bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Investigation of the Impact of Biogas on a 3 kW Micro Gas Turbine FLOX®-Based Combustor
Authors: Seliger-Ost Hannah , Kutne Peter , Zanger Jan , Aigner Manfred
Published: January 2021

The use of biogas has currently two disadvantages. Firstly, processing biogas to natural gas quality for feeding into the natural gas grid is a rather energy consuming process. Secondly, the conversion into electricity directly in biogas plants produces waste heat, which largely cannot be used. Therefore, a feed-in of the desulfurized and dry biogas to local biogas grids would be preferable. Thus, the biogas could be used directly at the end consumer for heat and power production. As biogas varies in its methane (CH4) and carbon dioxide (CO2) content, respectively, this paper studies the influence of different biogas mixtures compared to natural gas on the combustion in a FLOX®-based six nozzle combustor. The single staged combustor is suitable for the use in a micro gas turbine (MGT) based combined heat and power (CHP) system with an electrical power output of 3 kW. The combustor is studied in an optically accessible atmospheric test rig, as well as integrated into the MGT system. This paper focuses on the influence of the admixture of CO2 to natural gas on the NOX and CO emissions. Furthermore, at atmospheric conditions the shape and location of the heat release zone is investigated using OH* chemiluminescence (OH* CL). The combustor could be stably operated in the MGT within the complete stationary operating range with all fuel mixtures.
An Experimental and Computational Investigation of Absolute Pressure Effects on Deposition in an Effusion Cooling Geometry
Authors: Bowen Christopher P. , Bons Jeffrey P.
Published: January 2021

The effect of absolute pressure on deposition is studied in the High-Pressure Deposition Facility at The Ohio State University. Mass flow blockage trends are presented for the case of deposition in a single-wall flat plate effusion cooling geometry. Arizona Road Dust in the ranges of 0–10 μm and 0–3.5 μm is delivered to a 950 K coolant flow at a pressure ratio of 1.03 at absolute pressures ranging from 1 to 15.77 atm. The primary results indicate a non-linear decrease in blockage with increasing absolute pressure. Additional targeted experimental and companion computational fluid dynamics simulations are used to elucidate the relative importance of 3 physical mechanisms responsible for the trend with pressure: (1) the increase in effusion hole discharge coefficient (2) altered particle trajectories due to reduced effective Stokes and (3) altered erosion due to reduced effective Stokes. Results reveal that blockage and sticking rates are minimally affected by the changing velocity field due to the increase in discharge coefficient, thus the increased particle drag effect on particle trajectories and erosion due to changing flow density is the primary candidate. To support these conclusions, mesh morphing simulations of a 0–10 μm test are performed at 1 and 15.77 atm using the OSU Deposition Model, which captures both impact velocity and angle dependencies of deposition. The resulting structures and their unique characteristics are compared to experimental deposits, and the computational and experimental blockage histories support the conclusion that increased drag is the primary mechanism.
Experimental Investigation of an Ultra-High Bypass Ratio Embedded Boundary Layer Ingesting Propulsor for Subsonic Cruise Aircraft
Authors: Arend David J. , Wolter John D. , Hirt Stefanie M. , Gazzaniga John A. , Cousins William T. , Hardin Larry W. , Voytovych Dmytro M. , Sharma Om P.
Published: January 2021

An experimental investigation has been completed of the performance and operability of a first of its kind 0.289 scale boundary layer ingesting propulsor within the new 6.5ft × 6ft transonic embedded propulsor testbed of NASA’s 8ft × 6ft Supersonic Wind Tunnel. This propulsor consisted of a coupled inlet and distortion-tolerant fan stage design embedded in a simulated upper aft hybrid wing body aircraft installation. The boundary layer ingesting inlet had a length-to-diameter ratio of 0.67. The distortion tolerant fan was 22 inches in diameter and had a stage pressure ratio of 1.34 and a bypass ratio of 16. The embedded propulsor was evaluated at its Mach 0.78 local freestream conditions. At peak efficiency 100% design speed test conditions, it provided a mass flow weighted inlet total pressure recovery of 96.5% and an adiabatic fan stage efficiency of 87.9%. These values differed meaningfully from the pre-test computational fluid dynamic analysis based design intent. At this operating condition, the effects of inlet-fan coupling extended approximately 0.45 fan diameters upstream into the inlet. The inlet was measured to have a stability margin of approximately 28% and was pre-entry boundary layer separation limited. The fan had approximately 12% of stability margin at 100% corrected speed at which conditions it was flutter limited. It exhibited otherwise flutter free operation over its entire aircraft cruise operating map. Consistently increasing levels of fan stability margin were demonstrated at successively lower fan speeds to in excess of approximately 24% at 80% corrected speed. At each of these reduced speeds, fan stability margin was full annulus stall limited. Inlet airflow distortion remained one-per-rev throughout all tested conditions. At peak efficiency 100% speed test conditions, the boundary layer ingesting inlet airflow had steady state radial and circumferential ARP1420 distortion intensities of 1.2 and 7.2%, respectively. Peak time-variant distortion intensities of 2.3% radial and 8.9% circumferential were also recorded. Comparisons to pre-test computational fluid dynamic predictions are also provided.
Influence of Boundary Layer Skew on the Tip Leakage Vortex of an Axial Compressor Stator
Authors: Koppe Björn , Lange Martin , Mailach Ronald
Published: January 2021

