 5 mm. In addition, the LPM joints contain significantly lower concentrations of melting point depressants such as silicon and boron than conventional wide-gap repair techniques and exhibit superior microstructural features.

The characteristics and typical applications of the LPM process for blade and vane repairs are highlighted and the results of laboratory and engine tests are discussed.
TEMPER: A Gas-Path Analysis Tool for Commercial Jet Engines
Authors: Doel David L.
Published: March 2015

Almost from the inception of the gas turbine engine, airlines and engine manufacturers have sought an effective technique to determine the health of the gas-path components (fan, compressors, combustor, turbines) based on available gas-path measurements. The potential of such tools to save money by anticipating the need for overhaul and providing help in work scope definition is substantial, provided they produce reliable results. This paper describes a modern gas-path analysis tool (GE’s TEMPER1 program), discusses the benefits and problems experienced by current TEMPER users, and suggests promising research areas that may lead to an improved algorithm.
Measurement of Unsteady Flow and Heat Transfer in a Linear Turbine Cascade
Authors: Liu X. , Rodi W.
Published: March 2015

A detailed experimental study has been conducted on the wake-induced unsteady flow and heat transfer in a linear turbine cascade. The unsteady wakes with passing frequencies in the range zero to 240 Hz were generated by moving cylinders on a squirrel cage device. The velocity fields in the blade-to-blade flow and in the boundary layers were measured with hot-wire anemometers, the surface pressures with a pressure transducer and the heat transfer coefficients with a glue-on hot film. The results were obtained in ensemble-averaged form so that periodic unsteady processes can be studied. Of particular interest was the transition of the boundary layer. The boundary layer remained laminar on the pressure side in all cases and in the case without wakes also on the suction side. On the latter, the wakes generated by the moving cylinders caused transition, and the beginning of transition moves forward as the cylinder-passing frequency increases. Unlike in the flat-plate study of Liu and Rodi (1991a) the instantaneous boundary layer state does not respond to the passing wakes and therefore does not vary with time. The heat transfer increases under increasing cylinder-passing frequency even in the regions with laminar boundary layers due to the increased background turbulence.
Assessing the Economics of Industrial Gas Turbine Cogeneration Applications
Authors: Hill Jane P.
Published: March 2015

Gas turbines are often used at industrial plants to generate electricity. However, turbines convert a greater portion of the input fuel into waste heat than into electricity. The degree to which this waste heat can be captured and used to produce steam, hot water, or simply hot air for drying, greatly improves the overall efficiency of the turbine system. This process is called cogeneration. There is no question that cogeneration can improve overall efficiencies. The question is whether cogeneration can be accomplished in an economic manner.

This paper presents a straight-forward methodology for comparing the costs and benefits associated with cogeneration. All costs and savings are converted to a consistent before tax cent per kilowatt-hour basis. The inconsistencies encountered with simple payback analysis are avoided, as well as the complexities of discounted cash flow analysis. The effects of income taxes, depreciation, financing, and cogeneration load factor are incorporated.
Thermomechanical Damage Development in SiC(SCS6)/Ti-6-4 Metal Matrix Composite
Authors: Aksoy S.
Published: March 2015

A series of experiments were conducted to investigate the thermomechanical fatigue behavior of SiC(SCS-6)/Ti-6-4 composite. Three types of tests were conducted. In the first, specimens were subjected to load-controlled mechanical cycling under isothermal conditions. The other two types of test involved simultaneous cycling of load and temperature: in-phase and out-of-phase cycles. The effect of temperature cyclic ranges of 250°C to 528°C were evaluated for the out-of-phase (low temperature-high stress) conditions. A single temperature range of 250°C was employed for the in-phase (high temperature-high stress) condition. Fatigue-life diagrams were developed to evaluate the fatigue performance of the composite based on certain damage mechanism maps. In addition, micromechanical stresses in the fiber and matrix were computed using a generalized plane strain finite element analysis. The intention of this analytical effort was to provide the understanding of the fundamental mechanisms governing material behavior for guiding the development of life prediction methodology.
Turbine Cascade Optimization Against Particle Deposition
Authors: Kladas D. D. , Georgiou D. P.
Published: March 2015

Modern turbine cascades are usually being optimized for minimum total pressure losses. Gas turbines, however, operating in dirty environments or using coal–derived fuels need cascades that minimize the deposition, erosion and corrosion (DEC) implications of the particle–laden gas. This can be achieved by altering certain geometrical key–parameters of cascades and blades which influence the particle deposition rate, while keeping the inlet and outlet velocities and angles fixed. Since reference cascades have already been optimized for minimum aerodynamic losses, the associated loss increase penalty is accounted for.

