bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Blade Loading Criteria and Design Limits on the Cordier-Line for Axial Flow Fans
Authors: Willinger Reinhard , Köhler Michael
Published: September 2014

Volume flow rate, specific isentropic enthalpy difference, rotor outer diameter and rotational speed of a fan can be transformed to speed number and diameter number. These two non-dimensional numbers are related together in the so-called Cordier-diagram. For axial, radial and mixed flow fans, there is a single empirical relationship between both quantities and it is well accepted that this line represents “optimum” fan designs with high efficiency. Based on velocity triangles, a relationship between flow coefficient and pressure coefficient exists. This so-called performance curve captures off-design operating points as well as the design point of a fan. Therefore, the performance curve can be transformed to the Cordier-diagram to predict the relationship between speed number and diameter number. It is shown that the Cordier-line depends mainly on velocity triangles and the common argument of high efficiency, claimed in the majority of the literature, plays only a secondary role. Nevertheless, the requirement of high efficiency influences the fan design for a certain design point. This paper focuses mainly on axial flow fans. It gives a theoretical interpretation of the influence of blade loading criteria and design limits on the Cordier-line: (1) De Haller number, (2) cascade loading parameter, (3) Lieblein diffusion factor, (4) Strscheletzky swirl number. Criterion (1) reflects the minimum velocity ratio to avoid endwall separation in a linear compressor cascade. Criterion (2) is a combination of lift coefficient and cascade solidity. It reflects the aerodynamic loading of the suction side blade boundary layer. Criteria (1) and (2) are included in criterion (3). Finally, criterion (4) indicates the risk of hub separation due to strong swirl flow. The investigation shows that the transformation of these criteria to the Cordier-diagram gives very similar results. Furthermore, it is shown that the axial fan design limits in the Cordier-diagram are represented by certain hub-to-tip radius ratios.
A Coupled Blade Adjustment and Response Surface Method for the Optimization of Radial Fans Without Housing
Authors: Ratter H. , Çağlar Ş. , Gabi M.
Published: September 2014

The optimization process of a fan based on 3D viscous CFD calculations is time consuming, especially if many variables are taken into account. With the focus on computational cost efficiency and reliable CFD-results a specific optimization algorithm for radial fans based on CFD calculations is presented. The algorithm is derived from the classical knowledge of flow phenomena occurring in radial fans. The leading edge is adjusted in reference to the stagnation point caused by the incoming flow. The trailing edge is adjusted to achieve the required pressure rise. The 5 blades of the investigated fan are constructed as 3D free surface blades; each blade is separated into 5 profile sections. The optimization process regarding the blade includes 10 independent parameters of the leading and trailing edges.

An additional potential to increase efficiency is obtained by changing the meridional shape of the impeller. To investigate the meridional shape, the blade adjustment algorithm is coupled with a response surface method using the Kriging approximation to find a highly efficient meridional shape.
Aerodynamic Calibration and Thrust Correction Method With Inflow Separation in Indoor Sea Level Test Facility
Authors: Wu Feng , Gong XiaoQi , Su JinYou
Published: September 2014

Thrust performance, which can be obtained by indoor sea level test facility, plays a critical role in jet and turbofan engine performance. In this study, to obtain the aerodynamic characteristics in test cell and the final thrust correction coefficient, a standard turbofan engine is chosen as the testing engine, which is mounted separately on a fixed contracting or adjustable Laval nozzle. Experimental results show that the aerodynamic performance of intake is poor if no guide vanes are implemented. In this situation, inhomogeneity of intake flow is up to 97%. Besides, the flow would separate in the upstream of the engine, which is also proven by the CFD simulation results.

With the flow separating upstream of the test engine, the traditional intake momentum correction method by using ideal horizontal intake condition could result in greater correction error of intake momentum. Thus, a new formula is derived in the present paper to correct the intake momentum with flow separation by mechanic control system. Comparisons of thrust performance and specific fuel consumption are conducted between the result corrected by new formula suited for flow separation condition and those obtained from the performance data of the same engine tested in the sea level condition. And good agreement has been achieved. Thus it is proven that the new thrust correction method is correct and reliable.

Result of this study indicates that: 1) intake flow separation has a great influence on thrust measurement in jet engine test facility, which will result in the 1.4 to 2 times greater correction error. Thus, guide vanes should be implemented at inlet tower corner in preventing from the flow separation. 2) The new correction method derived in this paper is very effective to correct the engine thrust performance with the flow separation upstream of the test engine.
Computational and Experimental Study of the Effect of Inlet Swirl on Mixing Mechanisms in an Axisymmetric Lobed Mixer
Authors: Brinkerhoff Joshua R. , Yaras Metin I.
Published: September 2014

