bluuebunny/crossref_metadata_2025 huggingface dataset:
What we still don't know about weed diversity: A scoping review
Authors: Westbrook Anna S. , Wilcox Natalie Rose K. , Stup Rebecca S. , Xu Sky , Djuric Natasha , Coffey Ryleigh E. , Özaslan Cumali , Xia Rosa H. , Urmaza Serafinn , Sher Micah A. , DiTommaso Antonio
Published: September 2024

Increased agricultural weed diversity is associated with reduced dominance of competitive weeds that reduce crop yields. In addition, diverse weed communities can promote biodiversity at other trophic levels and enhance ecosystem services. For both reasons, there is increasing interest in the relationship between agricultural management and weed diversity. Existing information in this area is limited, relative to the large number of influential factors, but knowledge is increasing rapidly. We conducted a scoping review to determine when, where, and how weed diversity has been evaluated in relation to management. From an initial set of 10 236 items retrieved from Web of Science and Scopus, 7198 were screened and 331 were included. The median publication year was 2015. Nearly half of all studies were conducted in Europe (n = 161, 49%). Organic cropping systems were included in 48 studies (15%). Tillage was the most common management factor (n = 111, 34%), followed by crop rotation (n = 73, 22%). There were 135 studies in which management factors were implemented for six or more years (41%). Most studies included measurements of species richness (n = 265, 80%) and/or Shannon–Wiener diversity (n = 145, 44%). Overall, this review identified a small and heterogenous—but quickly growing—body of literature on weed diversity. Priority areas for future research should include weed diversity beyond field crops in temperate environments, weed seedbanks, functional diversity, and best practices for measuring weed diversity.
Writing Script and Audio Production: Movement to Strengthen Javanese Radio Drama in Yogyakarta, Indonesia
Authors: Suwondo Tirto , Zamzuri Ahmad , Satiyoko Yohanes Adhi , Murdowo Drajat Agus , Yono Sri , Sumiyardana Kustri , Sudaryani Rina Ratih Sri
Published: September 2024

This study aims to gain a deep understanding of the subjective experiences of participants who are directly involved in the strengthening movement to uncover the development of Javanese radio dramas in Yogyakarta. Due to the abstract nature of the data, including people's experiences in drama radio and radio broadcast fields, this study employs the interpretative phenomenological approach (IPA) to explore and understand these experiences. We used IPA to process qualitative data from interviews with nine participants who were actively involved in strengthening Javanese radio dramas. The study's findings indicate that participants' subjective experiences in the reinforcement movement provide an overview of the positive development of Javanese radio dramas. Several actions, such as raising awareness, writing scripts (through workshops and competitions), nurturing talent, producing audio, evaluating, and enhancing the community's role, sparked this development. These actions encourage the manager's optimism about restoring Javanese dramas as an important part of the Javanese people's identity. This research not only helps policymakers re-evaluate local cultural preservation and development programs, but it also opens up space for cultural movers in general to find alternative ways to prevent the degradation of Javanese culture in the digital era.
Deloopings of Hurwitz spaces
Authors: Bianchi Andrea
Published: September 2024

For a partially multiplicative quandle (PMQ) ${\mathcal {Q}}$ we consider the topological monoid $\mathring {\mathrm {HM}}({\mathcal {Q}})$ of Hurwitz spaces of configurations in the plane with local monodromies in ${\mathcal {Q}}$. We compute the group completion of $\mathring {\mathrm {HM}}({\mathcal {Q}})$: it is the product of the (discrete) enveloping group ${\mathcal {G}}({\mathcal {Q}})$ with a component of the double loop space of the relative Hurwitz space $\mathrm {Hur}_+([0,1]^2,\partial [0,1]^2;{\mathcal {Q}},G)_{\mathbb {1}}$; here $G$ is any group giving rise, together with ${\mathcal {Q}}$, to a PMQ–group pair. Under the additional assumption that ${\mathcal {Q}}$ is finite and rationally Poincaré and that $G$ is finite, we compute the rational cohomology ring of $\mathrm {Hur}_+([0,1]^2,\partial [0,1]^2;{\mathcal {Q}},G)_{\mathbb {1}}$.
On the Gross–Prasad conjecture with its refinement for (SO(5), SO(2)) and the generalized Böcherer conjecture
Authors: Furusawa Masaaki , Morimoto Kazuki
Published: September 2024

We investigate the Gross–Prasad conjecture and its refinement for the Bessel periods in the case of $(\mathrm {SO}(5), \mathrm {SO}(2))$. In particular, by combining several theta correspondences, we prove the Ichino–Ikeda-type formula for any tempered irreducible cuspidal automorphic representation. As a corollary of our formula, we prove an explicit formula relating certain weighted averages of Fourier coefficients of holomorphic Siegel cusp forms of degree two, which are Hecke eigenforms, to central special values of $L$-functions. The formula is regarded as a natural generalization of the Böcherer conjecture to the non-trivial toroidal character case.
A Hamiltonian ∐nBO(n)-action, stratified Morse theory and the J-homomorphism
Authors: Jin Xin
Published: September 2024