Two stator and two rotor cascades were optimized by a penalty function method. The results suggest that solid particle deposition rates can be minimized by as much as 40 per cent while keeping profile losses to acceptable limits in both stator and rotor cascades for the particle size range 0.1 to 1 μm.
Experimental Study of Mixed Compression Air-Intake for Hypersonic Airbreathing Engines
Authors: Sakata Kimio , Yanagi Ryoji , Murakami Akira , Shindo Shigemi , Honami Shinji , Tanaka Atsushige , Shiraishi Ksazuo
Published: March 2015

Supersonic air-intake for Mach number higher than 2.5 is being investigated with experimental, analytical and computational methods. The study is performed in a part of the joint research program led by National Aerospace Laboratory (NAL) on the hypersonic airbreathing turbo-engines with subsonic ram combustion. The wind tunnel models are designed in two-dimensional mixed compression type with multi-shock system and tested in NAL’s Mach 4 supersonic wind tunnel. Pressure measurements and flow visualization by schlieren method, oil-flow and vapor screen techniques are being done.

Here, the test results of Mach 4 and Mach 5 models are discussed. The Mach 4 model is fixed geometry with 5-shock system and the Mach 5 one is variable geometry with 6-shock and an isentropic compression surface. An expansion fore-plate was installed at the Mach 5 model inlet to accelerate the air-speed at the entry. The bleed systems at throat, ramp and cowl are adopted and evaluated in terms of pressure recovery and stability. Importance of establishment of the internal shock wave system, reduction of upstream Mach number of terminal shock wave and suppression of flow separation at diffusers are found. It is also found that ramp bleed is effective to confirm intake start and to minimize shock/boundary layer interaction.
Technical and Economical Aspects of Using Gas Turbine Technology in Eastern Europe Including the Commonwealth of Independent States (CIS)
Authors: Boehm B. , Marks R.-R.
Published: March 2015

An overview of the installed electrical generating capacity in the entire Eastern European region is given along with the plants intended for expansion to meet the forecasted system load demands.

The emphasis with future power plants in the region will be attached to attaining considerably higher generating efficiency and operating availability than are presently being achieved, as well as to directly reducing pollutant emissions to protect the environment more effectively.

Modern Western technology will be adopted on a certain scale to meet the objectives of better economy and ecological conservation. In many cases this will be accomplished by cooperating with Western companies to ensure long-term technology transfer. In particular, many of the new power plants required will be built in the form of combined-cycle installations. Gas turbines may in some cases be retrofitted to existing reheat steam boiler/turbine units (topping or repowering) to improve overall station efficiency.

Particular power plant projects in Eastern Europe including the Commonwealth of Independent States are presented as examples of typical solutions to achieving the goals that are so important to the region.
Development of High Temperature High Pressure Filtration Technology
Authors: Higashi Katsumi , Oda Noriyuki
Published: March 2015

Advanced Ceramic Tube Filters (ACTF) have been developed by Asahi Glass Co., Ltd (AGC) using innovative concepts aimed at hot gas clean-up system feasible for large scale industrial processes. More than 25 ACTF units of pilot and demonstration scale have been installed to demonstrate its readiness for various industrial applications. Among these applications, pressurized fluidized bed combustion (PFBC) combined cycle power generation system is the one in which the largest market size is foreseen until the 21st century. In this paper, the latest status of the development and commercialization of ACTF as well as the principle, basic configuration and operation of the system are described.
The Flame Structure of High Intensity Multi-Jet Shear Layer Enclosed Turbulent Diffusion Flames
Authors: Andrews G. E. , Al-Shaikhly A. F. Ali
Published: March 2015