The effect of circumferential inflow swirl on the instability of the shear layer formed between the core and bypass flows discharged from an axisymmetric twelve-lobed mixer is studied through a combined experimental and computational investigation. A series of unsteady Navier-Stokes simulations are performed with 0 and 31 degrees of circumferential swirl specified in the core stream of the lobed mixer. Comparison of the axial- and swirling-inflow cases highlights the effect of swirl on the instability-driven transient flow structures that develop within and downstream of the lobed mixer. Medium- and large-scale unsteady motions are captured by the fine spatial and temporal resolution of the unsteady Navier-Stokes simulations. The simulations are validated against four-wire thermal anemometry measurements in a scaled lobed-mixer wind-tunnel model with turbulent, swirling inflow conditions. The simulation results illustrate that while the axial-inflow case develops layers of streamwise vorticity uniformly along the lobe walls, the core flow in the swirling-inflow case separates from the suction side of the lobe wall near the lobe trough. Roll-up and axial stretching of the separated flow produces Λ-shaped vortical structures upstream of the discharge plane. The Λ-shaped structures interact with the shear layers discharged from the lobe trailing edge and accelerate the breakdown of the shear layer in the swirling-inflow case relative to the axial-inflow case. The extent of this interaction is shown to strongly affect the streamwise mixing rate of the flow downstream of the discharge plane.
Experimental Investigation Into the Efficiency of an Aero Engine Oil Jet Supply System
Authors: Krug Matthias B. , Peduto Davide , Kurz Wolfram , Bauer Hans-Jörg
Published: September 2014

This paper presents results of investigations on the interaction between a targeted oil jet and a rotating shaft in an aero engine typical bearing chamber. Measurements were performed at atmospheric temperature and pressure in order to study the influence of the operating conditions, nozzle diameters and impingement angles on the efficiency of such an oil supply system. The flow phenomena of the jet-shaft interaction were visualised.

A qualitative analysis of the jet-shaft interaction revealed massive droplet generation due to the jet break-up in the air crossflow and its impact on the shaft. The latter could be reduced with shallower impingement angles. Measurements showed that the oil inflow rate, the shaft speed and the nozzle diameter have a strong influence on the collected oil quantity, which is expressed as catch efficiency, i.e. the ratio of collected and supplied oil. The impingement angle was also identified to have a strong influence on the catch efficiency. The ratio of the momentum fluxes of supplied oil and chamber air flow is proposed as a parameter to correlate the catch efficiency to the operating conditions.
Flow Induced Noise Predictions of an Automotive Alternator Using a Lattice Boltzmann Method
Authors: Le Goff Vincent , Vidal Vincent , Fakes Michel , Chiozzi Philippe , Le Goff Erwan , Perot Franck , Kim Min-Suk
Published: September 2014

The increasing demand for comfort and quietness from the automotive industry transforms the acoustics performances of subsystems as a critical input for the selection of a specific design. Among this market, rotating systems noise takes a growing importance and automotive alternators are strongly impacted by this aspect. Alternators contain many different types of rotating parts such as cooling fans and claw poles and their corresponding flow-induced noise contributions and interaction mechanisms driving the noise generation have to be assessed as early as possible in the product development process.

Experimental methods have been historically used to identify and reduce the most obvious phenomena at the origin of the broadband and tonal contents of the noise. Considering the complexity of this device, it appears practically more and more difficult to understand the involved mechanisms and to identify and treat the remaining aeroacoustics sources. The use of digital solutions to simulate the corresponding flow-induced noise contributions and to provide an insight on the noise generation mechanisms represents an alternative to this experimental approach. Furthermore, numerical approach allows a broader design space exploration, where experimental testing can sometime be limited by other constraints, such as mechanical, thermal and electromagnetic aspects. Another advantage of using CAE method is to reduce the product development cycle and the number of expensive prototypes. The highly detailed geometry features and the constrained environment of alternators however represented a real challenge for computational aeroacoustics solutions.

In this paper, an unsteady and compressible computational approach based on the Lattice Boltzmann Method (LBM) is used to simultaneously predict the 3-D turbulent flow and the corresponding acoustic field of an automotive alternator. The complete rotor-stator model including all geometrical details and the truly rotating geometry is simulated. Numerical and experimental far field sound pressure levels and acoustic power comparisons are presented. Additional transient and spectral flow analysis are performed to diagnose flow-induced noise problems and to provide a better understanding of the aeroacoustics sources.
Numerical Study of the Effect of Multiple Tightly-Wound Vortices on a Transonic Fan Stage Performance
Authors: Pardo Alejandro Castillo , Mehdi Ahad , Pachidis Vassilios , MacManus David G.
Published: September 2014

As a result of the new engine design trends, the likelihood of tightly-wound vortices being ingested by the engine rises. Therefore, the risk associated with the ingestion of swirl distortion becomes a major concern.

A numerical analysis of the response of a transonic fan stage to the ingestion of different distorted flow patterns is carried out using steady-state CFD. The CFD approach is generated and validated against experimental data for undistorted inlet conditions. Following the validation, a wide range of configurations with vortex flow distortions are analysed and evaluated. The change in global performance is quantified and the flow field is extensively analysed. Consequently, the parameters that have the most critical impact on the performance of the fan stage are identified.

