bluuebunny/crossref_metadata_2025 huggingface dataset:
Externally Fired Gas Turbine: Layout Optimization for Micro CHP Generation With Residual Biomass Firing
Authors: Zampilli Mauro , Bidini Gianni , Laranci Paolo , Fantozzi Francesco
Published: September 2016

The Externally Fired Gas Turbine (EFGT) systems allows the use of unrefined fuels, such as biomass and waste in cogeneration arrangement for adequate efficiencies and high reliability, with respect to internal combustion systems based on gasification. The technology has some technological barriers related to thermal and mechanical resistance of the high temperature heat exchanger (HTHE), which is subject to fouling and corrosion phenomena of the parts exposed to flue gas and fly ash deposits. In this paper an investigation aimed to optimize a 100 kWel, Externally Fired micro Gas Turbine (EFmGT) for combined heat and power generation is presented and discussed. A techno-economic analysis was performed for different plant layouts which are energetically analysed for the case of complete external combustion and co-firing with natural gas, comparing power production, electrical and global efficiency. Each layout was studied by means of mass and energy balance.

An economic analysis is also provided, focused on a comparison of initial investment, NPV and IRR. In the economic analysis the best feed in tariff for energetic valorisation of residual biomass was used to calculate the revenue of electric energy generated from biomass.
Beyond Brayton Cycle: It is Time to Change the Paradigm
Authors: Gülen S. Can
Published: September 2016

A detailed look at the gas turbine technology over the last three decades clearly shows that an asymptotic limit is reached in thermal efficiency in combined cycle configuration. There is little reason to expect a technology leap anytime soon to change this appreciably as long as the industry sticks to the classic Brayton cycle configuration and the brute force approach of ever higher turbine inlet temperatures. The changing landscape of electric power generation, especially integration of fossil fuel fired technologies with renewable generation and wide variation in natural gas prices, suggests that it is time to look at the direction of future development efforts differently. This paper looks at the need of a paradigm shift in gas turbine combined cycle technology using thermodynamic and economic arguments.
Adapting the Zero-Emission Graz Cycle for Hydrogen Combustion and Investigation of Its Part Load Behaviour
Authors: Sanz Wolfgang , Braun Martin , Jericha Herbert , Platzer Max F.
Published: September 2016

A modern energy system based on renewable energy like wind and solar power inevitably needs a storage system to provide energy on demand. Hydrogen is a promising candidate for this task. For the re-conversion of the valuable fuel hydrogen to electricity a power plant of highest efficiency is needed.

In this work the Graz Cycle, a zero emission power plant based on the oxy-fuel technology, is proposed for this role. The Graz Cycle originally burns fossil fuels with pure oxygen and offers efficiencies up to 65 % due to the recompression of about half of the working fluid. The Graz Cycle is now adapted for hydrogen combustion with pure oxygen so that a working fluid of nearly pure steam is available. The changes in the thermodynamic layout are presented and discussed. The results show that the cycle is able to reach a net cycle efficiency based on LHV of 68.5 % if the oxygen is supplied “freely” from hydrogen generation by electrolysis.

An additional parameter study shows the potential of the cycle for further improvements. The high efficiency of the Graz Cycle is also achieved by a close interaction of the components which makes part load operation more difficult. So in the second part of the paper strategies for part load operation are presented and investigated. The thermodynamic analysis predicts part load down to 30 % of the base load at remarkably high efficiencies.
An Innovative Approach to Model Temperature Influence on Particle Deposition in Gas Turbines
Authors: Agati Giuliano , Borello Domenico , Rispoli Franco , Venturini Paolo
Published: September 2016

The mechanism of deposit formation on the blade surfaces of a cooled turbine vane is investigated numerically. The prediction of dispersed particles trajectories is affected by temperature, by the mechanics of impact on a solid surface, and by the interaction between particles and film cooling jets and all these aspects must be accounted for. The model here proposed is obtained as a high temperature extension of the well-known Thornton and Ning (1998) approach in a temperature interval ranging between 500 K (where basic model — based on an elastic-plastic impact mechanism assumption — holds) and 1500 K (where the critical viscosity model of Walsh et al., 1990 is usually employed). The transition between the two extreme conditions is modelled through a temperature-driven modification of the mechanical properties of both particles and target surfaces.

Our computations demonstrate that the updated model is able to return credible predictions of deposit formation when compared with the baseline models of Thornton and Ning and of Walsh and co-authors. Moreover in the region where particles bounce off, the model predict the coefficient of restitution according to the actual mechanical properties of particles, thus providing a better particle dynamics description than in both the critical viscosity and original Thornton and Ning models.
Fan Performance Scaling With Inlet Distortions
Authors: Defoe J. J. , Hall D. K.
Published: September 2016

Applications such as boundary-layer-ingesting fans, and compressors in turboprop engines require continuous operation with distorted inflow. A low-speed axial fan with incompressible flow is studied in this paper. Previous work in the literature has shown that the same flow mechanisms contributing to the response of a fan to distortion are at play in incompressible and transonic flows. The objective is to determine how fan performance scales as the type and severity of inlet distortion varies at the design flow coefficient.