Fuel injection into high velocity jet shear layers in an enclosed 140mm diameter conical flame stabiliser, with four large jet shear layers and a central radial fuel injector, was studied at operating conditions relevant to high intensity burners and gas turbine primary zones. The mean exhaust emissions for propane were shown exhibit a high efficiency over a wide range of equivalence ratios with a good turn down ratio. Fuel and air mixing, propane combustion development and NOx formation was investigated using internal gas composition measurements at three simulated lean primary zone operating conditions. The combustion development and emissions was shown to be dominated by fuel and air mixing between a rich outer recirculation zone and a high velocity lean inner shear layer outflow region. An aerodynamically generated rich lean combustion system was generated without fuel or air staging, but the interface mixing region resulted in significant NOx generation.
Impact of Ceramic Components in Gas Turbines for Industrial Cogeneration
Authors: Anson D. , Sheppard W. J. , Parks W. P.
Published: March 2015

A development thrust for the adoption of ceramic components in industrial gas turbines, now being sponsored by the U.S. Department of Energy, may have a considerable impact on the growth rate and ultimate capacity of the cogeneration sector.

The economic justification for cogeneration rests on the ability to undercut the cost of purchased power after taking credit for the useful heat recovery, and it is frequently marginal after consideration of fuel, maintenance, and pollution control devices. After reviewing briefly the factors contributing to the economic viability of cogeneration systems, this paper presents arguments to show how the use of ceramics in industrial gas turbine can be instrumental in reducing installation and operating costs. Improved gas turbines based on ceramic materials technology also will provides means for meeting environmental protection requirements without the use of back end flue gas treatment, and will be able to utilize byproduct industrial gaseous and liquid fuels more effectively. These improvements can increase substantially the economic return from cogeneration systems, and are expected to result in increased cogeneration capacity and a sustained market for industrial gas turbines.

Predictions are made of the size of the U.S. industrial gas turbine cogeneration market. The annual fuel savings resulting from displacement of utility generation capacity could amount to 2 × 1017 joules (2 × 1014 Btu’s) by the year 2010.
Evolution of Spanwise-Hole Blade Cooling in Industrial Combustion Turbines
Authors: Whidden G. L. , North W. E.
Published: March 2015

The evolution of the spanwise-hole blade cooling technique is described from its employment in the original blade cooling design of the late 1960’s to its current applications in modern industrial combustion turbines. Descriptions of the design, along with analytical and manufacturing advances which have enabled this technique to remain competitive at higher firing temperatures with the relatively complex designs are included. Verification of the spanwise cooling hole designs by means of pyrometer testing is also presented.
Automated Decision-Analytic Diagnosis of Thermal Performance in Gas Turbines
Authors: Breese John S. , Horvitz Eric J. , Peot Mark A. , Gay Rodney , Quentin George H.
Published: March 2015

We have developed an expert system for diagnosis of efficiency problems for large gas turbines. The system relies on a model-based approach that combines an expert’s probabilistic assessments with statistical data and thermodynamic analysis. The system employs a causal probabilistic graph, called a belief network, to update the likelihoods of alternative faults given information about diverse classes of information. In response to any subset of findings or reported observations, the system suggests the most cost-effective tests to perform to determine the source of a performance problem. We discuss the decision-analytic methodology that underlies the development of the system and present results of an initial version of the system. Finally, we discuss future planned development and evaluation, toward the ultimate goal of applying the system in the day-to-day maintenance of gas-turbine power plants.
On-Board Condition Management for Aircraft Gas Turbines
Authors: Gallops G. W. , Gass F. D. , Kennedy M. H.
Published: March 2015

A revolutionary approach to gas turbine condition monitoring is made possible by the recent development of accurate real-time gas turbine performance models. This paper describes an approach for an integrated condition management system operating concurrently with the gas turbine control system for improved availability, safety and economy. This paper considers the system subject to the requirements and constraints of aircraft gas turbines. A system architecture is described based on a primary, gas path performance model with supplementary models representing the secondary air, fuel and lubrication systems and the rotor system dynamics. Measurement and processing requirements for the system are defined. Preflight, in-flight and postflight application and analysis by the gas turbine operator are discussed.
A Study of Transient Response of Flexible Rotors in High Speed Turbomachinery
Authors: Pavelic V. , Amano R. S.
Published: March 2015

In many applications the design operating range of the turbomachinery may be well above the rotor first critical speed which leads to the problem of insuring that the turbomachinery performs with a stable, low-level amplitude of vibration.

