bluuebunny/crossref_metadata_2025 huggingface dataset:
Tribological Performance of Soft Magnetic Composite Materials for Gas Turbine Applications
Authors: Suman Alessio , Fortini Annalisa
Published: August 2024

Soft magnetic composites (SMCs) have gained attention in the last years of their usage in more compact and powerful electromechanical systems. These materials are used to combine the application of metallic material to the capability of generating (without external supply) a magnetic field. Automotive and aerospace technologies push the applications of these original materials to even higher power and mechanical stress to reduce the number of components, the size, and, in turn, the weight of complex systems. Considering gas turbine application, SMCs were formerly developed for bearings, but in the last decades, the new era of gas turbine electrification (e.g., hybrid-electric fly) has determined the need for mechanical improvement of such materials. At the same time, the reliability of soft magnetic material has to be discovered to avoid failure and reduce the maintenance schedule.

In the present work, tribological behaviors of SMCs were investigated by standard wear tests. In particular, two different types of SMSc were prepared through the powder metallurgy technique. Tests were conducted by a tribometer using a ball-on-disk configuration in lubricated condition. The effect of oil temperature and applied load were investigated. In addition to the tribological tests, an extensive post-mortem analysis was conducted on the worn surface to recognize the mechanisms responsible for the deterioration of the materials. The results showed the effects of the oil viscosity on the useful operating life of the SMCs. Removal mechanisms depend on the load conditions, and the proper selection of the oil characteristics and load was assessed.
Experimental Analysis of the Micro-Sized Particle Adhesion in a Subsonic Stationary Cascade
Authors: Suman Alessio , Zanini Nicola , Piovan Mattia , Pinelli Michele
Published: August 2024

The particle deposition phenomenon represents the critical factor for studying gas turbine fouling. Solid particle adhesion drives the contamination of the relevant surfaces of the power unit. Both compressor and turbine sides are affected by the performance degradation over time due to the contaminant adhesion. The performance losses are strongly related to the contaminants’ characteristics and the gas turbine’s operation. Solid contaminants like soil or soot coupled with environmental conditions such as temperature and humidity modify their stickiness, determining a difficult to predict effects on the gas turbine operation and reliability. According to the blade shape, surface characteristics, and flow field structures, particle impact determines the deposited layer growth process or the detachment/spallation of the previously deposited layer. This work analyzes the sticking and detachment processes generated by the interaction between solid substrate and micro-sized solid particles. The tests are carried out on a stationary linear subsonic cascade in which soil and soot particles are used to contaminate the flow field. A sensitivity analysis of the relative humidity values has shown how a slight increase in the relative humidity values determines the increment of the deposited contaminants by an order of magnitude. Blade regions and the overtime assessment of sticking and detachment processes are also assessed. Microsized contaminants interact with the blade surface, modifying the shape of the leading edge and the surface roughness, especially on the pressure side.
Modelling of Casing Containment in an Overspeeding Turbine Stage
Authors: Eryilmaz Ibrahim
Published: August 2024

This manuscript is on the structural characterization of a turbine casing in terms of blade containment. Gas turbines experience unintentional blade loss events in service for various reasons such as fatigue and the engines are certified on the basis that these events do not cause hazardous outcomes. In certain conditions, such as permanent loss of load after a shaft or transmission failure, the turbine stage(s) may accelerate to excessively high speeds creating the possibility of disk burst.

An LS-DYNA explicit finite element model of a bullet to plate experiment have been prepared with flat nose projectiles. Following the method verification, the procedure was applied for a turbine stage with a single layer and a multi-layer casing to assess the performance of those in a blade-off at overspeed conditions when turbine experiences permanent loss of load. The intention with the multi-layer casing is to allow penetration within the first layer to dissipate the energy of the fragments and to contain them within the second layer.
Calibration and Validation of a Novel Particle Rebound and Deposition Model
Authors: Jiang Lei-Yong , Patnaik Prakash , Suzuki Masaya
Published: August 2024

Environmental particles (e.g., sand, volcanic ash and other airborne dust) ingested into a gas turbine engine can significantly reduce engine performance, and even lead to complete power loss. This is particularly true for helicopters during taking-off, hovering, and landing. To predict this degradation quantitatively, a novel particle rebound/deposition model has been developed based on measured particle rebound characteristics and non-dimensional parameter analysis from more than seventy particle deposition tests relevant to engine hot-sections.

The model was calibrated/validated with the experimental data, where sand particles impinged on square ceramic coupons at a velocity of 215 m/s and a temperature range of 1300–1580 K. Numerical simulations were carried out for these testing cases, and the particle impact rate on the coupon for each test case was obtained with a user defined function. With the particle impact rates on the coupon, the experimental particle deposition rates based on the total released particles, and the operating conditions, the coefficient of a defined model formulation was obtained. The calibrated rebound and deposition model was compiled and linked to the flow solver, and the predicted results were in good agreement with the experimental data. With added model functions, the distributions of deposited particle parameters on the coupon surface are provided.
The Effect of Rotor Leakage Flows on Hot Gas Ingestion
Authors: Dawson Michael G. , Atkins Nicholas R.
Published: August 2024

