bluuebunny/crossref_metadata_2025 huggingface dataset:
A Handheld Robot for Endoscopic Endonasal Skull Base Surgery: Updated Preclinical Validation Study (IDEAL Stage 0)
Authors: Starup-Hansen Joachim , Newall Nicola , Dimitrakakis Emmanouil , Khan Danyal Z. , Dwyer George , Iyengar Keshav , Psychogyios Dimitrios , Hanrahan John G. , Sinha Siddharth , Booker James , Stoyanov Danail , Marcus Hani J.
Published: April 2024

Background and Objectives Endoscopic endonasal surgery (EES) has become increasingly popular, yet anatomical constraints posed by the nose and limitations of nonarticulated instruments render EES technically challenging, with a steep associated learning curve. Therefore, we developed a handheld robot to enhance dexterity in endoscopic neurosurgical procedures. A previous trial of the robot demonstrated its potential advantages in endoscopic neurosurgery but also the need for improvements. In this study, we assess the feasibility, acceptability, and comparative performance of the updated robotic prototype (version 0.2) against standard instruments in a preclinical phantom and cadaveric trial.

Methods Ethical approval was received. Participants were stratified according to their neurosurgical experience. In the phantom study, a randomized crossover design compared the robot against standard instruments at a phantom tumor resection task. Statistical analysis was performed using Mann–Whitney U tests and paired t-tests. In the cadaver-based user study, participants evaluated the device's functional domains through a qualitative interview design.

Results In the phantom study, the device demonstrated a learning curve: initial resection attempts favored the traditional instrument (84% vs. 59%, p = 0.055), but parity was achieved by the fifth attempt (80% vs. 83%, p = 0.76). Acceptability was evident, as most clinicians (7/8) preferred the robot for its superior range, ergonomics, and precision. Also, the robot exhibited a diminished cognitive workload. The cadaveric study underscored the robot's clinical feasibility, through sufficient workspace reach and force delivery.

Conclusion: Overall, our robot demonstrates promising acceptability and feasibility for endoscopic neurosurgery, yet further iterative developments are required before proceeding to in-human clinical trials.
Pharmacoinformatics-enabled Interventions Improved Care Coordination and Identified Pharmacy-Related Safety Issues in a Multicultural Medicare Population
Authors: Craig Kelly J. T. , Zaleski Amanda L. , MacKenzie Shannon M. , Butler Brenda L. , Youngerman Rebecca A. , McNutt Sherrie L. , Baquet-Simpson Alena M.
Published: April 2024

Background Compared to White populations, multicultural older adults experience more gaps in preventive care (e.g., vaccinations, screenings, chronic condition monitoring), social determinants of health barriers (e.g., access to care, language, transportation), and disparities and inequities (e.g., comorbidities, disease burden, and health care costs).

Objectives This study aims to describe an informatics-based approach used to execute and evaluate results of a member-centric, pharmacoinformatics-informed engagement program to deliver culturally tailored microinterventions to close medication-related gaps in care utilizing multidisciplinary care coordination that leverages the expanded role of the pharmacist. The operational framework will be described, and the influence of the medication use processes will be reported in a multicultural Medicare Advantage cohort.

Methods A pharmacoinformatics framework was leveraged to conduct a retrospective, observational cohort analysis of the program. Claims data were used to evaluate the influence of medication use process microinterventions from a large Medicare Advantage cohort of members who self-identify as Black and/or Hispanic, and have type 2 diabetes mellitus and/or hypertension, and meet eligibility criteria for multidisciplinary (e.g., nursing and pharmacy) care management (CM) and received pharmacy referral from January 1, 2022, through September 30, 2023.

Results A total of 3,265 Medicare Advantage members (78.3% Black and 21.7% Hispanic) received CM and pharmacy referral. Pharmacovigilance reviews conducted during this timeframe identified 258 acute events that escalated member CM. Provider outreach (n = 185) informed of safety issues (drug duplication, n = 48; drug interactions, n = 21; drug–disease interactions, n = 5; noncompliance and/or dosing issues, n = 27). Outreach to members (n = 160) and providers (n = 164) informed of open quality-related measure gaps for medication adherence.

Conclusion The application of pharmacoinformatics by a payor-led multicultural clinical program demonstrated quality improvements in Medicare Advantage member identification including risk stratification, timely outreach for pharmacy-related safety issues, and improved efficiency of multidisciplinary care coordination involving medication use process workflows.
Type 1 Narcolepsy in Pregnancy: A Case Report and Review of Literature
Authors: Yuabov Asnat , Kilinsky Alexandra , El Kady Dina
Published: April 2024

Background Type 1 narcolepsy (with cataplexy) is a rare disorder affecting the central nervous system and is characterized by the inability to control sleep–wake cycles. There is a paucity of data regarding management during pregnancy.

