bluuebunny/crossref_metadata_2025 huggingface dataset:
RB211 Development and Experience With TransCanada Pipelines
Authors: Handy P. J. , Cooke L. A. , Pethrick D. J.
Published: March 2015

This paper presents a brief history of RB211 operation from initial use in 1974 to present day tracing progressive uprating of original units from 22,000 horsepower to today’s 35,000 horsepower installations.

Problems associated with continuous operation are identified and the solutions discussed.

The maintenance philosophy that has evolved at TransCanada PipeLines to meet specific operational requirements is described, as well as maintenance techniques jointly developed to carry out the program. The merits of an Operator staffed repair base are described. TCPL’s RB211 operating costs per fired hour on a historical basis are summarized.

RB211 performance retention on the TCPL system is described, along with methods and modifications used to minimize or recover performance deterioration.

Finally, future trends in condition monitoring, modular maintenance, and future upgrade possibilities of older standards of the RB211 are discussed.
Operating Experiences of the First LM1600 Installation
Authors: Braun Ardean L. , Price Stan R.
Published: March 2015

In the winter of 1988–1989, NOVA Corporation of Alberta commissioned three of the first GE LM1600 gas generators in turbine/compressor packages at compressor stations on its natural gas pipeline system. In the summer of 1989 a fourth unit was added at another station on the NOVA system. This paper describes the facilities in which the turbine/compressor packages were installed. In addition our experiences in commissioning, startup and operation will be discussed along with results of field performance testing.
Natural Gas Compressor Station Noise Abatement Systems
Authors: Pappas George P.
Published: March 2015

In recent years urban residential growth has created a serious encroachment problem to all industrial complexes including natural gas compressor stations. Union Gas Ltd. has recently been involved in the design of an acoustically treated compressor station. Noise emanating from a station into the environment outside the property perimeter is caused by mechanical equipment in operation and gas flowing through piping and valves. Noise generated from a turbine station varies in power level and frequency. The noises, varying from the high frequency startling type to the low frequency throbbing type, create a number of problems for surrounding residential homes. This paper describes the Parkway Compressor Station located near Toronto, Ontario, Canada at which various items of mechanical equipment were identified and acoustically treated with satisfactory results.
Materials Issues for PFBC Expander Turbines
Authors: Stringer John
Published: March 2015

Several large pressurized fluidized bed combustion systems have recently been installed. In addition, second-generation concepts are being developed, in which the turbine inlet temperature will be appreciably higher. The durability of the gas turbine expander remains a question for the technology, and experience is limited. The available information is presented, and the potential problems of erosion, corrosion, and erosion/corrosion are discussed.
‘Recycling’ of Gas Turbines From Obsolete Aircraft
Authors: Morquillas Jose M. , Pilidis Pericles
Published: March 2015

This paper examines the utilisation of aero gas turbines fitted to aircraft which are close to the end of their useful lives. When the aircraft are scrapped the engines can be removed, modified and employed for land or sea applications. The engine chosen as a possible candidate for ‘recycling’ is a two spool bypass engine.

A performance analysis has been carried out, which indicates that this scheme can yield good levels of output and efficiency.

Preliminary examinations indicate that there are economic advantages in converting these engines for other uses. Two possible conversions are examined: one for a pure industrial engine, and one as the gas side of a combined cycle power plant. The results obtained from this feasibility analysis appear attractive; the anticipated cost of purchasing and conversion is predicted to be significantly lower than purchasing new equipment.
The Assumed Mode Method in Structural Dynamics of Bladed-Disk-Shaft Systems
Authors: Khader Naim , Masoud Sanier
Published: March 2015

Analytical investigation into the effect of transverse bending of continuous flexible shafts is presented. While the blades are allowed both in-plane and out-of-plane deformations, the considered disk is rigid, and the shaft is allowed to bend in two planes. The assumed mode method is used to express flexible blade and shaft deformations, and the Lagrangian approach is used to derive the governing equations of motion for the considered structure. Stiffness and inertia properties of an actual experimental rotor, typical of a fan stage, are used in the analysis. Calculations are performed for three different disk-shaft configurations, and results are presented for different shaft stiffness and inertia parameters, as well as for a wide range of rotational speed.
Fatigue Strength Enhancement Using Shape Memory Alloy Bushings
Authors: Buchanan Edward R. , Celin Regina B.
Published: March 2015

In recent years, there have been a number of failures of aircraft engine and structural components which are believed to have resulted from the accumulation of fatigue damage. The treatment of such damage is therefore of great significance from the standpoints of increased reliability and extended usage.

This paper presents the initial results of a program to evaluate a new process for the repair of fatigue-damaged aircraft engine components. In this process, the fatigue-damaged area is drilled out and replaced with a bushing manufactured from a new class of material called a ‘shape memory’ alloy. This material has the capability to expand in place following insertion, thus placing the surrounding material into compression.

A significant improvement in low cycle fatigue life was observed at 288°C in Ti-6Al-4V specimens treated with the above technique. The degree of improvement is about twice that which was obtained with a mechanical cold expansion technique used commercially to extend fatigue life. The degree of improvement of the subject process is greater at high numbers of cycles than at low numbers of cycles.