We use sheaves of spectra to quantize a Hamiltonian $\coprod _n BO(n)$-action on $\varinjlim _{N}T^*\mathbf {R}^N$ that naturally arises from Bott periodicity. We employ the category of correspondences developed by Gaitsgory and Rozenblyum [A study in derived algebraic geometry, vol. I. Correspondences and duality, Mathematical Surveys and Monographs, vol. 221 (American Mathematical Society, 2017)] to give an enrichment of stratified Morse theory by the $J$-homomorphism. This provides a key step in the work of Jin [Microlocal sheaf categories and the$J$-homomorphism, Preprint (2020), arXiv:2004.14270v4] on the proof of a claim of Jin and Treumann [Brane structures in microlocal sheaf theory, J. Topol. 17 (2024), e12325]: the classifying map of the local system of brane structures on an (immersed) exact Lagrangian submanifold $L\subset T^*\mathbf {R}^N$ is given by the composition of the stable Gauss map $L\rightarrow U/O$ and the delooping of the $J$-homomorphism $U/O\rightarrow B\mathrm {Pic}(\mathbf {S})$. We put special emphasis on the functoriality and (symmetric) monoidal structures of the categories involved and, as a byproduct, we produce several concrete constructions of (commutative) algebra/module objects and (right-lax) morphisms between them in the (symmetric) monoidal $(\infty, 2)$-category of correspondences, generalizing the construction out of Segal objects of Gaitsgory and Rozenblyum, which might be of independent interest.
Improved algebraic fibrings
Authors: Fisher Sam P.
Published: September 2024

We show that a virtually residually finite rationally solvable (RFRS) group $G$ of type $\mathtt {FP}_n(\mathbb {Q})$ virtually algebraically fibres with kernel of type $\mathtt {FP}_n(\mathbb {Q})$ if and only if the first $n$$\ell ^2$-Betti numbers of $G$ vanish, that is, $b_p^{(2)}(G) = 0$ for $0 \leqslant p \leqslant n$. This confirms a conjecture of Kielak. We also offer a variant of this result over other fields, in particular in positive characteristic. As an application of the main result, we show that amenable virtually RFRS groups of type $\mathtt {FP}(\mathbb {Q})$ are virtually Abelian. It then follows that if $G$ is a virtually RFRS group of type $\mathtt {FP}(\mathbb {Q})$ such that $\mathbb {Z} G$ is Noetherian, then $G$ is virtually Abelian. This confirms a conjecture of Baer for the class of virtually RFRS groups of type $\mathtt {FP}(\mathbb {Q})$, which includes (for instance) the class of virtually compact special groups.
Computational modelling of mouse atrio ventricular node action potential and automaticity
Authors: Bartolucci Chiara , Mesirca Pietro , Ricci Eugenio , Sales‐Bellés Clara , Torre Eleonora , Louradour Julien , Mangoni Matteo Elia , Severi Stefano
Published: September 2024

The atrioventricular node (AVN) is a crucial component of the cardiac conduction system. Despite its pivotal role in regulating the transmission of electrical signals between atria and ventricles, a comprehensive understanding of the cellular electrophysiological mechanisms governing AVN function has remained elusive. This paper presents a detailed computational model of mouse AVN cell action potential (AP). Our model builds upon previous work and introduces several key refinements, including accurate representation of membrane currents and exchangers, calcium handling, cellular compartmentalization, dynamic update of intracellular ion concentrations, and calcium buffering. We recalibrated and validated the model against existing and unpublished experimental data. In control conditions, our model reproduces the AVN AP experimental features, (e.g. rate = 175 bpm, experimental range [121, 191] bpm). Notably, our study sheds light on the contribution of L‐type calcium currents, through both Cav1.2 and Cav1.3 channels, in AVN cells. The model replicates several experimental observations, including the cessation of firing upon block of Cav1.3 or INa,r current. If block induces a reduction in beating rate of 11%. In summary, this work presents a comprehensive computational model of mouse AVN cell AP, offering a valuable tool for investigating pacemaking mechanisms and simulating the impact of ionic current blockades. By integrating calcium handling and refining formulation of ionic currents, our model advances understanding of this critical component of the cardiac conduction system, providing a platform for future developments in cardiac electrophysiology.

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Key points

This paper introduces a comprehensive computational model of mouse atrioventricular node (AVN) cell action potentials (APs).

Our model is based on the electrophysiological data from isolated mouse AVN cells and exhibits an action potential and calcium transient that closely match the experimental records.

By simulating the effects of blocking specific ionic currents, the model effectively predicts the roles of L‐type Cav1.2 and Cav1.3 channels, T‐type calcium channels, sodium currents (TTX‐sensitive and TTX‐resistant), and the funny current (If) in AVN pacemaking.

The study also emphasizes the significance of other ionic currents, including IKr, Ito, IKur, in regulating AP characteristics and cycle length in AVN cells.

The model faithfully reproduces the rate dependence of action potentials under pacing, opening the possibility of use in impulse propagation models.