Case This is a 23-year-old primigravida with narcolepsy and cataplexy, treated with methylphenidate in the third trimester, resulting in an improvement of episodes of cataplexy. A review of the literature reveals information regarding options for medical management and the mode of delivery for these women.

Conclusion Type 1 narcolepsy can be treated with medications after consideration of risks and benefits. For patients who are symptomatic at the time of birth, cesarean section may be the preferred mode of delivery in women with type 1 narcolepsy.
Machine Alarm Fatigue among Hemodialysis Nurses in 29 Tertiary Hospitals
Authors: Sun Chaonan , Bao Meirong , Pu Congshan , Kang Xin , Zhang Yiping , Kong Xiaomei , Zhang Rongzhi
Published: April 2024

Objectives To understand the status quo and related influencing factors of machine alarm fatigue of hemodialysis nurses in tertiary hospitals in Liaoning Province.

Methods This cross-sectional study employed convenience sampling to select 460 nurses from 29 tertiary hospitals in Liaoning Province, who are involved in hemodialysis care. Surveys were conducted using the General Information Questionnaire, Alarm Fatigue Scale, National Aeronautics and Space Administration Task Load Index, and Maslach Burnout Inventory Scale.

Results The overall machine alarm fatigue score for 460 hemodialysis nurses from 29 tertiary hospitals in Liaoning Province was 17.04 ± 3.21, indicating a moderate level. The multiple linear regression analysis shows that years of experience in hemodialysis nursing, the number of patients managed per shift, whether specialized nursing training has been received, self-reported health status, emotional exhaustion, and workload have statistically significant associations with alarm fatigue among hemodialysis nurses (p < 0.05). Among them, the years of experience in hemodialysis nursing are negatively correlated with alarm fatigue among hemodialysis nurses, whereas the number of patients managed per shift and workload are positively correlated with alarm fatigue among hemodialysis nurses.

Conclusion This study indicates that certain demographic factors, workload, and occupational burnout are associated with machine alarm fatigue among hemodialysis nurses. Therefore, hemodialysis-related managers should establish a Machine Alarm Management System, implement Personalized Thresholds and Delayed Alarms, ensure reasonable staffing arrangements, improve compassion fatigue, and enhance anticipatory care. Our findings have implications for improving the health and well-being of hemodialysis nurses, providing a conducive environment for professional training in hemodialysis, and ultimately addressing the current situation of machine alarm fatigue among hemodialysis nurses.
Comparison of Ga-68 PSMA PET/CT and Multiparametric MRI for Initial Detection and Staging of Prostate Cancer
Authors: Gauthaman Dinesh Kumar , Luthra Karuna , Lele Vikram
Published: April 2024

Background Multiparametric magnetic resonance imaging (mpMRI) is widely used for the evaluation of prostate cancer and is known to have better accuracy. Gallium-68 prostate-specific membrane antigen (Ga-68 PSMA) is a radiotracer that shows high localization in prostate cancer cells.

Purpose The purpose of this study was to assess the sensitivity and utility of Ga-68 PSMA positron emission tomography/computed tomography (PET/CT) in comparison with mpMRI as a noninvasive imaging technique for the initial diagnosis and locoregional staging of prostate cancer using transrectal ultrasound (TRUS)-guided biopsy as gold standard.

Materials and Methods This prospective observational study conducted from August 2017 to April 2020 evaluated 60 men (n = 60) with biopsy-proven prostate carcinoma. They underwent mpMRI and Ga-68 PSMA PET/CT scans within 14 days with TRUS biopsy being gold standard. T staging of disease, N staging of lymph nodes within the pelvis, and M staging of lesions in pelvic bones (within the imaging field of mpMRI) were compared using PSPP version 1.0.1 statistical software.

Results All 60 men with a mean age of 69.9 ± 9.35 years showed Ga-68 PSMA avid disease, whereas 55 were detected by mpMRI. The sensitivity in detection of prostate lesions (with 95% confidence interval) was 99.08% for Ga-68 PSMA PET/CT and 84.40% for mpMRI. Ga-68 PSMA PET/CT detected greater number of patients with regional lymph nodal involvement (19/60) as compared with mpMRI (12/60). Ga-68 PSMA PET/CT showed PSMA avid pelvic skeletal lesions in nine patients, whereas mpMRI detected pelvic lesions in six patients. In addition, four other patients showed extrapelvic skeletal lesions on Ga-68 PSMA PET/CT.