The geometry of a turbine rotor disc has spaces through which parasitic leakage flows can leave the upstream disk cavity, affecting the purge flow required to maintain acceptable cavity temperatures. This paper presents a study of the effects of leakage flows through gas turbine rotors on hot gas ingestion into rotor-stator cavities. By modulating the area of rotor leakage paths, it is shown experimentally and numerically that, as expected, rotor leakage increases the purge flow required to maintain acceptable average cavity temperatures. However, the study also shows that through disc leakage exacerbates the effects of non-uniform ingestion, increasing the magnitude of local peaks in surface temperature for a given cavity average value. An empirical low-order model is proposed for the flow in the rotorstator cavity which captures the sensitivity of seal effectiveness to purge flow when leakage is present.
Development of Detailed and Reduced Chemical Kinetic Models for Ammonia Combustion Under Gas Turbine Operating Conditions
Authors: Rahman Ramees K. , Pierro Michael , Winquist Mark , Subbaraman Ganesan , Sun Wenting , Steele Robert , Vega John , Vasu Subith S.
Published: August 2024

The power generation sector has been recently moving towards decarbonization and there is an increased interest in replacing conventional fossil fuels with fuels that produce reduced/zero carbon emissions. One such fuel is ammonia (NH3). However, ammonia is hard to ignite, has a low flame speed, and produces a significantly large amount of nitrogen oxide (NOx) emissions. Hence, using 100% ammonia as fuel in gas turbines requires significant modifications and the development of novel combustors. Blending hydrogen with ammonia, however, helps in having better control over the combustion properties. For example, a 70%/30% mixture of NH3/H2 mixture has a flame speed comparable to natural gas. Before utilizing hydrogen-blended ammonia in an actual gas turbine combustor, thorough simulation studies are required to evaluate its performance, possible hazards, and emissions. The literature lacks well-validated chemical kinetic models for the combustion of hydrogen-blended ammonia for undiluted mixtures at gas turbine-relevant conditions (∼20 bar). Most models available in the literature have been developed for ammonia extremely diluted in diluents such as argon or nitrogen. Hence, in this work, we develop a detailed chemical kinetic model for hydrogen blended ammonia combustion and validate it with a wide range of experimental data for both dilute and undiluted mixtures relevant to gas turbine operating conditions. We outline the strengths and weaknesses of the current mechanism to aid future users of our chemical kinetic mechanism. The detailed chemical kinetic mechanism was reduced to a smaller version (32 species mechanism) without significant loss in accuracy using the direct relation graph with error propagation (DRGEP) and full species sensitivity analysis. The resultant mechanism can predict a wide range of experimental results with the least cumulative error and will be a valuable tool in CFD simulations that will enable the development of gas turbines for zero-carbon power generation.
Development of Transonic Centrifugal Compressor With an Inducer Casing Bleed System
Authors: Erdem Erinc , Sepetci Kutmaral Gulsevim , Cay Seyfullah , Alican Ozan , Yazgan Bora , Arslan Ahmet
Published: August 2024

A transonic centrifugal compressor (MU2 > 1.5) is developed with an inducer bleed system. The configuration is comprised of an axial intake, an impeller and a vaned diffuser that are suited for high efficiency applications. Rig test data is based on performance rakes, wall static pressure taps distributed along static parts, dynamic pressure measurements at critical locations, etc. acquired at various rotational speeds. Impeller and diffuser performance are deduced and the inlet recirculation is observed upstream of the impeller from the test. Numerical method is validated against test data and different turbulence models are also tried. Inducer bleed system widens the flow range and improves stall margin, efficiency (by more than 5%) at low rotational speeds by correcting the incidence at the impeller inlet. On the other hand at design speed operations, choke margin is enhanced by the drawing air from the inducer port into the impeller. The benefit of the inducer bleed system is clearly shown in the results from the stall margin, efficiency and flow range standpoints. Impeller stall is entirely averted and vaned diffuser stall is observed in all occasions, in terms of choking, vaned diffuser is responsible for the entire range of operation.
Comparison of Geothermal Power Systems in Texas
Authors: Pryor Owen , Replogle Cole , Roddy Reese
Published: August 2024

The state of Texas has the highest renewable energy production in the United States with 31% of their total power generation from wind and solar resources. This study explores the ability to utilize geothermal energy as an underutilized resource in the state. Different cycle architectures and fluids have been compared given the specific geological conditions in the state. The cycle architectures include a supercritical carbon dioxide (sCO2) thermosiphon, a natural-convection-driven system utilizing the temperature gradient between the geological reservoir and the surface level power generation system, and water-brine binary simple cycle for both sCO2 and ORC systems. Four different fluids were assessed for the different architectures: sCO2, R134a, R-600a, and R-601a. The cycles were compared through the total power output for the cycles, the cooling duty required, the thermal efficiency and the exergetic efficiency for geothermal reservoir source temperatures between 100–200°C. The pressures and the flow rates were varied to maximize the variables of interest. The results show that all the architectures are viable for power production, but the sCO2 thermosiphon is least attractive due to the low flow rate achieved from natural convection alone. The ORC systems performed the best for low temperature reservoirs while the directly heated sCO2 system performed the best for the higher temperature reservoirs.
On the Predicted Effects of Recess Depth and Orifice Diameter on Pneumatic Hammer Instability in Hydrostatic Journal Bearings Using Compressible Fluid and Comparisons With Test Data
Authors: Jung Hyunsung , Kim Kyuman , Ryu Keun
Published: August 2024