A distributed source term approach to modeling the rotor and stator blade rows is used in numerical simulations in this paper. The approach has been shown to capture overall stage performance and flow field behavior with distortions having length scales much longer than the blade pitch. The approach requires only knowledge of the blade geometry, but the model does not include viscous losses. As a result, efficiency is not assessed but instead a metric based on changes in diffusion factor is defined which is conjectured to be related to efficiency changes.

Distortions in stagnation pressure, swirl, and stagnation temperature are considered. By studying the distortions individually, it is found that the diffusion metric scales linearly with the intensity of the distortions (i.e. the ratio of minimum to maximum values) but that changes in distortion location relative to the fan axis produce nonlinear changes in the diffusion metric. Combinations of distortions are also studied and it is found that the diffusion metric associated with the combined distortion can be predicted using a summation procedure for the metrics associated with the individual constituent distortions. The mechanism found to govern the effectiveness of this summation procedure is the incidence distortions at rotor and stator inlet.
Gas Turbine Performance Enhancement by Inlet Air Cooling and Coolant Pre-Cooling Using an Absorption Chiller
Authors: Kwon Hyun Min , Kim Jeong Ho , Kim Tong Seop
Published: September 2016

The gas turbine combined cycle is the most mature and efficient power generation system. While enhancing design performance continuously, a parallel effort to make up for the shortcomings of the gas turbine should be pursued. The most critical drawback is the large power loss in hot season when electricity demand is usually the highest. Therefore, it is important to implement an effective power boosting measure in gas turbine based power plants, especially in areas where the annual average temperature is much higher than the standard design ambient temperature. The simplest method in general is to reduce the gas turbine inlet air temperature by any means. Several schemes are commercially available, such as mechanical chilling, evaporative cooling, inlet fogging and absorption chilling. All of them have merits and demerits, either thermodynamically and economically. In this study, we focused our interest on the absorption chilling method. Theoretically, absorption chilling provides as much cooling effect (air temperature reduction) as the mechanical chilling, while electric power consumption is negligibly small. A distinct feature of an absorption chiller in contrast to a mechanical chiller is that thermal energy (heat) is needed to drive the chilling system. In this research, we propose an innovative idea of making the independent heat supply unnecessary. The new method provides simultaneous cooling of the turbine coolant and the inlet air using an absorption chiller. The inlet cooling and coolant precooling boost the gas turbine power synergistically. We predicted the system performance using cycle simulation and compared it with that of the conventional mechanical cooling system.
Combustion of Aldehydes in the Negative Temperature Coefficient Region: Products and Pathways
Authors: Barari Ghazal , Koroglu Batikan , Masunov Artëm E. , Vasu Subith
Published: September 2016

Aldehydes are major intermediates in oxidation and pyrolysis of hydrocarbons and particularly biofuels. While the high temperature oxidation chemistry of C3-C5 aldehydes have been studied in the literature, a comprehensive low temperature kinetics remains unaddressed. In this work, acetaldehyde, propanal, and 2-propenal (acrolein) oxidation was investigated at low-temperature combustion condition (500–700 K). The isomer specific products concentrations as well as the time-resolved profiles were studied using Sandia’s multiplexed photoionization mass spectroscopy (MPIMS) with synchrotron radiation from the Advanced Light Source (ALS). The laser pulsed photolysis generates chlorine atoms which react with aldehydes to form the parent radicals. In the presence of excess oxygen, these radicals react with O2 and form RO2 radicals. The temperature dependent products yields are determined for 500 K to 700 K and the competition between the channels contributing to the formation of each product is discussed. In acetaldehyde oxidation, the formation of the main products are associated with HO2 elimination channel from QOOH or direct H atom elimination from the parent radicals. In propanal oxidation, the most intensive signal peak was associated with acetaldehyde (m/z=44) which was formed through the reaction of α′-R with O2. α′-RO2 intermediate decomposes to acetaldehyde+OH+CO via Waddington mechanism and formation of five-member ring transition state. In 2-propenal oxidation, the unsaturated radical produced from α-R reacts with O2 to form the primary products.
Optimization of Cycle and Expander Design of an Organic Rankine Cycle Unit Using Multi-Component Working Fluids
Authors: Meroni Andrea , Andreasen Jesper Graa , Pierobon Leonardo , Haglind Fredrik
Published: September 2016

Organic Rankine cycle (ORC) power systems represent attractive solutions for power conversion from low temperature heat sources, and the use of these power systems is gaining increasing attention in the marine industry. This paper proposes the combined optimal design of cycle and expander for an organic Rankine cycle unit utilizing waste heat from low temperature heat sources. The study addresses a case where the minimum temperature of the heat source is constrained and a case where no constraint is imposed. The former case is the waste heat recovery from jacket cooling water of a marine diesel engine onboard a large ship, and the latter is representative of a low-temperature geothermal, solar or waste heat recovery application. Multi-component working fluids are investigated, as they allow improving the match between the temperature profiles in the heat exchangers and, consequently, reducing the irreversibility in the ORC system. This work considers mixtures of R245fa/pentane and propane/isobutane. The use of multi-component working fluids typically results in increased heat transfer areas and different expander designs compared to pure fluids. In order to properly account for turbine performance and design constraints in the cycle calculation, the thermodynamic cycle and the turbine are optimized simultaneously in the molar composition range of each mixture. Such novel optimization approach enables one to identify to which extent the cycle or the turbine behaviour influences the selection of the optimal solution. It also enables one to find the composition for which an optimal compromise between cycle and turbine performance is achieved. The optimal ORC unit employs pure R245fa and provides approximately 200 kW when the minimum hot fluid temperature is constrained. Conversely, the mixture R245fa/pentane (0.5/0.5) is selected and provides approximately 444 kW when the hot fluid temperature is not constrained to a lower value. In both cases, a compact and efficient turbine can be manufactured.
CFD Modeling of Equivalence Ratio Effects on a Pressurized Turbulent Premixed Flame
Authors: Jella Sandeep E. , Bergthorson Jeffrey M. , Gauthier Pierre Q. , Bourque Gilles
Published: September 2016