Conclusion Ga-68 PSMA PET/CT has superior sensitivity in detection of primary prostate tumor, as compared with mpMRI. Both modalities correlate well in detection of seminal vesicle involvement. Ga-68 PSMA PET/CT outperformed mpMRI in detection of lymph nodal and skeletal metastases. Hence, Ga-68 PSMA PET/CT should be considered as first-line diagnostic modality for carcinoma prostate.

Summary Statement: Ga-68 PSMA PET/CT shows superior diagnostic performance than mpMRI in the evaluation of prostate cancer.
The complex relationship between credit and liquidity risks: a linear and non-linear analysis for the banking sector
Authors: Bouslimi Jihen , Hakimi Abdelaziz , Zaghdoudi Taha , Tissaoui Kais
Published: April 2024

This article explores the reciprocal link between credit risk and liquidity risk in Tunisia. To the best of our knowledge, no study has examined the linear and non-linear relationships between credit risk (CR) and liquidity risk (LR) taken in both directions. We utilized a sample of Tunisian banks from 2000 to 2018 to investigate this link in both causative directions and within a linear and non-linear framework. Unlike previous investigations, we used two empirical approaches. The linear link was assessed using the Seemingly Unrelated Regression (SUR) model, whilst the non-linear correlation was investigated using the Panel Smooth Transition Regression (PSTR) model.The results of the linear analysis show that credit and liquidity risks are positively related in both directions. The non-linear analysis proves that there is a threshold impact in both connections. More specifically, we discovered that the NPLs ratio, which measures credit risk, is 9.87%, while the LTD ratio measures liquidity risk, which is 102%. Below this threshold, there is a negative and significant relationship; beyond these thresholds, the effect is positive but only significant for the influence of credit risk on liquidity risk.
Folk religion as the “life-world”: revival of folk beliefs and renewal of religious categorization in contemporary China
Authors: Chi Shuai , Liu Chao
Published: April 2024

Religious studies in the past paid more attention to the changes of institutional religion than to the status characteristic of folk beliefs. This paper argues that religious categorization based on institutional religion is not conducive to understanding the cultural and religious life of Chinese society, but rather leads to the stigmatization of folk religion and the reduction of the life-world. From this perspective, the historical development of folk religion affects the relationship between national elites, institutionalized religion, and civil society. Folk religion can be foregrounded and exerts great impact on the rise and fall of institutional religion. The folk religion revival in contemporary China and the development of related studies also promote the renewal of religious categorization. The revival of folk religion in the new millennium can consequently facilitate social integration and provide new possibilities for overcoming institutional religion’s exclusiveness and for increasing the cultural diversity of Chinese society.
Gigahertz streaking and compression of low-energy electron pulses
Authors: Epp Dennis , Schröder Benjamin , Möller Marcel , Ropers Claus
Published: April 2024

Although radio frequency (RF) technology is routinely employed for controlling high-energy pulses of electrons, corresponding technology has not been developed at beam energies below several kiloelectronvolts. In this work, we demonstrate transverse and longitudinal phase-space manipulation of low-energy electron pulses using RF fields. A millimeter-sized photoelectron gun is combined with synchronized streaking and compression cavities driven at frequencies of 0.5 and 2.5 GHz, respectively. The phase-controlled acceleration and deceleration of photoelectron pulses is characterized in the energy range of 50–100 eV. Deflection from a transient space-charge cloud at a metal grid is used to measure a fourfold compression of 80−eV electron pulses, from τ=34 to τ=8 ps pulse duration.
Precision-controlled ultrafast electron microscope platforms. A case study: Multiple-order coherent phonon dynamics in 1T-TaSe2 probed at 50 fs–10 fm scales
Authors: Sun Xiaoyi , Williams Joseph , Sharma Sachin , Kunjir Shriraj , Morris Dan , Zhao Shen , Ruan Chong-Yu
Published: April 2024