The population‐of‐models approach showed the robustness of this new AP model in simulating a wide spectrum of cellular pacemaking in AVN.
Studies of the Thermalhydraulics Subchannel Code ASSERT-PV 3.2-SC for Supercritical Applications
Authors: Nava-Dominguez Armando , Huang Xianmin , Liu Songyu
Published: September 2024

Over the last decade, several international thermalhydraulics benchmarking efforts have been carried out to support the development of the Generation IV supercritical water-cooled reactor (SCWR) concept. These benchmarking efforts aimed to assess the readiness of computer codes to predict the thermalhydraulics behavior of supercritical fluids for nuclear fuel assembly applications. The results from the benchmarking also shed light on knowledge gaps. Throughout the years, several advancements in this area have been achieved, resulting in relevant conclusions and observations. Furthermore, experimental campaigns have been carried out worldwide to further our knowledge on the thermalhydraulics of supercritical fluids. The nuclear industry uses the subchannel approach to study the thermalhydraulics behavior of nuclear fuel assemblies in detail. In Canada, the subchannel code advanced solution of subchannel equations in reactor thermalhydraulics—pressure velocity (ASSERT-PV) is the qualified code for subchannel applications. ASSERT-PV was modified to handle supercritical conditions, resulting in an interim code version. This publication presents relevant subchannel analyses using the interim supercritical version of ASSERT-PV for fuel assemblies cooled with supercritical fluids.
Study of the Mechanism of Perceived Rotational Acceleration of a Bionic Semicircular Canal on the Basis of the “Circular Geometry Hypothesis”
Authors: Bian Yixiang , Liu Wujie , Dai Junjie , Wen Xianhua , Jiang Yani
Published: September 2024

Academia often uses the “circular geometry hypothesis” to explain the sensing principle of the human semicircular canal (SCC) system for angular acceleration, which is widely accepted as an important angular acceleration sensor in the human balance system. On the basis of this hypothesis and the anatomical structure of human SCCs, a series of physical SCC models with different geometries at 4× magnification were prepared via three-dimensional printing and modification of hydrogels. Theoretical models of the SCC perception mechanism were established. Then, impulse angular acceleration, sinusoidal rotation, and sinusoidal linear stimulation were applied to the models, and their responses were visually observed and analyzed in detail. As a result, the circular SCC model had a larger system gain and a smaller phase difference for angular acceleration stimulation but a smaller system gain and a larger phase difference for linear acceleration stimulation. These results verified that the circular semicircular canal was more sensitive to angular acceleration. Our bionic model is hoped to be used for demonstrating the human SCC working process, facilitating researchers in better understanding of the working mechanism of the human SCC, or as a manual model for medical staff to simulate the diagnosis and treatment of human SCC.
Influences of Tooth Crack on Dynamic Characteristics of a Multi-Stage Gear Transmission System Considering the Flash Temperature
Authors: Zhang Xu , Li Qiu , Li Hongwei
Published: September 2024

The crack failure is prone to happen for the gear teeth under alternating loads. The crack reduces the time-varying meshing stiffness, thus causing changes in the system vibration responses. Moreover, the tooth friction leads to the flash temperature on the tooth surface, and the flash temperature causes the deformation of the tooth profile. The flash temperature stiffness generated by this deformation is an important component of the resultant meshing stiffness, and inevitably influences the dynamic characteristics. Hence, this paper makes an effort to provide a clear understanding of the relationship between the tooth crack and nonlinear dynamics for a multistage gear transmission system considering the flash temperature in a mixed friction state. The time-varying meshing stiffness and flash temperature stiffness are separately calculated using the potential energy method and Hertz's theory, and the torsional dynamic model is established by the lumped mass method for the system with high-speed driving gear crack in the mixed friction state. The influences of the flash temperature and crack on the dynamic behaviors are studied through a bifurcation diagram, frequency spectrum, phase portrait, and Poincare map, and the frequency spectra of numerical simulation and experimental testing are compared. The results indicate that both flash temperature and tooth crack decrease the time-varying meshing stiffness, the flash temperature increases the displacement amplitude of chaotic motion, and the tooth crack enlarges the interval of chaotic motion. Meanwhile, the results provide a suitable meshing frequency, which puts the system in a stable working state. The research provides significant guidance for monitoring the crack fault of multistage gear transmission systems.
Navigating Technological Risks: An Uncertainty Analysis of Powertrain Technology in Hybrid-Electric Commuter Aircraft
Authors: Diamantidou Dimitra-Eirini , Soibam Jerol , Zaccaria Valentina , Kalfas Anestis I.
Published: September 2024

This study addresses the uncertainties in hybrid-electric powertrain technology for a 19-passenger commuter aircraft, focusing on two future Entry-Into-Service timeframes: 2030 and 2040. The methodology is split into a preliminary optimization of aircraft design based on nominal technology scenarios followed by Monte Carlo simulations to investigate the impact of diverse technology projections and distribution types. Advanced surrogate modeling techniques, leveraging deep neural networks (DNN) trained on a dataset from an aircraft design framework, are employed. Key outcomes from this work reveal a marked increase in computational efficiency, with a speed-up factor of approximately 500 times when utilizing surrogate models. The results indicate that the 2040 entry-into-service (EIS) scenario could achieve larger reductions in fuel and total energy consumption—20.4% and 15.8% respectively—relative to the 2030 scenario, but with higher uncertainty. Across all scenarios examined, the hybrid-electric model showcased superior performance compared to its conventional counterpart. The battery-specific energy density is proved to be a critical parameter of the aircraft’s performance across both timeframes. The findings emphasize the importance of continuous innovation in battery and motor technologies to target toward greater system-level efficiency and reduced environmental impact.
Aerodynamic Feasibility Investigation of the Novel Experimental Rig on Turbine Blade Tip With High Relative Motion
Authors: Peng X. , Jiang H. , Lu S. , Zhang Z.
Published: September 2024