Under certain conditions of high speed and loading the rotor system can start orbiting in its bearing at a rate which is less than the rotor angular speed, and this phenomena is commonly known as whirling or whipping action. This whipping action may produce additional undesirable dynamic loads on the overall flexible assembly and eventually destroy the rotor. Some of this action is also transient in nature.

Whirling is a self-exited vibration caused mainly by the fluid bearings and by the internal friction damping of the rotor. To understand this occurrence, a general dynamic mathematical model was derived considering also the complete viscous characteristic of hydrodynamic journal bearings.

The general equations of motions of the system are obtained from Lagrange’s equation of motion. The system kinetic, potential, and dissipation functions are determined based on the generalized coordinates of the system.

The journal displacements are related to the overall dynamics of the rotor using deformable bearings. The loads acting at the journals of the shaft are integrated from the fluid film pressure distribution in the journal bearings using mobility method.

A unique mathematical model is formulated and solved. This model includes the elastic and inertial properties of the flexible rotor, the elastic, damping and inertial properties of supports and the hydrodynamic characteristics of the journal bearings.

The equations of motions result in a system of nonlinear second order differential equations which are solved by using finite difference method. The solution of the equations of motions is used to plot maps of motion of journal centers.

A computer program was implemented to aid in the solution of the system of equations and to verify analytical model. The computer program used test data available in literature and the results were compared to be very good.

The analytical model and results obtained in this study can be of great help to designers of high speed turbomachinery.
Optimum Selection of the Vibration Monitoring System for Turbomachines
Authors: Rihak Pavel , Schmidt Reinhold
Published: March 2015

Different vibration measurement systems are widely used in turbomachines to monitor their vibration behavior. There is, however, little information available for judging, which of the different options (monitoring of casing vibration velocities, relative or absolute shaft displacements) should be selected for a specific machine. The present paper describes a simple method allowing to make this selection. A formula is provided for prediction of the expected ratio of bearing casing vibrations to relative shaft vibrations caused by unbalance. By comparing this ratio to the values prescribed by the specified vibration limits, one can decide which of both systems is more suitable for monitoring purposes. Based on an example of an industrial gas turbine, it will be shown that the procedure results in a selection of the correct vibration monitoring system.
Experimental Study on the Three Dimensional Flow Within a Compressor Cascade With Tip Clearance: Part II — The Tip Leakage Vortex
Authors: Kang Shun , Hirsch Ch.
Published: March 2015

An analysis of the experimental data of a linear compressor cascade with tip clearance is presented with special attention to the development of the tip leakage vortex. A method for determining the tip vortex core size, centre position and vorticity or circulation from the measured data is proposed, based on the assumption of a circular tip vortex core. It is observed that the axial velocity profile passing through the tip vortex centre is wake-like. The vorticity of the tip vortex increases rapidly near the leading edge and reaches its highest values at a short distance downstream, from which it gradually decreases. In the whole evolution, its size is growing and its centre is moving away from both the suction surface and the endwall, approximately in a linear way.
Properties of Cu(In,Ga,Al)Se2 thin films fabricated by magnetron sputtering
Authors: Hameed Talaat A. , Cao Wei , Mansour Bahiga A. , Elzawaway Inas K. , Abdelrazek El-Metwally M. , Elsayed-Ali Hani E.
Published: March 2015

Cu(In,Ga,Al)Se2 (CIGAS) thin films were studied as an alternative absorber layer material to Cu(InxGa1−x)Se2. CIGAS thin films with varying Al content were prepared by magnetron sputtering on Si(100) and soda-lime glass substrates at 350 °C, followed by postdeposition annealing at 520 °C for 5 h in vacuum. The film composition was measured by an electron probe microanalyzer while the elemental depth profiles were determined by secondary ion mass spectrometry. X-ray diffraction studies indicated that CIGAS films are single phase with chalcopyrite structure and that the (112) peak clearly shifts to higher 2θ values with increasing Al content. Scanning electron microscopy images revealed dense and well-defined grains, as well as sharp CIGAS/Si(100) interfaces for all films. Atomic force microscopy analysis indicated that the roughness of CIGAS films decreases with increasing Al content. The bandgap of CIGAS films was determined from the optical transmittance and reflectance spectra and was found to increase as Al content increased.
Lower Body Predictors of Glenohumeral Compressive Force in High School Baseball Pitchers
Authors: Keeley David W. , Oliver Gretchen D. , Dougherty Christopher P. , Torry Michael R.
Published: March 2015