At a given power level, lean premixed (DLE) gas turbines vary equivalence ratio (ϕ) for optimal performance. This range is usually determined by variations in ambient conditions, acoustic response of the system, and emissions trade-off (e.g. between NOx and CO). In this work, the effects of ϕ variation on premixed jet flame lengths are investigated, by modeling the pressurized jet experiments of Griebel et al. [1]. While previous modeling of these experiments focused on a priori tabulated chemistry based methods, in this work we investigate an approach that represents finite-rate effects explicitly using skeletal chemistry (16 species, 41 reactions) in RANS and LES. Two equivalence ratios (ϕ = 0.56 and ϕ = 0.43) corresponding to the two extremes of flame lengths are chosen from the experimental database for 673K mixture preheat, 5 bar and 40 m/s jet velocity. A better correspondence with the experimentally measured flame length was achieved for ϕ = 0.43 than for ϕ = 0.56 indicating that the model is suitable when finite-rate effects are dominant but requires extensions for flames closer to the flamelet regime. It was found, further, that the RANS-EDC models failed to predict the confined turbulent jet development, as well as the flame lengths accurately, and demonstrated that scale resolution is required even for a relatively simple configuration.
Meanline Modeling of a Radial-Inflow Turbine Nozzle With Supersonic Expansion
Authors: Li Shuo , Krivitzky Eric M. , Qiu Xuwen
Published: September 2016

High pressure ratio, radial-inflow turbines typically experience supersonic expansion in the nozzle section. Accurate estimation of the flow conditions and velocity triangle at the nozzle outlet is of critical importance in correctly predicting the overall turbine performance. The meanline modeling of such a nozzle requires special attention, due to the significantly altered flow field downstream of the throat.

In this study, the flow field of a supersonic expansion nozzle is investigated, using a three-dimensional (3D) computational fluid dynamics (CFD) simulation calibrated with test data. Three different CFD configurations are explored: the nozzle alone, the nozzle plus rotor coupled with a mixing plane, and the nozzle plus rotor coupled with the nonlinear harmonic (NLH) method. These configurations are compared to each other to gauge the effect of the rotor and stator interaction and the potential for error in establishing the velocity triangles. The exit vane angle, number of vanes, and expansion ratio across the nozzle are systematically varied to provide the data as the base for nozzle modeling. Finally, a meanline method is proposed to calculate the pressure loss and flow deviation at the nozzle outlet and is compared with CFD results.
Impingement Cooling in Narrow Rectangular Channel With Novel Surface Features
Authors: Parbat Sarwesh Narayan , Siw Sin Chien , Chyu Minking K.
Published: September 2016

This paper describes a detailed experimental investigation of narrow jet impingement channel with surface features. Three novel surface features: aerofoil shaped dimple cavities on the target plate, chevron elements extending between the jet issuing plate and the target plate and 45 degree wedges mounted on the jet-issuing plate, are proposed. The narrow rectangular channel is 254 mm × 57.2 mm × 19.1 mm (10” × 2.25” × 0.75”) in dimensions and consists of five jets with a constant diameter, D of 9.525 mm (0.375”). The inter-jet spacing and jet-to-target plate distance is 4D and 2D, respectively. Three test cases with different novel surface features are proposed, and the effect of these surface features on the distribution of heat transfer coefficient on the target plate is characterized using the transient liquid crystal technique. In the first test case, dimpulated surface features are introduced on the target plate. The second case consists of chevron elements which extend between the jet issuing plate and the target plate, while the third case has 45 degree wedges mounted on the jet-issuing plate. The smooth jet impingement channel is used as a baseline case for comparison of the heat transfer coefficient distribution on the target plate. The Reynolds number is defined based on the jet diameter, D and bulk velocity of the jet. The experiments were performed at Reynolds number ranging between 61,000 to 98,000. In order to gain a better insight of the flow field within the channel for each of these features, a steady state numerical simulation was performed for each case using the commercially available software, ANSYS CFX. The boundary conditions for these simulations were set as close to the experimental conditions as possible. For turbulence closure, the Shear Stress Transport (SST) model was used which has been shown to be reasonably accurate with moderate computational costs. The numerical results are in favorable trend compared to the values obtained through experimentation. However, in certain regions, the SST turbulence model has overpredicted the heat transfer coefficient values. The results show that the first test case with dimpulated surface features exhibits the highest heat transfer enhancement among all the tested configurations. This enhancement is approximately 25 percent higher than that of the baseline case. The presence of the chevron elements has minimized the deflection of the jets due to crossflow, but, inhibited the spreading of the impinging jets on the target plate. This, in turn, has reduced the local heat transfer performance quite substantially. In case of the 45 degree wedges, the heat transfer enhancement was augmented at the downstream, which was ultimately caused by the diversion of the crossflow towards the target plate.
Design of the Purdue Experimental Turbine Aerothermal Laboratory for Optical and Surface Aero-Thermal Measurements
Authors: Paniagua G. , Cuadrado D. , Saavedra J. , Andreoli V. , Meyer T. , Meyer S. , Lawrence D.
Published: September 2016

