bluuebunny/crossref_metadata_2025 huggingface dataset:
Recent Developments in Hot Isostatic Pressing (HIP) of Components for Turbomachinery Applications
Authors: Beamer Chad
Published: September 2021

With advancements in hot isostatic pressing (HIP) systems it is now possible to also perform heat treatment by achieving the desired microstructure during the HIP cycle. This modern approach offers the freedom to consider a combined HIP and heat treatment cycle known as high pressure heat treatment (HPHT™). There are many potential benefits from this processing route such as shorter process times, cost reductions, increased quality, and improved productivity. Material benefits also exist from this processing route. This paper will cover the fundamentals of HPHT™ highlighting key technology changes enabling this approach in modern HIP equipment. Then a transition to recent studies capturing the benefits for aerospace applications leveraging HIP and the HPHT™ methodology along with future possibilities with steered cooling will be reviewed.
Experimental Investigation of Acoustic Characteristic on Orifice Shaped With Bias Flow
Authors: Ikwubuo Melvin , Song Jinkwan , Lee Jong Guen
Published: September 2021

Combustion dynamics has been a significant problem for a lean, premixed, prevaporized (LPP) combustor. Understanding the acoustic characteristics of combustor components is essential to modeling thermoacoustic behavior in a gas turbine combustion system. Acoustic characteristics such as impedance and scattering matrix elements are experimentally determined for different-shape orifices with an emphasis on the effect of the flow field on them. These orifices are used to represent premixed swirl cups in LP combustors. The validity and limitation of two different methodologies are evaluated by comparing measured results with those of others. Consistent with analytical predictions, the measured resistance through an orifice increases as the bias flow increases. Different types of orifices considered in this study behave similarly to a thin orifice at high bias flow even though the discharge coefficients vary as much as 30% between them. The conventional method produces impedance values independent of waves reflected from the end boundary condition only when the scattering elements at the orifice downstream are roughly equal to those upstream of the orifice. However, the scattering matrix method produces impedance values that are not affected by the source or reflected waves at the system’s boundary. The scattering matrix measurements show that the reflection and transmission elements increases and decreases, respectively, as the bias flow through an orifice increases.
Characterization of Dynamics of Unstable Fuel-Rich Flame
Authors: Weber M. , Song J. , Lee J. G.
Published: September 2021

The flame dynamics during unstable combustion occurring in a model gas turbine combustor under fuel-rich conditions analogous to idle and sub-idle conditions in an aero-engine is characterized by simultaneous measurement of flame emissions and dynamic pressure fluctuation as well as high-speed imaging. Pressure fluctuation during unstable combustion causes linearly increasing velocity fluctuation at the combustor inlet. The fluctuation level of CH*-band emission which is mainly from soot linearly increases with respect to the combustor inlet velocity fluctuation up to ∼40% of mean velocity while that of OH*-band emission which is from OH* is non-linear. Highspeed imaging shows that the OH*-band emission fluctuation occurs mainly near the dump plane but the CH*-band emission fluctuation occurs downstream of it. When the pressure fluctuation is more than 1% of mean pressure, there exists an almost constant phase delay between emissions from OH*- and CH*-band and dynamic pressure fluctuations and the phase delay satisfies the Rayleigh criterion. In addition, the Rayleigh integral made over the whole flame and one period of oscillation of thermoacoustic instability becomes positive. These may suggest either OH*- or CH*-band emission can be used as a representation of heat release. However, the observations that the mean OH*-band emission intensity increases but the mean CH*-band emission intensity does not as the mean equivalence ratio increases and the fluctuation level of emission in OH*-band increases but that in CH*-band emission does not as the pressure fluctuation level increases strongly suggest that the emission from OH*-band should be considered as a representation of heat release for sooty flames under the employed operating condition in this study.
Multi-Objective Optimization of Turbine Blade Tip With Film Cooling Holes
Authors: Yang Shuai , Zhang Min , Liu Yan , Yang Jinguang
Published: September 2021

Tip leakage flow is inevitable due to the tip clearance over rotor blades in turbines. This phenomenondeteriorates blade aerodynamic performance and induces severe thermal damage to the tip surface.Introduction of cooling jets to the tip can effectively controls the tip leakage flow and improves the tip heat transfer. Therefore, this paper aims to optimize film cooling holes on a flat tip of a subsonic cascade and an topology-optimized tip of a transonic cascade. A design variable is a material parameter defined at each grid node along the blade camber line. This idea is based on the topology optimization method. The objective is to minimize blade energy loss and maximize tip heat transfer intensity. A response surface optimization based on the design of experiment (DOE) analysis is employed, and a multi-objective Genetic Algorithm is used to get Pareto optimum solutions. During the DOE process, a CFD method using injection source terms is integrated for numerical simulations to reduce computational costs. Optimized tip film cooling holes are finally re-constructed. The influence of the newly designed tip cooling holes configuration on blade aero-thermal performance is evaluated via CFD simulations using body-fitted mesh. Results show that compared with the uniform arrangement of cooling film holes along the axial direction, all the optimized film cooling holes can improve both blade aerodynamic performance and tip heat transfer performance.
Using Autoencoders and Output Consolidation to Improve Machine Learning Models for Turbomachinery Applications
Authors: Pongetti Julie , Kipouros Timoleon , Emmanuelli Marc , Ahlfeld Richard , Shahpar Shahrokh
Published: September 2021