The subject project was funded as a Phase I Small Business Innovation Research award administered by the U.S. Naval Air Propulsion Center. Additional work in this area is planned which will a) identify the process parameters which will optimize the properties of shape memory alloy bushings, b) define the properties of shape memory alloy bushings over a wide range of temperature and loading conditions, and c) evaluate the effect in actual turbine engine hardware in a simulated engine environment.
An Evaluation of Waspaloy Expander Blade Tip Weld Repairs
Authors: Cameron David W.
Published: March 2015

The abrasive wear of blade tips in fluid catalytic cracking unit power recovery turbines is one of the principal ‘failure’ mechanisms for the parts. The occurrence of tip wear considerably shortens the effective life of the blade: generally well below the anticipated mechanical life of the component. This paper details the evaluation of mechanical properties and metallographic characteristics of a fully re-heat treated, Waspaloy on Waspaloy weldment for blade tip repair that will allow re-utilization of the blades.
Platinum Modified Aluminides-Present Status
Authors: Smith J. S. , Boone D. H.
Published: March 2015

Since their development in the early 1970’s, platinum modified aluminide diffusion coatings have been recognized for their superior oxidation and hot corrosion resistance on nickel based superalloys. More recently, advances in gas phase aluminizing have been utilized to afford coating protection to the internal as well as external surfaces of hollow gas turbine airfoils. This paper presents a brief review of the development history of the platinum aluminide coating system and discusses the various coating morphologies observed. The results of recent work in applying the low pressure chemical vapor deposition process for the production of platinum modified aluminide gas phase coatings on gas turbine components are highlighted.
Evaluation of a 50,000 HP Marine Gas Turbine for Use in Future U.S. Navy Surface Ships
Authors: Franks Charles B. , White Jonathan R. , Ness Jon C.
Published: March 2015

Analytical studies conducted by the U.S. Navy for the future marine gas turbine propulsion engines have concentrated in the mid-20,000 horsepower (HP) range. This power range meets the propulsion requirements of current surface ships, such as auxiliary and amphibious, frigate, destroyer, and light-cruiser ship types. In looking at future ship propulsion requirements, the possibility of developing a 50,000 HP marine gas turbine should be considered. This paper discusses the results of an initial investigation into the feasibility of a 50,000 HP marine gas turbine propulsion engine for surface ships. The current U.S. Navy 25,000 HP marine gas turbine and a theoretical 50,000 HP marine gas turbine propulsion engine performance characteristics are compared to establish performance trends of simple cycle marine engines. In addition, an advanced cycle 50,000 HP gas turbine with intercooling and recuperating is analyzed. This paper provides comparative results of engine performance for various ship operating profiles, engine size and weight and developmental cost.
Accelerated Mission Tests and Reliability Improvement of F3-30 Engine
Authors: Yanagihara Hideaki , Tateno Akira
Published: March 2015

F3-30 is the low-bypass-ratio turbofan engine which has been developed to power the T-4 intermediate trainer for the Japan Air Self Defence Force (JASDF). The qualification tests of the engine were successfully completed in March, 1986, and the actual field service was started in September, 1988.

Before the start of the actual use, accelerated mission tests (AMT) were conducted for the purpose of finding deficiencies which would occur in the actual mission usage, and verifying the time between overhaul (TBO) of the initial service.

This paper describes the test method, the results, and the evaluation for them. Also it presents current status and basic ideas for the future reliability improvement of the F3-30 engine.
Active Control Application to a Model Gas Turbine Combustor
Authors: Brouwer J. , Ault B. A. , Bobrow J. E. , Samuelsen G. S.
Published: March 2015

Closed-loop feedback control, developed in a axisymmetric can combustor, is demonstrated in a model can combustor with discrete wall jets. The study represents the initial steps toward the application of feedback control technology to practical gas turbine combustion systems. For the present application, the radiative flux from soot particulate is used as an indication of combustor performance, and nozzle atomizing air is selected as the input parameter. A measurement of radiative flux at the exit plane of the combustor is conveyed to a control computer which invokes an optimization algorithm to determine changes in the dome region necessary to minimize the radiative flux from soot. The results demonstrate the utility and potential of active control for maintaining optimal performance in real-time.
High Turning Limit and Jet Like Profiles in Secondary Flow Field of Axial Turbines
Authors: Kaldellis J. K. , Ktenidis P. D.
Published: March 2015

The evolution of the secondary flow field in cases of axial turbine bladings is examined in the present work.

Our secondary flow calculation method is successfully used, in an improved form including the complete meridional vorticity transport equation, to predict common viscous flow phenomena in axial turbines, such as high turning of the flow direction and jet-like velocity profiles.

The method used, although close to the parabolized Navier-Stokes approach, preserve several integral approximations thus minimizing the computer time required as compared to equivalent differential approaches. Our method provide fast and reliable tools for industrial applications with results comparable to those obtained by the differential solutions of the Navier-Stokes equations.