The purpose of this study was to better understand how lower body kinematics relate to peak glenohumeral compressive force and develop a regression model accounting for variability in peak glenohumeral compressive force. Data were collected for 34 pitchers. Average peak glenohumeral compressive force was 1.72% ± 33% body weight (1334.9 N ± 257.5). Correlation coefficients revealed 5 kinematic variables correlated to peak glenohumeral compressive force (P < .01, α = .025). Regression models indicated 78.5% of the variance in peak glenohumeral compressive force (R2 = .785, P < .01) was explained by stride length, lateral pelvis flexion at maximum external rotation, and axial pelvis rotation velocity at release. These results indicate peak glenohumeral compressive force increases with a combination of decreased stride length, increased pelvic tilt at maximum external rotation toward the throwing arm side, and increased pelvis axial rotation velocity at release. Thus, it may be possible to decrease peak glenohumeral compressive force by optimizing the movements of the lower body while pitching. Focus should be on both training and conditioning the lower extremity in an effort to increase stride length, increase pelvis tilt toward the glove hand side at maximum external rotation, and decrease pelvis axial rotation at release.
Integrating p38α MAPK immune signals in nonimmune cells
Authors: Gaffen Sarah L. , McGeachy Mandy J.
Published: March 2015

Signaling by p38α in resident cells of the CNS mediates the inflammatory effects of the T cell–derived cytokine interleukin-17 in a mouse model of multiple sclerosis.
Efficacy of Skin and Nasal Povidone-Iodine Preparation against Mupirocin-Resistant Methicillin-Resistant Staphylococcus aureus and S. aureus within the Anterior Nares
Authors: Anderson Michele J. , David Maren L. , Scholz Matt , Bull Sally J. , Morse Dan , Hulse-Stevens Michelle , Peterson Marnie L.
Published: March 2015

Mupirocin decolonization of nasal
Staphylococcus aureus
prior to surgery decreases surgical-site infections; however, treatment requires 5 days, compliance is low, and resistance occurs. In 2010, 3M Company introduced povidone-iodine (PVP-I)-based skin and nasal antiseptic (Skin and Nasal Prep [SNP]). SNP has rapid, broad-spectrum antimicrobial activity. We tested SNP's efficacy using full-thickness tissue (porcine mucosal [PM] and human skin) explant models and human subjects. Prior to or following infection with methicillin-resistant
Staphylococcus aureus
(MRSA) (mupirocin sensitive and resistant), explants were treated with Betadine ophthalmic preparation (Bet), SNP, or mupirocin (Bactroban nasal ointment [BN]) or left untreated. One hour posttreatment, explants were washed with phosphate-buffered saline (PBS) plus 2% mucin. One, 6, or 12 h later, bacteria were recovered and enumerated. Alternatively, following baseline sampling, human subjects applied two consecutive applications of SNP or saline to their anterior nares. One, 6, and 12 h after application of the preparation (postprep), nasal swabs were obtained, and
S. aureus
was enumerated. We observed that treatment of infected PM or human skin explants with SNP resulted in >2.0 log
10
CFU reduction in MRSA, regardless of mupirocin sensitivity, which was significantly different from the values for BN- and Bet-treated explants and untreated controls 1 h, 6 h, and 12 h after being washed with PBS plus mucin. Swabbing the anterior nares of human subjects with SNP significantly reduced resident
S. aureus
compared to saline 1, 6, and 12 h postprep. Finally, pretreatment of PM explants with SNP, followed by a mucin rinse prior to infection, completely prevented MRSA infection. We conclude that SNP may be an attractive alternative for reducing the bioburden of anterior nares prior to surgery.
The Assembly of GM1 Glycolipid- and Cholesterol-Enriched Raft-Like Membrane Microdomains Is Important for Giardial Encystation
Authors: De Chatterjee Atasi , Mendez Tavis L. , Roychowdhury Sukla , Das Siddhartha
Published: March 2015