Machine learning models are becoming an increasingly popular way to exploit data from fluid dynamics simulations. This project investigates how autoencoders and output consolidation can be used to increase the accuracy of machine learning models, by injecting knowledge of the full flow field in the predictions of Quantities of Interest (QoI) used in the optimisation of highly loaded transonic compressor blades. Results show that the accuracy of the predicted QoI can indeed be increased, by using both an appropriate autoencoder and output consolidation. Most significantly, the prediction accuracy is increased in the range of QoI values which is involved in optimisation problems. As a result, a more accurate and faster computational design approach driven by machine learning methods has been demonstrated.
Ozone Production With Plasma Discharge: Comparisons Between Activated Air and Activated Fuel/Air Mixture
Authors: Mehdi Ghazanfar , De Giorgi Maria Grazia , Fontanarosa Donato , Bonuso Sara , Ficarella Antonio
Published: September 2021

This study focused on the comparative analysis about the production of ozone and active radicals in presence of nanopulsed plasma discharge on air and on fuel/air mixture to investigate its effect on combustion enhancement. This analysis is based on numerical modeling of air and methane/air plasma discharge with different repetition rates (100 Hz, 1000 Hz and 10000 Hz). To this purpose, a two-step approach has been proposed based on two different chemistry solvers: a 0-D plasma chemistry solver (ZDPlasKin toolbox) and a combustion chemistry solver (CHEMKIN software suite). Consequently, a comprehensive chemical kinetic scheme was generated including both plasma excitation reactions and gas phase reactions. Validation of air and methane/air mechanisms was performed with experimental data. Kinetic models of both air and methane/air provides good fitting with experimental data of O atom generation and decay process. ZDPlasKin results were introduced in CHEMKIN in order to analyze combustion enhancement. It was found that the concentrations of O3 and O atom in air are higher than the methane/air activation. However, during the air activation peak concentration of ozone was significantly increased with repetition rates and maximum was observed at 10000 Hz. Furthermore, ignition timings and flammability limits were also improved with air and methane/air activation but the impact of methane/air activation was comparatively higher.
Numerical Investigation on Hydrodynamic Characteristics of Supercritical CO2 Cylindrical Film Seal
Authors: Du Qiuwan , Liu Zhufeng , Zhang Di , Xie Yonghui
Published: September 2021

The cylindrical film seal, with prominent advantages of non-contact, little wear, long durability and high stability, is suitable for high-speed turbomachinery theoretically. To improve the leakage problem and design seals with significant performance for supercritical carbon dioxide (SCO2) turbomachinery, this paper establishes a spiral-grooved cylindrical film seal structure and aims to numerically investigate the effects of structural and operating parameters. The hydrodynamic characteristics are obtained by the computational fluid dynamics method. It indicates that with the increase of eccentricity, the leakage, floating force, friction torque and Nu all ascend. When the film thickens, the leakage increases while the floating force and friction torque decrease, and there is a transition from heat dissipation to absorption. The rotating speed and inlet pressure have a significant influence on the sealing performance under different working conditions. The leakage, floating force, friction torque and Nu all rise up with the increase of inlet pressure. The leakage and Nu decrease while the floating force and friction torque increase with the escalation of rotating speed. In addition, great results are obtained by arranging cylindrical film seal on the impeller back of a SCO2 radial-inflow turbine. Its power and efficiency are only slightly reduced by 0.58% and 0.41% respectively compared with the configuration without considering leakage, which suggests the potential applicability of cylindrical film seal to SCO2 turbomachinery.
Gas Turbine Based Electric Vehicle Charging Station
Authors: Ganiger Manjush , Pandey Maneesh , Wagh Rahul , Govindasamy Rakesh
Published: September 2021

Transition towards electric vehicles (EV) is the key enabler for fighting against climate change as well as for sustainable future. However, to build more confidence on EV transition, availability of charging infrastructure is key. One of the important criterions for vehicle charging station is to have a stable electricity source that can meet varying charging demand. The paper attempts to explore the eco-system of self-sustainable and quasi-renewable charging infrastructure.

This paper outlines a circular economy model for EV charging station (EVCS) using a gas turbine from the Baker Hughes™ portfolio. The proposed solution includes Solid Oxide Electrolyzer and a carbon capture unit, integrated to the gas turbine. This integrated system is decarbonized using the hydrogen generated by the electrolysis unit.

Proposed solution on EVCS can charge about 1500 EVs in half a day of operation (50% power split). Solution is lucrative and has attractive return on investment. The solution here is having high power density, compared to the actual renewable energy dependent charging stations. The solution is flexible to incorporate Power-to-X conversions. Modular nature of the solution makes it easy to implement in city limits as well as in remote locations, along the highways, where grid availability can be challenging.
Numerical Investigation of the Effect of an Axial Pre-Swirl Nozzle With a Radial Angle in a Pre-Swirl Rotor-Stator System
Authors: Zhao Gang , Ding Shuiting , Qiu Tian , Zhang Shenghui
Published: September 2021