The study identifies a close relation between the number of vortices ingested and the change in rotor performance. However, the deviation from the clean rotor performance has been found to be independent of the circumferential distance between vortices. Additionally, the effects of the radial location, polarity and vortex magnitude have been assessed. Ingested co-rotating vortices cause a significant reduction in pressure ratio and corrected mass flow. In contrast, counter-rotating vortices are associated with an increase in the pressure ratio and corrected mass flow. The change in rotor performance increases with the strength. However, a dramatical drop in pressure ratio is observed for counter-rotating vortices when the vortex strength exceeds a critical value.
Numerical and Experimental Study of Swirling Flow in a Short Annular to Round Diffuser/Nozzle
Authors: Namet-Allah A. , Birk A. M.
Published: September 2014

The objective of the current paper is to gain an understanding of the effects of inlet swirling flow on the flow field through short annular transition diffusers and nozzles. These devices are representative of the primary driving nozzles for certain exhaust ejector systems. It is known that strongly swirling flow can degrade ejector performance due to core separation. It is believed that minor changes in driving nozzle shape can improve ejector performance significantly.

Two configurations of a diffuser/nozzle were tested experimentally and numerically under different swirl strengths. The two configurations were mounted on an annular flow wind tunnel. Two shapes of the annulus’ centre body end; square and elliptical, were used. Based on the hydraulic inlet diameter, average velocity and temperature in the annulus of the wind tunnel, the measurements were carried out at Mach range of 0.21 to 0.26 with Reynolds number of 2.3 to 2.7×105.

Ansys14 was used for the CFD simulations. The measured velocity profiles in the annulus were used as input flow conditions in the CFD investigation. The RNG k-ε turbulence model was used in the CFD simulations. The measured velocity profiles at the device exit, and measured surface pressures on the annulus, duct and nozzle walls were compared with the CFD predictions. The measured back pressure coefficient and total pressure loss through the diffuser systems were compared with the CFD predictions. A reasonable agreement between the experimental data and numerical predictions was observed.

It was found computationally that the size of the central recirculation zone behind the annulus centre body has negative effects on the diffuser performance under different swirl numbers. The square shape of the annulus’ centre body end increased the back pressure and total pressure loss coefficients over the elliptical shape. However, the flow uniformity at the duct and nozzle exits improved with the square shape over the elliptical end. These differences may have a significant effect on ejector pumping.
Laser Insight Into the Turbulent Swirl Flow Behind the Axial Flow Fan
Authors: Čantrak Đorđe S. , Janković Novica , Lečić Milan R.
Published: September 2014

Complex experimental study of the turbulent swirl flow behind the axial fan is reported in this paper. Axial fan with nine blades, designed to generate Rankine vortex, was positioned in the circular pipe entrance transparent section with profiled free bell mouth inlet. Two test rigs were built in order to study the turbulent swirl flow generated on the axial fan pressure side in the case of axially unrestricted and restricted swirl flows. One-component laser Doppler anemometry (LDA) and stereo particle image velocimetry (SPIV) were used in the first test rig in the measuring section 3.35D, measured from the test rig inlet. One of the latest measurement techniques, high speed SPIV (HSS PIV), was used for the measurements in the second test rig in the section 2.1D downstream the fan’s trailing edge. Achieved Reynolds numbers in the first test rig are Re = 182600 and 277020, while in the second Re = 186463. Turbulent velocity field non-homogeneity and anisotropy is revealed using the LDA system. Calculated turbulent statistical properties, such as moments of the second and higher orders, reveal complex mechanisms in turbulent swirl flow. It is shown for the used axial fan construction that swirl number has almost constant value for two various duty points generated by changing rotation number. Study of the instant and mean velocity fields obtained using SPIV discovers vortex core dynamics. Obtained percentage of the unique positions of the total velocity minimum are 10% for the first regime, while 11.5% for the second regime in the first test rig. HSS PIV experimental results have also shown the three-dimensionality and non-homogeneity of generated turbulent swirl flow. Experimentally determined and calculated invariant maps revealed three-component isotropic turbulence in the vortex core region.
Transonic Axial Compressors With Total Pressure Inlet Flow Field Distortions
Authors: Lesser Andreas , Niehuis Reinhard
Published: September 2014

Non-uniform inlet flow has come back into focus of research during the last years due to the need of increasing the operational range of airborne engines. Higher climbing rates for lower noise pollution at airports as well as boundary layer ingesting inlet designs lead to the demand of inlet distortion resistant engines and compressors, in particular. To fulfill this design task, a deep understanding of the dominant flow physics of the distortion transport through the compressor as well as the influence of the compressor on the upstream flow field is needed. This paper starts with the transport of a circumferential total pressure distortion through a compressor stage. Using numerical results, previously validated by experimental data, a phenomenological approach for the transport is presented. The most important finding is the essential role of the different propagation speeds of the static pressure distortion and the inflow velocity distortion and its decoupling. A static pressure and an inflow velocity distortion are present for all kinds of total pressure distortions caused by the upstream flow field redistribution of the compressor. This decoupling causes not only a significant circumferential increase of the distorted sector but also a strong variation of the distortion magnitude downstream of the compressor stage. All relevant phenomena are present in the phenomenological approach as well as in the numerical and the referred experimental results. Inlet distortions result in a decrease of stability margin [1],[2]. The crucial area for the stability of most modern transonic compressors is the tip region; therefore, the tip region was under particular investigation. The numerical results show that the flow field in the distorted area is shifted toward the stall line. The shock system and the tip clearance vortex behave similar to the results near stall with uniform inflow. No local stall can be observed, although the local operating points within the distorted sector travel beyond the stall line of the compressor map with uniform inflow.