Several test cases, covering a wide deflection angle and acceleration ratio range, are analyzed. The results, concerning the secondary flow field, are very encouraging and Justify the choice of using approximate methods to estimate viscous phenomena in axial turbines.
Steady-State Analysis of a Nonlinear Rotor-Housing System
Authors: Kim Y. B. , Noah S. T.
Published: March 2015

The periodic steady state response of a high pressure oxygen turbopump (HPOTP) of a space shuttle main engine (SSME), involving a clearance between the bearing and housing carrier, is sought. A harmonic balance method utilizing Fast Fourier Transform (FFT) algorithm is developed for the analysis. An impedance method is used to reduce the number of degrees of freedom to the displacements at the bearing clearance. Harmonic and subharmonic responses to imbalance for various system parameters are studied. The results show that the computational technique developed in this study is an effective and flexible method for determining the stable and unstable periodic response of complex rotor-housing systems with clearance type nonlinearity.
An Experimental Investigation of Heat Transfer in an Orthogonally Rotating Channel Roughened With 45 Degree Criss-Cross Ribs on Two Opposite Walls
Authors: Taslim M. E. , Bondi L. A. , Kercher D. M.
Published: March 2015

Turbine blade cooling is imperative in advanced aircraft engines. The extremely hot gases that operate within the turbine section require turbine blades to be cooled by a complex cooling circuit. This cooling arrangement increases engine efficiency and ensures blade materials a longer creep life. One principle aspect of the circuit involves serpentine internal cooling passes throughout the core of the blade. Roughening the inside surfaces of these cooling passages with turbulence promoters provides enhanced heat transfer rates from the surface.

The purpose of this investigation was to study the effects of rotation, aspect ratio, and turbulator roughness on heat transfer in these rib-roughened passage. The investigation was performed in an orthogonally rotating setup to simulate the actual rotation of the cooling passages. Single pass channels, roughened on two opposite walls, with turbulators positioned at a 45° angle to the flow, in a criss-cross arrangement, were studied throughout this experiment. The ribs were arranged such that their pitch-to-height ratio remained at a constant value of 10. An aspect ratio of unity was investigated under three different rib blockage ratios (turbulator height/channel hydraulic diameter) of 0.1333, 0.25, and 0.3333. A channel with an aspect ratio of 2 was also investigated for a blockage ratio of 0.25. Air was flown radially outward over a Reynolds number range of 15000 to 50000. Rotation number was varied from 0 to 0.3. Stationary and rotating cases of identical geometries were compared. Results indicate that rotational effects are more pronounced in turbulated passages of high aspect and low blockage ratios for which a steady increase in heat transfer coefficient is observed on the trailing side as rotation number increases while the heat transfer coefficient on the leading side shows a steady decrease with rotation number. However, the all-smooth-wall classical pattern of heat transfer coefficient variation on the leading and trailing sides is not followed for smaller aspect ratios and high blockage ratios when the relative artificial roughness is high.
Airframe/Propulsion Integration at Transonic Speeds
Authors: Henderson William P.
Published: March 2015

A significant level of research is ongoing at NASA’s Langley Research center on integrating the propulsion system with the aircraft. This program has included nacelle/pylon/wing integration for turbofan transports, propeller/nacelle/wing integration for turboprop transports, and nozzle/afterbody/empennage integration for high performance aircraft. The studies included in this paper focus more specifically on pylon shaping and nacelle bypass ratio studies for turbofan transports, nacelle and wing contouring and propeller location effects for turboprop transports, empennage effects, and thrust vectoring for high performance aircraft. The studies were primarily conducted in NASA Langley’s 16-Foot Transonic Tunnel at Mach numbers up to 1.20.
Fault Detection and Diagnosis in Gas Turbines
Authors: Merrington Graeme , Kwon Oh-Kyu , Goodwin Graham , Carlsson Bengt
Published: March 2015

Modern military aircraft are fitted with Engine Monitoring Systems (EMS) which have the potential to provide maintenance personnel with valuable information for diagnosing engine faults and assessing engine condition. In this study, analytical redundancy methods have been applied to gas turbine engine transient data with the view to extracting the desired fault information. The basic idea is to use mathematical models to interrelate the measured variables and then monitor the effects of fault conditions on the new estimates of the model parameters. In most of the existing literature the models used are assumed to be perfect with the primary source of error arising from the measurement noise. In the technique to be described, a new method of quantifying the effects of changes in the operating conditions is presented when simplified models are employed. The technique accounts for undermodelling effects and errors arising from linearization of an inherently nonlinear system. Results obtained show a marked improvement over those obtained with traditional methods.
Fast Response Wall Pressure Measurement as a Means of Gas Turbine Blade Fault Identification
Authors: Mathioudakis K. , Papathanasiou A. , Loukis E. , Papailiou K.
Published: March 2015

The distortions of the pressure field around rotating blades of turbomachinery components due to alterations of their shape, can be utilized for the identification of faults related to the blading. Measurement of the unsteady pressure field in the wall proximity, provides information on such flow and pressure distortions and can thus be used for diagnostic purposes. An experimental investigation of the compressor rotating blades pressure field of an industrial gas turbine has been undertaken, in order to demonstrate the feasibility of the above mentioned principle. Various realistic gas turbine blade faults have been examined. The application of the appropriate processing techniques, demonstrates that unsteady pressure measurements can be used to identify the occurrence of minor blade faults (not traceable by standard techniques) as well as the kind of the fault. The proposed methodology has the potential for being incorporated in a computerized engine health monitoring system.
Simulation of Aircraft Gas Turbine Engines
Authors: Ismail I. H. , Bhinder F. S.
Published: March 2015