Following three decades of research in short duration facilities, Purdue University has developed an alternative turbine facility in view of the modern technology in computational fluid mechanics, structural analysis, manufacturing, heating, control and electronics. The proposed turbine facility can perform both short transients and long duration tests, suited for precise heat flux, efficiency and optical measurement techniques to advance turbine aero-thermo-structural engineering. The facility has two different test sections, linear and annular, to service both fundamental and applied research. The linear test section is completely transparent for visible spectra, aimed at TRL 1 and 2. The annular test section was designed with optical access to perform proof of concepts as well as validation of turbine components at the relevant non-dimensional parameters in small engine cores, TRL 3 to 4. The large mass flow (28 kg/s) combined with a minimum hub radius to tip radius of 0.85 allows high spatial resolution. The Reynolds (Re) number extends from 60,000 to 3,000,000, based on the vane outlet flow with an axial chord of 0.06 m and a turning angle of 72 deg. The pressure ratio can be independently adjusted, allowing for testing from low subsonic to Mach 3.2. To ensure that the thermal boundary layer is fully developed the test duration can range from milliseconds to minutes. The manuscript provides a detailed description of the sequential design methodology from zero-dimensional to three-dimensional unsteady analysis as well as of the measurement techniques available in this turbine facility.
The University of Queensland Refrigerant and Supercritical CO2 Test Loop
Authors: Twomey Braden , Nagy Andras , Russell Hugh , Rowlands Andrew , Czapla Jason , Singh Rajinesh , Ventura Carlos A de M , Jahn Ingo
Published: September 2016

The use of organic refrigerants or supercritical CO2 (sCO2) as a working fluid in closed loop power cycles has the potential to revolutionise power generation. Thermodynamic cycle efficiency can be improved by selecting bespoke working fluids that best suit a given combination of heat source and heat sink temperatures, but thermal efficiency can be maximised by pairing this with a custom made turbine. This work describes the development and design of a new 100kW thermal laboratory-scale test loop at the University of Queensland. The loop has capabilities for characterising both simple and recuperated refrigerant and sCO2 organic Rankine cycles in relation to overall cycle performance and for the experimental characterisation of radial inflow turbines. The aim of this facility is to generate high quality validation data and to gain new insight into overall loop performance, control operation, and loss mechanisms that prevail in all loop components, including radial turbines when operating with supercritical fluids. The paper describes the current test loop and provides details on the available test modes: an organic Rankine cycle mode, a closed loop Brayton cycle mode, and heat exchanger test mode and their respective operating ranges. The bespoke control and data acquisition system has been designed to ensure safe loop operation and shut down and to provide high quality measurement of signals from more than 60 sensors within the loop and test turbine. For each measurement, details of the uncertainty quantification in accordance with ASME standards are provided, ensuring data quality. Data from the commissioning of the facility is provided in this paper. This data confirms controlled operation of the loop and the ability to conduct both cycle characterisation tests and turbomachinery tests.
Numerical Research on the Mixing Mechanism of Lobed Mixer With New De-Swirling Structure
Authors: Lei Zhijun , Gong Jianbo , Zhang Yanfeng , Su Shangmei , Hu Chunyan
Published: September 2016

A detailed numerical simulation is presented to investigate the new de-swirling methods and their effect on the mixing mechanisms of a turbofan mixer with 12 lobes. The numerical simulation employed a commercial solver, ANSYS CFX, using k-ω SST model. The core-to-bypass temperature ratio and pressure ratio were set to 2.59, and 0.97 respectively, giving the Mach number of 0.66 and bypass ratio of 2.65 at mixing nozzle outlet. The inlet swirl typically accelerates the jet-flow mixing by enhancing the vortices intensity and interaction, but leakage swirling flow can cause a three-dimensional separation bubble and the recirculation zone resulting in the dramatic increasing the total pressure loss and thrust loss. Removal of the leakage swirling flow between the lobes’ trough and centre-body was the key to limit the negative influence of inlet swirl.