We report on the first detailed beam tests attesting the fundamental principle behind the development of high-current-efficiency ultrafast electron microscope systems where a radio frequency (RF) cavity is incorporated as a condenser lens in the beam delivery system. To allow for the experiment to be carried out with a sufficient resolution to probe the performance at the emittance floor, a new cascade loop RF controller system is developed to reduce the RF noise floor. Temporal resolution at 50 fs in full-width-at-half-maximum and detection sensitivity better than 1% are demonstrated on exfoliated 1T-TaSe2 system under a moderate repetition rate. To benchmark the performance, multi-terahertz edge-mode coherent phonon excitation is employed as the standard candle. The high temporal resolution and the significant visibility to very low dynamical contrast in diffraction signals via high-precision phase-space manipulation give strong support to the working principle for the new high-brightness femtosecond electron microscope systems.
Improved continuous measurement system for atmospheric total peroxy and total organic nitrate under the high NOx condition
Authors: Ohara Nagomi , Shioji Takahiro , Matsumoto Jun , Inomata Satoshi , Sakamoto Yosuke , Kajii Yoshizumi , Shiigi Hiroshi , Sadanaga Yasuhiro
Published: April 2024

We improved the thermal dissociation cavity attenuated phase shift spectroscopy (TD-CAPS) instrument to measure atmospheric total peroxy nitrates (PNs) and organic nitrates (ONs) continuously under the condition of high NOx. In TD-CAPS, PNs and ONs are dissociated in heated quartz tubes to form NO2, and the NO2 concentration is measured by cavity attenuated phase shift spectroscopy (CAPS). The original TD-CAPS system overestimates PN and ON concentrations in the presence of high NO concentrations. Our laboratory experiments and numerical simulations showed that the main cause of the overestimation was NO oxidation to NO2 by peroxy radicals generated in the heated quartz tubes. In the improved system, NO was converted to NO2 by adding excess O3 after the quartz tubes so that CAPS detected NOx (NO and NO2) instead of NO2. The uncertainty of the improved system was less than 20% with ∼15 parts per billion by volume (ppbv) NO and ∼80 ppbv NO2. The estimated detection limit (3σ) was 0.018 ppbv with an integration time of 2 min in the presence of 64 ppbv NO2. The improved system was tested for measurement of PNs and ONs in an urban area, and the results indicated that interference from NO was successfully suppressed.
The origin of memory window closure with bipolar stress cycling in silicon ferroelectric field-effect-transistors
Authors: Passlack Matthias , Tasneem Nujhat , Park Chinsung , Ravindran Prasanna Venkat , Chen Hang , Das Dipjyoti , Yu Shimeng , Chen Edward , Wang Jer-Fu , Chang Chih-Sheng , Lin Yu-Ming , Radu Iuliana , Khan Asif
Published: April 2024

A comprehensive quantitative root cause study of defect evolution leading to memory window closure from a charge balance and charge trapping perspective throughout all phases of a Si channel Hf0.5Zr0.5O2 (HZO) ferroelectric field-effect-transistor (FEFET) is reported. Starting with the first write pulse, an excessive SiO2 interlayer field is revealed that triggers the creation of defect levels Dit in excess of 1015 cm−2 eV−1 at the HZO–SiO2 interface screening ferroelectric (FE) polarization while enabling FE switching. Under subsequent early bipolar fatigue cycling (up to 104 cycles), defect creation commences at the SiO2–Si interface due to the high injected hole fluence (0.39 C/m2) during each stress pulse causing negative bias instability (NBI), which shifts the threshold voltage of the erase state VT,ERS by −0.3 V with accrual of permanently captured charge Nit of up to +5 × 10−3 C/m2 (3 × 1012 cm−2). Subsequently, Nit NBI generation at the SiO2–Si interface accelerates reaching levels of +7 × 10−2 C/m2, locking both FEFET program and erase drain current vs gate–source-voltage (ID–VGS) characteristics in the FEFET on-state inducing memory window closure at 105 cycles while FE switching (switched polarization Psw = 0.34 C/m2) remains essentially intact. These findings guide the down-selection toward suitable semiconductor/FE systems for charge balanced, reliable, and high endurance FEFETs.
Evolution of the electron phase space of the two-stream and bump-on-tail instabilities in collisional plasma
Authors: Hou Y. W. , Yu M. Y. , Wang J. F. , Liu C. Y. , Chen M. X. , Wu B.
Published: April 2024