For an axial compressor stator with tip gap the boundary layer in the hub end-wall region has a significant influence on the development and progression of the tip leakage vortex. Herein the so-called boundary layer skew, which develops through relative motion of the hub, is of particular interest. Therefore, experimental and numerical investigations of a single axial compressor stator row with varying tip gap height (tip gap height/chord length = 2.0%|5.4%|6.7%) have been conducted. Comparing cases with rotating or stationary hub end-wall segments upstream of the examined vanes allowed to determine the effect of skewed and un-skewed inflow boundary layer. The steady state flow fields up- and downstream of the stator row were measured using five-hole pressure probes. For validation and to improve the understanding of the existing flow phenomena 3D-RANS CFD simulations using a commercial flow solver were carried out. Furthermore, analog cases with no tip gap were examined and considered in the comparisons to extend the knowledge on this boundary layer characteristic. The results show that the boundary layer skew has a major influence on the trajectory and size of the tip leakage vortex for the cases with tip clearance. The effect of reduction of the produced losses decreases with increasing tip gap height.
Locked-In Phenomenon Between Tip Clearance Flow Instabilities and Enforced Blade Motion in Axial Transonic Compressor Rotors
Authors: Han Le , Wei Dasheng , Wang Yanrong , Zhang Xiaobo , Fang Mingchang
Published: January 2021

In this paper, tip clearance flow (TCF) instabilities and their relationship to blade motion are investigated numerically on a transonic transonic rotor with a large tip clearance. The numerical methods are verified by comparing with the experimental data of NACA0012 and show reliable results. It is found that the TCF instabilities are caused by the radial vortex formed in passage, which is induced by the interaction of tip clearance vortex (TCV) and main flow. When the blade is enforced vibrating with small amplitude, the results show that TCF instabilities are hardly affected by the blade vibration, and almost no phenomenon of locked-in is found. However, when the amplitude of blade vibration is increased, the interaction becomes stronger and the pressure fluctuation is enhanced. A wider locked-in region is observed. In addition, the simulation results show that the locked-in region is affected significantly by modal shapes. For the rotor here, it seems that the bending mode has a greater effect on the TCV instabilities than the torsional mode and causes a wider locked-in region. In locked-in region, the phase differences between TCV and the blade motion change with the flow conditions. In unlocked region, the period of TCF instabilities fluctuates over time, and the process is similar to that in the locked-in region.
Investigating the Causes of Outlet Guide Vane Buffeting
Authors: Harris Jonah R. , Lad Bharat , Stapelfeldt Sina
Published: January 2021

In the more aggressive architectures of future high-bypass aero engines, outlet guide vanes (OGVs) will be deployed even closer to the fan. Under certain circumstances this can lead to OGV buffeting. Buffeting is an aeroelastic instability, characterized as the structural response to aerodynamic excitations caused by self-sustaining flow instabilities. Buffeting of OGVs can cause structural fatigue within the low pressure system. This study aims to identify indications of buffet on an engine’s operating map, before assessing how the flow field interacts with the relevant vibrational mode. Steady simulations of the whole low pressure system were used to produce characteristics for three fan speeds and the operating points suspected of buffet were then subject to time-accurate simulations. The steady simulations were used to detect buffet symptoms and examine the change in shock formation, separation patterns and simulation residuals with changing conditions. The time-accurate CFD predicted the highest excitation of the first bow mode at the engine speed where high vibration levels were detected during static off-design engine tests. Time-averaged results of the time-accurate simulations were used to look for trends linking buffeting behaviour with aerodynamic parameters. The time-accurate data also gave indications of a transonic buffet phenomenon.
Quantitative Flow Imaging of Film Cooling Jets in a Cross-Flow Using Particle Image Velocimetry and Computational Fluid Dynamics
Authors: Brakmann Robin G. , Schöffler Robin , Kocian Frank , Schroll Michael , Willert Christian , Müller Martin , Kügeler Edmund
Published: January 2021

The investigated generic configuration consists of cylindrical film cooling holes with a diameter of D = 8.4 mm and an inclination angle of α = 35°. The jets are characterized by a momentum flux ratio of I = 0.63, a density ratio of DR = 0.94 and a cross-flow Reynolds number of Re = 5500. Stereoscopic PIV allows creating a (pseudo) three dimensional image of the flow field. High resolution PIV is used to evaluate velocity fluctuations. The numerical model uses the SST and an EARSM turbulence model. The turbulent scalar fluxes are computed by a constant turbulent Prandtl number as well as algebraic models for the turbulent heat flux. The presented results consist of field cuts and line profiles of the velocity, vorticity and turbulent kinetic energy. All considered numerical options can predict the velocity field accurately, the SST turbulence model is the numerically most stable model and has the lowest demands in computational costs.
Performance Improvement of a Mixed Flow Turbine Using 3D Blading
Authors: Elliott Matthew , Spence Stephen , Seiler Martin , Geron Marco
Published: January 2021

Mixed flow turbines have reached a level of maturity where iterative performance improvements are very small, with real performance benefits coming from better matching to a given application as opposed to improvements in technology. One ubiquitous design feature of mixed flow turbines used to control stress within the wheel is the radial fibre constraint, wherein blade material is stacked radially outward along the entirety of the blade. While this constraint yields a mechanical benefit, it constrains the aerodynamic design significantly, with the blade shape defined by one camberline.