Pre-swirl nozzles are often used in gas turbines to deliver the cooling air to the turbine blades. The static axial nozzles swirl the cooling air in the direction of rotation of the turbine disk, thereby reducing the relative total temperature of the air. Most studies about nozzles focus on its shape, radial location, tangential angle to reduce the pressure loss and increase the temperature drop of the pre-swirl system, but few of them consider the benefit of a radial angle of nozzles. This paper investigated numerically the performance of a pre-swirl system whose pre-swirl nozzles have a radial angle. Six radial angles are selected to study the flow dynamics of a direct-transfer pre-swirl system in terms of the total pressure loss coefficient of the pre-swirl cavity, the discharge coefficient of the receiver holes, and the adiabatic effectiveness. It is shown that the nozzles with radial angles can adjust the tangential velocity and radial velocity and thus can influence the performance of a pre-swirl system. There is a lowerest value of total pressure loss in pre-swirl cavity, that is α = 90°, which can hardly be influenced by the radial angle of nozzle and pressure ratio π. For a specific swirl ratio β∞, there exists an optimal αopt where the discharge coefficient of receiver hole is maximum. Moreover, αopt decreases as pressure ratio π increases. And so is the adiabatic effectiveness Θad.
Enhancing Turbine Deposition Prediction Capability With Conjugate Mesh Morphing
Authors: Bowen Christopher P. , Bons Jeffrey P.
Published: September 2021

A framework for performing mesh morphing in a conjugate simulation in the commercial Computational Fluid Dynamics (CFD) software ANSYS Fluent is presented and validated. A procedure for morphing both the fluid and solid domains to simulate the protrusion of deposit into the fluid while concurrently altering and adding to the solid regions is detailed. The ability to delineate between the original metal sections of the solid and the morphed regions which represent deposit characteristics is demonstrated. The validity and predictive capability of the process is tested through simulation of a canonical impingement jet. A single over-sized impingement jet (6.35 mm) at 894 K and an average flow velocity of 56.5 m/s is used to heat a nickel-alloy target plate. One gram of 0-5 μm Arizona Road Dust (ARD) is delivered to the target and a Particle Shadow Velocimetry (PSV) technique is used to capture the transient growth of the deposit structure on the target. Thermal infrared images are taken on the backside of the target and synchronized with the PSV images. The experiment is modeled computationally using the Fluent Discrete Phase Model (DPM) and the Ohio State University (OSU) Deposition Model for sticking prediction. The target is morphed according to the particulate volume prediction. The deposit regions are assigned an effective conductivity (keff) representative of porous deposit, and the fluid and thermal computations are reconverged. 10 mesh morphing iterations are performed accounting for the first half of the experiment. The morphed deposit volume and height are compared to the experiment and show reasonable agreement. The backside target temperatures are also compared, and the simulations show the ability to predict the reduction in temperature that occurs as the growing deposit insulates the metal surface. It is demonstrated that the assignment of unique thermal conductivities to the deposit and metal cells within the solid is critical. With a more robust and accurate implementation of the deposit keff, this conjugate mesh morphing framework shows potential as a tool for predicting the thermal impact of deposition.
Acoustic Pyrometry Robustness to Time of Flight Estimation Errors
Authors: Caposciutti Gianluca , Ferrari Lorenzo
Published: September 2021

Acoustic pyrometry is a widely used technique for contactless temperature measurement. It may be used in several applications, especially when high temperatures and harsh environments are involved. For instance, it has been applied to measure the temperature distribution at gas turbine outlet. This technique is based on the measurement of the time of flight of an acoustic wave through a medium. If multiple emitter-receiver couples are used, by using a computational procedure a reconstruction of a temperature map is possible. On the other hand, a full assessment of the robustness of this technique to potential errors in time of flight estimation is still missing. In this study, the impact of an inaccuracy in time of flight estimation on the reconstruction of a correct temperature map is investigated by means of a statistical approach. As a general result, it was found that when the time of flight was measured without inaccuracies, temperature estimation errors may be lowered by simply increasing the number of cells in which the estimation is performed. However, when the estimation of the time of flight is affected by errors, an optimal configuration exists that minimize the temperature estimation errors.
Conjugate Heat Transfer Simulation of an Industrial Gas Turbine Blade With Harmonic Balance Method
Authors: Zwiener Kim , Carpenter Cassie , Hodges Justin
Published: September 2021

The performance of turbomachines is often dependent on the unsteady flow fields they naturally produce, owing primarily to row-to-row interactions from both moving and stationary components, as well as the unsteady nature of the turbulent flow. When it comes to computational fluid dynamics, a disparity exists between steady state and transient simulation as far as accuracy is concerned, albeit the computational cost of transient simulation on fully complex industrial hardware can be overwhelming. This study bridges the gap by presenting a harmonic balance conjugate heat transfer simulation approach in Simcenter STAR-CCM+, to model the unsteady flow phenomena while also providing accurate temperature predictions throughout the gas turbine blade solid bodies. The harmonic balance method used is a mixed time domain and frequency domain technique, which is suitable for periodic unsteady flows and is much less expensive than transient simulation. With this method, the impact of capturing these unsteady flow structures, such as the wake interactions and secondary cooling flows, is quantified on the resulting metal temperature distribution. Such is investigated and characterized throughout an industrial gas turbine blade with fully complex internal cooling passages, as well as film cooling for the external blade surface. Comparisons to steady simulation and transient simulation are also made to quantify the relative fidelity of each approach. Regarding the final resulting blade heat transfer, analysis is also provided to differentiate between important sources: the unsteadiness in the primary gas path flow and the classical unsteady nature of turbulence. Often these effects are lumped together when analyzing the resulting heat transfer, which is incorrect and can be better understood with more detailed analysis.
Optimum Multi-Nozzle Configuration for Minimizing the Rayleigh Integral During High-Frequency Transverse Instabilities
Authors: Acharya Vishal , Lieuwen Timothy
Published: September 2021