Particle collisions can have significant effects on plasma instabilities, especially in dense and/or low temperature plasmas. To understand the influence of collisional effects on the plasma waves, the Vlasov–Poisson system with Krook collisions is applied to study the long-term evolution of the two-stream (TS) and bump-on-tail (BOT) instabilities. The system is solved numerically with the fourth-order Runge–Kutta scheme and the Thomas algorithm. It is found that collisions can enhance the wave damping and mitigate the energy of the characteristic slow evolving nonlinear Landau damping oscillations associated with the wave-trapped electrons, especially if the collision rate ν is higher than 0.01ωp, where ωp is the plasma frequency of the background plasma. Collisions can also decrease the growth rate and saturation level of the TS and BOT unstable waves and tend to shrink the phase space vortex and narrow the phase-mixed region of the trapped electrons. However, our simulations show that collisions cannot readily prevent the nonlinear Landau damping oscillations. In fact, only with ν>0.001ωp for the TS instability and ν>0.01ωp for the BOT instability, as well as evolution times greater than several hundred ωp−1, the vortex structure of the wave-trapped electrons can be undetectable. The corresponding growth rates also drop dramatically, and the maximum wave energy can be one or two orders lower than that of the collisionless limits.
Emergent quasi-two-dimensional ferromagnetic state with perpendicular magnetic anisotropy at La0.7Sr0.3MnO3/SrCuO2 interface
Authors: Shi Wenxiao , Zhang Jing , Zhan Xiaozhi , Li Jialiang , Li Zhe , Zheng Jie , Wang Mengqin , Zhang Jine , Zhang Hui , Zhu Tao , Chen Yunzhong , Hu Fengxia , Shen Baogen , Chen Yuansha , Sun Jirong
Published: April 2024

Due to the strong interlayer coupling between multiple degrees of freedom, oxide heterostructures usually produce distinct interfacial phases with unexpected functionalities. Here, we report on the realization of quasi-two-dimensional ferromagnetic state in ultrathin La0.7Sr0.3MnO3 (LSMO) layer down to two unit cells (u.c.), being sandwiched by the planar infinite-layer structured SrCuO2 layers (P-SCO). We find the LSMO/P-SCO interface coupling has greatly suppressed the magnetic dead layer of LSMO, resulting in an emergent interfacial ferromagnetic phase. Thus, robust ferromagnetic order can be maintained in the 2 u.c.-thick LSMO layer (∼7.7 Å), showing a Curie temperature of ∼260 K and remarkable perpendicular magnetic anisotropy. X-ray absorption spectra reveal notable charge transfer from Mn to Cu at the interface, and thus, resulted preferential d3z2−r2 orbital occupation for interfacial Mn ions plays an important role in the inducing of perpendicular magnetic anisotropy in quasi-two-dimensional LSMO layer. Our work demonstrates a unique approach for tuning the properties of oxides via an interface engineering of oxygen coordination in perovskite/infinite-layer heterostructures.
Boosting the photosensitivity of organic phototransistors with photomultiplication via Corbino configurations
Authors: Choi Dongho , Park Sanghoon , Moon Hanul , Yoo Seunghyup
Published: April 2024

An organic phototransistor (OPT) with a photomultiplication mechanism is studied, where a bulk-heterojunction of C70 and 1,1-bis-(4-bis(4-methyl-phenyl)-amino-phenyl)-cyclohexane is used as a channel and a light-absorbing layer with an Al Schottky contact as source/drain electrodes. The light absorption in the source-side region is found to dominate the photomultiplication effect. In addition, the source electrode area that is up to 100 μm away from the channel is identified as the most effective region in the OPTs with contact-limited operation used in this study. Therefore, to maximize the light-sensing performance of the contact-limited OPTs, we propose Corbino source/drain geometries that have a larger source electrode area than that of the drain electrode. The Corbino-type OPTs show improved photo-response properties proportional to the relative increment of the source-side area, reaching 1.7-fold higher performance in terms of photosensitivity compared to the conventional lateral-type OPTs.
Uniqueness of conservative solutions to the modified Camassa-Holm equation via characteristics
Authors: He Zhen , Yin Zhaoyang
Published: April 2024

In this paper, for a given conservative solution, we introduce a set of auxiliary variables tailored to this particular solution, and prove that these variables satisfy a particular semilinear system having unique solutions. In turn, we get the uniqueness of the conservative solution in the original variables.
Introducing dusty plasma particle growth of nanospherical titanium dioxide
Authors: Ramkorun Bhavesh , Jain Swapneal , Taba Adib , Mahjouri-Samani Masoud , Miller Michael E. , Thakur Saikat C. , Thomas Edward , Comes Ryan B.
Published: April 2024