The paper describes a computer program to simulate aircraft gas turbine engines. The program has been written for IBM compatible micro computers and is modular in its approach. Either analytical equations or detailed performance characteristics of individual components are used to model the steady state operation of the complete engine.
A Proposed Method for Assessing the Susceptibility of Axial Compressors to Fouling
Authors: Seddigh F. , Saravanamuttoo H. I. H.
Published: March 2015

Although the overall effect of compressor fouling on engine performance has been recognized for many years, remarkably little has been published on the quantifiable effects. Mathematical modelling of compressors using stage stacking methods has recently been used for a systematic study of compressor fouling and earlier investigations led to an interest in the effects of engine size and compressor stage loading. This paper presents a proposed index showing the susceptibility of compressors to fouling, which could be useful in helping operators to determine cleanup intervals. Three engines of widely differing performance were used in developing this index and additional operator experience would be useful in confirming its validity.
Control Systems for Turbo Expanders in Pressure Reduction Service
Authors: Barmby T. Hugh , Cleveland Anthony
Published: March 2015

This paper considers some of the aspects of control of a turbo expander used in pressure reduction service to generate electricity. The parameters governing the performance of the expander and the connection of the expander generator system into a grid or electric supply system are discussed and the practical requirements of a suitable control system are outlined. The essential elements of a system to provide stability and control of certain selected parameters are described and extensions of control to include other functions and to provide additional data for evaluation are reviewed.
A Computer Method for Thermal Power Cycle Calculation
Authors: Perz E.
Published: March 2015

This paper describes a highly flexible computer method for thermodynamic power cycle calculations (PCC). With this method the user can model any cycle scheme by selecting components from a library and connecting them in an appropriate way. The flexibility is not restricted by any predefined cycle schemes.

A power cycle is mathematically represented by a system of algebraic equations. The structure of mathematical cycle models as well as different approaches to set up and solve the resulting equations with computer programs are discussed in the first section.

The second section describes the developed method. The mass and energy balance equations are set up and solved with an semi-parallel algorithm. As input only the cycle’s topology and component parameters must be entered. Information about the calculation sequence and the convergence method can be omitted completely. The example of two simple steam cycles demonstrates the applied technique.

The method requires only a few — if any at all — iterations. Calculation time and storage requirements can be kept low enough to calculate even very complex cycles on personal computers. At the end of the paper input data and results for a complex cycle scheme as it may occur in reality are given to demonstrate the performance finally.
An Approach to Describing the Simultaneous Erosion and High Temperature Oxidation of Alloys
Authors: Wright I. G. , Sethi V. K. , Nagarajan V.
Published: March 2015

The rate of wastage of an alloy surface subjected to erosion under conditions where high-temperature oxidation can occur can be significantly greater than that arising from erosion alone. This is because the erosion conditions can act to accelerate the oxidation process by causing regular shedding of the otherwise protective oxide scale. It is suggested that an important parameter in determining the rate of erosion-oxidation is the erodent flux, since the time available for oxide growth (or regrowth) in a given area is determined by the interval between successive erodent impacts. Using this simple premise, an approach is suggested by which the rate of erosion-oxidation can be related to the factors that control the alloy oxidation process, and those that describe the erosive environment. The assumptions made are examined, and some of the implications of this approach are discussed.
Experience With External Fires in Gas Turbine Installations and Implications for Fire Protection
Authors: Dundas R. E.
Published: March 2015

This paper summarizes a body of experience with external fires, such as those involving lube oil, liquid fuel, or fuel gas, in gas turbine–generator installations. It then describes one such fire in a sprinklered building, indicating the lack of effectiveness of the sprinklers in controlling the fire and preventing damage to the building. Conclusions are then drawn as to the optimum methods of protecting against such fires.

A concept of using excess–flow check valves in fuel lines, and throughout the lubrication system, for maximum protection from fires and other effects of a fuel or lubrication line break or separation, is described.
Experimental Evaluation of a Low NOx LBG Combustor Using Bypass Air
Authors: Nakata T. , Sato M. , Ninomiya T. , Abe T. , Mandai S. , Sato N.
Published: March 2015

A 150-MW, 1300°C (1573 K) class gas turbine combustor firing coal-gasified fuel has been designed. Main purpose of the present paper is first to estimate CO and NOx emissions, and second to discuss the low NOx combusion technology burning such a low-BTU gas. The full-scale, atmospheric-pressure combustion tests were conducted over a wide range of conditions using bypass air.

The results are summarized as follows:

(1) A designed combustor has an excellent combustion efficiency of 99.6 percent even when the calorific value of fuel drops to 650 kcal/m3N.

(2) CO and NOx emissions can be estimated by the air ratio in primary combustion zone.

(3) The role of air bypass valve is important for low NOx combustion, and to give stable combustion at lower load conditions.