The relative casing motion can significantly alter the over-tip-leakage (OTL) flow aerodynamic performances. Traditional tip experimental facilities for relative motion researches, including stationary linear cascade with low-speed moving belt, annular cascade with rotating outer wall, and full-scale experimental rig with rotating blade, were either extremely costly or not capable to reproduce engine-representative casing Mach number. Very recently, a novel design concept for high-speed disk rotor rig has been proposed for tip research. Subsequent to this research, the present study evaluates the aerodynamic performances and the periodicity of the disk rotor rig design using Reynolds-averaged Navier–Stokes computational fluid dynamics simulation. Furthermore, first-of-its-kind experimental results of total pressure loss distributions measured by five-hole probe under high relative casing Mach number are reported. The results demonstrate the applicability of the disk rotor experimental rig for tip aerodynamic investigations.
Investigation of Flame Response in a Swirling Micromix Hydrogen–Methane Combustor
Authors: Liu Dewen , Feng Zhenzhen , Tian Xiaojing , Xu Liangliang , Gu Mingming , Lin Yang , Xia Xi , Qi Fei
Published: September 2024

Hydrogen-enriched natural gas combustion is a hot topic in industrial and academic communities due to the need for carbon emission reduction. However, thermoacoustic instability poses a major challenge for lean combustion development, particularly the higher frequency combustion oscillations. This study investigates the flame response in micromix hydrogen/methane flames within a low to medium frequency range of 50–1200 Hz, revealing a critical mixing ratio. Above this threshold, the flame response is dominated by hydrogen combustion, whereas below it, methane combustion takes precedence. Overall speaking, the hydrogen addition significantly enlarges the low-pass filter limit of the flame transfer function (FTF). Simultaneous OH* chemiluminescence and particle image velocimetry (PIV) experiments demonstrate that the gain is associated with the flame size and the number of acoustic-induced vortices on the flame surface. Higher frequency acoustic forcing leads to flame responses out of phase at different longitudinal positions, resulting in a low global flame response. Hydrogen addition reduces the flame length and enhances the FTF gain at specific frequencies.
Numerical Study of Low Engine Order Excitations Due to Manufacturing Variability Part II: An Efficient Approach for Stochastic Studies
Authors: Gallardo Juan Manuel , Escobar Óscar Pérez
Published: September 2024

In turbomachinery rows, the geometric variability between the airfoils induces nonuniformity in the flow, which directly translates into low engine order (LEO) excitation and vibration in the adjacent rows. Direct simulations of this phenomenon involve full-row computational fluid dynamics (CFD) analyses, where the exact geometry of each individual blade needs to be properly reproduced. The related computational cost of such simulations is very significant. Since the geometric variability due to the manufacturing scatter is stochastic, valuable information could be derived from Monte Carlo analyses involving randomly generated geometries; nevertheless, this approach would be very resource-intensive. In this paper, we propose a simplified method to determine the flow perturbation generated by this geometric variability. The method is based on studying the underlying properties of the geometric scatter using principal component analysis (PCA) techniques, obtaining a compact description of the variability of the airfoils. The flow perturbation due to a reduced number of reference cases is obtained through direct, large scale simulations. By assuming linearity in the flow perturbations, the solution for a general case of geometric distortion may be obtained very efficiently from these reference cases, which makes Monte Carlo studies to analyze stochastic geometric distortion easily affordable. The capabilities of the method are demonstrated in a test case considering the real geometry scatter from an aircraft turbine. According to the results, the average LEO response due to the random geometry scatter involves significant vibration levels, comparable (in terms of alternating stress) to the response due to the blade-passing excitation.
Dynamic Response of a Rotor Supported on Hybrid Bearings in Air, Water, and Liquid Nitrogen: Measurements and Comparisons to Predictions
Authors: Yi Howon , Kim Kyuman , Jung Hyunsung , Ryu Keun
Published: September 2024