In dusty plasma environments, spontaneous growth of nanoparticles from reactive gases has been extensively studied for over three decades, primarily focusing on hydrocarbons and silicate particles. Here, we introduce the growth of titanium dioxide, a wide bandgap semiconductor, as dusty plasma nanoparticles. The resultant particles exhibited a spherical morphology and reached a maximum monodisperse radius of 235 ± 20 nm after growing for 70 s. The particle grew linearly, and the growth displayed a cyclic behavior; that is, upon reaching their maximum radius, the largest particles fell out of the plasma, and the next growth cycle immediately followed. The particles were collected after being grown for different amounts of time and imaged using scanning electron microscopy. Further characterization was carried out using energy dispersive x-ray spectroscopy, x-ray diffraction, and Raman spectroscopy to elucidate the chemical composition and crystalline properties of the maximally sized particles. Initially, the as-grown particles exhibited an amorphous structure after 70 s. However, annealing treatments at temperatures of 400 and 800 °C induced crystallization, yielding anatase and rutile phases, respectively. Annealing at 600 °C resulted in a mixed phase of anatase and rutile. These findings open avenues for a rapid and controlled growth of titanium dioxide via dusty plasma.
Mass dependency of high-wavenumber turbulence in a linear partially magnetized plasma
Authors: Kawachi Yuichi , Sasaki Makoto , Nishizawa Takashi , Kosuga Yusuke , Terasaka Kenichiro , Inagaki Shigeru , Yamada Takuma , Kasuya Naohiro , Moon Chanho , Nagashima Yoshihiko , Fujisawa Akihide
Published: April 2024

We investigated the mass dependency of the high-wavenumber turbulence, which occurs at scales smaller than the ion effective Larmor radius, in a partially magnetized plasma column. In this system, two different types of fluctuations were observed: one exhibiting a coherent discrete spectrum, while the other displaying a broadband continuous spectrum. The phase velocities of both types showed a similar mass dependency, approximately matching the ion sound velocity or electron diamagnetic drift velocity. Additionally, we found that the discrete spectrum has a peak interval frequency comparable to the ion cyclotron frequency, which is consistent with ion cyclotron ranges of fluctuations, including ion Bernstein waves.
Analysis of dynamics of a map-based neuron model via Lorenz maps
Authors: Bartłomiejczyk Piotr , Llovera Trujillo Frank , Signerska-Rynkowska Justyna
Published: April 2024

Modeling nerve cells can facilitate formulating hypotheses about their real behavior and improve understanding of their functioning. In this paper, we study a discrete neuron model introduced by Courbage et al. [Chaos 17, 043109 (2007)], where the originally piecewise linear function defining voltage dynamics is replaced by a cubic polynomial, with an additional parameter responsible for varying the slope. Showing that on a large subset of the multidimensional parameter space, the return map of the voltage dynamics is an expanding Lorenz map, we analyze both chaotic and periodic behavior of the system and describe the complexity of spiking patterns fired by a neuron. This is achieved by using and extending some results from the theory of Lorenz-like and expanding Lorenz mappings.
Scanning ex situ solid-state magnetic resonance imaging on polymeric films using a static magnetic field gradient by an electromagnet
Authors: Kawabata Natsuki , Asakawa Naoki
Published: April 2024

A new technique for ex situ solid-state nuclear magnetic resonance imaging of polymeric films has been developed. This method uses the static magnetic field gradient generated by a water-cooled copper electromagnet. The imaging process involves scanning the sample in the plane of the film under a static magnetic field gradient. Two-dimensional (2D) 19F MRI measurements are attempted, where the fast Fourier transform (FFT) spectra of the second half of a Hahn echo peak is used for the depth (X-axis) direction, and the sample film is mechanically moved for the Y-axis, which is in-plane with respect to the film surface and normal to the inter-magnetic-pole line (Z-axis). The sample is a poly(tetrafluoroethylene) [PTFE] film with carved stripes on its surface. Furthermore, three-dimensional (3D) measurements of the film surface and thickness orientations were also performed for an analogous PTFE film. For 2D profiling on the film surface, 2D sample-moving was used. For depth profiling, FFT spectrum analysis was undertaken for each voxel situated at a specific (Y, Z) coordinate within the film. As a result, a 3D image of the sample and its corresponding geometry were obtained, although the scanning area was restricted to a part of the sample. Finally, numerical simulations of the spatial distribution of the static magnetic field were performed to confirm the validity of the present method.
Depletion forces in dense mixtures of spheres and rods
Authors: Pedrozo-Romero Jorge J. , Pérez-Ángel Gabriel
Published: April 2024