(4) Ammonia conversion to NOx is minimized with a optimum air ratio in primary combustion zone.
TFE1042: A New Low Bypass Ratio Engine
Authors: Finkelstein A. R.
Published: March 2015

The TFE1042-70 is a modern low-bypass ratio afterburning military engine for light-weight fighters and high performance trainers. Designed, developed, and qualified in the 1980’s, it is intended to power the latest aircraft in the 1990’s and beyond. A version without the afterburner has been given the United States Military Engine designation of F124-GA-100. The engine is rugged, compact, durable, and easily maintained. It has been designed to meet the latest U. S. Military specification standards. This paper describes the engine and the development program.
Problems and Use of the Scaling Factors in the Numerical Simulation of Jet Engines
Authors: Torella G.
Published: March 2015

The possibility of the use of scaling factors in the calculations and in the simulation of gas turbine engines have been considered.

Application of this technique to the simulation of trend analysis, the evaluation of the component maps shifting during the operational life of the engine and the calculation of matrices of influence have been presented.

Moreover, some problems related to the use of scaling factors have been studied and their effects on the engine performance have been presented.
Optical Fan Blade Profile Measurement in Rotating Turbomachinery
Authors: Davinson I. , Mutton J. E. , Parker R. , Parnell A. , Roberts J. P.
Published: March 2015

An optical technique for measuring the profile of a fan blade at a range of radial heights in a rotating turbofan by laser triangulation has been developed and tested. The technique has been successfully used on fan rigs and on full size engines. The data thus obtained is now being used to verify the current models of fan blade behaviour.
Non-Intrusive Sensing Techniques for Advanced Turbine Engine Structures
Authors: Stange William A.
Published: March 2015

This paper presents an overview of current research efforts aimed at improving turbine engine structural instrumentation capabilities. Emphasis is placed on non-intrusive concepts which will be applicable to the advanced engines currently being designed for initial operational testing around the turn of the century. Technologies to be described include; blade tip deflection sensors to determine dynamic stress, thermographic phosphors to measure metal temperature, fiber optics to measure both temperature and steady-state strain while embedded in composites, and neutron diagnostic techniques. Advantages of the various systems, potential problems and limitations, as well as, an assessment as to when the various technologies are likely to be ready for actual engine test usage are discussed.
Adaptation of a Small Commercial Fan Jet Trainer for Military Applications
Authors: Boyd D. I.
Published: March 2015

The JTI5D-4 engine is a successful small fan jet with a history of reliable service in fast, economical executive jet aircraft. This paper describes the unique design features which were necessary to convert it to the military combat trainer role, together with the associated development program. It includes details of a special test facility constructed to simulate aerobatic flight conditions, and discusses some aspects of field experience in a single engine trainer application.
NOx Exhaust Emissions for Gas-Fired Turbine Engines
Authors: Malte P. C. , Bernstein S. , Bahlmann F. , Doelman J.
Published: March 2015

A database consisting of 18 heavy-duty and aeroderivative gas turbine engine models, fired on natural gas, is evaluated for NOx exhaust emissions with and without water and steam injection. CO exhaust emissions are also considered. Engine baseload power outputs range from 2.9 to 83.5 MW, compressor pressure ratios are from 7.2 to 30.0, and turbine inlet temperatures are from 1150 to 1515K. The engine models are from the late 1970s to the current period, and all use diffusion flame combustors.

Baseload, uncontrolled NOx exhaust emissions, corrected to 15% O2 dry conditions, vary from 67 to 240 ppmv. CO exhaust emissions vary from 7 to 96 ppmv. Except for three low-NOx aero-derivative engines, the uncontrolled NOx exhaust emissions scale with engine pressure ratio and fuel-air ratio. A correlation formula is developed, and discussed relative to formulas in the literature. NOx control by water injection shows a fairly wide band; at a water-to-fuel mass ratio of 0.8, the NOx reduction varies from 58 to 82 percent. Engines with the highest uncontrolled NOx show the largest percentage reduction by water injection. On the other hand, NOx control response with steam injection exhibits less variation across the engine models. The relation of CO to NOx levels and and the response of CO to water and steam injection are examined, though quantitative correlations are not made.
Flow Distribution in a Model Recuperator of an Intercooled-Recuperative Marine Gas Turbine
Authors: Uhlig Robert A. , Kiang Robert L. , Buyer Janet L.
Published: March 2015

An intercooled-recuperative Brayton cycle is known to have a significantly higher thermal efficiency and hence a lower specific fuel consumption. The success of an ICR gas turbine engine, however, depends heavily on the performance of the recuperator. Uniform flow leading into the recuperator is usually assumed in the recuperator design. This experimental work represents an initial effort to understand and to improve the flow distribution in a marine gas turbine exhaust diffuser/recuperator configuration. Velocity measurements immediately downstream of the recuperator show that the flow through the recuperator is nonuniform; but the nonuniform flow distribution remains invariant with respect to the engine power level.
A record “longest echo” within the Inchindown oil despository
Authors: Cox Trevor J. , Kilpatrick Allan
Published: March 2015