Hydrostatic journal bearings (HJBs), employed in highspeed turbomachinery under extreme operating conditions, offer enhanced reliability, durability, load-carrying capacity, and stiffness, even when lubricated with low-viscosity fluids. A significant challenge with these bearings, particularly when deep recesses are involved and compressible fluids are used, is the occurrence of pneumatic hammer instability. This phenomenon poses a substantial risk, potentially leading to catastrophic system failures. The focus of this research is to quantify the influence of orifice diameter and recess depth on pneumatic hammer instability in HJBs. The study employs a predictive model, prioritizing the understanding and mitigation of this instability. Key to this research is the examination of volume and pressure ratios, particularly the recess volume to fluid film volume ratio and the recess pressure to supply pressure ratio. These ratios are fundamentally influenced by the orifice diameter and recess depth, which in turn significantly affect the HJBs’ characteristics and susceptibility to pneumatic hammer instability. The current study reveals that both the load-carrying capacity and flow rate of the bearings increase progressively with the recess pressure ratio. Meanwhile, the bearing stiffness peaks at a specific orifice diameter and recess depth, typically where the recess pressure ratio is around 0.6. Under these conditions, the bearings demonstrate maximum stiffness with minimized risk of instability. This research also proposes a framework for selecting design parameters in HJBs, aiming to maximize stiffness while averting pneumatic hammer instability. The effectiveness of these design strategies is validated through experimental data from two test bearings, each with different recess depths and orifice diameters. This work contributes significantly to the field by offering strategies for optimizing HJBs. It provides a balance between achieving high performance and mitigating the risks associated with pneumatic hammer instability. By careful selection of orifice diameter and recess depth, it is possible to attain maximum bearing performance, effectively circumventing the challenges posed by pneumatic hammer instability.
The NexGen Burner: Analysis of Turbulent Fuel-Air Mixing
Authors: Kamin Manu , Bravo Luis , Khare Prashant
Published: August 2024

Improving aircraft survivability in case of a fire is the key to improving safety. To achieve this goal, the Federal Aviation Administration (FAA) requires fire certification to determine the survivability of aircraft components in case of a fire. Any test environment used for certification must meet the temperature and heat flux requirements defined by federal regulations. To this end, the FAA is developing the NexGen burner in an attempt to standardize fire tests. In support of this effort, this paper describes a comprehensive computational investigation to identify the interactions between high-temperature air and (vaporizing) Jet A and its subsequent mixing with air in the NexGen burner. This is a sister paper to our previous article [1], where we discussed the dynamics of spray and swirling air under room temperature conditions. The burner consists of a draft tube, a stator that introduces swirl to the incoming air, a turbulator downstream of the stator to intensify turbulence, and a burner cone where Jet A fuel, injected through a Delavan type W nozzle at 2.5 Gph under room temperature conditions, vaporizes and subsequently burns. Air enters the burner at a velocity of 3.5 m/s at a temperature of 600 K; these conditions correspond to a Reynolds number of 26,872. The liquid jet is injected as a semi-hollow cone characterized by a sauter mean diameter of 38.0 microns. The gas phase is described in an Eulerian frame using a compressible large eddy simulation framework, and the discrete phase is modeled in the Lagrangian frame to simulate droplet kinematics, heating, and vaporization. Observations indicate that maximum vaporization occurs in the conical zone created by the semi-hollow spray cone. However, the vaporized fuel extends outward as a result of the expansion of the swirling core. A detailed turbulence budget analysis is conducted to discern energy transfers and interactions within the turbulent flow field. Turbulence production is observed to lead primarily to the generation of axial Reynolds normal stress Rxx. Furthermore, the correlation between pressure and strain rate plays an important role in coupling the axial Reynolds stress Rxx with the normal components Rrr and Rθθ, leading to a transfer of turbulent kinetic energy from the axial component to the azimuthal and radial components.
Design and Integration of a Microtube Precooler Into an Aircraft Engine Waste Heat Recovery and Fuel Systems
Authors: Bury Claire-Phonie , Vesely Ladislav , Kapat Jayanta , Shi Mingxuan , Stoia Michael
Published: August 2024

In the context of advancing aviation technology towards greater efficiency and reduced environmental impact, the design of a Microtube Precooler Heat Exchanger integrated with a Waste Heat Recovery System (WHRS) for a Jet Engine fuel system has emerged. The primary objective is to harness energy from the WHRS to preheat, NH3, ammonia before undergoing a cracking process, where it is decomposed into its constituent elements — nitrogen and hydrogen. The WHRS precooler design meets requirements for prolonged cruise operation, which ensures its robustness and viability across diverse operational regimes. The inlet parameters for the supercritical carbon dioxide (sCO2) side are derived from the results of a modified simple Brayton cycle analysis at the specified steady state operating condition. Concurrently, the demands of the ammonia side at this condition dictate the corresponding boundary conditions for effective heat transfer. The successful design and integration of this component is crucial because it enhances the overall efficiency of the jet engine and consequently reduces the carbon footprint.
Forecasting High Cycle and Very High Cycle Fatigue Through Enhanced Strain-Energy Based Fatigue Life Prediction
Authors: Celli Dino , Sheridan Luke , George Tommy , Warner Justin , Smith Lucas
Published: August 2024