Two IGV design were investigated, DS1 and DS2. DS1 was installed at the upstream of the lobed mixer, could remove the negative effect of inlet swirl properly, but also inhibited the active role of the inlet swirl. The total pressure and thrust loss reduced by 0.31% and 3.8%, respectively, but the mixing efficiency also decreased by 1.72%. DS2, an integrated strut with the lobed mixer design, not only ensured the structure strength of the lobed mixer, but also reduced the length and weight of the exhaust system. This method suppressed the flow separation bubble on centre-body to some extent, and eliminated the recirculation zone downstream of the cenrebody, resulting in the total pressure loss decrease of 0.31% and thrust gain of 3.63%. On the other hand, the method DS2 also made full use of the inlet swirl to enhance the jet-flow mixing, resulting in the mixing efficiency increased 1.54% compared with that of the DS1 case. Under the off-design conditions with the incidence angle of ±10°, the aerodynamic performance of the DS2 cases didn’t changed too much such as the DS1 cases.
Design of a Centrifugal Turbo Compressor With the Working Fluid Water for the Operation in a Hybrid Sorption/Compression Heat Pump Cycle
Authors: Eckert Thomas , Dostal Leo , Helm Martin , Schweigler Christian
Published: September 2016

In various applications the use of sorption chillers and heat pumps is limited by the available temperature level of the driving heat source or the heat sink for export of reject heat. These constraints can be overcome by integrating an efficient high-speed transonic turbo compressor into the internal cycle of a thermally driven water/lithium bromide absorption heat pump.

The operation in a hybrid heat pump with the refrigerant water implies specific challenges for the design of the compressor: Saturation pressures in the sub-atmospheric range, low vapor density, high volume flows and a targeted pressure ratio of 3 result in high impeller tip speeds with machine Mach numbers close to 1. Here the authors present a theoretical design study based on a numerical simulation of a centrifugal compressor, targeted at the given operating conditions. Evaluation of the results is conducted with regard to the relevant thermodynamic and fluid mechanic figures. The optimization of the impeller geometry comprises both fluid dynamic behavior and structural stability.
Abnormal thin film structures in vapor-phase deposited methylammonium lead iodide perovskite
Authors: Llanos Adrian , Thibau Emmanuel S. , Lu Zheng-Hong
Published: September 2016

The authors report on the observation of abnormal growth features in methylammonium lead iodide thin films synthesized by vapor-phase deposition with high methylammonium iodide (MAI) flux. The morphological and crystallographic impact of varying flux of MAI is characterized using scanning electron microscopy and x-ray diffractometry. It was found that increasing organic flux results in large, angular, yet hollow nonuniformities growing within the film. Diffraction patterns show good perovskite crystallinity across all samples, but show texture development with the (220) diffraction peak growing in intensity relative to the (004) peak as organic content increases. A possible mechanism for the growth of these features is discussed. These results highlight some potential critical pitfalls for perovskite thin film deposition by coevaporation and emphasize the importance of microscopy-based characterization.
Computational study of the piccolo: Evidence for chaotic tones
Authors: Giordano N.
Published: September 2016

Direct numerical solutions of the Navier-Stokes equations have been used to compute tones produced by a model of the piccolo. The behavior depends on the angle at which the air jet is directed at the embouchure hole and the displacement of the jet center from the embouchure edge. Values of the jet angle and displacement are found that produce pure tones with spectra similar to those of real piccolo tones. The behavior of calculated tones as a function of the blowing speed u is studied, and it is found that unsteady behavior can occur depending on the value of u, the jet angle, and the jet displacement. Detailed analysis of these unsteady tones suggests that the model piccolo studied here exhibits chaotic behavior with a positive Lyapunov exponent. The implications for piccolo tones produced with real piccolos by real piccolo players are discussed.
Single-sensor, cue-counting population density estimation: Average probability of detection of broadband clicks
Authors: Küsel Elizabeth T. , Siderius Martin , Mellinger David K.
Published: September 2016

Odontocete echolocation clicks have been used as a preferred cue for density estimation using single-sensor data sets, requiring estimation of detection probability as a function of range. Many such clicks can be very broadband in nature, with 10-dB bandwidths of 20–40 kHz or more. Detection distances are not readily obtained from single-sensor data. Here, the average detection probability is estimated in a Monte Carlo simulation using the passive sonar equation along with transmission loss calculations to estimate the signal-to-noise ratio (SNR) of tens of thousands of click realizations. Continuous-wave (CW) analysis, i.e., single-frequency analysis, is inherent to basic forms of the passive sonar equation. Using CW analysis with the click's center frequency while disregarding its bandwidth has been shown to introduce bias into detection probabilities and hence to density estimates. In this study, the effects of highly broadband clicks on density estimates are further examined. The usage of transmission loss as an appropriate measure for calculating click SNR is also discussed. The main contributions from this research are (1) an alternative approach to estimate the average probability of detection of broadband clicks, and (2) understanding the effects of multipath clicks on population density estimates.
Paired stars sculpt nebulae into fanciful shapes
Authors: Sokol Joshua
Published: September 2016

Survey suggests fast-orbiting binaries at work within many of the gas clouds shed by dying stars.
Aborigines and Eurasians rode one migration wave
Authors: Culotta Elizabeth , Gibbons Ann
Published: September 2016

Tide of genetic data refutes idea that an earlier expansion of modern humans populated the island continent.
A secreted bacterial peptidoglycan hydrolase enhances tolerance to enteric pathogens
Authors: Rangan Kavita J. , Pedicord Virginia A. , Wang Yen-Chih , Kim Byungchul , Lu Yun , Shaham Shai , Mucida Daniel , Hang Howard C.
Published: September 2016