One potential means of realizing a performance improvement is the use of 3D blading, where the blade is not constrained to a radially fibred structure. In such a design, the blade shape could be freely modified to better control blade loading and secondary flows. This study investigated the viability of such 3D blading through optimization of a state of the art mixed flow turbine. An equivalent design was ensured by maintaining the meridional shape and operating conditions of the baseline wheel, thus facilitating a fair comparison between the radial and 3D wheels.

The paper details the optimization including an innovative constraint-driven geometry modification tool, experimental validation of performance predictions, and an investigation into why 3D blading facilitated a performance improvement.

The optimization process identified a performance improvement across the entire turbocharger operating line. With performance improvements facilitated through a reduction in tip leakage loss, and improved pressure recovery within the conical diffuser. Importantly, the optimized design met targets for mass flow, maximum stress levels, and modal behaviour, through the use of the novel geometry modification process.
Fan Aerodynamics With a Short Intake at High Angle of Attack
Authors: Mohankumar Ben , Hall Cesare A. , Wilson Mark J.
Published: January 2021

Future turbofan engines seek shorter intakes to reduce the cruise fuel burn of a low pressure ratio, large diameter fan. However, shorter intakes increase the level of flow distortion entering the rotor when the aircraft angle of attack (AOA) is high, reducing thrust when critically needed. This paper considers how the fan rotor radial pressure ratio distribution and tip velocity triangle can be designed to improve thrust at high AOA. Full annulus, unsteady CFD is performed on three rotor designs coupled to a short intake. We show that rotor design for high AOA should be guided by three flow mechanisms. Mechanism i) is caused by high Mach number flow over the bottom intake lip, which chokes the rotor leading to high loss. Mechanism ii) is the loss generation in the rotor tip as it passes through an intake separation. Mechanism iii) shows radial flows through the rotor change both the amount and the way work is imparted on the flow. Two comparable rotor design philosophies for high thrust are proposed; high work or low loss. Rotors designed to a mid-high radial pressure ratio distribution impart high work on streamlines that migrate radially towards the hub and exit the rotor at highly cambered sections. Meanwhile, tip-high designs reduce choking losses in the midspan when operating with a separated intake, particularly when the tip velocity triangle is designed to high axial velocity diffusion over high camber. However, such designs suffer with higher tip losses after exiting an intake separation.
Dynamic Mode Decomposition Analysis of Separated Boundary Layers Under Variable Reynolds Number and Free-Stream Turbulence
Authors: Dellacasagrande M. , Verdoya J. , Barsi D. , Lengani D. , Simoni D.
Published: January 2021

A flat plate boundary layer has been surveyed by means of time-resolved particle image velocimetry (PIV) under variable Reynolds number (70000 < Re < 150000) and turbulence intensity level (1.5% < Tu < 2.5%). The PIV visualizations were completed in two measuring planes, that are oriented both normal and parallel to the wall. For the wall-parallel configuration, the measuring plane is located inside the boundary layer. The PIV data were post-processed by applying Dynamic Mode Decomposition (DMD), which provides frequency based modes and their corresponding growth rate. The effects of Re and Tu variation on the amplification of the dominant wavelength within the separated shear layer, which is responsible for transition, is the main subject of the present work.

The DMD modes and related eigenvalues were computed with reference to the main streamwise coordinate. This allowed discussing the effects due to the main flow parameters on the amplification of the dominant streamwise wavelengths within the separated shear layer (Kelvin-Helmholtz modes). The growth of such streamwise modes ends with the formation of large scale vortices, whose breakup forces transition. In order to obtain the effective distribution of the maximum growth rate of fluctuations at different locations and times, the DMD domain was continuously extended in the streamwise direction, accounting for a specified number of periods characterizing the large scale K-H vortices.

In order to reduce the time-space dependent results obtained by the DMD procedure, a probability density function of the most unstable wavelength and the corresponding growth rate has been computed. For the present data set, the spatial growth rate of fluctuations is found to increase at the higher Reynolds number, while it slightly reduces with increasing the Tu level. The procedure and findings discussed in this work shall be suitable for designing active control systems, such as harmonic blowing for separation control.
Microwave Chipless Resonator Strain Sensor for Pipeline Safety Monitoring
Authors: Baghelani Masoud , Abbasi Zahra , Daneshmand Mojgan
Published: January 2021

Real-time hoop strain monitoring is known as an important parameter for the evaluation of pipeline safety and integrity. Internal corrosion and consequently variation of wall thickness directly reflects in hoop strain variation. In addition, leakage causes a pressure drop and strain reduction due to negative pressure wave. Due to their promising features such as extremely low cost, relatively high sensitivity, compatibility with harsh environmental conditions, distant and non-contact sensing with negligible power consumption, microwave resonator-based sensors achieved great deals of interest during the last decade. In this work, a chipless flexible microwave sensor for pipeline hoop strain real-time monitoring is presented. The sensor structure comprises a flexible chipless split ring microwave tag resonator attached to the pipeline and electromagnetically coupled to a pair of gap coupled transmission lines form the reader located at a certain distance from the tag strain sensor. Strain variations as the results of the mentioned pipeline defects change the overall length of the attached tag sensor which consequently causes a shift in its resonance frequency. For assuring the tag sensor to mechanically follow the strain variation of the pipeline, the Young modulus of its structural material should be much lower than that of the pipeline. This condition also important for the integrity of the sensor-pipe system because their connection will be accomplished by an adhesive. Since copper as the standard microwave conductive material is relatively highly stiff, it is not an appropriate candidate for such an important application. For addressing this issue, the chipless tag structure is fabricated by a conductive rubber layer in this work with extremely low Young modulus guaranteeing the length of the tag strain sensor to exactly follow the strain variation of the pipeline and forms a reliable and precise pipeline strain sensor. The spectrum of the tag sensor is reflected on the reader structure spectrum which could be measured to monitor the resonance frequency shift of the tag resulted from length variation of the tag sensor directly related to the pipeline strain fluctuation.
Study on Polishing Method Using Double Magnet System by Superconductive Assisted Machining Method
Authors: Suzuki Keisuke , Nakasaki Tatsuya , Nakashima Hidetaka , Kajornrunruan Panart , Onomata Misaki , Kinoshita Yushi , Zhang Ruizhe , Otabe Edmund Soji
Published: January 2021