This paper develops a formalism for optimizing nozzle location/configuration with respect to combustion stability of high-frequency transverse modes in a can combustor. The stability of these acoustically non-compact flames was assessed using the Rayleigh Integral (RI). Several key control parameters influence RI – flame angle, swirling strength, nozzle location, as well as nozzle location with respect to the acoustic mode shape. In this study, we consider a N-around-1 configuration such as typically used in a multi-nozzle can system and study the overall stability of this system for different natural transverse modes. Typically, such nozzles are distributed in a uniformly circular manner for which we study the overall RI and for cases where RI > 0, we optimize the nozzle distribution that can reduce and minimize RI. For a fixed geometry such a circular configuration, the analysis shows how the flame’s parameters must vary across the different nozzles, to result in a relatively stable system. Additionally, for a fixed set of flame parameters, the analysis also indicates the non-circular distribution of the N nozzles that minimizes RI. Overall, the analysis aims to provide insights on designing nozzle locations around the center nozzle for minimal amplification of a given transverse mode.
Influence of Working Fluid Composition on the Optimum Characteristics of Blended Supercritical Carbon Dioxide Cycles
Authors: Crespi F. , Martínez G. S. , Rodriguez de Arriba P. , Sánchez D. , Jiménez-Espadafor F.
Published: September 2021

The supercritical Carbon Dioxide power cycle technology has attracted growing interest from the scientific community, becoming one of the most important options currently considered for CSP applications. This is thanks to its high thermal efficiency, even at moderate turbine inlet temperatures, and small footprint. Nevertheless, sCO2 power cycles require a fairly low compressor inlet temperature to exploit their full thermodynamic potential. When this cannot be achieved, as it is usually the case for Concentrated Solar Power plants where ambient temperatures are high, the interest of the technology is compromised. To compensate for this effect, the SCARABEUS project is working on the development of certain chemical dopants that could be added to the raw CO2, obtaining new working fluids with the same or even better performance than pure CO2 even at higher minimum cycle temperatures.

This paper studies the impact of using CO2 mixtures blended with Hexaflurorobenzene (C6F6) and Titanium Tetrachloride (TiCl4). It is found that these mixtures enable thermal efficiencies that are higher than if pure CO2 were used. The efficiency gain can be as high as 3 percentage points, depending on the dopant used and the operating conditions considered.

In addition to this absolute performance gain, the paper reveals that there are additional degrees of freedom that enable more effective cycle optimisation. These are the dopant molar content, not only its composition, and the cycle layout used. When this is studied, it is found that the optimum molar content ranges from 10 to 20% and that the layouts of interest when using mixtures are simpler than if plain CO2 were used. These results open the way for a significant performance enhancement of Concentrated Solar Power plants.
Effect of the Axial Casing Groove Geometry on the Production and Distribution of Reynolds Stresses in the Tip Region of an Axial Compressor Rotor
Authors: Koley Subhra Shankha , Saraswat Ayush , Chen Huang , Katz Joseph
Published: September 2021

Stereo PIV measurements performed in a refractive index matched facility examine the effect of axial casing grooves (ACGs) geometry on the turbulence in the tip region of an axial compressor rotor. The ACGs delay the onset of stall by entraining the Tip Leakage Vortex (TLV), and by causing periodic changes to incidence angle as their outflow impinges on the rotor blade. To decouple these effects, measurements have been performed using a series of grooves having similar inlets, but different outflow directions. The performance and flow structure associated with three grooves, namely a semi-circular ACG, as well as U and S shaped grooves have been presented in several recent papers. This paper focuses on the impact of passage flow-groove interactions on the distribution, evolution, and production rates of turbulent kinetic energy (TKE) and all the Reynolds stress components. The analysis is performed at flow rates corresponding to pre-stall conditions and best efficiency point (BEP) of the untreated end wall, and for different blade orientations relative to the groove. Interactions of the tip flow with the ACGs modifies the magnitude and spatial distribution of the highly anisotropic and inhomogeneous turbulence in the passage. Owing to TLV entrainment into the grooves, at low flowrate, the ACGs actually reduce the turbulence in the passage compared to that in the smooth endwall. However, the geometry -dependent tip flow-groove interactions introduce new elevated turbulence centers. In all cases, the TKE is high in the: (i) TLV center, (ii) corner vortex generated as the backward tip leakage flow separates at the downstream end of the groove, and (iii) shear layer connecting the TLV to the rotor blade suction side tip. The location of peaks and the dominant components vary among grooves. For example, the axial component is dominant for the semicircular ACG, and its peak is located in the shear layer. The radial component is the dominant contributor for the U and S grooves, and it peaks inside the grooves at different locations. The circumferential component peaks in the TLV for the U and semicircular ACG, but inside the S groove. The shear layers generated as the flows jet out from the upstream ends of the grooves also bring varying elevated turbulence. At BEP, interactions of the TLV with secondary flows generated by the U and semi-circular grooves, for which the outflow is oriented in the negative circumferential direction, generate high turbulence levels, which extend deep into the passage. In contrast, the interactions associated with the S grooves are limited, resulting in a substantially lower turbulence level. Many of the various trends can be readily explained by examining the corresponding spatial distributions of the turbulence production rates. Such understanding elucidates the different mechanisms involved and provides a unique database for modelling turbulence in the passage.
Combustion and Oxidation of Lube Oils at Gas Turbine Conditions: Experimental Methods
Authors: Petersen Eric L. , Mathieu Olivier , Thomas James C. , Cooper Sean P. , Teitge David S. , Juárez Raquel , Gutierrez Nobel , Mashuga Chad V.
Published: September 2021