Although encystation (or cyst formation) is an important step of the life cycle of
Giardia
, the cellular events that trigger encystation are poorly understood. Because membrane microdomains are involved in inducing growth and differentiation in many eukaryotes, we wondered if these raft-like domains are assembled by this parasite and participate in the encystation process. Since the GM1 ganglioside is a major constituent of mammalian lipid rafts (LRs) and known to react with cholera toxin B (CTXB), we used Alexa Fluor-conjugated CTXB and GM1 antibodies to detect giardial LRs. Raft-like structures in trophozoites are located in the plasma membranes and on the periphery of ventral discs. In cysts, however, they are localized in the membranes beneath the cyst wall. Nystatin and filipin III, two cholesterol-binding agents, and oseltamivir (Tamiflu), a viral neuraminidase inhibitor, disassembled the microdomains, as evidenced by reduced staining of trophozoites with CTXB and GM1 antibodies. GM1- and cholesterol-enriched LRs were isolated from
Giardia
by density gradient centrifugation and found to be sensitive to nystatin and oseltamivir. The involvement of LRs in encystation could be supported by the observation that raft inhibitors interrupted the biogenesis of encystation-specific vesicles and cyst production. Furthermore, culturing of trophozoites in dialyzed medium containing fetal bovine serum (which is low in cholesterol) reduced raft assembly and encystation, which could be rescued by adding cholesterol from the outside. Our results suggest that
Giardia
is able to form GM1- and cholesterol-enriched lipid rafts and these raft domains are important for encystation.
The Bacillus subtilis tyrZ Gene Encodes a Highly Selective Tyrosyl-tRNA Synthetase and Is Regulated by a MarR Regulator and T Box Riboswitch
Authors: Williams-Wagner Rebecca N. , Grundy Frank J. , Raina Medha , Ibba Michael , Henkin Tina M.
Published: March 2015

Misincorporation ofd-tyrosine (d-Tyr) into cellular proteins due to mischarging of tRNATyrwithd-Tyr by tyrosyl-tRNA synthetase inhibits growth and biofilm formation ofBacillus subtilis. Furthermore, manyB. subtilisstrains lack a functional gene encodingd-aminoacyl-tRNA deacylase, which prevents misincorporation ofd-Tyr in most organisms.B. subtilishas two genes that encode tyrosyl-tRNA synthetase:tyrSis expressed under normal growth conditions, andtyrZis known to be expressed only whentyrSis inactivated by mutation. We hypothesized thattyrZencodes an alternate tyrosyl-tRNA synthetase, expression of which allows the cell to grow whend-Tyr is present. We show that TyrZ is more selective forl-Tyr overd-Tyr than is TyrS; however, TyrZ is less efficient overall. We also show that expression oftyrZis required for growth and biofilm formation in the presence ofd-Tyr. BothtyrSandtyrZare preceded by a T box riboswitch, buttyrZis found in an operon withywaE, which is predicted to encode a MarR family transcriptional regulator. Expression oftyrZis repressed by YwaE and also is regulated at the level of transcription attenuation by the T box riboswitch. We conclude that expression oftyrZmay allow growth when excessd-Tyr is present.

IMPORTANCEAccurate protein synthesis requires correct aminoacylation of each tRNA with the cognate amino acid and discrimination against related compounds.Bacillus subtilisproducesd-Tyr, an analog ofl-Tyr that is toxic when incorporated into protein, during stationary phase. Most organisms utilize ad-aminoacyl-tRNA deacylase to prevent misincorporation ofd-Tyr. This work demonstrates that the increased selectivity of the TyrZ form of tyrosyl-tRNA synthetase may provide a mechanism by whichB. subtilisprevents misincorporation ofd-Tyr in the absence of a functionald-aminoacyl-tRNA deacylase gene.
Mechanism for Inhibition of Vibrio cholerae ToxT Activity by the Unsaturated Fatty Acid Components of Bile
Authors: Plecha Sarah C. , Withey Jeffrey H.
Published: March 2015