Superconductive Assisted Machining Method (SUAM) has been studied for polishing methods inside the hollow structure such as SUS tube. Levitation tool with Nd permanent magnet in the SUAM system is trapped by magnetic flux pinning effect into the superconductor bulk mounted in the liquid nitrogen box. In this case, initial displacement of the levitation tool can be adjusted until 12mm during cooling process under magnetic field. Movement of the superconductor bulk controls the applied force and rotation speed of the levitation tool. In previous research, we demonstrated that the SUAM could be applied lapping and polishing process on concave and flat shapes of the resin, aluminum and SUS materials. In present study, we develop the double magnet system that Nd permanent magnet fixed under the superconductor to increase holding force of the levitation tools. As results, holding force and levitation amount of the double magnet system increase against the conventional single magnet system. We also evaluate dominant parameters such as the placement of the superconductors and magnet flux density distribution from double permanent magnets on the holding force and levitation amount. In this case, the holding force and floating amount is calculated by JMAG using Finite Element Method to compare with the experimental results.
High-Temperature Oxidation Kinetics of Additively Manufactured NiTiHf
Authors: Dabbaghi Hediyeh , Nematollahi Mohammadreza , Safaei Baghbaderani Keyvan , Bayatimalayeri Parisa , Elahinia Mohammad
Published: January 2021

NiTi-based high-temperature shape memory alloys (HTSMAs) such as NiTiHf have been utilized in a broad range of applications due to their high strength and work output, as well as, their ability to increase the transformation temperatures (TTs). Recently, additive manufacturing techniques (AM) have been widely used to fabricate complex shape memory alloy components without any major modifications or tooling and has paved the way to tailor the manufacturing and fabrications of microstructure and critical properties of their final parts. NiTi alloys properties such as transformation temperatures can be significantly altered due to oxidation, which can occur during the manufacturing process or post-processing. In this work, the oxidation behavior of Ni-rich NiTi20Hf shape memory alloys, which was fabricated by the selective laser melting (SLM) method, is evaluated. Thermogravimetric analysis (TGA) is used to assess the kinetic behavior of the oxidation at different temperature ranges of 500, 700, and 900 °C for 20 hours in the air. After oxidation, to evaluate the microstructure and chemical composition X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) was conducted. The isothermal oxidation kinetics of conventional NiTi20Hf alloys were studied, and the results were compared to AM samples. Results show a two-stage oxidation rate at which oxidation increased with the high rate at the initial stage. As the oxidation time increased, the oxidation rate gradually decreased. The oxidation behavior of NiTiHf alloys initially obeyed logarithmic rate law and then followed by parabolic rate law. SEM results showed the formation of a multi-layered oxide scale, including TiO2, NiTiO3, and Hf oxide.
Autonomous Manufacturing Using Machine Learning: A Computational Case Study With a Limited Manufacturing Budget
Authors: Alam Md. Ferdous , Shtein Max , Barton Kira , Hoelzle David J.
Published: January 2021

This paper studies the concept of manufacturing systems that autonomously learn how to build parts to a user-specified performance. To perform such a function, these manufacturing systems need to be adaptable to continually change their process or design parameters based on new data, have inline performance sensing to generate data, and have a cognition element to learn the correct process or design parameters to achieve the specified performance. Here, we study the cognition element, investigating a panel of supervised and reinforcement learning machine learning algorithms on a computational emulation of a manufacturing process, focusing on machine learning algorithms that perform well under a limited manufacturing, thus data generation, budget. The case manufacturing study is for the manufacture of an acoustic metamaterial and performance is defined by a metric of conformity with a desired acoustic transmission spectra. We find that offline supervised learning algorithms, which dominate the machine learning community, require an infeasible number of manufacturing observations to suitably optimize the manufacturing process. Online algorithms, which continually modify the parameter search space to focus in on favorable parameter sets, show the potential to optimize a manufacturing process under a considerably smaller manufacturing budget.
Experimental and Computational Analysis of the Mechanical Properties of Biocompatible Bone Scaffolds, Fabricated Using Fused Deposition Modeling Additive Manufacturing Process
Authors: Zhao Daguan , Hart Christoph , Weese Nathan A. , Rankin Chantz M. , Kuzma James , Day James B. , Salary Roozbeh (Ross)
Published: January 2021

Fused deposition modeling (FDM), a material extrusion additive manufacturing process, has emerged as a method of choice for the fabrication of polymeric tissue engineering scaffolds. The FDM process is intrinsically complex, consisting of a multitude of parameters; in addition, there are material-machine-process interactions, which inevitably influence the mechanical properties, the surface morphology, and ultimately the functional integrity of fabricated bone structures. Consequently, physics-based process characterization and optimization in the FDM process is a burgeoning need. The overarching goal of this research work is to fabricate patient-specific, biocompatible, and biodegradable bone scaffolds for the treatment of osseous defects, fractures, and diseases. In pursuit of this goal, the objectives are to: (i) investigate the influence of consequential parameters of FDM on the functional properties of fabricated femur bone structures; and (ii) investigate the underlying physical phenomena behind the experimental observations using a computational finite-element model.