Modern liquid rocket engine turbopumps implement hybrid bearings, which combine hydrostatic and hydrodynamic fluid film principles, in compact and lightweight units known for their superior reusability, durability, and reliability. This study aims to provide extensive and reliable test data for the purpose of anchoring and benchmarking predictive tools for these bearings. This paper provides comprehensive dynamic response measurements of a rotor weighing 10.40 kg and approximately 60 mm in diameter at the bearing locations. The test rotor is supported on two hybrid journal bearings with a bearing length to bearing diameter ratio of approximately 0.42 and a bearing radial clearance to rotor radius ratio of around 0.0017. The bearings are tested with air, water, and liquid nitrogen, serving as surrogate test fluids for common propellants in liquid rocket engines. Rotor run-up and speed coast-down tests are conducted to measure shaft motion responses. The results clearly demonstrate that the rotordynamic characteristics of the test rotor supported on the hybrid journal bearings largely rely on properties of the test fluids and their feeding conditions. Notably, when air is pressurized into the test bearings, the shaft motion responses differ markedly from those observed with water and liquid nitrogen, primarily due to significantly lower stiffness and damping coefficients. Furthermore, rotor speed coast-down tests for each test fluid exhibit notable differences in coast-down speed over time characteristics, depending on the test fluid properties. The predicted rotor imbalance responses exhibit excellent correlation with the measurement data. The steady increase of demand and growth of the fluid film bearing technology for reusable rocket engines require accurate bearing design tools, the extensive component testing, and the implementation of the technology. The validated and developed bearing predictive models from previous research demonstrate well the characteristics of bearings under various operating fluids conditions. The findings and database presented in this work contribute not only to comprehending the performance of hybrid bearings but also to understanding and enhancing the dynamic characteristics of rotor systems supported on hybrid bearings.
Isothermal Flow Field Characterization of a Full-Scale Sector Combustor at Elevated Pressures
Authors: Rathod Darshan D. , Kumar Sonu , Chaudhuri Swetaprovo , Panda Pratikash , Basu Saptarshi
Published: September 2024

An experimental investigation in a sector (20 deg) of full-scale annular gas turbine combustor is performed. The sector combustor is optically accessible for the flow and flame visualization of the primary and exit zones of the combustor. The distinctive feature of the experimental setup is that it preserves the geometrical details of an annular combustor that includes the casing, dome and combustor liner. The combustor design features a series of primary and secondary dilution holes with multiple film cooling strips on the outer and inner liner. In the present study, the combustor is operated at inlet Mach numbers of 0.02–0.3 at operating absolute pressures of 1–5 bar. Static pressure measurements are performed at multiple locations in the rig to characterize the pressure drop across the combustor. Two-dimensional particle image velocimetry (PIV) is performed to measure the velocity fields of the primary and exit zones of the combustor simultaneously. The results show the presence of a central recirculation zone (CRZ), high-velocity annular jets, and a pair of dilution jets in the primary zone of the combustor. The steady-state flow structures are invariant of inlet Mach number and pressures. The relationship between the relative pressure drop across the combustor and the combustor inlet condition is obtained. Mass flowrate and momentum flux are calculated for the flow through the swirler, central recirculation zone, the primary dilution jets, and the exit zone. The paper shows how the flow structures in a realistic combustor change with variations in global combustor parameters.
Development of a Virtual Chemistry Reaction Mechanism for H2/CH4 Turbulent Combustion Modelling
Authors: Castellani S. , Andreini A. , Meloni R.
Published: September 2024

The identification of the combustion model is always guided by the compromise between accuracy and computational cost. While species transport models offer accuracy, their computational cost requirement can become prohibitive, especially when de-aling with higher-order hydrocarbon fuels. To mitigate this, the virtual mechanism definition aims to optimize the predictivity minimizing the amount of information to be transported. Thereby the virtual mechanism leverages fictitious species and a few step reactions whose parameters calibration is performed with a genetic algorithm. This work outlines the procedure for the derivation of a virtual reaction mechanism for the study of lean H2/CH4 fuel mixtures with 60% of H2 content (by vol.). These conditions require an adequate characterization of the virtual species differential diffusion oriented to reconstruct the flame sensitivity toward the aerodynamic stretch. After the mechanism derivation, its predictivity has been validated on a swirl-stabilized perfectly premixed turbulent test case. The artificially thickened flame model has been adopted to allow the flame front discretization on an large eddy simulation (LES) grid and to model the turbulence chemistry interaction. The numerical results show a very good agreement with the experimental optical measurements confirming the effectiveness of this approach for predicting the H2/CH4 blend.
Modeling of Ball Screw–Nut Interface Stiffness With Wear (Ball Screw Wear Dynamics)
Authors: Heydarnia Hoda , Altintas Yusuf
Published: September 2024

The effects of wear, preload loss, and missing balls on the dynamics of ball screw drives in machine tools are modeled and incorporated into the finite element model of the drive assembly for condition monitoring. The contacts between the ball–nut and ball–screw are modeled using Hertzian springs, whose stiffnesses vary as a function of the worn contact area. These contact stiffnesses are then transformed to the finite element nodes on the nut and screw. The frequency response functions at the motor shaft and table, which can be measured by commercial computer numerical control (CNC), are predicted for various faults at different positions of the table. The experimentally validated model demonstrates that the faults primarily affect the first coupled torsional-axial mode of the ball screw drive and can be utilized for automated condition monitoring of ball screw drives.
Hyperspectral Analysis of Silicon Nanowires Manufactured Through Metal-Assisted Chemical Etching
Authors: Lee Pee-Yew , Lu Guo-Hao , Bai Yi-Hong , Chen Cheng-You , Wu Li-Yan , Weng Chun-Jen , Huang Hung Ji , Lin Yung-Sheng
Published: September 2024