The Gram-negative curved bacillus
Vibrio cholerae
causes the severe diarrheal illness cholera. During host infection, a complex regulatory cascade results in production of ToxT, a DNA-binding protein that activates the transcription of major virulence genes that encode cholera toxin (CT) and toxin-coregulated pilus (TCP). Previous studies have shown that bile and its unsaturated fatty acid (UFA) components reduce virulence gene expression and therefore are likely important signals upon entering the host. However, the mechanism for the bile-mediated reduction of TCP and CT expression has not been clearly defined. There are two likely hypotheses to explain this reduction: (i) UFAs decrease DNA binding by ToxT, or (ii) UFAs decrease dimerization of ToxT. The work presented here elucidates that bile or UFAs directly affect DNA binding by ToxT. UFAs, specifically linoleic acid, can enter
V. cholerae
when added exogenously and are present in the cytoplasm, where they can then interact with ToxT. Electrophoretic mobility shift assays (EMSAs) with ToxT and various virulence promoters in the presence or absence of UFAs showed a direct reduction in ToxT binding to DNA, even in promoters with only one ToxT binding site. Virstatin, a synthetic ToxT inhibitor, was previously shown to reduce ToxT dimerization. Here we show that virstatin affects DNA binding only at ToxT promoters with two binding sites, unlike linoleic acid, which affects ToxT binding promoters having either one or two ToxT binding sites. This suggests a mechanism in which UFAs, unlike virstatin, do not affect dimerization but affect monomeric ToxT binding to DNA.

IMPORTANCE
Vibrio cholerae
must produce the major virulence factors cholera toxin (CT) and toxin-coregulated pilus (TCP) to cause cholera. CT and TCP production depends on ToxT, the major virulence transcription activator. ToxT activity is negatively regulated by unsaturated fatty acids (UFAs) present in the lumen of the upper small intestine. This study investigated the mechanism for inhibition of ToxT activity by UFAs and found that UFAs directly reduce specific ToxT binding to DNA at virulence promoters and subsequently reduce virulence gene expression. UFAs inhibit ToxT monomers from binding DNA. This differs from the inhibitory mechanism of a synthetic ToxT inhibitor, virstatin, which inhibits ToxT dimerization. Understanding the mechanisms for inhibition of virulence could lead to better cholera therapeutics.
Sociality in Escherichia coli: Enterochelin Is a Private Good at Low Cell Density and Can Be Shared at High Cell Density
Authors: Scholz Rebecca L. , Greenberg E. Peter
Published: March 2015

Many bacteria produce secreted iron chelators called siderophores, which can be shared among cells with specific siderophore uptake systems regardless of whether the cell produces siderophores. Sharing secreted products allows freeloading, where individuals use resources without bearing the cost of production. Here we show that theEscherichia colisiderophore enterochelin is not evenly shared between producers and nonproducers. Wild-typeEscherichia coligrows well in low-iron minimal medium, and an isogenic enterochelin synthesis mutant (ΔentF) grows very poorly. The enterochelin mutant grows well in low-iron medium supplemented with enterochelin. At high cell densities the ΔentFmutant can compete equally with the wild type in low-iron medium. At low cell densities the ΔentFmutant cannot compete. Furthermore, the growth rate of the wild type is unaffected by cell density. The wild type grows well in low-iron medium even at very low starting densities. Our experiments support a model where at least some enterochelin remains associated with the cells that produce it, and the cell-associated enterochelin enables iron acquisition even at very low cell density. Enterochelin that is not retained by producing cells at low density is lost to dilution. At high cell densities, cell-free enterochelin can accumulate and be shared by all cells in the group. Partial privatization is a solution to the problem of iron acquisition in low-iron, low-cell-density habitats. Cell-free enterochelin allows for iron scavenging at a distance at higher population densities. Our findings shed light on the conditions under which freeloaders might benefit from enterochelin uptake systems.

IMPORTANCESociality in microbes has become a topic of great interest. One facet of sociality is the sharing of secreted products, such as the iron-scavenging siderophores. We present evidence that theEscherichia colisiderophore enterochelin is relatively inexpensive to produce and is partially privatized such that it can be efficiently shared only at high producer cell densities. At low cell densities, cell-free enterochelin is scarce and only enterochelin producers are able to grow in low-iron medium. Because freely shared products can be exploited by freeloaders, this partial privatization may help explain how enterochelin production is stabilized inE. coliand may provide insight into when enterochelin is available for freeloaders.
Assessing distortion of the AF 6 − (A=As, Sb) octahedra in solid hexafluorometallates(V) via NMR spectroscopy
Authors: Faucher Alexandra , Terskikh Victor V. , Wasylishen Roderick E.
Published: March 2015