Finally, a new analytical approach for the critical distortion angle is presented. The main finding is the circumferential extent has to be big enough to separate the zones of decoupled distortion quantities.
Effect of BLI–Type Inlet Distortion on Turbofan Engine Performance
Authors: Lucas James R. , O’Brien Walter F. , Ferrar Anthony M.
Published: September 2014

Boundary Layer Ingestion (BLI) is currently being researched as a potential method to improve efficiency and decrease emissions for the next generation of commercial aircraft. While re-energizing the boundary layer formed over the fuselage of an aircraft has many system level benefits, ingesting the low velocity boundary layer flow through a serpentine inlet into a turbofan engine adversely affects the performance of the engine. This work reports an experimental investigation of the effects of a BLI-type distortion on a turbofan engine’s performance. A modified JT15D-1 turbofan engine was used in this study. Inlet flow distortion was created by a layered wire mesh distortion screen designed to create a total pressure distortion profile at the aerodynamic interface plane (AIP) similar to NASA’s Inlet A boundary layer ingesting inlet flow profile. Results of this investigation showed a 15.5% decrease in stream thrust and a 14% increase in TSFC in the presence of BLI-type distortion. The presence of the distortion screen resulted in a 24% increase in mass-averaged entropy production along the entire fan flow path compared to the non-distorted test.
Contribution of Acoustic and Structural Sources to the Tonal Sound Radiation of Side Channel Blowers
Authors: Münsterjohann Sven , Becker Stefan , Grohmann Thomas , Dittmar Rudi
Published: September 2014

Structural excitation and direct production of acoustic sources in the flow lead to the sound emission of side channel blowers. Pressure fluctuations in the region of the interrupter excite the structure and result in a tonal sound emission at the blade passing frequency (BPF). Furthermore the flow phenomena produce acoustic sources that are radiated in the far field. These different mechanisms of the structural and acoustic excitation are calculated in a simplified way. In a second step each source is separately coupled into the side channel blower. The structural excitation is realized with a shaker. The acoustic sources are generated with a horn driver (speaker) and are induced into the system through the outlet of the blower. Using this setup, the contribution of each source to the tonal sound in the far field can be estimated and compared to the total measured sound pressure level (SPL) at the corresponding frequency.
Particle Dynamics of a 2-D Inertial Particle Separator
Authors: Barone Dominic , Loth Eric , Snyder Philip H.
Published: September 2014

The effects of sand and dust ingestion often limit the useful life of turbine engines operating in austere environments and efforts are needed to reduce the quantity of particulate entering the engine. Several Engine Air Particle Separation (EAPS) systems exist to accomplish this task. Inertial Particle Separators (IPS) are of particular interest because they offer significant weight savings and are more compact. This study focuses on the how small particles are affected by the dynamic fluid forces present in the IPS. Using Multi-Phase Particle Image Velocimetry (MP-PIV), 10um and 35um glass spheres were tracked through the IPS. Further, the data was also used to analyze the particles Coefficient of Restitution, (CORn̂), where they impact the Outer Surface Geometry (OSG) of the IPS.
Helicopter Mission Analysis Using a Multidisciplinary Simulation Framework
Authors: Karamolegkos K. , Goulos I. , Pachidis V. , Stevens J. , Smith C. , Thevenot L. , d’Ippolito R.
Published: September 2014

This paper describes the work done and strong interaction between the Technology Evaluator (TE), Green Rotorcraft (GRC) Integrated Technology Demonstrator (ITD) and Sustainable and Green Engine (SAGE) ITD of the Clean Sky Joint Technology Initiative (JTI). The GRC and SAGE ITDs are responsible for developing new helicopter airframe and engine technologies respectively, whilst the TE has the distinctive role of assessing the environmental impact of these technologies at single flight (mission), airport and Air Transport System levels (ATS). The assessments reported herein have been performed by using a GRC-developed multidisciplinary simulation framework called PhoeniX (Platform Hosting Operational and Environmental Investigations for Rotorcraft) that comprises various computational modules. These modules include a rotorcraft performance code (EUROPA), an engine performance and emissions simulation tool (GSP) and a noise prediction code (HELENA). PhoeniX can predict the performance of a helicopter along a prescribed 4D trajectory offering a complete helicopter mission analysis. In the context of the TE assessments reported herein, two helicopter classes are examined namely a Twin Engine Light (TEL) configuration for Emergency Medical Service (EMS) and Police missions and a Single Engine Light (SEL) configuration for Passenger/Transport missions. The different technologies assessed reflect three simulation points which are the ‘Baseline’ Year 2000 technology, ‘Reference’ Y2020 technology, without Clean Sky benefits, and finally the ‘Conceptual’, reflecting Y2020 technology with Clean Sky benefits. The results of this study illustrate the potential that incorporated technologies possess in terms of improving performance and gas emission metrics such as fuel burn, CO2, NOx as well as the noise footprint on the ground.
Isolating Effects of Area Ratio From Lobe Number for Turbofan Engine Exhaust Systems
Authors: Wright Alex , Mahallati Ali , Militzer Julio
Published: September 2014