The intestinal microbiome modulates host susceptibility to enteric pathogens, but the specific protective factors and mechanisms of individual bacterial species are not fully characterized. We show that secreted antigen A (SagA) from
Enterococcus faecium
is sufficient to protect
Caenorhabditis elegans
against
Salmonella
pathogenesis by promoting pathogen tolerance. The NlpC/p60 peptidoglycan hydrolase activity of SagA is required and generates muramyl-peptide fragments that are sufficient to protect
C. elegans
against
Salmonella
pathogenesis in a
tol-1
–dependent manner. SagA can also be heterologously expressed and secreted to improve the protective activity of probiotics against
Salmonella
pathogenesis in
C. elegans
and mice. Our study highlights how protective intestinal bacteria can modify microbial-associated molecular patterns to enhance pathogen tolerance.
A Pleistocene ice core record of atmospheric O
2
concentrations
Authors: Stolper D. A. , Bender M. L. , Dreyfus G. B. , Yan Y. , Higgins J. A.
Published: September 2016

The history of atmospheric O
2
partial pressures (
P
o
2
) is inextricably linked to the coevolution of life and Earth’s biogeochemical cycles. Reconstructions of past
P
o
2
rely on models and proxies but often markedly disagree. We present a record of
P
o
2
reconstructed using O
2
/N
2
ratios from ancient air trapped in ice. This record indicates that
P
o
2
declined by 7 per mil (0.7%) over the past 800,000 years, requiring that O
2
sinks were ~2% larger than sources. This decline is consistent with changes in burial and weathering fluxes of organic carbon and pyrite driven by either Neogene cooling or increasing Pleistocene erosion rates. The 800,000-year record of steady average carbon dioxide partial pressures (
P
co
2
) but declining
P
o
2
provides distinctive evidence that a silicate weathering feedback stabilizes
P
co
2
on million-year time scales.
Strange bedfellows
Doomed to Cooperate How American and Russian Scientists Joined Forces to Avert Some of the Greatest Post–Cold War Nuclear Dangers
Siegfried S. Hecker, Ed.
Bathtub Row Press, 2016. 976 pp.
Authors: Hippel Frank von
Published: September 2016

Scientific collaboration takes center stage in a participants' account of post–Cold War nuclear disarmament
How hybrid perovskites get their groove
Authors: Ziffer Mark E. , Ginger David S.
Published: September 2016

Rotational motions of organic cations may screen charge carriers from defects
Cool by neuronal decision
Authors: Bartfai Tamas
Published: September 2016

An ion channel expressed in specific brain neurons is required for regulating core body temperature
Speaking of insects…
Authors: Berenbaum May R.
Published: September 2016

Given that
Aedes aegypti
, the main mosquito vector of Zika virus, has been an intense focus of public health attention in the Americas, most recently in Florida, it seems apt that next week, 7000 entomologists from around the world will converge on Orlando, Florida, for the 25th International Congress of Entomology (ICE), where, among other activities, 175 discipline thought-leaders will join policy-makers and other experts to address “Improving the Human Condition through Insect Science.” The ICE summit's goals are to define the major global insect-related challenges—from arthropod-borne diseases to the protection of beneficial species—and plan collaborative efforts to meet these challenges through research and technology. These “grand challenges” aren't new. What's new, however, is an explicit effort to address one of the greatest challenges: effective engagement with the public about the value of insect science.
The boldness of philanthropists
Authors: Baltimore David
Published: September 2016

Last week, Priscilla Chan and Mark Zuckerberg announced their new philanthropic initiative with the goal of “curing, preventing, and managing all diseases by the end of the century.” This may raise some eyebrows, but this effort—part of the $45 billion Chan Zuckerberg Initiative—joins forces with other philanthropists to push the envelope and support audacious ideas, with long-term commitments, to solve some of our greatest challenges.
Highlights of the 11th International Bordetella Symposium: from Basic Biology to Vaccine Development
Authors: Carbonetti Nicholas H. , Wirsing von König Carl Heinz , Lan Ruiting , Jacob-Dubuisson Francoise , Cotter Peggy A. , Deora Rajendar , Merkel Tod J. , van Els Cécile A. , Locht Camille , Hozbor Daniela , Rodriguez Maria E.
Published: September 2016

Pertussis is a severe respiratory disease caused by infection with the bacterial pathogenBordetella pertussis. The disease affects individuals of all ages but is particularly severe and sometimes fatal in unvaccinated young infants. OtherBordetellaspecies cause diseases in humans, animals, and birds. Scientific, clinical, public health, vaccine company, and regulatory agency experts on these pathogens and diseases gathered in Buenos Aires, Argentina from 5 to 8 April 2016 for the 11th InternationalBordetellaSymposium to discuss recent advances in our understanding of the biology of these organisms, the diseases they cause, and the development of new vaccines and other strategies to prevent these diseases. Highlights of the meeting included pertussis epidemiology in developing nations, genomic analysis ofBordetellabiology and evolution, regulation of virulence factor expression, new model systems to studyBordetellabiology and disease, effects of different vaccines on immune responses, maternal immunization as a strategy to prevent newborn disease, and novel vaccine development for pertussis. In addition, the group approved the formation of an InternationalBordetellaSociety to promote research and information exchange on bordetellae and to organize future meetings. A new Bordetella.org website will also be developed to facilitate these goals.
Burkholderia pseudomallei: Challenges for the Clinical Microbiology Laboratory
Authors: Hemarajata Peera , Baghdadi Jonathan D. , Hoffman Risa , Humphries Romney M.
Published: September 2016