In this study, biocompatible femur bone structures were FDM-deposited, based on a medical-grade polymer composite, composed of polyamide, polyolefin, and cellulose fibers. A new test specimen was designed, based on an X-ray micro-CT scan of a femur bone as well as the ASTM D638-14 (Type II) standard. In addition, the experimental characterization was on the basis of a cascade approach, composed of the following experimental deigns: (i) fractional-factorial design, utilized for factor screening and identification of consequential process parameters; (ii) Taguchi design, utilized for process optimization. Besides, a computational finite-element model was forwarded to investigate the underlying physical phenomena behind the experimental observations.
Inversion of surficial sediment thickness from under-ice acoustic transmission measurement
Authors: Chotiros Nicholas P. , Hope Gaute , Storheim Espen , Hobaek Halvor , Freitag Lee , Sagen Hanne
Published: January 2021

The under-ice acoustic transmission experiment of 2013, conducted under ice cover in the Fram Strait, was analyzed for bottom interactions for the purpose of developing a model of the seabed. Using the acoustic signals, as well as data from other sources, including cores, gravimetric, refraction, and seismic surveys, it was deduced that the seabed may be modeled as a thin surficial layer overlaid on a deeper sediment. The modeling was based on the Biot–Stoll model for acoustic propagation in porous sediments, aided by more recent developments that improve parameter estimation and depth dependence due to consolidation. At every stage, elastic and fluid approximations were explored to simplify the model and improve computational efficiency. It was found the surficial layer could be approximated as a fluid, but the deeper sediment required an elastic model. The full Biot–Stoll model, while instrumental in guiding the model construction, was not needed for the final computation. The model could be made to agree with the measurements by adjusting the surficial layer thickness.
Aberrant type 1 immunity drives susceptibility to mucosal fungal infections
Authors: Break Timothy J. , Oikonomou Vasileios , Dutzan Nicolas , Desai Jigar V. , Swidergall Marc , Freiwald Tilo , Chauss Daniel , Harrison Oliver J. , Alejo Julie , Williams Drake W. , Pittaluga Stefania , Lee Chyi-Chia R. , Bouladoux Nicolas , Swamydas Muthulekha , Hoffman Kevin W. , Greenwell-Wild Teresa , Bruno Vincent M. , Rosen Lindsey B. , Lwin Wint , Renteria Andy , Pontejo Sergio M. , Shannon John P. , Myles Ian A. , Olbrich Peter , Ferré Elise M. N. , Schmitt Monica , Martin Daniel ,   Genomics and Computational Biology Core, Barber Daniel L. , Solis Norma V. , Notarangelo Luigi D. , Serreze David V. , Matsumoto Mitsuru , Hickman Heather D. , Murphy Philip M. , Anderson Mark S. , Lim Jean K. , Holland Steven M. , Filler Scott G. , Afzali Behdad , Belkaid Yasmine , Moutsopoulos Niki M. , Lionakis Michail S.
Published: January 2021

Type 1 immunity gives fungi a foothold

Type 17 immune responses play a vital role against fungal infections of the mucosa. It remains unclear whether other types of immune responses can also contribute to host defense against these pathogens. The yeast
Candida albicans
prominently infects patients with autoimmune polyendocrinopathy–candidiasis–ectodermal dystrophy (APECED), an inherited disease caused by loss-of-function mutations in the
AIRE
gene. Break
et al.
report that the oral susceptibility of
Aire
-deficient mice to
C. albicans
is not due to aberrant type 17 responses. Rather, the overproduction of interferon-γ by local CD4
+
and CD8
+
T cells in these mice disrupts the epithelial barrier, which increases susceptibility to
C. albicans
invasion. Similar type 1 immune pathways are operational in APECED patients. Inhibition of interferon-γ or the JAK-STAT signaling pathway in mice ameliorates disease symptoms, suggesting potential future therapeutic interventions for certain classes of fungal disease.

Science
, this issue p.
eaay5731
Senolysis by glutaminolysis inhibition ameliorates various age-associated disorders
Authors: Johmura Yoshikazu , Yamanaka Takehiro , Omori Satotaka , Wang Teh-Wei , Sugiura Yuki , Matsumoto Masaki , Suzuki Narumi , Kumamoto Soichiro , Yamaguchi Kiyoshi , Hatakeyama Seira , Takami Tomoyo , Yamaguchi Rui , Shimizu Eigo , Ikeda Kazutaka , Okahashi Nobuyuki , Mikawa Ryuta , Suematsu Makoto , Arita Makoto , Sugimoto Masataka , Nakayama Keiichi I. , Furukawa Yoichi , Imoto Seiya , Nakanishi Makoto
Published: January 2021

Selective destruction of senescent cells

Senescent cells are associated with a variety of age-related medical conditions and thus have been proposed as potential targets for therapy, but we do not yet have a full understanding of the underlying mechanisms. Johmura
et al.
used RNA interference to screen for enzymes essential to the survival of senescent cells (see the Perspective by Pan and Locasale). The authors identified a key role for glutamine metabolism, particularly the enzyme glutaminase 1, and demonstrated that inhibition of this pathway induced the death of senescent cells. Glutaminase targeting also ameliorated aging-related organ dysfunction and obesity-related disorders in mouse models, suggesting the potential therapeutic value of this approach.