This study applies a novel strain-energy based fatigue life prediction method to low cycle fatigue (LCF) data of conventionally wrought and additive manufactured (AM) Inconel 718 round dog-bones, specifically focusing on cycles to failure less than 105. The objective is to forecast high cycle fatigue (HCF, 106–107) and very high cycle fatigue (VHCF > 107), aiming to approximate stress versus cycles to failure (SN) behavior and the inherent variability in the fatigue life of the material system. This tool is motivated by the need to characterize an expanding and diverse array of materials produced by additive manufacturing methods, process modifications, and optimizations, which can significantly impact fatigue life and overall structural reliability. The fatigue life prediction method achieves this by generating a fatigue life distribution as a function of stress level. Bayesian statistical inference and stochastic sampling techniques are employed iteratively for each test data point, incorporating stress, cycles to failure, and total strain-energy dissipated leading to fatigue failure. Experimental LCF fatigue data are acquired using a standard axial servo-hydraulic load frame equipped with an axial extensometer for strain and strain-energy data collection. HCF and VHCF data is generated utilizing an ultrasonic fatigue test frame capable of cycling at 20kHz. The fatigue data obtained from both servo-hydraulic and ultrasonic fatigue testing are presented and compared. The energy-based fatigue life prediction framework, utilizing only LCF data, is deployed to forecast HCF and VHCF fatigue behavior for both conventionally wrought and AM Inconel 718 fatigue. The HCF and VHCF data generated are then used to validate the forecasts generated from the novel energy-based fatigue life prediction method. Comparisons are made against Random Fatigue Limit curve estimations to assess the effectiveness and accuracy of the proposed methodology.
Commissioning and Operation of an Inventory Management System
Authors: Warren Joshua , Khawly George
Published: August 2024

The DOE STEP 10 MWe Pilot Scale sCO2 Power Plant encompasses several pieces of turbomachinery that utilize dry gas seals to contain the process fluid. The system also has a large piping loop and multiple heat exchangers making it a large volume to fill with CO2. The plant requires an inventory management system (IMS) in order to supply the dry gas seal systems, fill the process volume, and allow for the system to change load while operating. The size of this system is important to have the ability to support the operation of the plant. In order to allow the plant to change load quickly, the pressure of the IMS needs to stay between the low pressure of the compressor suction and the high pressure of the compressor discharge. This allows the natural pressure differential to drive flow in and out of the IMS as the plant changes load. The major factor in changing load is the mass flow through the system. With CO2 near the critical point, the temperature of the tanks will be an important part of the design selection of the IMS volume required. In order to supply the dry gas seal systems when the machinery is stopped, there also needs to be a system to increase the pressure and drive flow to the dry gas seals. This paper will discuss the commissioning and operation of the IMS system in the STEP power plant.
Sweeping Jet Film Cooling Over the Suction Surface of HP Turbine NGV With Forward and Reversed Hole Configurations
Authors: Sharma Hitesh , Mistry Chetankumar S. , Roy Arnab
Published: August 2024

Film cooling is essential for the proper functioning and desired operation of modern gas turbine engines. In this study, numerical investigations were performed to study the effects of forward and reversed hole configurations on the performance of sweeping jet film cooling. A comparison of film cooling performance is presented for sweeping jet and straight jet over a flat plate with both forward and reversed configurations. Operating parameters were maintained for matching the real engine conditions with freestream Reynolds number of 1 × 106 and favorable pressure gradient of HP turbine NGV suction surface imposed on the flat plate. The blowing ratio (M) was varied in the range of 0.35 to 2.0, at a density ratio (DR) of 1.8 with an injection angle of 30° for both the steady and sweeping jet for each configuration. The results indicated that the sweeping jet with a reversed configuration provides the highest coolant coverage and the straight jet with a forward configuration provides the highest cooling effectiveness out of all the configurations. The averaged adiabatic film cooling effectiveness reduces with the blowing ratio for all the configurations except for the straight jet in the forward configuration. Sweeping jet and reversed configuration both are prone to higher diffusion of coolant stream as compared to straight jet and forward configuration comparatively. Instantaneous CRVP (contra-rotating vortex pairs) is detected in sweeping jet with a reversed hole configuration at a higher blowing ratio (M = 2.0).
Numerical Investigation on Mechanism and Modeling of Tip Leakage Flow Loss in Partially Shrouded Axial Flow Fans
Authors: Qin Jinkong , Hu Xiaowen , Wang Mingyi , Fan Hongzhou , Wang Zhiheng , Xi Guang
Published: August 2024