Because of the high temperatures involved, undesirable ignition events can happen during gas turbine operation, often necessitating expensive down time and repairs. The ignition events are frequently linked to the lubricant, a flammable mixture of large hydrocarbons with a very low vapor pressure. To understand better the role of the lubricant in such ignition events, increased understanding of the fundamental thermal and oxidation characteristics of such oils is needed. To this end, a suite of different tests has been set up and demonstrated at the TEES Turbomachinery Laboratory at Texas A&M University (TAMU) to study various aspects of lubrication oil breakdown and oxidation at elevated temperatures, mostly those related to their coking and ignition behaviors. Five types of tests have been implemented: ignition delay time measurements using a shock tube; hot surface ignition (HSI); autoignition temperature (AIT) determination; thermal cook-off under controlled heating; and a high-temperature coking experiment. Such tests can be used both for fundamental understanding of how lube oils burn and for comparing the reactivity of various types and grades of oil. Each technique at TAMU is briefly described in this paper as they pertain to gas turbine lube oils, and sample results are presented for a common lubrication oil, Mobil DTE 732. For this oil, the HSI tests produced a lowest temperature without ignition of 510°C, and in shock-tube measurements, lower-temperature ignition kinetics are observed below about 1300 K, even at 1 atm. Typical AIT values for oils have been found to be around 370°C but do vary amongst brands, types, and level of degradation. The measured temperatures for the exothermic and boiling events were measured as 166±2 °C and 277±4 °C using the cook-off rig.
Investigating Heat Transfer in a Straight Cooling Passage Using Transient Infrared Temperature Data and URANS Conjugate Heat Transfer Analysis
Authors: Christensen Louis , Celestina Richard , Sperling Spencer , Mathison Randall , Aksoy Hakan , Liu Jong , Nickol Jeremy
Published: September 2021

Experimental work measuring heat transfer due to internal convection on a smooth straight passage is recreated using unsteady Reynolds averaged Navier-Stokes conjugate heat transfer simulations. The experimental work utilizes 1-dimensional and 3-dimensional conduction models to determine internal heat transfer rates from external surface temperature measurements collected with an infrared camera. The numerical simulations recreated these experiments to verify the conduction model and investigate the differences between the k-ω shear stress transport turbulence model, Reynolds stress turbulence model, and the k-ε turbulence model. It is found that the conduction model can accurately predict the heat transfer in the passage within an average error of 6% but with reduced spatial accuracy. The lower spatial accuracy can be accounted for by utilizing both the conduction model to predict the magnitude of the heat transfer and the numerical simulations to capture the spatial distribution. No one turbulence model was found to provide consistently superior heat transfer predictions, but rather each model excelled in some scenarios and underperformed in others. Overall, the k-ε model was found to best match the experimental heat transfer calculations with an average error of 5.9% of the total heat transfer, and it takes a more conservative approach as it can over predict the external surface temperatures by approximately 0.4 K. The end goal of this study is to develop a way to derive heat-flux data from infrared measurements on a range of geometries. A simple and well-understood geometry is investigated here to provide a firm foundation for future work.
Optimization of three-dimensional metamaterials for terahertz energy harvesting
Authors: Yang Shendu , Thacker Zachary , Allison Evan , Pinhero Patrick
Published: September 2021

This work focuses on finite element modeling (FEM) of a three-dimensional metamaterial used as an absorber for terahertz energy harvesting. The metamaterial consists of patterned pillars of an SU-8 dielectric photoresist coupled to a copper metal overlayer. Our study shows that the electromagnetic performance of the metamaterial is dependent on the following characteristic design parameters of the SU-8 dielectric: pillar height, bottom side length, and spacing between adjacent pillars. Using FEM, the metamaterial geometry is successfully optimized and the surface plasmon can be tuned to a peak frequency of 1.2 THz and a maximum terahertz absorption amplitude of 30%.
Etching damage induced performance degradation in spin transfer torque magnetic random access memory fabrication
Authors: Wang Shuguang , Zuo Zhenghu , Ji Zhenghui , Chen Xiaorui , Ye Hui , Han Guchang
Published: September 2021

Damage mechanisms and related performance degradations induced by ion beam etching (IBE) process in the fabrication of magnetic tunnel junctions (MTJs) were studied systematically. The loss in tunneling magnetoresistance (TMR) and coercive field (Hc) was investigated with different MTJ pillar sizes and IBE incident angles. It is found that IBE-induced damage is the formation of a surficial amorphous shell in the outer rim of an MTJ pillar. This amorphous shell is of low conductivity and TMR, mainly arising from the lattice damage of MgO barrier and partial oxidation of free/reference layers. Based on experimental and theoretical findings, we optimized the IBE process to reduce the damage as well as recover from degradation. As a result, the TMR loss ratio in comparison with a blanket film is reduced from about 18% to 7%, and Hc is increased from 1490 to 2280 Oe for the same stack.
Cryoforged nanotwinned titanium with ultrahigh strength and ductility
Authors: Zhao Shiteng , Zhang Ruopeng , Yu Qin , Ell Jon , Ritchie Robert O. , Minor Andrew M.
Published: September 2021