Science
, this issue p.
265
; see also p.
234
Tracking, targeting, and conserving soil biodiversity
Authors: Guerra Carlos A. , Bardgett Richard D. , Caon Lucrezia , Crowther Thomas W. , Delgado-Baquerizo Manuel , Montanarella Luca , Navarro Laetitia M. , Orgiazzi Alberto , Singh Brajesh K. , Tedersoo Leho , Vargas-Rojas Ronald , Briones Maria J. I. , Buscot François , Cameron Erin K. , Cesarz Simone , Chatzinotas Antonis , Cowan Don A. , Djukic Ika , van den Hoogen Johan , Lehmann Anika , Maestre Fernando T. , Marín César , Reitz Thomas , Rillig Matthias C. , Smith Linnea C. , de Vries Franciska T. , Weigelt Alexandra , Wall Diana H. , Eisenhauer Nico
Published: January 2021

A monitoring and indicator system can inform policy
Three-quarters attack rate of SARS-CoV-2 in the Brazilian Amazon during a largely unmitigated epidemic
Authors: Buss Lewis F. , Prete Carlos A. , Abrahim Claudia M. M. , Mendrone Alfredo , Salomon Tassila , de Almeida-Neto Cesar , França Rafael F. O. , Belotti Maria C. , Carvalho Maria P. S. S. , Costa Allyson G. , Crispim Myuki A. E. , Ferreira Suzete C. , Fraiji Nelson A. , Gurzenda Susie , Whittaker Charles , Kamaura Leonardo T. , Takecian Pedro L. , da Silva Peixoto Pedro , Oikawa Marcio K. , Nishiya Anna S. , Rocha Vanderson , Salles Nanci A. , de Souza Santos Andreza Aruska , da Silva Martirene A. , Custer Brian , Parag Kris V. , Barral-Netto Manoel , Kraemer Moritz U. G. , Pereira Rafael H. M. , Pybus Oliver G. , Busch Michael P. , Castro Márcia C. , Dye Christopher , Nascimento Vítor H. , Faria Nuno R. , Sabino Ester C.
Published: January 2021

Attack rate in Manaus

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) incidence peaked in Manaus, Brazil, in May 2020 with a devastating toll on the city's inhabitants, leaving its health services shattered and cemeteries overwhelmed. Buss
et al.
collected data from blood donors from Manaus and São Paulo, noted when transmission began to fall, and estimated the final attack rates in October 2020 (see the Perspective by Sridhar and Gurdasani). Heterogeneities in immune protection, population structure, poverty, modes of public transport, and uneven adoption of nonpharmaceutical interventions mean that despite a high attack rate, herd immunity may not have been achieved. This unfortunate city has become a sentinel for how natural population immunity could influence future transmission. Events in Manaus reveal what tragedy and harm to society can unfold if this virus is left to run its course.

Science
, this issue p.
288
; see also p.
230
The Golgin Protein RUD3 Regulates Fusarium graminearum Growth and Virulence
Authors: Wang Chenyu , Wang Yao , Zhang Liyuan , Yin Ziyi , Liang Yuancun , Chen Lei , Zou Shenshen , Dong Hansong
Published: January 2021

Fusarium
head blight (FHB) caused by the fungal pathogen
Fusarium graminearum
is an economically important disease of wheat and other small grain cereal crops worldwide, and limited effective control strategies are available. A better understanding of the regulation mechanisms of
F. graminearum
development, deoxynivalenol (DON) biosynthesis, and pathogenicity is therefore important for the development of effective control management of this disease.
Glycosyltransferases within the
psrP
Locus Facilitate Pneumococcal Virulence
Authors: Middleton Dustin R. , Aceil Javid , Mustafa Seema , Paschall Amy V. , Avci Fikri Y.
Published: January 2021

PsrP has previously been identified as a necessary virulence factor for many serotypes of
S. pneumoniae
and studied as a surface glycoprotein. Thus, studying the effects on virulence of each glycosyltransferase (GT) that builds the PsrP glycan is of high importance.
Structural Basis for the Shared Neutralization Mechanism of Three Classes of Human Papillomavirus Type 58 Antibodies with Disparate Modes of Binding
Authors: He Maozhou , Chi Xin , Zha Zhenghui , Li Yunbing , Chen Jie , Huang Yang , Huang Shiwen , Yu Miao , Wang Zhiping , Song Shuo , Liu Xinlin , Wei Shuangping , Li Zekai , Li Tingting , Wang Yingbin , Yu Hai , Zhao Qinjian , Zhang Jun , Zheng Qingbing , Gu Ying , Li Shaowei , Xia Ningshao
Published: January 2021

Cervical cancer primarily results from persistent infection with high-risk types of human papillomavirus (HPV). HPV type 58 (HPV58) is an important causative agent, especially in Asia.
A Highly Conserved Circular RNA, circRasGEF1B, Enhances Antiviral Immunity by Regulating the miR-21-3p/MITA Pathway in Lower Vertebrates
Authors: Chu Qing , Zheng Weiwei , Su Hui , Zhang Lei , Chang Renjie , Gao Wenya , Xu Tianjun
Published: January 2021