The Partially Shrouded Axial-Flow Fan (PSAFF), extensively used in air conditioning and various industrial settings, exhibits a unique design wherein the shroud encompasses only a portion of the blade tips. However, there is a research gap in comprehending the tip leakage flow (TLF) behavior and developing more accurate loss models for PSAFF. The study addresses the gap by conducting numerical simulations on several structures with isolated fixed blades that replicate PSAFF’s blade tip design, and performing numerical simulations over diverse attack angles, shrouded ratios, and tip clearance heights, the paper elucidates how PSAFF’s structural intricacies significantly influence TLF’s flow pattern. The results underscore that the distinctive flow configuration profoundly affects TLF’s genesis and progression. Furthermore, pronounced disparities exist in the intensity and distribution of TLF loss in PSAFF compared to conventional fans. The straightforward application of prevailing axial compressor blade tip leakage flow loss models to the PSAFF leads to considerable prediction discrepancies. To remedy this, the study introduces tailored structural factors peculiar to PSAFF, in conjunction with traditional semi-empirical models. The new model effectively forecasts the total pressure loss coefficient and its fluctuation across different attack angle, marking a substantial progress in precisely predicting TLF loss in PSAFF and surmounting the constraints of current models.
Blade Excitation Alleviation of a Nozzleless Radial Turbine by Casing Treatment Based on Reduced Order Model
Authors: Yang Mingyang , Lu Zhaokai , Sato Wataru , Kuwata Teppei
Published: August 2024

High cycle fatigue (HCF) is the most common form of blade failure in nozzleless radial turbines. Current studies relating to blade vibration reduction focus on redesign of blade and volute geometries. These methods have the drawbacks of time consuming, performance sacrifice and lack of generalizability. This paper investigates a novel flow control method for blade vibration reduction without sacrificing the aerodynamic performance based on a reduced order model. Firstly, the mechanism of the blade excitation is studied by the numerical method validated by experimental measurement. It is confirmed that the blade excitation is triggered by different mechanism between low- and high-pressure ratios. An equivalent excitation pressure is proposed to quantitatively evaluate vibration behaviors of the turbine blade. Based on the mechanism, a reduced order model is developed to predict the equivalent excitation pressure at high pressure ratio when the excitation is triggered mainly be the disturbance of potential flow field. The method of casing treatment is proposed inspired by the reduced order model and then optimized to attenuate the blade vibration. The experiment is carried out for the validation of the method and results show that the displacement of the vibration is reduce by 48% by this new method.
An Analytical Study on the Effect of Non-Uniform Vane Spacing on Forced Response Reduction in a Mistuned Blisk Rotor in a Multistage Axial Compressor
Authors: Leng Yujun , Dodda Jhansi R. , Key Nicole L.
Published: August 2024

Stators with non-uniform vane spacing (NUVS) have been sought as an effective way to reduce the rotor forced response at certain resonance crossing of concern. A comprehensive experimental study has been conducted in Purdue 3-stage axial research compressor to evaluate the effectiveness of NUVS stator on reducing the forced response of the downstream rotor using strain gage measurement. The experimental results showed that the classical estimation method failed to predict the reduction factor correctly, mainly due to the lack of consideration for the damping and mistuning effects.

To better understand the experimental results, and to provide an efficient and more accurate analysis tool for the rotor forced response under NUVS stator excitation, a detailed analytical study was conducted in this paper. The blade forced response was solved using an efficient, steady-state linearized approach. A single blade analysis was done first to study the effect of damping. The case studies show that higher damping causes more overlap of the blade forced response from adjacent engine order (EO) excitations and, thus, increases the total normalized blade response under NUVS stator excitation. A mistuned blisk aeroelastic model was introduced next, with the mistuning effect modelled using Fundamental Mistuning Model (FMM). Both structural coupling and aerodynamic coupling effects can be included in the aeroelastic model. Similar to the experimental results, the mistuned blisk case study shows a large blade-to-blade variation in the blade forced response under both symmetric and asymmetric NUVS stator excitation, even at a low, non-intentional mistuning level. A statistical study with 100 randomly generated mistuned blisks shows that the forced response reduction effect of a specific NUVS design could vary significantly with a small change of the mistuning pattern, which suggests that mistuning has to be carefully considered in the design, evaluation, and optimization of a NUVS stator.
Embedded real-time ultrasound-based multi-touch system
Authors: Bilodeau Maxime , Moriot Jérémy , Fréchette-Viens Joëlle , Bouchard Raphaël , Boulais Philippe , Quaegebeur Nicolas , Masson Patrice
Published: August 2024

In this paper, an active ultrasound-based touchscreen technology is presented for real-time monitoring of multiple contacts on a glass panel of 20 × 19 cm. Both fundamental Lamb wave modes are generated by sending a linear chirp between 50 and 100 kHz to a single piezoelectric ceramic lead zirconate titanate. Measurement is performed using four piezoelectric ceramic lead zirconate titanate elements, and real-time localization and detection are performed on a system on module i.MX 8 M Nano. Results show that Lamb waves can be used for real-time multi-touch detection and localization on both sides of the panel. Moreover, the prototype developed allows for relative pressure measurement.
Tumor-induced natural killer cell dysfunction is a rapid and reversible process uncoupled from the expression of immune checkpoints
Authors: Pouxvielh Kévin , Marotel Marie , Drouillard Annabelle , Villard Marine , Moreews Marion , Bossan Anna , Poiget Mathilde , Khoryati Liliane , Benezech Sarah , Fallone Lucie , Hamada Sarah , Rousseaux Noémi , Picq Louis , Rocca Yamila , Berton Aurore , Teixeira Marine , Mathieu Anne-Laure , Ainouze Michelle , Hasan Uzma , Fournier Alain , Thaunat Olivier , Marçais Antoine , Walzer Thierry
Published: August 2024