This paper presents a numerical investigation of lobed mixer performance at experimentally validated low speed conditions and conditions representative of high speed engine operation. The purpose of this study was to first assess and understand how variations in bypass-to-core area ratio (AR) can affect engine performance, then isolate those effects to determine the efficacy of increasing the number of mixer lobes. The area ratio was manipulated via adjustment of the lobe crest and valley radiuses. No other geometric features were altered in any of the 5 mixers studied (12-lobe AR of 3, 2.5 and 3.5, 16-lobe AR of 3 and 18-lobe AR of 3). Results indicate that performance can be affected by area ratio. Low-speed results showed that pressure loss and thrust output were improved at lower area ratios. High speed results showed the opposite. This behavior is believed to be the result of a bypass-to-core momentum ratio difference between the two test conditions. These effects were avoided when studying the number of lobes by maintaining a constant area ratio. Results indicate that adding lobes enhanced exhaust mixing but hampered performance at low speed conditions. No appreciable performance difference was observed at high speed conditions. Fluid viscosity and associated viscous mixing losses are believed to be the parameters at fault for the reduced low-speed performance results.
Accessory Gear Box Architecture Evaluation Tool
Authors: Sharma Pankaj , Moniz Thomas , Chaudhari Vinod
Published: September 2014

An architectural modeling tool has been developed to support Accessory Gearbox (AGB) design. This is a structured approach which allows the Preliminary Design team to design an AGB with high fidelity in a short time and earlier in the design process. The program can accommodate a large variety of accessories with different attributes to generate a gearbox of minimum size. The final gearbox shape includes curvature which enables a close fit to the engine carcass. By setting the size, shape and location of the gearbox and accessories earlier, the designer can begin the process of locating external configurations around the gearbox more efficiently. The tool systematically explores the design space to optimize geometry based on multiple design criteria. It successfully constructs the intermediate gear train needed within the gearbox. It provides graphical output to the user with primitive models of the gears, accessories and housing. Once located in engine coordinates, these primitives provide the reference for the next level for detailed design.
Simple colloidal lithography method to fabricate large-area moth-eye antireflective structures on Si, Ge, and GaAs for IR applications
Authors: Lora Gonzalez Federico , Chan Lesley , Berry Alex , Morse Daniel E. , Gordon Michael J.
Published: September 2014

A two-step colloidal lithography process (Langmuir–Blodgett dip coating + reactive ion etching) was developed to fabricate single and double-sided moth-eye structures in Si, Ge, and GaAs for antireflection applications in the IR. Large increases in transmittance were obtained in all three material platforms (up to 97% single-side and 91% absolute transmittance) over the λ = 4−20+ μm region. Effective medium theory and the transfer matrix method were used to predict IR optical response of moth-eye substrates as well as investigate the effect of protuberance shape on antireflectance behavior. Overall, it is demonstrated that colloidal lithography and etching provide an easy and generic way to synthesize moth-eyes in different IR material platforms.
Relations Between Sedentary Behavior and FITNESSGRAM Healthy Fitness Zone Achievement and Physical Activity
Authors: Tucker Jacob S. , Martin Scott , Jackson Allen W. , Morrow James R. , Greenleaf Christy A. , Petrie Trent A.
Published: September 2014

Purpose:

To investigate the relations between sedentary behaviors and health-related physical fitness and physical activity in middle school boys and girls.

Methods:

Students (n = 1515) in grades 6–8 completed the Youth Risk Behavior Survey sedentary behavior questions, the FITNESSGRAM physical fitness items, and FITNESSGRAM physical activity self-report questions.

Results:

When students reported ≤ 2 hours per day of sedentary behaviors, their odds of achieving the FITNESSGRAM Healthy Fitness Zone for aerobic capacity, muscular strength and endurance, flexibility, and body composition increased. Similarly, the odds of achieving physical activity guidelines for children increased when students reported ≤ 2 hours per day of sedentary behaviors.

Conclusions:

Results illustrate the importance of keeping sedentary behaviors to ≤ 2 hours per day in middle school children, thus increasing the odds that the student will achieve sufficient health-related fitness benefits and be more likely to achieve the national physical activity guidelines.
Multilevel Correlates of Physical Activity for Early, Mid, and Late Adolescent Girls
Authors: Young Deborah , Saksvig Brit I. , Wu Tong Tong , Zook Kathleen , Li Xia , Champaloux Steven , Grieser Mira , Lee Sunmin , Treuth Margarita S.
Published: September 2014

Background:

We examined associations among multilevel variables and girls’ physical activity to determine whether they vary at different adolescent ages.