Titanium gets some twins

Introducing a network of nanotwins is known to improve the properties of face-centered cubic metal alloys. Zhao
et al
. used gentle compression in liquid nitrogen to introduce a similar network of nanotwins in hexagonal closed-packed titanium. By starting with a titanium that has little oxygen, the twin network can be more easily established. The nanotwinned network improved the yield strength by 50% and ductility by 20% at room temperature. The cryogenic properties were even better, with a yield strength of two gigapascals and a tensile ductility of 100% before failure. —BG
Silver nanoparticles boost charge-extraction efficiency in
Shewanella
microbial fuel cells
Authors: Cao Bocheng , Zhao Zipeng , Peng Lele , Shiu Hui-Ying , Ding Mengning , Song Frank , Guan Xun , Lee Calvin K. , Huang Jin , Zhu Dan , Fu Xiaoyang , Wong Gerard C. L. , Liu Chong , Nealson Kenneth , Weiss Paul S. , Duan Xiangfeng , Huang Yu
Published: September 2021

Silver in the linings

The bacterium
Shewanella oneidensis
is well known to use extracellular electron sinks, metal oxides and ions in nature or electrodes when cultured in a fuel cell, to power the catabolism of organic material. However, the power density of microbial fuel cells has been limited by various factors that are mostly related to connecting the microbes to the anode. Cao
et al
. found that a reduced graphene oxide–silver nanoparticle anode circumvents some of these issues, providing a substantial increase in current and power density (see the Perspective by Gaffney and Minteer). Electron microscopy revealed silver nanoparticles embedded or attached to the outer cell membrane, possibly facilitating electron transfer from internal electron carriers to the anode. —MAF
A priori control of zeolite phase competition and intergrowth with high-throughput simulations
Authors: Schwalbe-Koda Daniel , Kwon Soonhyoung , Paris Cecilia , Bello-Jurado Estefania , Jensen Zach , Olivetti Elsa , Willhammar Tom , Corma Avelino , Román-Leshkov Yuriy , Moliner Manuel , Gómez-Bombarelli Rafael
Published: September 2021

Selectivity control in zeolite synthesis

Zeolites are widely used in many industrial applications, but despite decades of research, their synthesis still relies on trial-and-error approaches. Complex nucleation mechanisms and topological diversity lead to strong phase competition, complicating the issue of rational design of zeolite synthesis. Using atomistic simulations, literature mining, human-computer interaction, synthesis, and characterization, Schwalbe-Koda
et al
. developed a computational strategy that enables a priori control of phase selectivity in zeolite synthesis (see the Perspective by Chaikittisilp and Okubo). This approach uses several metrics for designing organic structure–directing agents to crystallize target zeolites with controlled phase competition and intergrowth. These results may have profound implications for the materials science community if this method is shown to be successful in the synthesis of practically useful uncommon zeolites. —YS
Comment on “Aberrant type 1 immunity drives susceptibility to mucosal fungal infections”
Authors: Kisand Kai , Meager Anthony , Hayday Adrian , Willcox Nick
Published: September 2021

Break
et al
. (Research Articles, 15 January 2021, eaay5731) conclude that T cell overproduction of interferon-γ causes chronic mucocutaneous candidiasis (CMC), a typical early feature of autoimmune polyendocrinopathy–candidiasis–ectodermal dystrophy (APECED). This contradicts studies implicating interleukin IL-17 and IL-22 deficiencies as a cause of CMC. We propose that Break
et al
. have focused on late-arising events rather than more common primary causes of CMC.
Rethinking resilience
The End of Trauma: How the New Science of Resilience Is Changing How We Think About PTSD
George A. Bonanno
Basic Books, 2021. 336 pp.
Authors: Gruber June
Published: September 2021

A flexible mindset can help us bounce back after adversity
Opposing roles of the immune system in tumors
Authors: Ho Won Jin , Wood Laura D.
Published: September 2021

Inflammation promotes early tumorigenesis but must be evaded as tumors progress
Climate science speaks: “Act now”
Authors: Lubchenco Jane , Kerry John F.
Published: September 2021

Last month, one of the most remarkable scientific endeavors on the planet delivered a report to the world. Hundreds of international scientists volunteered thousands of hours to evaluate more than 14,000 scientific publications, respond to over 78,000 comments, and produce a comprehensive scientific assessment to inform government policy-makers. What topic could justify such an intense global effort? The crisis posed by climate change.
In Science Journals
Authors: Sugden Andrew M. , Stajic Jelena , Grocholski Brent , Jiang Di , Funk Michael A. , Lavine Marc S. , McAlpine Michael C. , Czajka Caitlin , Alderton Gemma , Scanlon Seth Thomas , Osborne Ian S. , Suleymanov Yury , Kelly Priscilla N. , Olingy Claire , Vignieri Sacha , VanHook Annalisa M. , Nusinovich Yevgeniya
Published: September 2021

Highlights from the
Science
family of journals
‘Zero COVID’ countries seek exit strategies
Authors: Normile Dennis
Published: September 2021

They successfully kept the the virus at bay. Now, some are gingerly opening up
Vaccine equity hopes dashed
Authors: Cohen Jon
Published: September 2021

Latest forecast slashes this year’s global supply by 25%
Draft Genome Sequences of Staphylococcus sp. Strain CWZ226, of Unknown Origin, and Pseudomonas sp. Strain CVAP#3, Antagonistic to Strain CWZ226
Authors: McCall Brianna L. , Vriezen J. A. C.
Published: September 2021