This study used hyperspectral imaging to analyze localized near-field interactions between incident electromagnetic waves and silicon nanowire (SiNW) arrays manufactured through catalytic etching of Si wafers for different durations. The results revealed that the unetched upper surface area on Si wafers and reflection of incident light decreased with increasing etching time. A light reflection band peaking at approximately 880 nm was generated from arrays etched for more than 1 h. We used six separate hyperspectral images to analyze the wavelength-dependent spatial optical responses of the fabricated SiNW arrays. The images revealed hot spots of light reflection from unetched Si surfaces in the wavelength range of 470–750 nm and a resonant peak at 880 nm for a photonic crystal derived from a random SiNW array. Accordingly, hyperspectral imaging enables the assessment of localized optical responses of SiNW arrays, which can then be optimized to cater to various applications.
Local Conjugate Meshing Performance Analysis of an Enveloping Hourglass Worm Drive Based on Medium Gear
Authors: Li Zhongtao , Chen Yonghong , Wang Xinhua , Luo Wenjun , Chen Bingkui
Published: September 2024

Due to the low error sensitivity, the local conjugate enveloping hourglass worm drive based on medium gear is being intensively investigated, and this article examines the local conjugate meshing performance of such a worm drive. In this article, the local conjugate principle grounded in modified involute is proposed, and the local conjugate meshing hourglass worm drive using this approach is established; the boundary conditions of the modified involute are set up, and the oblique planar gear is converted to modified involute gear form; the meshing contact area of the worm drive is analyzed using tooth contact analysis (TCA), and finite element analysis (FEA) is executed to validate TCA's accuracy and perform loaded tooth contact analysis (LTCA); the mathematical models of the micro meshing properties are derived, and the effects of the modification position and range on meshing performance are examined. The findings indicate that the modification parameters influence the transmission pair's meshing performance, which subsequently affects the transmission performance. Thus, by reasonably selecting the modification position and range, a local conjugate hourglass worm drive with better meshing performance can be obtained.
Modeling, Simulation, and Kinematic Validation of Transfemoral Prosthetic Mechanism With Ankle Varus–Valgus Characteristic
Authors: Song Majun , Li Zhongyi , Zheng Hao , Chen Weihai , Guo Sheng , Niu Lianzheng
Published: September 2024

Inspired by the kinesiology of human bionic joints, a transfemoral prosthetic mechanism based on a functional structure of parallel mechanism is developed for the transfemoral amputees. The walking interactive simulation is implemented based on human-prosthesis modeling to verify the kinematics of the designed prosthetic mechanism, as well as to explore compatibility between the amputees and prosthesis. Then, simulation-based prosthetic optimization is performed to pursue an optimized human-prosthesis model with economic metabolic consumption while eliminating compatibility errors including the joints' misalignment error between the affected limb and healthy limb, and the assembly error between human and prosthesis, so that the potential physical health problems can be avoided efficiently. This method is valuable for the optimal design of interactive rehabilitation robots. Finally, a developed proportional-integral-derivative-based (PID-based) finite-state machine (FSM) strategy is used, and the kinematic validation is carried out. The results show that the designed prosthesis possesses ankle varus–valgus characteristic, and it has a high human-like motion accuracy due to the FSM control can track prosthetic motion in each gait event. What's more, the prosthetic optimization can be an efficient method to enhance the biomechanical performance of human-prosthetic model so that the amputees have a more natural and symmetry gait.
Design, Kinematics, and Deployment of a Continuum Underwater Vehicle-Manipulator System
Authors: Sitler Justin , Wang Long
Published: September 2024

Underwater vehicle-manipulator systems (UVMSs) are underwater robots equipped with one or more manipulators to perform intervention missions. This article provides the mechanical, electrical, and software design of a novel UVMS equipped with a continuum manipulator, referred to as a continuum-UVMS. A kinematic model for the continuum-UVMS is derived in order to build an algorithm to resolve the robot’s redundancy and generate joint space commands. Different methods to optimize the trajectory for specific tasks are proposed using both the weighted least norm solution and the gradient projection method. Kinematic simulation results are analyzed to assess the performance of the proposed algorithm. Finally, the continuum-UVMS is deployed in an experimental demonstration in which both teleoperation and autonomous control are tested for a given reference trajectory.
Influence of Dilution and Effusion Flows in Generating Variable Inlet Profiles for a High-Pressure Turbine
Authors: Schaeffer Chad B. , Barringer Michael D. , Lynch Stephen P. , Thole Karen A.
Published: September 2024