We evaluate depletion forces in molecular dynamics simulation of a binary mixture of spheres (depleted particles) and rods (depletant particles) for a wide range of densities for both species. This evaluation was carried out using a recently proposed least squares fitting algorithm. We found that the restriction of the rods’ rotational degrees of freedom, when the distance between two spheres is less than the rods length, creates a shallow, and apparently linear, attractive force ramp. For intersphere distances smaller than the rods’ diameter, a much stronger attractive force is found, and a large repulsive barrier appears between these aforementioned regimes, roughly at the distance of the rods’ thickness. The evaluated forces are validated via a comparison of the pairwise correlation functions obtained from molecular dynamics simulation of a mono-disperse sphere fluid, using the evaluated effective forces, against the original (full system) pairwise correlation functions. Agreement is excellent. We also record the angular pairwise correlation function, using the P2(x) Legendre polynomial, and find that for high densities of both species, a local nematic ordering starts to appear. This nematic order may be a factor in the small differences found between original and effective pairwise correlation functions at high densities of rods.
Dielectric properties of low-temperature-grown homoepitaxial (−201) β-Ga2O3 thin film by atmospheric pressure plasma-assisted CVD
Authors: Islam Md. Earul , Shimamoto Kento , Yoshimura Takeshi , Fujimura Norifumi
Published: April 2024

The atmospheric pressure plasma-assisted chemical vapor deposition technique has successfully demonstrated unintentionally doped (UID) Ga2O3 growth at 350 °C. This technique allows independent and homogeneous multiple nuclei growth of Ga2O3, leading to three-dimensional grain growth at a rate of ⁓0.17 μm/h. In the study of Schottky barrier diodes, the Schottky-like current (I)–voltage (V) response shows typical behavior on Ga2O3. This is a good sign at an early stage of device development on the grown sample. The extracted barrier height of ⁓2.20 eV was higher, which may be due to unintentional PtOx formation on the Ga2O3 surface. Furthermore, the extracted capacitance (C)–voltage (V) depth profiling of the effective impurity concentration was nearly flat, ⁓1.5 × 1017 cm−3, in the unintentionally doped grown film. The effective impurity concentration is comparable to the UID carrier concentration of epitaxial films fabricated using the high temperature growth technique. Therefore, low-temperature-grown homoepitaxial Ga2O3 thin films grown by atmospheric pressure-plasma-assisted chemical vapor deposition can be used in future Ga2O3-based power device applications.
Effect of pore size polydispersity on the acoustic properties of high-porosity solid foams
Authors: Nguyen C. T. , Langlois V. , Guilleminot J. , Duval A. , Perrot C.
Published: April 2024

This study investigates the influence of pore size polydispersity on the acoustic behavior of high-porosity solid foams using numerical simulations. The effect of the size of the periodic unit cell (PUC) on the transport parameters is first examined. It is found that the size of the PUC required for properly estimating the acoustic properties of random foams depends on both the analyzed transport parameter(s) and level of polydispersity. Assuming identical and constant aperture ratio of membranes, the results indicate that (i) the viscous permeability is a reliable indicator regarding the size of the PUC (a more constraining property than the other transport parameters), and (ii) high-polydispersity foams require a larger number of pores in the PUC to achieve convergence with respect to morphological characteristics and acoustic properties. The influence of polydispersity on dimensionless transport parameters is then analyzed. It is found that polydispersity has a negligible effect on the high-frequency tortuosity but induces substantial variations in the remaining macroscopic parameters. Simulations further show that the ratio of the dimensionless transport parameters does not depend on membrane aperture ratio. This important result allows us to propose a fast method to estimate the acoustic properties of a random foam from the transport parameters of monodisperse foams with different pore sizes, for each studied transport parameter. The proposed method is finally employed to characterize the pore size and polydispersity in two real foams (with and without membranes), solving an inverse problem.
On viscous stratified Darcy–Forchheimer flow in a horizontal porous layer with thermal anisotropy and variable permeability
Authors: Mourya Pappu Kumar , Kumar Gautam , Narayana P. A. L.
Published: April 2024