Arsenic and antimony hexafluoride salts have played an important role in the history of both solution and solid-state NMR spectroscopy. Here, solid polycrystalline KAsF6 and KSbF6 have been studied via high-resolution variable temperature 19F, 75As, 121Sb, and 123Sb solid-state NMR spectroscopy at high magnetic field (B0 = 21.14 T). Both KAsF6 and KSbF6 undergo solid-solid phase transitions at approximately 375 and 301 K, respectively. We use variable temperature NMR experiments to explore the effects of crystal structure changes on NMR parameters. CQ(75As) values for KAsF6 at 293, 323, and 348 K are −2.87 ± 0.05 MHz, −2.58 ± 0.05 MHz, and −2.30 ± 0.05 MHz, respectively, the sign determined via DFT calculations. In the higher temperature cubic phase, CQ(75As) = 0 Hz, consistent with the crystal symmetry at the arsenic nucleus in this phase. In contrast, CQ values for 121Sb and 123Sb in the cubic phase of KSbF6 are nonzero. E.g., at 293 K, CQ(121Sb) = 6.42 ± 0.10 MHz, and CQ(123Sb) = 8.22 ± 0.10 MHz. In the higher temperature tetragonal phase (343 K) of KSbF6, these values are 3.11 ± 0.20 MHz and 4.06 ± 0.20 MHz, respectively. CASTEP calculations performed on the cubic and tetragonal structures support this trend. Isotropic indirect spin-spin coupling constants are 1J(75As,19F) = −926 ± 10 Hz (293 K) and −926 ± 3 Hz (348 K), and 1J(121Sb,19F) = −1884 ± 3 Hz (293 K), and −1889 ± 3 Hz (343 K). Arsenic-75 and antimony-121,123 chemical shift values show little variation over the studied temperature ranges.
Initial value sensitivity of the Chinese stock market and its relationship with the investment psychology
Authors: Ying Shangjun , Li Xiaojun , Zhong Xiuqin
Published: March 2015

This paper discusses the initial value sensitivity (IVS) of Chinese stock market, including the single stock market and the Chinese A-share stock market, with respect to real markets and evolving models. The aim is to explore the relationship between IVS of the Chinese A-share stock market and the investment psychology based on the evolving model of genetic cellular automaton (GCA). We find: (1) The Chinese stock market is sensitively dependent on the initial conditions. (2) The GCA model provides a considerable reliability in complexity simulation (e.g. the IVS). (3) The IVS of stock market is positively correlated with the imitation probability when the intensity of the imitation psychology reaches a certain threshold. The paper suggests that the government should seek to keep the imitation psychology under a certain level, otherwise it may induce severe fluctuation to the market.
A Novel Minority Cloning Technique for Cost-Sensitive Learning
Authors: Jiang Liangxiao , Qiu Chen , Li Chaoqun
Published: March 2015

In many real-world applications, it is often the case that the class distribution of instances is imbalanced and the costs of misclassification are different. Thus, the class-imbalanced cost-sensitive learning has attracted much attention from researchers. Sampling is one of the widely used techniques in dealing with the class-imbalance problem, which alters the class distribution of instances so that the minority class is well represented in the training data. In this paper, we propose a novel Minority Cloning Technique (MCT) for class-imbalanced cost-sensitive learning. MCT alters the class distribution of training data by cloning each minority class instance according to the similarity between it and the mode of the minority class. The experimental results on a large number of UCI datasets show that MCT performs much better than Minority Oversampling with Replacement Technique (MORT) and Synthetic Minority Oversampling TEchnique (SMOTE) in terms of the total misclassification costs of the built classifiers.
Accidental Entrepreneurs: Kwench Library Solutions
Authors: Monippally Mathukutty M.
Published: March 2015

Kwench Library Solutions (Kwench), a Mumbai-based startup that offered library services to corporate clients (B2B2C model), looked anxiously for angel funding to establish itself and expand to other parts of India. The time — the first few months of the 2008–09 global recession — was bad. The angel investors who offered to provide INR 10 million valued the start-up at one-third of what the promoters had confidently expected. The valuation was unacceptable, but spurning the offer was fraught with additional risks. The promoters, who had given up high-paying corporate jobs and invested heavily in the start-up, had to find a way out.