Natural killer (NK) cells often become dysfunctional during tumor progression, but the molecular mechanisms underlying this phenotype remain unclear. To explore this phenomenon, we set up mouse lymphoma models activating or not activating NK cells. Both tumor types elicited type I interferon production, leading to the expression of a T cell exhaustion-like signature in NK cells, which included immune checkpoint proteins (ICPs). However, NK cell dysfunction occurred exclusively in the tumor model that triggered NK cell activation. Moreover, ICP-positive NK cells demonstrated heightened reactivity compared to negative ones. Furthermore, the onset of NK cell dysfunction was swift and temporally dissociated from ICPs induction, which occurred as a later event during tumor growth. Last, NK cell responsiveness was restored when stimulation was discontinued, and interleukin-15 had a positive impact on this reversion. Therefore, our data demonstrate that the reactivity of NK cells is dynamically controlled and that NK cell dysfunction is a reversible process uncoupled from the expression of ICPs.
PneumaOCT: Pneumatic optical coherence tomography endoscopy for targeted distortion-free imaging in tortuous and narrow internal lumens
Authors: Zhang Tinghua , Yuan Sishen , Xu Chao , Liu Peng , Chang Hing-Chiu , Ng Sze Hang Calvin , Ren Hongliang , Yuan Wu
Published: August 2024

The complex anatomy of internal luminal organs, like bronchioles, poses challenges for endoscopic optical coherence tomography (OCT). These challenges include limited steerability for targeted imaging and nonuniform rotation distortion (NURD) with proximal scanning. Using rotary micromotors for distal scanning could address NURD but raises concerns about electrical safety and costs. We present pneumaOCT, the first pneumatic OCT endoscope, comprising a steerable catheter with a soft pneumatic actuator and an imaging probe with a miniature pneumatic turbine. With a diameter of 2.8 mm, pneumaOCT allows for a bending angle of up to 237°, facilitating navigation through narrow turns. The pneumatic turbine enables adjustable imaging speeds from 51 to 446 revolutions per second. We demonstrate the pneumaOCT in vivo imaging of mouse esophagus and colon, as well as targeted and distortion-free imaging of peripheral bronchioles in a bronchial phantom and a porcine lung. This advancement substantially improves endoscopic OCT for navigational imaging in curved and narrow lumens.
Fluoroamphiphilic polymers exterminate multidrug-resistant Gram-negative ESKAPE pathogens while attenuating drug resistance
Authors: Zhou Qian , Li Kunpeng , Wang Kun , Hong Weilin , Chen Jingjie , Chai Jin , Yu Luofeng , Si Zhangyong , Li Peng
Published: August 2024

ESKAPE pathogens are a panel of most recalcitrant bacteria that could “escape” the treatment of antibiotics and exhibit high incidence of drug resistance. The emergence of multidrug-resistant (MDR) ESKAPE pathogens (particularly Gram-negative bacteria) accounts for high risk of mortality and increased resource utilization in health care. Worse still, there has been no new class of antibiotics approved for exterminating the Gram-negative bacteria for more than 50 years. Therefore, it is urgent to develop novel antibacterial agents with low resistance and potent killing efficacy against Gram-negative ESKAPE pathogens. Herein, we present a class of fluoropolymers by mimicking the amphiphilicity of cationic antimicrobial peptides. Our optimal fluoroamphiphilic polymer (PD
45
HF
5
) displayed selective antimicrobial ability for all MDR Gram-negative ESAKPE pathogens, low resistance, high in vitro cell selectivity, and in vivo curative efficacy. These findings implied great potential of fluoroamphiphilic cationic polymers as promising antibacterial agents against MDR Gram-negative ESKAPE bacteria and alleviating antibiotic resistance.
Online tree-based planning for active spacecraft fault estimation and collision avoidance
Authors: Ragan James , Riviere Benjamin , Hadaegh Fred Y. , Chung Soon-Jo
Published: August 2024

Autonomous robots operating in uncertain or hazardous environments subject to state safety constraints must be able to identify and isolate faulty components in a time-optimal manner. When the underlying fault is ambiguous and intertwined with the robot’s state estimation, motion plans that discriminate between simultaneous actuator and sensor faults are necessary. However, the coupled fault mode and physical state uncertainty creates a constrained optimization problem that is challenging to solve with existing methods. We combined belief-space tree search, marginalized filtering, and concentration inequalities in our method, safe fault estimation via active sensing tree search (s-FEAST), a planner that actively diagnoses system faults by selecting actions that give the most informative observations while simultaneously enforcing probabilistic state constraints. We justify this approach with theoretical analysis showing s-FEAST’s convergence to optimal policies. Using our robotic spacecraft simulator, we experimentally validated s-FEAST by safely and successfully performing fault estimation while on a collision course with a model comet. These results were further validated through extensive numerical simulations demonstrating s-FEAST’s performance.
Automated calculation and reporting of vancomycin area under the concentration–time curve: a simplified single-trough concentration-based equation approach
Authors: Kim Hyun-Ki , Jeong Tae-Dong , Ji Misuk , Kim Sollip , Lee Woochang , Chun Sail
Published: August 2024