Melioidosis is a potentially fatal infection caused by the bacteriumBurkholderia pseudomallei. Clinical diagnosis of melioidosis can be challenging since there is no pathognomonic clinical syndrome, and the organism is often misidentified by methods used routinely in clinical laboratories. Although the disease is more prevalent in Thailand and northern Australia, sporadic cases may be encountered in areas where it is not endemic, including the United States. Since the organism is considered a tier 1 select agent according to the Centers for Disease Control and Prevention and the U.S. Department of Agriculture Animal and Plant Health Inspection Service, clinical laboratories must be proficient at rapidly recognizing isolates suspicious forB. pseudomallei, be able to safely perform necessary rule-out tests, and to refer suspect isolates to Laboratory Response Network reference laboratories. In this minireview, we report a case of melioidosis encountered at our institution and discuss the laboratory challenges encountered when dealing with clinical isolates suspicious forB. pseudomalleior clinical specimens from suspected melioidosis cases.
The Respiratory Syncytial Virus Phosphoprotein, Matrix Protein, and Fusion Protein Carboxy-Terminal Domain Drive Efficient Filamentous Virus-Like Particle Formation
Authors: Meshram Chetan D. , Baviskar Pradyumna S. , Ognibene Cherie M. , Oomens Antonius G. P.
Published: September 2016

Virus-like particles (VLPs) are attractive as a vaccine concept. For human respiratory syncytial virus (hRSV), VLP assembly is poorly understood and appears inefficient. Hence, hRSV antigens are often incorporated into foreign VLP systems to generate anti-RSV vaccine candidates. To better understand the assembly, and ultimately to enable efficient production, of authentic hRSV VLPs, we examined the associated requirements and mechanisms. In a previous analysis in HEp-2 cells, the nucleoprotein (N), phosphoprotein (P), matrix protein (M), and fusion protein (F) were required for formation of filamentous VLPs, which, similar to those of wild-type virus, were associated with the cell surface. Using fluorescence and electron microscopy combined with immunogold labeling, we examined the surfaces of transfected HEp-2 cells and further dissected the process of filamentous VLP formation. Our results show that N is not required. Coexpression of P plus M plus F, but not P plus M, M plus F, or P plus F, induced both viral protein coalescence and formation of filamentous VLPs that resembled wild-type virions. Despite suboptimal coalescence in the absence of P, the M and F proteins, when coexpressed, formed cell surface-associated filaments with abnormal morphology, appearing longer and thinner than wild-type virions. For F, only the carboxy terminus (Fstem) was required, and addition of foreign protein sequences to Fstem allowed incorporation into VLPs. Together, the data show that P, M, and the F carboxy terminus are sufficient for robust viral protein coalescence and filamentous VLP formation and suggest that M-F interaction drives viral filament formation, with P acting as a type of cofactor facilitating the process and exerting control over particle morphology.

IMPORTANCE
hRSV is responsible for >100,000 deaths in children worldwide, and a vaccine is not available. Among the potential anti-hRSV approaches are virus-like particle (VLP) vaccines, which, based on resemblance to virus or viral components, can induce protective immunity. For hRSV, few reports are available concerning authentic VLP production or testing, in large part because VLP production is inefficient and the mechanisms underlying particle assembly are poorly understood. Here, we took advantage of the cell-associated nature of RSV particles and used high-resolution microscopy analyses to examine the viral proteins required for formation of wild-type-virus-resembling VLPs, the contributions of these proteins to morphology, and the domains involved in incorporation of the antigenically important viral F protein. The results provide new insights that will facilitate future production of hRSV VLPs with defined shapes and compositions and may translate into improved manufacture of live-attenuated hRSV vaccines.
The P Protein of Spring Viremia of Carp Virus Negatively Regulates the Fish Interferon Response by Inhibiting the Kinase Activity of TANK-Binding Kinase 1
Authors: Li Shun , Lu Long-Feng , Wang Zhao-Xi , Lu Xiao-Bing , Chen Dan-Dan , Nie Pin , Zhang Yong-An
Published: September 2016

Spring viremia of carp virus (SVCV) is an efficient pathogen causing high mortality in the common carp. Fish interferon (IFN) is a powerful cytokine enabling host cells to establish an antiviral response; therefore, the strategies that SVCV uses to avoid the cellular IFN response were investigated. Here, we report that the SVCV P protein is phosphorylated by cellular TANK-binding kinase 1 (TBK1), which decreases IFN regulatory factor 3 (IRF3) phosphorylation and suppresses IFN production. First, overexpression of P protein inhibited the IFN promoter activation induced by SVCV and the IFN activity activated by the mitochondrial antiviral signaling protein (MAVS) although TBK1 activity was not blocked by P protein. Second, P protein colocalized and interacted with TBK1. Dominant negative experiments suggested that the TBK1 N-terminal kinase domain interacted with P protein and was essential for P protein and IRF3 phosphorylation. Finally, P protein overexpression reduced the IRF3 phosphorylation activated by TBK1 and reduced host cellular
ifn
transcription. Collectively, our data demonstrated that the SVCV P protein is a decoy substrate for the host phosphokinase TBK1, preventing IFN production and facilitating SVCV replication.