Siniperca chuatsi
rhabdovirus (SCRV) is a typical fish RNA rhabdovirus, which is one of the most significant viral pathogens in teleost fish and can cause severe hemorrhagic septicemia in freshwater and marine fishes. Here, we discovered a highly conserved circRNA called circRasGEF1B, which acts as a key regulator for innate antiviral responses upon SCRV infection. circRasGEF1B acts as an endogenous sponge of miR-21-3p that downregulates miR-21-3p expression levels. circRasGEF1B is able to bind to miR-21-3p directly and regulates MITA expression.
A Possible Action of Divalent Transition Metal Ions at the Interpentameric Interface of Inactivated Foot-and-Mouth Disease Virus Provides a Simple but Effective Approach To Enhance Stability
Authors: Lin Xuan , Yang Yanli , Song Yanmin , Li Shuai , Zhang Xuan , Su Zhiguo , Zhang Songping
Published: January 2021

How to stabilize the inactivated FMDV without affecting virus infectivity and immunogenicity is a big challenge in the vaccine industry. The electrostatic repulsion induced by protonation of a large amount of histidine residues at the interpentameric interface of viral capsids is one of the major mechanisms causing the dissociation of capsids.
A detrital zircon test of large-scale terrane displacement along the Arctic margin of North America
Authors: Gibson Timothy M. , Faehnrich Karol , Busch James F. , McClelland William C. , Schmitz Mark D. , Strauss Justin V.
Published: January 2021

Detrital zircon U-Pb geochronology is one of the most common methods used to constrain the provenance of ancient sedimentary systems. Yet, its efficacy for precisely constraining paleogeographic reconstructions is often complicated by geological, analytical, and statistical uncertainties. To test the utility of this technique for reconstructing complex, margin-parallel terrane displacements, we compiled new and previously published U-Pb detrital zircon data (n = 7924; 70 samples) from Neoproterozoic–Cambrian marine sandstone-bearing units across the Porcupine shear zone of northern Yukon and Alaska, which separates the North Slope subterrane of Arctic Alaska from northwestern Laurentia (Yukon block). Contrasting tectonic models for the North Slope subterrane indicate it originated either near its current position as an autochthonous continuation of the Yukon block or from a position adjacent to the northeastern Laurentian margin prior to >1000 km of Paleozoic–Mesozoic translation. Our statistical results demonstrate that zircon U-Pb age distributions from the North Slope subterrane are consistently distinct from the Yukon block, thereby supporting a model of continent-scale strike-slip displacement along the Arctic margin of North America. Further examination of this dataset highlights important pitfalls associated with common methodological approaches using small sample sizes and reveals challenges in relying solely on detrital zircon age spectra for testing models of terranes displaced along the same continental margin from which they originated. Nevertheless, large-n detrital zircon datasets interpreted within a robust geologic framework can be effective for evaluating translation across complex tectonic boundaries.
Comparison of inspiratory effort with three variable-flow nasal continuous positive airway pressure devices in preterm infants: a cross-over study
Authors: Bordessoule Alice , Moreira Amelia , Felice Civitillo Cristina , Combescure Christophe , Polito Angelo , Rimensberger Peter C
Published: January 2021

Objective

Patient’s work of breathing may vary between different neonatal nasal continuous positive airway pressure (NCPAP) devices. Therefore, we aimed to compare the inspiratory effort of three variable-flow NCPAP delivery systems used in preterm infants.

Design

Cross-over study.

Patients/setting

From June 2015 to August 2016, 20 preterm infants weighing ≤2500 g requiring NCPAP for mild respiratory distress syndrome were enrolled.

Interventions

Each patient was successively supported by three randomly assigned variable-flow NCPAP systems (MedinCNO, Infant Flow and Servo-i) for 20 min while maintaining the same continuous positive airway pressure level as the patient was on before the study period.

Main outcome measures

Patients’ inspiratory effort was estimated by calculating the sum of the difference between maximal inspiratory and baseline electrical activity of the diaphragm (∆EAdi) for 30 consecutive breaths, and after normalising this obtained value for the timing of the 30 breaths.

Results

Physiological parameters (oxygen saturation measured by pulse oximetry, respiratory rate, heart beat, transcutaneous partial pressure CO2) and oxygen requirements remained identical between the three NCPAP systems. Although a wide variability in inspiratory effort could be observed, there were no statistically significant differences between the three systems for the sum of ∆EAdi for 30 breaths: CNO, 262 (±119) µV; IF, 352 (±262) µV; and SERVO-i, 286 (±126) µV, and the ∆EAdi reported on the timing of 30 breaths (sum ∆EAdi/s): CNO, 6.1 (±2.3) µV/s; IF, 7.9 (±4.9) µV/s; SERVO-i, 7.6 (±3.6) µV/s.

Conclusion

In a neonatal population of preterm infants, inspiratory effort is comparable between the three tested modern variable-flow NCPAP devices.
Economics of physical activity in low-income and middle- income countries: a systematic review
Authors: Ranasinghe Priyanga Diloshini , Pokhrel Subhash , Anokye Nana Kwame
Published: January 2021

Background

Promotion of physical activity (PA) among populations is a global health investment. However, evidence on economic aspects of PA is sparse and scattered in low-income and middle-income countries (LMICs).

Objective

The objective of this study was to summarise the available evidence on economics of PA in LMICs, identify potential target variables for policy and report gaps in the existing economic evidence alongside research recommendations.