The elevated flow temperatures and pressures exiting gas turbine combustors affect the efficiency and durability of the high-pressure turbine stage. Understanding the effects that result from the upstream dilution and effusion flow interaction in creating the combustor exit profiles is important to advancing gas turbines. Understanding how common combustor features, such as dilution jets and effusion cooling, interact based on computational predictions guided the design of a non-reacting profile simulator capable of producing a wide range of non-uniform temperature profiles representative of those entering high-pressure turbines. The mechanical design of a new simulator device, which will be experimentally tested in the future, is presented in this paper along with computational predictions of flow and thermal fields. The simulator was designed for modular installation into the Steady Thermal Aero Research Turbine (START), which is a continuous-duration, steady-state turbine facility that houses a single-stage test turbine. Features of the simulator included interchangeable liner panels with multiple rows of dilution jets and wall effusion cooling to study various hole diameters and patterns. The dilution jets generate elevated turbulence intensities and tailor the temperature profiles in the radial and circumferential directions. The air mass flow distribution and source flow temperatures are independently controlled. To aid in the simulator design, computational fluid dynamics (CFD) simulations using Reynolds-averaged Navier–Stokes modeling were conducted with a two-level Design of Experiments (DOE) approach to determine a number of engine-representative target profiles with temperature shapes that are mid-radius peaked, outer-diameter peaked, inner-diameter peaked, and uniform. A sensitivity analysis of the CFD DOE results determined which factors significantly affected the profile shape so that the target profiles could be produced. The analysis indicated that the main contributor to the temperature profile shape at near-wall vane radial span locations of 0–15% and 85–100% was the injection temperature of the effusion flow. The main contributor at radial span locations of 15–40% and 60–85% was the injection temperature of the third-row dilution jets, and at the mid-radius location of 40–60% vane radial span, the main contributor was the diameter of the first-row dilution holes.
Molecular-level studies of extracellular matrix proteins conducted using atomic force microscopy
Authors: Walker Ashley R. , Sloneker Jonathan R. , Garno Jayne C.
Published: September 2024

Extracellular matrix (ECM) proteins provide anchorage and structural strength to cells and tissues in the body and, thus, are fundamental molecular components for processes of cell proliferation, growth, and function. Atomic force microscopy (AFM) has increasingly become a valuable approach for studying biological molecules such as ECM proteins at the level of individual molecules. Operational modes of AFM can be used to acquire the measurements of the physical, electronic, and mechanical properties of samples, as well as for viewing the intricate details of the surface chemistry of samples. Investigations of the morphology and properties of biomolecules at the nanoscale can be useful for understanding the interactions between ECM proteins and biological molecules such as cells, DNA, and other proteins. Methods for preparing protein samples for AFM studies require only basic steps, such as the immersion of a substrate in a dilute solution or protein, or the deposition of liquid droplets of protein suspensions on a flat, clean surface. Protocols of nanolithography have been used to define the arrangement of proteins for AFM studies. Using AFM, mechanical and force measurements with tips that are coated with ECM proteins can be captured in ambient or aqueous environments. In this review, representative examples of AFM studies are described for molecular-level investigations of the structure, surface assembly, protein-cell interactions, and mechanical properties of ECM proteins (collagen, elastin, fibronectin, and laminin). Methods used for sample preparation as well as characterization with modes of AFM will be discussed.
Individual differences in the perception of phonetic category structure predict speech-in-noise performance
Authors: Myers Emily , Phillips Matthew , Skoe Erika
Published: September 2024

Speech sounds exist in a complex acoustic–phonetic space, and listeners vary in the extent to which they are sensitive to variability within the speech sound category (“gradience”) and the degree to which they show stable, consistent responses to phonetic stimuli. Here, we investigate the hypothesis that individual differences in the perception of the sound categories of one's language may aid speech-in-noise performance across the adult lifespan. Declines in speech-in-noise performance are well documented in healthy aging, and are, unsurprisingly, associated with differences in hearing ability. Nonetheless, hearing status and age are incomplete predictors of speech-in-noise performance, and long-standing research suggests that this ability draws on more complex cognitive and perceptual factors. In this study, a group of adults ranging in age from 18 to 67 years performed online assessments designed to measure phonetic category sensitivity, questionnaires querying recent noise exposure history and demographic factors, and crucially, a test of speech-in-noise perception. Results show that individual differences in the perception of two consonant contrasts significantly predict speech-in-noise performance, even after accounting for age and recent noise exposure history. This finding supports the hypothesis that individual differences in sensitivity to phonetic categories mediates speech perception in challenging listening situations.
Observation of the Achilles Tendon and Gastrocnemius Muscle’s Passive Stiffness During an Incremental Running Protocol
Authors: Nguyen Anh Phong , Bosquet Laurent , Cugnet-Evans Laureen , Detrembleur Christine , Mahaudens Philippe
Published: September 2024

Objective: Passive stiffness, a biomechanical parameter, has a potential influence on running economy, thus playing a pivotal role in performance. This study aimed to quantify passive stiffness of the Achilles tendon and gastrocnemius muscle using myotonometry throughout an incremental running protocol. Methods: Twenty-one male participants underwent a multistage incremental test (Bordeaux test) on a treadmill until exhaustion. Passive stiffness of the gastrocnemius muscle and Achilles tendon was measured using a MyotonPRO device. Measurements were taken before, during, and after the incremental test. Results: Our findings indicated that passive stiffness of the medial gastrocnemius decreased at rest between prerun and postrun assessments (−20.12 N·m−1, P = .012). Furthermore, during the test, stiffness increased at low intensity (at 50% of maximal aerobic speed: +104.8 N·m−1, P = .042), returning to baseline values as intensity increased. Conclusions: Throughout an incremental running protocol, both Achilles tendon and gastrocnemius muscle stiffness initially increased and then decreased with escalating percentages of maximal aerobic speed. A deeper understanding of stiffness in running can inform more effective recommendations for runners’ strengthening and training.
Blocking tumor-intrinsic MNK1 kinase restricts metabolic adaptation and diminishes liver metastasis
Authors: Preston Samuel E. J. , Dahabieh Michael S. , Flores González Raúl Ernesto , Gonçalves Christophe , Richard Vincent R. , Leibovitch Matthew , Dakin Eleanor , Papadopoulos Theodore , Lopez Naranjo Carolina , McCallum Paige A. , Huang Fan , Gagnon Natascha , Perrino Stephanie , Zahedi René P. , Borchers Christoph H. , Jones Russell G. , Brodt Pnina , Miller Wilson H. , del Rincón Sonia V.
Published: September 2024