Methods:

All field sites of the Trial of Activity for Adolescent Girls contributed participants from 6th (n = 1576) and 8th grades (n = 3085). The Maryland site contributed an 11th grade sample (n = 589). Questionnaires were used to obtain demographic and psychosocial information (individual- and social-level variables); height, weight, and triceps skinfold to assess body composition; interviews and surveys for school-level data; and geographical information systems and self-report for neighborhood-level variables. Moderate to vigorous physical activity minutes (MVPA) were assessed from accelerometers. Mixed models (13 individual, 5 social, 15 school, 12 neighborhood variables) were used to determine multilevel associations.

Results:

Variables at individual, social, school, and neighborhood levels were associated with MVPA, but differed across grades. Lower percent body fat, higher social support from friends, and lower school math scores were associated with higher MVPA at 6th and 8th grade. Higher physical activity self-efficacy was associated with higher MVPA at 11th grade. Only lower physical activity barriers were associated with higher MVPA at all grades.

Conclusion:

MVPA is a complex behavior with fluid, multilevel correlates that differ among girls across middle and high school.
Clustering of Risk Factors for Noncommunicable Diseases in Brazilian Adolescents: Prevalence and Correlates
Authors: Cureau Felipe Vogt , Duarte Paola , dos Santos Daniela Lopes , Reichert Felipe Fossati
Published: September 2014

Background:

Few studies have investigated the prevalence and correlates of risk factors for noncommunicable diseases among Brazilian adolescents. We evaluated the clustering of risk factors and their associations with sociodemographic variables.

Methods:

We used a cross-sectional study carried out in 2011 comprising 1132 students aged 14–19 years from Santa Maria, Brazil. The cluster index was created as the sum of the risk factors. For the correlates analysis, a multinomial logistic regression was used. Furthermore, the observed/expected ratio was calculated.

Results:

Prevalence of individual risk factors studied was as follows: 85.8% unhealthy diets, 53.5% physical inactivity, 31.3% elevated blood pressure, 23.9% overweight, 22.3% excessive drinking alcohol, and 8.6% smoking. Only 2.8% of the adolescents did not present any risk factor, while 21.7%, 40.9%, 23.1%, and 11.5% presented 1, 2, 3, and 4 or more risk factors, respectively. The most prevalent combination was between unhealthy diets and physical inactivity (observed/expected ratio =1.32; 95% CI: 1.16–1.49). Clustering of risk factors was directly associated with age and inversely associated with socioeconomic status.

Conclusions:

Clustering of risk factors for noncommunicable diseases is high in Brazilian adolescents. Preventive strategies are more likely to be successful if focusing on multiple risk factors, instead of a single one.
Fulleropyrrolidine interlayers: Tailoring electrodes to raise organic solar cell efficiency
Authors: Page Zachariah A. , Liu Yao , Duzhko Volodimyr V. , Russell Thomas P. , Emrick Todd
Published: September 2014

Layering on solar cell power and stability

Solar cells made from carbon-based polymers are helpfully flexible. However, there's been a frustrating tradeoff between cell stability and efficiency when converting solar power to electrical power. Page
et al.
offer a strategy to partially resolve this dilemma by inserting a layer of polar organic compound (a fullerene derivative) between the cathode (the positive pole in the circuit) and the rest of the cell. Aluminum is an efficient cathode material but is prone to oxidative degradation. The easily applied polar layer enables the use of more stable metals, such as silver and copper, for the cathode, while counteracting their tendencies to diminish power conversion efficiency.

Science
, this issue p.
441
Draft Genome Assembly of Delftia acidovorans Type Strain 2167
Authors: Davenport K. W. , Daligault H. E. , Minogue T. D. , Bishop-Lilly K. A. , Bruce D. C. , Chain P. S. , Coyne S. R. , Frey K. G. , Jaissle J. , Koroleva G. I. , Ladner J. T. , Palacios G. F. , Redden C. L. , Scholz M. B. , Teshima H. , Johnson S. L.
Published: September 2014

The
Delftia acidovorans
2167 (ATCC 15668,
Delftia
type strain) genome was sequenced into a 6-contig scaffolded assembly of 6.78-Mb. This environmental microbe, previously named to both the
Comamonas
and
Pseudomonas
genera, is an opportunistic pathogen and often the subject of phylogenetic placement debates.
Genome Sequence of Pectobacterium atrosepticum Strain 21A
Authors: Nikolaichik Yevgeny , Gorshkov Vladimir , Gogolev Yuri , Valentovich Leonid , Evtushenkov Anatoli
Published: September 2014