Data sources

A systematic review of the electronic databases (Scopus, Web of Science and SPORTDiscus) and grey literature.

Study eligibility criteria

Cost-of-illness studies, economic evaluations, interventions and descriptive studies on economic factors associated with PA using preset eligibility criteria.

Study appraisal and synthesis of methods

Screening, study selection and quality appraisal based on standard checklists performed by two reviewers with consensus of a third reviewer. Descriptive synthesis of data was performed.

Results

The majority of the studies were from upper-middle-income countries (n=16, 88.8%) and mainly from Brazil (n=9, 50%). Only one economic evaluation study was found. The focus of the reviewed literature spanned the economic burden of physical inactivity (n=4, 22%), relationship between PA and costs (n=6, 46%) and socioeconomic determinants of PA (n=7, 39%). The findings showed a considerable economic burden due to insufficient PA, with LMICs accounting for 75% of disability-adjusted life years (DALYs) globally due to insufficient PA. Socioeconomic correlates of PA were identified, and inverse relationship of PA with the cost of chronic diseases was established. Regular PA along with drug treatment as a treatment scheme for chronic diseases showed advantages with a cost–utility ratio of US$3.21/quality-adjusted life year (QALY) compared with the drug treatment-only group (US$3.92/QALY) by the only economic evaluation conducted in the LMIC, Brazil.

Limitations

Meta-analysis was not performed due to heterogeneity of the studies.

Conclusions and recommendations

Economic evaluation studies for PA promotion interventions/strategies and local research from low-income countries are grossly inadequate. Setting economic research agenda in LMICs ought to be prioritised in those areas.

PROSPERO registration number

CRD42018099856.
Infection-related complications after common infection in association with new antibiotic prescribing in primary care: retrospective cohort study using linked electronic health records
Authors: van Bodegraven Birgitta , Palin Victoria , Mistry Chirag , Sperrin Matthew , White Andrew , Welfare William , Ashcroft Darren M , van Staa Tjeerd Pieter
Published: January 2021

Objective

Determine the association of incident antibiotic prescribing levels for common infections with infection-related complications and hospitalisations by comparing high with low prescribing general practitioner practices.

Design retrospective cohort study

Retrospective cohort study.

Data source

UK primary care records from the Clinical Practice Research Datalink (CPRD GOLD) and SAIL Databank (SAIL) linked with Hospital Episode Statistics (HES) data, including 546 CPRD, 346 CPRD-HES and 338 SAIL-HES practices.

Exposures

Initial general practice visit for one of six common infections and the proportion of antibiotic prescribing in each practice.

Main outcome measures

Incidence of infection-related complications (as recorded in general practice) or infection-related hospital admission within 30 days after consultation for a common infection.

Results

A practice with 10.4% higher antibiotic prescribing (the IQR) was associated with a 5.7% lower rate of infection-related hospital admissions (adjusted analysis, 95% CI 3.3% to 8.0%). The association varied by infection with larger associations in hospital admissions with lower respiratory tract infection (16.1%; 95% CI 12.4% to 19.7%) and urinary tract infection (14.7%; 95% CI 7.6% to 21.1%) and smaller association in hospital admissions for upper respiratory tract infection (6.5%; 95% CI 3.5% to 9.5%) The association of antibiotic prescribing levels and hospital admission was largest in patients aged 18–39 years (8.6%; 95% CI 4.0% to 13.0%) and smallest in the elderly aged 75+ years (0.3%; 95% CI −3.4% to 3.9%).

Conclusions

There is an association between lower levels of practice level antibiotic prescribing and higher infection-related hospital admissions. Indiscriminately reducing antibiotic prescribing may lead to harm. Greater focus is needed to optimise antibiotic use by reducing inappropriate antibiotic prescribing and better targeting antibiotics to patients at high risk of infection-related complications.
Comparison of effects of different dietary interventions on cognitive function in Alzheimer’s disease: protocol for systematic review and network meta-analysis
Authors: Chen Lili , Xu Xinhua , Cao Huizhen , Li Hong
Published: January 2021

Introduction

Alzheimer’s disease (AD) is the most common neurodegenerative disease and is characterised by cognitive impairment. Non-pharmacological treatments such as diet therapy have been widely investigated in studies on AD. Given the synergistic effects of nutrients present in foods, considering overall dietary composition rather than focusing on a single nutrient may be more useful for evaluating the relationship between diet and AD cognition. The present study aimed to assess the efficacy of different dietary interventions (eg, ketogenic and Mediterranean diets) on cognitive function in patients with AD in a systematic review and pairwise and network meta-analyses of randomised controlled trials or clinical trials.

Methods and analysis

Two reviewers will independently conduct searches of PubMed, Cochrane Central Register of Controlled Trials, Embase, CINAHL, PsycINFO and China National Knowledge Infrastructure databases. Data will be extracted from selected studies and risk of bias will be assessed using the revised Cochrane risk-of-bias tool, and evidence quality will be assessed according to the Grading of Recommendations, Assessment, Development and Evaluation framework. The primary outcome of interest is cognitive function in patients with AD; secondary outcomes include biochemical biomarkers of AD and oxidative stress and/or inﬂammatory biomarkers in cerebrospinal fluid or plasma. For each outcome, random-effects pairwise and network meta-analyses will be carried out to determine the pooled relative effect of each intervention relative to every other intervention.

Ethics and dissemination

As this study is based solely on published literature, no ethics approval is required. The research will be published in a peer-reviewed journal.