IMPORTANCE
TBK1 is a pivotal phosphokinase that activates host IFN production to defend against viral infection; thus, it is a potential target for viruses to negatively regulate IFN response and facilitate viral evasion. We report that the SVCV P protein functions as a decoy substrate for cellular TBK1, leading to the reduction of IRF3 phosphorylation and suppression of IFN expression. These findings reveal a novel immune evasion mechanism of SVCV.
PrP
C
Governs Susceptibility to Prion Strains in Bank Vole, While Other Host Factors Modulate Strain Features
Authors: Espinosa J. C. , Nonno R. , Di Bari M. , Aguilar-Calvo P. , Pirisinu L. , Fernández-Borges N. , Vanni I. , Vaccari G. , Marín-Moreno A. , Frassanito P. , Lorenzo P. , Agrimi U. , Torres J. M.
Published: September 2016

Bank vole is a rodent species that shows differential susceptibility to the experimental transmission of different prion strains. In this work, the transmission features of a panel of diverse prions with distinct origins were assayed both in bank vole expressing methionine at codon 109 (Bv109M) and in transgenic mice expressing physiological levels of bank vole PrP
C
(the BvPrP-Tg407 mouse line). This work is the first systematic comparison of the transmission features of a collection of prion isolates, representing a panel of diverse prion strains, in a transgenic-mouse model and in its natural counterpart. The results showed very similar transmission properties in both the natural species and the transgenic-mouse model, demonstrating the key role of the PrP amino acid sequence in prion transmission susceptibility. However, differences in the PrP
Sc
types propagated by Bv109M and BvPrP-Tg407 suggest that host factors other than PrP
C
modulate prion strain features.

IMPORTANCE
The differential susceptibility of bank voles to prion strains can be modeled in transgenic mice, suggesting that this selective susceptibility is controlled by the vole PrP sequence alone rather than by other species-specific factors. Differences in the phenotypes observed after prion transmissions in bank voles and in the transgenic mice suggest that host factors other than the PrP
C
sequence may affect the selection of the substrain replicating in the animal model.
Female hypospadias presenting with urinary retention and renal failure in an adolescent: uncommon and late presentation with significant hidden morbidity
Authors: Prakash Gaurav , Singh Manmeet , Goel Apul , Jhanwar Ankur
Published: September 2016

An 11-year-old girl presented with poor urinary stream with vaginal voiding since childhood. She had palpable bladder and raised serum creatinine (671 µmol/L). Suprapubic catheterisation was performed after a failed urethral attempt. Following catheterisation she improved symptomatically. She underwent cystoscopy through the suprapubic portal as a guide wire could be negotiated through bladder neck; external urethral meatus was found as a dimple higher up in anterior vaginal wall. Female hypospadias is usually an incidental diagnosis during catheterisation for various reasons. Diagnosis could be established only after antegrade cystoscopy. Anecdotal cases have been reported in the literature with similar presentation. Early diagnosis is essential as renal failure could be a late presentation if patients continue to void with stenosed meatus. Long-term follow-up is needed as these patients may need definitive management later on.
One-year visual outcome of small incision lenticule extraction (SMILE) surgery in high myopic eyes: retrospective cohort study
Authors: Wu Wenjing , Wang Yan , Zhang Hui , Zhang Jiamei , Li Hua , Dou Rui
Published: September 2016

Objective

To determine whether the long-term visual outcome of small incision lenticule extraction (SMILE) surgery is consistent with the short-term results in high myopic eyes.

Design

Retrospective cohort study; data collected from 8 August 2011 to 31 August 2015.

Setting

Single refractive surgery centre.

Participants

A total of 156 eyes were studied: 65 eyes of 39 subjects (22 female/17 male) in the high myopic group (manifest refraction spherical equivalent (MRSE) ≥−6.0 D), and 91 eyes of 54 subjects (29 female/25 male) in the control group (MRSE <−6.0 D). The inclusion criteria were subjects who had follow-ups after 1 day, 1 week, 1 month, 3, 6 months and 1 year with the manifest refraction, uncorrected and corrected distance visual acuity (UDVA/CDVA). There were no statistically significant differences between the two groups in the subjects' gender, age, or cylindrical dioptre, preoperatively (p=0.835, p=0.055, p=0.341, respectively).

Primary and secondary outcome measures

UDVA, refractive stability, safety index (postoperative CDVA/preoperative CDVA), and predictability (the percentage of eyes within ±0.50 D).

Results

In both groups, the 1-year UDVA and safety index were significantly better than results at 1 day (high myopic group: p=0.035, p<0.001; control group: p<0.016, p<0.001); the 1-year predictability showed no significant difference with the short-term results (p=1.00 in both groups). In the high myopic eyes, the 1-year MRSE was significantly worse than the short-term result (p=0.048). To correct it, the added magnitude (D) for the high myopic eyes may equal 0.13×Attempted SE (D)−0.66 D. However, the postoperative MRSE showed no differences from 1 day to 1 year (p=0.612) in the control group.

Conclusions

The 1-year visual outcomes were better than the short-term results after the SMILE surgery on the visual acuity and safety. However, the high myopic eyes suffered a significant regression at 1 year, which may be corrected by adding additional magnitude to the SE for high myopic eyes.