Many
Staphylococcus
and
Pseudomonas
species, such as
Staphylococcus aureus
and
Pseudomonas aeruginosa
, are opportunistic human pathogens. However,
Pseudomonas
species are also known to produce bioactive compounds. Here, we report on the genome sequences of a
Pseudomonas
isolate and a
Staphylococcus
species of unknown origin that it inhibits.
Genome Sequence of Linnemannia hyalina Strain SCG-10, a Cold-Adapted and Nitrate-Reducing Fungus Isolated from Cornfield Soil in Minnesota, USA
Authors: Aldossari Nouf , Ishii Satoshi
Published: September 2021

We report here the genome sequence of
Linnemannia hyalina
strain SCG-10, a cold-adapted and nitrate-reducing fungus isolated from soil. The genome of strain SCG-10 (51.6 Mbp) contained 12,693 protein-coding sequences.
Draft Genome Sequences of Three
Shewanella
sp. Strains Isolated from Urban Freshwaters in the Ohio River Valley, USA
Authors: Kappesser Joy L. , Cooper Joshua T.
Published: September 2021

Draft genome sequences of three
Shewanella
sp. strains are reported. The strains NKUCC01_JLK, NKUCC05_KAH, and NKUCC06_TVS were isolated from freshwater sources in the Ohio River Valley, USA. These genome sequences provide insights into
Shewanella
adaptation to urban freshwaters and may help to elucidate their roles in biogeochemical cycling.
Making Sense of a Scent-Sensing Metaphor for Microbes and Environmental Predictions
Authors: Bowman Jeff S.
Published: September 2021

Microbes serve as sensitive indicators of ecosystem change due to their vast diversity and tendency to change in abundance in response to environmental conditions. Although we most frequently observe these changes to study the microbial community itself, it is increasingly common to use them to understand the surrounding environment.
Supplemental Material: Stratigraphy of the Eocene–Oligocene Titus Canyon Formation, Death Valley, California, and Eocene extensional tectonism in the Basin and Range
Authors: Midttun N. , al. et
Published: September 2021

Files removed. Please see Notice of Withdrawal at https://doi.org/10.1130/GES02363.1.
Validating clinical practice guidelines for the management of febrile infants presenting to the emergency department in the UK and Ireland
Authors: Waterfield Thomas , Lyttle Mark D , Munday Charlotte , Foster Steven , McNulty Marc , Platt Rebecca , Barrett Michael , Rogers Emma , Durnin Sheena , Jameel Nida , Maney Julie-Ann , McGinn Claire , McFetridge Lisa , Mitchell Hannah , Puthucode Deepika , Roland Damian
Published: September 2021

Objective

To report the performance of clinical practice guidelines (CPG) in the diagnosis of serious/invasive bacterial infections (SBI/IBI) in infants presenting with a fever to emergency care in the UK and Ireland. Two CPGs were from the National Institutes for Health and Care Excellence (NICE guidelines NG51 and NG143) and one was from the British Society for Antimicrobial Chemotherapy (BSAC).

Design

Retrospective multicentre cohort study.

Patients

Febrile infants aged 90 days or less attending between the 31 August 2018 to 1 September 2019.

Main outcome measures

The sensitivity, specificity and predictive values of CPGs in identifying SBI and IBI.

Setting

Six paediatric Emergency Departments in the UK/Ireland.

Results

555 participants were included in the analysis. The median age was 53 days (IQR 32 to 70), 447 (81%) underwent blood testing and 421 (76%) received parenteral antibiotics. There were five participants with bacterial meningitis (1%), seven with bacteraemia (1%) and 66 (12%) with urinary tract infections. The NICE NG51 CPG was the most sensitive: 1.00 (95% CI 0.95 to 1.00). This was significantly more sensitive than NICE NG143: 0.91 (95% CI 0.82 to 0.96, p=0.0233) and BSAC: 0.82 (95% 0.72 to 0.90, p=0.0005). NICE NG51 was the least specific 0.0 (95% CI 0.0 to 0.01), and this was significantly lower than the NICE NG143: 0.09 (95% CI 0.07 to 0.12, p<0.0001) and BSAC: 0.14 (95% CI 0.1 to 0.17, p<0.0001).

Conclusion

None of the studied CPGs demonstrated ideal performance characteristics. CPGs should be improved to guide initial clinical decision making.

Trial registration number

NCT04196192.
Xanthogranulomatous pyelonephritis due toAspergillusin a non-diabetic older patient
Authors: Khilar Neha , Gupta Navneet , Adhikari Prabha , Rao Abhijith Rajaram
Published: September 2021

Xanthogranulomatous pyelonephritis is a rare condition characterised by destructive granulomatous inflammation of renal parenchyma. Primary renalAspergillosis has been reported in patients with immunocompromised states such as diabetes, retroviral disease, organ transplant recipients, etc. We present a unique case of an older adult in his early 60s, presenting with fever and left flank pain with renal angle tenderness, diagnosed with primary renal aspergillosis with xanthogranulomatous pyelonephritis. These symptoms resolved with a long duration of antifungal (itraconazole) therapy and nephrectomy. The unique features are the development of fungal pyelonephritis in the absence of any immunocompromising conditions and the development of xanthogranulomatous changes with no risk factors.
Multisystem inflammatory syndrome in children (MIS-C) occurring in temporal proximity between siblings
Authors: Lim Lina , Lim Sheau Jen , Loy Jia Shyi , Ng David CE
Published: September 2021