We report the annotated genome sequence of the enterobacterial plant pathogen
Pectobacterium atrosepticum
strain 21A, isolated in Belarus from potato stem with blackleg symptoms.
Complete Genome Assembly of a Quality Control Reference Isolate, Moraxella catarrhalis Strain ATCC 25240
Authors: Daligault H. E. , Davenport K. W. , Minogue T. D. , Bishop-Lilly K. A. , Bruce D. C. , Chain P. S. , Coyne S. R. , Frey K. G. , Jaissle J. , Koroleva G. I. , Ladner J. T. , Lo C.-C. , Meincke L. , Munk C. , Palacios G. F. , Redden C. L. , Johnson S. L.
Published: September 2014

Generally an opportunistic pathogen in the United States,
Moraxella catarrhalis
has acquired resistance to multiple antibacterial/antimicrobial agents. Here, we present the complete 1.9-Mb genome of
M. catarrhalis
strain ATCC 25240, as deposited in NCBI under the accession number CP008804.
Healing of a pyoderma gangrenosum at the site of a percutaneous endoscopically sited gastrostomy tube without tube removal
Authors: Davis Charles , Wright Bethany
Published: September 2014

Pyoderma gangrenosum (PG) is a rare but important cause of pain and morbidity, and is associated with malignancy and shows pathergy. Occurrence at a percutaneous endoscopic gastrostomy (PEG) site is rare and may prompt PEG tube removal. This case describes management of PG at a PEG site in a man with squamous cell carcinoma of the orophayrnx. Successful healing of the lesion was achieved despite the PEG tube remaining in situ. Care was delivered within the hospice setting with support from the local dermatology service. Infection of the wound was treated with a recently licensed antimicrobial with a novel action. This allowed nutrition to continue, promoting healing further and ensuring a route of delivery for medications, avoiding intravenous therapy.
Intra-arterial chemotherapy for bilateral retinoblastoma via left ophthalmic artery and right anterior deep temporal artery
Authors: Amans Matthew R , Narvid Jared , Halbach Van V
Published: September 2014

A 12-month-old boy with a history of bilateral retinoblastoma refractory to systemic chemotherapy, laser therapy and cryotherapy, with excellent response to previous intra-arterial melphalan infusion, presents with active tumour deposits in the right eye. Repeat intra-arterial chemotherapy was recommended. Previous bilateral melphalan infusion was uneventful using flow-guided catheterisation technique. Direct catheterisation of the right ophthalmic artery was unsuccessful despite employment of several flow-guided and over-the-wire catheters. Superselective catheterisation of the ipsilateral middle meningeal artery was unable to identify an anastomotic connection to the ophthalmic artery; however, angiography of the anterior deep temporal artery identified an alternate route for chemotherapy infusion. The anterior deep temporal artery was successfully and safely catheterised to infuse chemotherapy into the ophthalmic artery. The anterior deep temporal artery is an important potential anastomotic connection to the ophthalmic artery that can be used safely and effectively for central retinal artery chemotherapy infusion for retinoblastoma treatment.
Acute acalculous cholecystitis in a patient with juvenile dermatomyositis
Authors: Sanches Bruno Fernandes , Martins Teresa , Santos Maria José , Azeredo Paula
Published: September 2014

Juvenile dermatomyositis (JDM) is a rare autoimmune disease, characterised by a systemic capillary vasculopathy that typically affects skin and muscle. Gastrointestinal involvement is relatively rare. We report the case of an 11-year-old girl admitted for investigation of skin rash, progressive symmetric proximal muscle weakness, dysphagia and weight loss. The diagnosis of JDM was confirmed and during hospitalisation the patient developed abrupt and intense right hypocondrium pain associated with nausea and vomiting. Abdominal ultrasound revealed a thick gallbladder wall (8 mm) with pericholecystic fluid and no evidence of gallstones. An acute acalculous cholecystitis was assumed and the patient was started on intravenous fluids, prednisolone and analgaesic therapy. Clinical resolution was verified after 48 h. We hypothesised that the vasculitic process of JDM could have been the basis for this complication as described in other autoimmune diseases.
Maxillary first molar with five canals
Authors: Umer Fahad
Published: September 2014

Root canal treatment is a technically demanding procedure especially in the case of maxillary first molar where the anatomy is extremely variable. Failure to recognise and treat these variations may lead to unpredictable outcomes. This case report describes non-surgical endodontic treatment of a maxillary first molar with two palatal and two mesiobuccal canals. It also highlights the need for good anatomical knowledge of root canal morphology and its variations in order to achieve consistently successful results.
A stitch in time: an unusual cause of enterovesical fistula
Authors: O'Callaghan John Matthew , Boyd Jason Timothy , Singh Anjana
Published: September 2014

A 64-year-old woman with a history of a Stamey procedure for stress incontinence 20 years previously, underwent a diagnostic flexible cystoscopy to investigate recurrent urinary sepsis. Cystoscopic examination demonstrated a large vesicular calculus. When traction was applied to the calculus it was shown to be attached to a 10 cm length of non-absorbable suture material. The suture was attached to two further calculi, apparently originating from outside the bladder wall. All visible calculi and the suture were removed. In the following weeks the patient reported passage of air and faeculent material per-urethra. A repeat cystoscopy revealed an opening in the posterolateral bladder wall and CT confirmed the presence of an enterovesical fistula. Laparoscopy demonstrated a fistula between the terminal ileum and bladder wall. A further 10 cm length of non-absorbable suture material was removed from the terminal ileum and omentum. Laparoscopic repair of the fistula was performed successfully and the patient has remained symptom free following the procedure.
An incidentally detected giant membranous interventricular septal aneurysm secondary to previous surgery for subaortic valvular stenosis
Authors: Karagöz Ahmet , Çelik Abdullah , Vural Aslı , Başer Bengi
Published: September 2014