In 2013, Guinness World Records awarded tank number 1 at the Inchindown oil despository, Ross-shire, Scotland, the record for the “longest echo” at 75 s. Guinness World Records calls it the longest echo because that was the name of the record that was broken, however, the correct name for the phenomenon measured is reverberation. This Letter has been written to document this unique acoustic space where the reverberation time is 112 s at 125 Hz, to detail the methodology for those who wish to attempt to break the record, and to discuss why the tank is so uniquely reverberant.
Treatment of ice cover and other thin elastic layers with the parabolic equation method
Authors: Collins Michael D.
Published: March 2015

The parabolic equation method is extended to handle problems involving ice cover and other thin elastic layers. Parabolic equation solutions are based on rational approximations that are designed using accuracy constraints to ensure that the propagating modes are handled properly and stability constrains to ensure that the non-propagating modes are annihilated. The non-propagating modes are especially problematic for problems involving thin elastic layers. It is demonstrated that stable results may be obtained for such problems by using rotated rational approximations [Milinazzo, Zala, and Brooke, J. Acoust. Soc. Am. 101, 760–766 (1997)] and generalizations of these approximations. The approach is applied to problems involving ice cover with variable thickness and sediment layers that taper to zero thickness.
New targets for ALK-driven lung cancer
Authors: Ferrarelli Leslie K.
Published: March 2015

A functional genomic screen reveals that the ligand neuregulin and the purinergic receptor P2Y mediate resistance to ALK inhibitors in lung cancer.
Sponsors meet scientists to speed pediatric medicines development
Authors: Davis Jonathan M. , Smoyer William E. , Connor Edward M. , Huskins W. Charles , Pastern Cindy , Purucker Mary , Schrader Elisabeth C. , Jackson Cynthia R. , Kaskel Frederick J. , Hirschfeld Steven
Published: March 2015

Child-health research initiative enables rapid response to opportunities for participation in multicenter pediatric clinical trials.
The ultimate combination immunotherapy
Authors: Maus Marcela V.
Published: March 2015

Combining two checkpoint blockers with radiation yields the best antitumor effects.
Knocked out: Sleep disturbances after traumatic brain injury
Authors: Nishijima Daniel K.
Published: March 2015

Traumatic brain injury patients have increased sleep need and daytime sleepiness relative to controls.
Trypanosoma brucei RRM1 Is a Nuclear RNA-Binding Protein and Modulator of Chromatin Structure
Authors: Naguleswaran Arunasalam , Gunasekera Kapila , Schimanski Bernd , Heller Manfred , Hemphill Andrew , Ochsenreiter Torsten , Roditi Isabel
Published: March 2015

TbRRM1 of
Trypanosoma brucei
is a nucleoprotein that was previously identified in a search for splicing factors in
T. brucei
. We show that TbRRM1 associates with mRNAs and with the auxiliary splicing factor polypyrimidine tract-binding protein 2, but not with components of the core spliceosome. TbRRM1 also interacts with several retrotransposon hot spot (RHS) proteins and histones. RNA immunoprecipitation of a tagged form of TbRRM1 from procyclic (insect) form trypanosomes identified ca. 1,500 transcripts that were enriched and 3,000 transcripts that were underrepresented compared to cellular mRNA. Enriched transcripts encoded RNA-binding proteins, including TbRRM1 itself, several RHS transcripts, mRNAs with long coding regions, and a high proportion of stage-regulated mRNAs that are more highly expressed in bloodstream forms. Transcripts encoding ribosomal proteins, other factors involved in translation, and procyclic-specific transcripts were underrepresented. Knockdown of TbRRM1 by RNA interference caused widespread changes in mRNA abundance, but these changes did not correlate with the binding of the protein to transcripts, and most splice sites were unchanged, negating a general role for TbRRM1 in splice site selection. When changes in mRNA abundance were mapped across the genome, regions with many downregulated mRNAs were identified. Two regions were analyzed by chromatin immunoprecipitation, both of which exhibited increases in nucleosome occupancy upon TbRRM1 depletion. In addition, subjecting cells to heat shock resulted in translocation of TbRRM1 to the cytoplasm and compaction of chromatin, consistent with a second role for TbRRM1 in modulating chromatin structure.

IMPORTANCE
Trypanosoma brucei
, the parasite that causes human sleeping sickness, is transmitted by tsetse flies. The parasite progresses through different life cycle stages in its two hosts, altering its pattern of gene expression in the process. In trypanosomes, protein-coding genes are organized as polycistronic units that are processed into monocistronic mRNAs. Since genes in the same unit can be regulated independently of each other, it is believed that gene regulation is essentially posttranscriptional. In this study, we investigated the role of a nuclear RNA-binding protein, TbRRM1, in the insect stage of the parasite. We found that TbRRM1 binds nuclear mRNAs and also affects chromatin status. Reduction of nuclear TbRRM1 by RNA interference or heat shock resulted in chromatin compaction. We propose that TbRRM1 regulates RNA polymerase II-driven gene expression both cotranscriptionally, by facilitating transcription and efficient splicing, and posttranscriptionally, via its interaction with nuclear mRNAs.
Novel Type III Effectors in Pseudomonas aeruginosa
Authors: Burstein David , Satanower Shirley , Simovitch Michal , Belnik Yana , Zehavi Meital , Yerushalmi Gal , Ben-Aroya Shay , Pupko Tal , Banin Ehud
Published: March 2015