Vancomycin, a crucial antibiotic for Gram-positive bacterial infections, requires therapeutic drug monitoring (TDM). Contemporary guidelines advocate for AUC-based monitoring; however, using Bayesian programs for AUC estimation poses challenges. We aimed to develop and evaluate a simplified AUC estimation equation using a steady-state trough concentration (C
trough
) value. Utilizing 1,034 TDM records from 580 general hospitalized patients at a university-affiliated hospital in Ulsan, we created an equation named SSTA that calculates the AUC by applying C
trough
, body weight, and single dose as input variables. External validation included 326 records from 163 patients at a university-affiliated hospital in Seoul (EWUSH) and literature data from 20 patients at a university-affiliated hospital in Bangkok (MUSI). It was compared with other AUC estimation models based on the C
trough
, including a linear regression model (LR), a sophisticated model based on the first-order equation (VancoPK), and a Bayesian model (BSCt). Evaluation metrics, such as median absolute percentage error (MdAPE) and the percentage of observations within ±20% error (P20), were calculated. External validation using the EWUSH data set showed that SSTA, LR, VancoPK, and BSCt had MdAPE values of 6.4, 10.1, 6.6, and 7.5% and P20 values of 87.1, 82.5, 87.7, and 83.4%, respectively. External validation using the MUSI data set showed that SSTA, LR, and VancoPK had MdAPEs of 5.2, 9.4, and 7.2%, and P20 of 95, 90, and 95%, respectively. Owing to its decent AUC prediction performance, simplicity, and convenience for automated calculation and reporting, SSTA could be used as an adjunctive tool for the AUC-based TDM.
Mo-doped LiNi0.8Co0.1Mn0.1O2 cathode materials with improved performance for lithium ion batteries
Authors: Feng Shanzhi , Song Cunhong , Huang Juntong , Zeng Haijun , Chen Zhi , He Xiaoshu , Li Xibao , Feng Zhijun
Published: August 2024

The high nickel ternary LiNi[Formula: see text]Co[Formula: see text]Mn[Formula: see text]O2 (NCM811) cathode material has attracted much attention owing to its advantages of high capacity and low price. However, NCM811 suffers from surface side reactions and cation mixing, which results in an unstable crystal structure and lower Coulomb efficiency and capacity in lithium ion batteries. In this work, Mo-doped cathode material NCM811 is effectively synthesized by high-temperature solidification approach. The characterization results show that the doped NCM811 can form a coating layer on the surface, preventing electrolyte side reactions with the electrode. As the cathode for lithium ion batteries, the Mo-doped NCM811 electrode shows an initial discharge capacity of 185.21[Formula: see text]mAh/g and obtains 156.33[Formula: see text]mAh/g with a capacity retention of 84.5% after 100 cycles at 1C. This study provides a simple and reliable method of fabricating high-performance NCM811 cathode materials.
Real-time SERS analysis of programmed cell death patterns based on black Phosphorus–gold nanoparticles
Authors: Chen Jieyi , Ye Binggang , Fan Ranran , Liu Jiaqi , Han Yaru , Chen Haolin , Zhang Wen , Guo Zhouyi , Liu Zhiming , Zhong Huiqing
Published: August 2024

Programmed cell death (PCD) plays a crucial role in the biological processes of living organisms and occurs in various forms, such as apoptosis, necroptosis and ferroptosis. However, traditional methods for PCD analysis are time-consuming and complex. In this paper, we propose a facile surface-enhanced Raman spectroscopy (SERS)-based strategy for the real-time analysis of three PCD patterns utilizing black phosphorus–gold nanoparticles (BP–Au NPs) as the ultrasensitive unlabeled Raman probe. BP–Au NPs, which possess excellent biocompatibility, are capable of detecting dye molecules at concentrations as low as [Formula: see text][Formula: see text]M and remain stable for at least one week in different physiological environments. In view of this, BP–Au NPs-based SERS technique can distinguish the tiny differences in the molecular fingerprints of cancer cells undergoing three PCD patterns (apoptosis, necroptosis and ferroptosis) triggered by doxorubicin, shikonin and erastin, respectively. We also have real-time monitoring of the intracellular molecular events during PCD, which spy the fluctuations of some typical SERS bands assigned to protein, DNA and lipid, revealing the unique phenotypic characteristics of each PCD pattern. This strategy provides a detailed and comprehensive analysis of the mechanisms of drug-induced PCD at the Raman level.
ProcessGAN: Generating Privacy-Preserving Time-Aware Process Data with Conditional Generative Adversarial Nets
Authors: Li Keyi , Yang Sen , Sullivan Travis M. , Burd Randall S. , Marsic Ivan
Published: August 2024