Dysregulation of the mitogen-activated protein kinase interacting kinases 1/2 (MNK1/2)–eukaryotic initiation factor 4E (eIF4E) signaling axis promotes breast cancer progression. MNK1 is known to influence cancer stem cells (CSCs); self-renewing populations that support metastasis, recurrence, and chemotherapeutic resistance, making them a clinically relevant target. The precise function of MNK1 in regulating CSCs, however, remains unexplored. Here, we generated MNK1 knockout cancer cell lines, resulting in diminished CSC properties in vitro and slowed tumor growth in vivo. Using a multiomics approach, we functionally demonstrated that loss of MNK1 restricts tumor cell metabolic adaptation by reducing glycolysis and increasing dependence on oxidative phosphorylation. Furthermore, MNK1-null breast and pancreatic tumor cells demonstrated suppressed metastasis to the liver, but not the lung. Analysis of The Cancer Genome Atlas (TCGA) data from breast cancer patients validated the positive correlation between MNK1 and glycolytic enzyme protein expression. This study defines metabolic perturbations as a previously unknown consequence of targeting MNK1/2, which may be therapeutically exploited.
Can we achieve atmospheric chemical environments in the laboratory? An integrated model-measurement approach to chamber SOA studies
Authors: Kenagy Hannah S. , Heald Colette L. , Tahsini Nadia , Goss Matthew B. , Kroll Jesse H.
Published: September 2024

Secondary organic aerosol (SOA), atmospheric particulate matter formed from low-volatility products of volatile organic compound (VOC) oxidation, affects both air quality and climate. Current 3D models, however, cannot reproduce the observed variability in atmospheric organic aerosol. Because many SOA model descriptions are derived from environmental chamber experiments, our ability to represent atmospheric conditions in chambers directly affects our ability to assess the air quality and climate impacts of SOA. Here, we develop an approach that leverages global modeling and detailed mechanisms to design chamber experiments that mimic the atmospheric chemistry of organic peroxy radicals (RO
2
), a key intermediate in VOC oxidation. Drawing on decades of laboratory experiments, we develop a framework for quantitatively describing RO
2
chemistry and show that no previous experimental approaches to studying SOA formation have accessed the relevant atmospheric RO
2
fate distribution. We show proof-of-concept experiments that demonstrate how SOA experiments can access a range of atmospheric chemical environments and propose several directions for future studies.
Clusters of lineage-specific genes are anchored by ZNF274 in repressive perinucleolar compartments
Authors: Begnis Martina , Duc Julien , Offner Sandra , Grun Delphine , Sheppard Shaoline , Rosspopoff Olga , Trono Didier
Published: September 2024

Long known as the site of ribosome biogenesis, the nucleolus is increasingly recognized for its role in shaping three-dimensional (3D) genome organization. Still, the mechanisms governing the targeting of selected regions of the genome to nucleolus-associated domains (NADs) remain enigmatic. Here, we reveal the essential role of ZNF274, a SCAN-bearing member of the Krüppel-associated box (KRAB)–containing zinc finger protein (KZFP) family, in sequestering lineage-specific gene clusters within NADs. Ablation of ZNF274 triggers transcriptional activation across entire genomic neighborhoods—encompassing, among others, protocadherin and KZFP-encoding genes—with loss of repressive chromatin marks, altered the 3D genome architecture and de novo CTCF binding. Mechanistically, ZNF274 anchors target DNA sequences at the nucleolus and facilitates their compartmentalization via a previously uncharted function of the SCAN domain. Our findings illuminate the mechanisms underlying NAD organization and suggest that perinucleolar entrapment into repressive hubs constrains the activation of tandemly arrayed genes to enable selective expression and modulate cell differentiation programs during development.
Phonon engineering of atomic-scale defects in superconducting quantum circuits
Authors: Chen Mo , Owens John Clai , Putterman Harald , Schäfer Max , Painter Oskar
Published: September 2024

Noise within solid-state systems at low temperatures can typically be traced back to material defects. In amorphous materials, these defects are broadly described by the tunneling two-level systems (TLSs) model. TLS have recently taken on further relevance in quantum computing because they dominate the coherence limit of superconducting quantum circuits. Efforts to mitigate TLS impacts have thus far focused on circuit design, material selection, and surface treatments. Our work takes an approach that directly modifies TLS properties. This is achieved by creating an acoustic bandgap that suppresses all microwave-frequency phonons around the operating frequency of a transmon qubit. For embedded TLS strongly coupled to the transmon qubit, we measure a pronounced increase in relaxation time by two orders of magnitude, with the longestT1time exceeding 5 milliseconds. Our work opens avenues for studying the physics of highly coherent TLS and methods for mitigating noise within solid-state quantum devices.