Ventricular septal aneurysms are rare clinical entities and their certain prevalence and clinical significance are not well known. Most of them are thought to develop during or after the closure process of the accompanying ventricular septal defects. Although a majority of the patients are typically asymptomatic, the potential risks should also be kept in mind. We present a case of a membranous interventricular septal aneurysm that developed after surgery for subaortic valvular stenosis. The points that make our case worth reporting are development of the aneurysm after aortic surgery and lack of a concomitant ventricular septal defect. On the basis of the existence of an aortic valve surgery history and reports that do not mention any ventricular septal defect and ventricular septal aneurysm when she was operated, we suggest that the aneurysmatic formation in the membranous portion of the interventricular septum developed due to valve surgery in the postoperative wound healing period.
Radiosensitive orbital metastasis as presentation of occult colonic adenocarcinoma
Authors: Ludmir Ethan B , McCall Shannon J , Czito Brian G , Palta Manisha
Published: September 2014

An 82-year-old man presented with progressive right frontal headaches. The patient's history was significant for benign polyps on surveillance colonoscopy 2 years prior, without high-grade dysplasia or carcinoma. MRI revealed an enhancing lesion arising within the superomedial aspect of the right orbit. Lesion biopsy demonstrated histological appearance and immunophenotype suggestive of colonic adenocarcinoma. Staging positron emission tomography/CT showed visceral metastases and diffuse activity in the posterior rectosigmoid, consistent with metastatic colon cancer. Treatment of the orbital lesion with external beam radiotherapy to 30 Gy resulted in significant palliation of the patient's headaches. The patient expired 2 months following treatment completion due to disease progression. Orbital metastasis as the initial presentation of an occult colorectal primary lesion is exceedingly rare, and occurred in this patient despite surveillance colonoscopy. Radiotherapy remains an efficacious modality for treatment of orbital metastases.
A mistaken identity: rhabdomyosarcoma of the middle ear cleft misdiagnosed as chronic suppurative otitis media with temporal lobe abscess
Authors: Muranjan Mamta , Karande Sunil , Parikh Shefali , Sankhe Shilpa
Published: September 2014

A 5-year-old girl presented with a 3-month history of left side facial palsy, followed sequentially by purulent ear discharge, complete external ophthalmoplaegia and blurred vision. On clinical examination she was febrile with left-sided conductive hearing loss. She was clinically diagnosed to have chronic suppurative otitis media of the unsafe type with petrous apicitis, middle cranial fossa abscess and cavernous sinus involvement. Preliminary CT scan findings were reported as a large left temporal lobe abscess and left otitis media with cholesteatoma. MRI of the brain obtained later corroborated the abnormalities detected on the CT scan. Ten days after admission, a mass was seen protruding from the external auditory canal. A biopsy of the mass was obtained and sent for histopathological examination. Meanwhile, review of the MRI suggested an aggressive neoplasm such as sarcoma/rhabdomyosarcoma. Histopathology clinched the final diagnosis of an anaplastic type of embryonal rhabdomyosarcoma of the middle ear cleft.
Moral experience and ethical challenges in an emergency department in Pakistan: emergency physicians’ perspectives
Authors: Zafar Waleed
Published: September 2014

Introduction

Emergency departments (ED) are often stressful environments posing unique ethical challenges—issues that primarily raise moral rather than clinical concerns—in patient care. Despite this, there are very few reports of what emergency physicians find ethically challenging in their everyday work. Emergency medicine (EM) is a relatively young but rapidly growing specialty that is gaining acceptance worldwide. The aim of this study was to explore the perspectives of EM residents and physicians regarding the common ethical challenges they face during patient care in one of only two academic EM departments in Pakistan. These challenges could then be addressed in residents’ training and departmental practice guidelines.

Methods

A qualitative research design was employed and in-depth interviews were conducted with ED physicians. Participants were encouraged to think of specific examples from their work, to highlight the particular ethical concerns raised and to describe in detail the process by which those concerns were addressed or left unresolved. Transcripts were analysed using grounded theory methods.

Results

Thirteen participants were interviewed and they described four key challenges: how to provide highest quality care with limited resources; how to be truthful to patients; what to do when it is not possible to provide or continue treatment to patients; and when (and when not) to offer life-sustaining treatments. Participants’ accounts provided important insights into how physicians tried to resolve these challenges in the ‘local moral world’ of an ED in Pakistan.

Conclusions

The study highlights the need for developing systematic and contextually appropriate mechanisms for resolving common ethical challenges in the EDs and for training residents in moral problem solving.