Process data constructed from event logs provides valuable insights into procedural dynamics over time. The confidential information in process data, together with the data’s intricate nature, makes the datasets not sharable and challenging to collect. Consequently, research is limited using process data and analytics in the process mining domain. In this study, we introduced a synthetic process data generation task to address the limitation of sharable process data. We introduced a generative adversarial network, called ProcessGAN, to generate process data with activity sequences and corresponding timestamps. ProcessGAN consists of a transformer-based network as the generator, and a time-aware self-attention network as the discriminator. It can generate privacy-preserving process data from random noise. ProcessGAN considers the duration of the process and time intervals between activities to generate realistic activity sequences with timestamps. We evaluated ProcessGAN on five real-world datasets, two that are public and three collected in medical domains that are private. To evaluate the synthetic data, in addition to statistical metrics, we trained a supervised model to score the synthetic processes. We also used process mining to discover workflows for synthetic medical processes and had domain experts evaluate the clinical applicability of the synthetic workflows. ProcessGAN outperformed the existing generative models in generating complex processes with valid parallel pathways. The synthetic process data generated by ProcessGAN better represented the long-range dependencies between activities, a feature relevant to complicated medical and other processes. The timestamps generated by the ProcessGAN model showed similar distributions with the authentic timestamps. In addition, we trained a transformer-based network to generate synthetic contexts (e.g., patient demographics) that were associated with the synthetic processes. The synthetic contexts generated by our model outperformed the baseline models, with the distributions similar to the authentic contexts. We conclude that ProcessGAN can generate sharable synthetic process data indistinguishable from authentic data. Our source code is available in
https://github.com/raaachli/ProcessGAN
.
Enhanced ECCD36 signaling promotes skeletal muscle insulin resistance in female mice
Authors: Dada Austin , Habibi Javad , Naz Huma , Chen Dongqing , Lastra Guido , Bostick Brian P. , Whaley-Connell Adam , Hill Michael A. , Sowers James R. , Jia Guanghong
Published: August 2024

ECCD36 exerts “extra endothelial cell” actions in skeletal muscle insulin resistance. ECCD36 is a major mediator of Western diet-induced lipid metabolic disorders and insulin resistance in skeletal muscle. Mitochondrial dysfunction is associated with diet-induced CD36 activation and related skeletal muscle insulin resistance.
The effect of repetitive magnetic stimulation on neuronal apoptosis and PI3K/Akt protein expression in rats with incomplete spinal cord injury
Authors: Su Junhong , Zhou Fujian , Hu Mengxuan , Xu Qingqin , Huang Ying , Chen Shi , Zhou Hongwei , Chen Hemu
Published: August 2024

Spinal cord injury is a serious disabling central nervous system disease. Recently, research on magnetic stimulation therapy for spinal cord injury has been increasing, and its potential has gradually attracted the attention of experts. This study found that repetitive magnetic stimulation (rMS) can improve motor function and reduce neuronal apoptosis in spinal cord injury rats. The mechanism may be related to increasing the expression of phosphatidylinositol-3 kinase (PI3K)/Akt protein, thereby inhibiting cell apoptosis and promoting neuronal survival.
Bidirectional generative adversarial representation learning for natural stimulus synthesis
Authors: Reilly Johnny , Goodwin John D. , Lu Sihao , Kozlov Andriy S.
Published: August 2024

A new type of artificial neural network is presented that can be used to generate animal vocalization waveforms and interpolate between them to create new vocalizations. We find that our synthetic naturalistic stimuli drive auditory cortical neurons in the mouse equally well and produce receptive field features with the same predictive power as those obtained with natural mouse vocalizations, confirming the quality of the stimuli produced by the neural network.
Upward Bullying as Experienced by Chinese Nurse Managers: A Qualitative Study
Authors: He Jia , Wang Yuhan , Wang Yangjing , Guo Xueqin , Li Xin , Jin Huan , Xiong Lijuan
Published: August 2024

Aim. To understand the current situation of upward bullying in the Chinese nursing field and explore the manifestations, reasons, and outcomes of upward bullying experienced by Chinese nurse managers. Background. Workplace bullying, a serious social problem, is characterised by recurring incidents of intimidating, aggressive, and hostile behaviour. Bullying in the nursing profession exhibits all or some of the above traits. The evidence of upward bullying by subordinate nurses against nurses in positions of authority or power is limited in China. Methods. This qualitative study was conducted with semistructured, in‐depth interviews involving 12 hospital nurse managers in Wuhan, Hubei Province, between June and August 2023. The data were analysed using the Colaizzi seven‐step analysis method with Nvivo 12.0 software as a support. Results. We grouped our findings into three main categories: manifestations of upward bullying; reasons for upward bullying; and outcomes of upward bullying. Conclusions. Nurse managers in China are exposed to upward bullying in many forms and for complex reasons. More emphasis needs to be given to creating a positive work environment for them to facilitate their managerial role. Implications for Nursing Management. This study probes the realities of upward bullying against Chinese nurse managers and highlights the need for managers to develop the skills needed to identify, manage, and prevent bullying from subordinates. By contributing to the development of interventions and strategies that address workplace bullying, this study shows promise for enhancing managerial effectiveness and improving the nursing practice environment.