Pseudomonas aeruginosa
is a Gram-negative, opportunistic pathogen that causes chronic and acute infections in immunocompromised patients. Most P. aeruginosa strains encode an active type III secretion system (T3SS), utilized by the bacteria to deliver effector proteins from the bacterial cell directly into the cytoplasm of the host cell. Four T3SS effectors have been discovered and extensively studied in P. aeruginosa: ExoT, ExoS, ExoU, and ExoY. This is especially intriguing in light of P. aeruginosa's ability to infect a wide range of hosts. We therefore hypothesized that additional T3SS effectors that have not yet been discovered are encoded in the genome of P. aeruginosa. Here, we applied a machine learning classification algorithm to identify novel P. aeruginosa effectors. In this approach, various types of data are integrated to differentiate effectors from the rest of the open reading frames of the bacterial genome. Due to the lack of a sufficient learning set of positive effectors, our machine learning algorithm integrated genomic information from another Pseudomonas species and utilized dozens of features accounting for various aspects of the effector coding genes and their products. Twelve top-ranking predictions were experimentally tested for T3SS-specific translocation, leading to the discovery of two novel T3SS effectors. We demonstrate that these effectors are not part of the injection structural complex and report initial efforts toward their characterization.

IMPORTANCE
Pseudomonas aeruginosa
uses a type III secretion system (T3SS) to secrete toxic proteins, termed effectors, directly into the cytoplasm of the host cell. The activation of this secretion system is correlated with disease severity and patient death. Compared with many other T3SS-utilizing pathogenic bacteria, P. aeruginosa has a fairly limited arsenal of effectors that have been identified. This is in sharp contrast with the wide range of hosts that this bacterium can infect. The discovery of two novel effectors described here is an important step toward better understanding of the virulence and host evasion mechanisms adopted by this versatile pathogen and may provide novel approaches to treat P. aeruginosa infections.
Simultaneous stent expansion/balloon deflation technique to salvage failed balloon remodeling
Authors: Ladner Travis R , He Lucy , Davis Brandon J , Froehler Michael T , Mocco J
Published: March 2015

Herniation, with possible embolization, of coils into the parent vessel following aneurysm coiling remains a frequent challenge. For this reason, balloon or stent assisted embolization remains an important technique. Despite the use of balloon remodeling, there are occasions where, on deflation of the balloon, some coils, or even the entire coil mass, may migrate. We report the successful use of a simultaneous adjacent stent deployment bailout technique in order to salvage coil prolapse during balloon remodeling in three patients. Case No 1 was a wide neck left internal carotid artery bifurcation aneurysm, measuring 9 mm×7.9 mm×6 mm with a 5 mm neck. Case No 2 was a complex left superior hypophyseal artery aneurysm, measuring 5.3 mm×4 mm×5 mm with a 2.9 mm neck. Case No 3 was a ruptured right posterior communicating artery aneurysm, measuring 4 mm×4 mm×4.5 mm with a 4 mm neck. This technique successfully returned the prolapsed coil mass into the aneurysm sac in all cases without procedural complications. The closed cell design of the Enterprise VRD (Codman and Shurtleff Inc, Raynham, Massachusetts, USA) makes it ideal for this bailout technique, by allowing the use of an 0.021 inch delivery catheter (necessary for simultaneous access) and by avoiding the possibility of an open cell strut getting caught on the deflated balloon. We hope this technique will prove useful to readers who may find themselves in a similar predicament.
The efficacy of sodium bicarbonate in preventing contrast-induced nephropathy in patients with pre-existing renal insufficiency: a meta-analysis
Authors: Zhang Bin , Liang Long , Chen Wenbo , Liang Changhong , Zhang Shuixing
Published: March 2015

Objective

The aim of this meta-analysis was to explore the efficacy of sodium bicarbonate in preventing contrast-induced nephropathy (CIN).

Methods

We searched PubMed, Medline and the Cochrane Library from 1 January 2004 to 1 August 2014. The effect estimate was expressed as a pooled OR with 95% CI, using the fixed-effects or random-effects model.

Results

20 randomised controlled trials (n=4280) were identified. Hydration with sodium bicarbonate was associated with a significant decrease in CIN among patients with pre-existing renal insufficiency (OR 0.67, 95% CI 0.47 to 0.96; p=0.027). However, moderate heterogeneity was noted across trials (I2=48%; p=0.008). Subgroup analyses indicated a better effect of sodium bicarbonate in studies using low-osmolar (OR 0.59, 95% CI 0.37 to 0.93; p=0.024) compared with iso-osmolar contrast agents (OR 0.76, 95% CI 0.43 to 1.34; p=0.351). The odds of CIN with sodium bicarbonate were lower in studies including only patients undergoing emergency (OR 0.16, 95% CI 0.05 to 0.51; p=0.002) compared with elective procedures (OR 0.76, 95% CI 0.54 to 1.06; p=0.105). Sodium bicarbonate was more beneficial in patients given a bolus injection before procedures (OR 0.15, 95% CI 0.04 to 0.54; p=0.004) compared with continuous infusion (OR 0.75, 95% CI 0.53 to 1.05; p=0.091). Sodium bicarbonate plus N-acetylcysteine (OR 0.17, 95% CI 0.04 to 0.79; p=0.024) was better than sodium bicarbonate alone (OR 0.71, 95% CI 0.48 to 1.03; p=0.071). The effect of sodium bicarbonate was considered greater in papers published before (OR 0.19, 95% CI 0.09 to 0.41; p=0.000) compared with after 2008 (OR 0.85, 95% CI 0.62 to 1.16; p=0.302). However, no significant differences were found in mortality (OR 0.69, 95% CI 0.36 to 1.32; p=0.263) or requirement for dialysis (OR 1.08, 95% CI 0.52 to 2.25; p=0.841).