We report a pair of siblings who developed multisystem inflammatory syndrome in children (MIS-C) in close temporal proximity after recent exposure to SARS-CoV-2. Both siblings presented with Kawasaki disease-like features and haemodynamic instability, with the onset of symptoms within 6 days of each other. Remarkably, one of the siblings was the elder of a pair of monozygotic twins. The younger monozygotic twin, however, did not develop MIS-C.
Lipid accumulation product (LAP) as a potential index to predict risk of insulin resistance in young, non-obese Asian Indian males from Southern India: observations from hyperinsulinemic-euglycemic clamp studies
Authors: Anoop S Shajith , Dasgupta Riddhi , Rebekah Grace , Jose Arun , Inbakumari Mercy Prem , Finney Geethanjali , Thomas Nihal
Published: September 2021

Introduction

We aimed to compare the predictive accuracy of surrogate indices namely the lipid accumulation product (LAP) index, homeostatic model of assessment of insulin resistance (HOMA-IR), fasting glucose-insulin ratio (FG-IR) and the quantitative-insulin sensitivity check index (QUICKI), against theMvalue of hyperinsulinemic-euglycemic clamp (HEC), and to determine a cut-off value for the LAP index to predict risk of insulin resistance in non-obese (body mass index <21 kg/m2), normoglycemic, Asian Indian males from Southern India.

Research design and methods

Data of HEC studies performed in 108 non-obese, normoglycemic, Asian Indian males was obtained retrospectively and theMvalue (a measure of whole-body insulin sensitivity) was calculated. TheMvalue is the rate of whole-body glucose metabolism at the hyperinsulinemic plateau (a measure of insulin sensitivity) and is calculated between 60 and 120 min after the start of the insulin infusion in the HEC procedure. The LAP index, the HOMA-IR, FG-IR and QUICKI were calculated. Spearman’s correlation and logistic regression analysis were performed. Cut-off value for the LAP index was obtained using receiver operating characteristics with area under curve (AUC) analysis at 95% CI. P value <0.05 was considered to be statistically significant.

Results

Significant negative correlation was observed for theMvalue with LAP index (r=−0.39, p<0.001) while significant positive correlation was noted with FG-IR (r=0.25; p<0.01) and QUICKI (r=0.22; p<0.01). The LAP index cut-off value ≥33.4 showed 75% sensitivity and 75% specificity with AUC (0.72) to predict risk of insulin resistance in this cohort.

Conclusion

The LAP index showed higher predictive accuracy for the risk of insulin resistance as compared with HOMA-IR, QUICKI and FG-IR in non-obese, normoglycemic Asian Indian males from Southern India.
Beta-cell failure rather than insulin resistance is the major cause of abnormal glucose tolerance in Africans: insight from the Africans in America study
Authors: Ishimwe M C Sage , Wentzel Annemarie , Shoup Elyssa M , Osei-Tutu Nana H , Hormenu Thomas , Patterson Arielle C , Bagheri Hadi , DuBose Christopher W , Mabundo Lilian S , Ha Joon , Sherman Arthur , Sumner Anne E
Published: September 2021

Introduction

Uncertainties exist on whether the main determinant of abnormal glucose tolerance (Abnl-GT) in Africans is β-cell failure or insulin resistance (IR). Therefore, we determined the prevalence, phenotype and characteristics of Abnl-GT due to β-cell failure versus IR in 486 African-born blacks (male: 64%, age: 38±10 years (mean±SD)) living in America.

Research design and methods

Oral glucose tolerance test were performed. Abnl-GT is a term which includes both diabetes and prediabetes and was defined as fasting plasma glucose (FPG) ≥5.6 mmol/L and/or 2-hour glucose ≥7.8 mmol/L. IR was defined by the lowest quartile of the Matsuda Index (≤2.98) and retested using the upper quartile of homeostatic model assessment of insulin resistance (HOMA-IR) (≥2.07). Abnl-GT-IR required both Abnl-GT and IR. Abnl-GT-β-cell failure was defined as Abnl-GT without IR. Beta-cell compensation was assessed by the Disposition Index (DI). Fasting lipids were measured. Visceral adipose tissue (VAT) volume was obtained with abdominal CT scan.

Results

The prevalence of Abnl-GT was 37% (182/486). For participants with Abnl-GT, IR occurred in 38% (69/182) and β-cell failure in 62% (113/182). Compared with Africans with Abnl-GT-IR, Africans with Abnl-GT-β-cell failure had lower body mass index (BMI) (30.8±4.3 vs 27.4±4.0 kg/m2), a lower prevalence of obesity (52% vs 19%), less VAT (163±72 vs 107±63 cm2), lower triglyceride (1.21±0.60 vs 0.85±0.42 mmol/L) and lower FPG (5.9±1.4 vs 5.3±0.6 mmol/L) and 2-hour glucose concentrations (10.0±3.1 vs 9.0±1.9 mmol/L) (all p<0.001) and higher DI, high-density lipoprotein (HDL), low-density lipoprotein particle size and HDL particle size (all p<0.01). Analyses with Matsuda Index and HOMA-IR yielded similar results. Potential confounders such as income, education, alcohol and fiber intake did not differ by group.

Conclusions

Beta-cell failure occurred in two-thirds of participants with Abnl-GT and may be a more frequent determinant of Abnl-GT in Africans than IR. As BMI category, degree of glycemia and lipid profile appeared more favorable when Abnl-GT was due to β-cell failure rather than IR, the clinical course and optimal interventions may differ.

Trial registration number

NCT00001853.