Conclusions

Sodium bicarbonate is effective in preventing CIN among patients with pre-existing renal insufficiency. However, it fails to lower the risks of dialysis and mortality and therefore cannot improve the clinical prognosis of patients with CIN.
Unintentional ingestion of cleaners and other substances in an immigrant Mexican population: a qualitative study
Authors: Crosslin Katie , Tsai Ray
Published: March 2015

Paediatric poisoning is a salient issue worldwide and also affects the USA. In past years, ingestion of household cleaners was the second leading cause of unintentional poisonings in children. All children are at risk for ingestions, although immigrant children may be at greater risk. The purpose of this study was to document child ingestion experiences from toxic household substances via semistructured interviews with immigrant Mexican mothers. Participants were recruited from a paediatric primary care practice in Dallas/Fort Worth, Texas (N=35). Eighteen of 35 respondents (51%) reported that their child, nephew/niece or a friend's child had accidentally ingested a cleaning solution, gasoline or herbal remedy. Of those ingestions, 12 were reportedly from an alternative container, such as a juice box or soda bottle. Improper storage was the primary reason for ingestion. Culturally appropriate home visits and interventions are needed to better prevent ingestion in young children.
Childhood conscientiousness predicts the social gradient of smoking in adulthood: a life course analysis
Authors: Pluess Michael , Bartley Mel
Published: March 2015

Background and aims

The social gradient in smoking is well known, with higher rates among those in less advantaged socioeconomic position. Some recent research has reported that personality characteristics partly explain this gradient. However, the majority of existing work is limited by cross-sectional designs unsuitable to determine whether differences in conscientiousness are a predictor or a product of social inequalities. Adopting a life course perspective, we investigated in the current paper the influence of conscientiousness in early and mid-life on the social gradient in smoking and the role of potential confounding factors in a large longitudinal cohort study.

Methods

Using data from the 1958 National Child Development Study, we examined the extent to which two measures of conscientiousness, one assessed with a personality questionnaire at age 50 and one derived from three related items at 16 years in childhood, explained the social gradient of smoking at age 50 by comparing nested logistic regression models that included social class at birth, cognitive ability, attention and conduct problems at age 7, and educational qualification.

Results

Childhood conscientiousness was a significant predictor of smoking at 50 years (OR=0.86, CI (95%) 0.84 to 0.88), explaining 5.0% of the social gradient independent of all other variables. Childhood conscientiousness was a stronger predictor than adult conscientiousness, statistically accounting for the observed direct association of adult conscientiousness with smoking.

Conclusions

Conscientiousness may be a predictor rather than a product of social differences in smoking. Inclusion of personality measures and adoption of a life course perspective add significantly to our understanding of health inequalities.
Protective efficacy of carnosic acid against hydrogen peroxide induced oxidative injury in HepG2 cells through the SIRT1 pathway
Authors: Hu Yan , Zhang Ning , Fan Qing , Lin Musen , Zhang Ce , Fan Guangjun , Zhai Xiaohan , Zhang Feng , Chen Zhao , Yao Jihong
Published: March 2015

Carnosic acid (CA), found in rosemary, has been reported to have antioxidant and antiadipogenic properties. Here, we investigate the molecular mechanism by which CA inhibits hydrogen peroxide (H2O2)-induced injury in HepG2 cells. Cells were pretreated with 2.5–10 μmol/L CA for 2 h and then exposed to 3 mmol/L H2O2 for an additional 4 h. CA dose-dependently increased cell viability and decreased lactate dehydrogenase activities. Pretreatment with CA completely attenuated the inhibited expression of manganese superoxide dismutase (MnSOD) and the B-cell lymphoma-extra large (Bcl-xL), and reduced glutathione activity caused by H2O2, whereas it reversed reactive oxygen species accumulation and the increase in cleaved caspase-3. Importantly, sirtuin 1 (SIRT1), a NAD+-dependent deacetylase, was significantly increased by CA. Considering the above results, we hypothesized that SIRT1 may play important roles in the protective effects of CA in injury induced by H2O2. As expected, SIRT1 suppression by Ex527 (6-chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide) and siRNA-mediated SIRT1 silencing (si-SIRT1) significantly aggravated the H2O2-induced increased level of cleaved caspase-3 but greatly reduced the decreased expression of MnSOD and Bcl-xL. Furthermore, the positive regulatory effect of CA was inhibited by si-SIRT1. Collectively, the present study indicated that CA can alleviate H2O2-induced hepatocyte damage through the SIRT1 pathway.