This study analyzes the effect of anisotropy and the internal heat source in a Darcy–Forchheimer porous layer. It is well known that the variations in viscosity can be attributed to the temperature. Therefore, in the present problem, we consider a linear variation in viscosity with temperature for simplicity. We first derived the linear instability theory and then established global stability using the energy functional approach. In the global stability analysis, we show that working with the L2 norm fails to give a sufficient condition for global stability by exhibiting that the associated maximization problem is unbounded in the underlying stability measure space. Then, we show that a conditional stability bound can be achieved by restricting the internal heat source parameter Q with higher-order norms. The eigenvalue problems obtained in linear and nonlinear theories were integrated numerically. The linear and nonlinear instability thresholds are then compared to identify the potential regions of sub-critical instabilities. It is observed that the system is stabilized when the horizontal component of thermal diffusivity dominates and is unstable when the vertical component of thermal diffusivity dominates. We also found that increasing the variable permeability parameter λ destabilized the system. It is observed that increasing viscosity stabilizes the system, and decreasing viscosity encourages the start of convection. It is also interesting that, in the presence of an internal heat source, the region of subcritical instability increases with increasing viscosity effect but reduces with increasing vertical permeability λ.
Resonant inductive coupling network for human-sized magnetic particle imaging
Authors: Mohn Fabian , Förger Fynn , Thieben Florian , Möddel Martin , Schmale Ingo , Knopp Tobias , Graeser Matthias
Published: April 2024

In magnetic particle imaging, a field-free region is maneuvered throughout the field of view using a time-varying magnetic field known as the drive-field. Human-sized systems operate the drive-field in the kHz range and generate it by utilizing strong currents that can rise to the kA range within a coil called the drive field generator. Matching and tuning between a power amplifier, a band-pass filter, and the drive-field generator is required. Here, for reasons of safety in future human scanners, a symmetrical topology and a transformer called an inductive coupling network are used. Our primary objectives are to achieve floating potentials to ensure patient safety while attaining high linearity and high gain for the resonant transformer. We present a novel systematic approach to the design of a loss-optimized resonant toroid with a D-shaped cross section, employing segmentation to adjust the inductance-to-resistance ratio while maintaining a constant quality factor. Simultaneously, we derive a specific matching condition for a symmetric transmit–receive circuit for magnetic particle imaging. The chosen setup filters the fundamental frequency and allows simultaneous signal transmission and reception. In addition, the decoupling of multiple drive field channels is discussed, and the primary side of the transformer is evaluated for maximum coupling and minimum stray field. Two prototypes were constructed, measured, decoupled, and compared to the derived theory and method-of-moment based simulations.
Elliptic pillars based metasurface for elastic waves focusing in a plate
Authors: Carpentier L. , Gueddida A. , Lévêque G. , Alcorta-Galvan R. , Croënne C. , Miniaci M. , Djafari-Rouhani B. , Pennec Y.
Published: April 2024

In this paper, the ability of a metasurface made of resonant elliptical pillars to focus flexural Lamb waves in the sub-wavelength regime is investigated. We report on the influence of the ellipticity parameter on the local resonances of the pillars, in particular the monopolar compressional and dipolar bending modes that are responsible for the desired focusing effect. We also discuss how the transmission through a line of pillars reveals these modes when the orientation of the pillars is changed with respect to the incident wave. Both the resonances can be superimposed for a particular choice of the ellipticity parameter, allowing a phase shift of 2π in the transmission coefficient for an incident antisymmetric Lamb wave, which is a necessary condition for the design of the metasurface. Finally, a gradient design for the pillar ellipticity is investigated, and its capacity to choose the focusing directionality of the transmitted wave at different targeted points is demonstrated.
Thermal and viscoelastic coupled influences analysis on mixed lubrication in dynamic journal bearings
Authors: Lian Shimiao , Xiong Guoqing , Jiang Qinglei , Bao Binbin , Xiang Liping , Zhang Jinjie , Mao Zhiwei
Published: April 2024

The interaction of temperature variations and viscoelastic deformation is critical in dynamically loaded journal bearings, especially under fluctuating heavy load conditions. Previous studies have not fully explored the coupling of these two factors. Addressing this gap, this research introduces a novel transient mixed lubrication model that simultaneously considers thermal and viscoelastic effects. This model reveals intricate dynamics influencing the lubrication performance of journal bearings. The findings show that the combined impact of thermal and viscoelastic factors significantly alters the amplitude and phase of lubrication performance parameters. Notably, thermal effects tend to decrease oil film pressure while increasing asperity contact pressure, whereas viscoelastic effects enhance the oil film pressure peak and adjust its phase, concurrently reducing asperity contact pressure. Moreover, varying the eccentric speed profoundly influences the interplay between bearing thermal and viscoelastic effects. This study contributes to a deeper understanding of mixed lubrication in journal bearings and provides technical support for more accurate and predictive reliability improvement in complex mechanical systems.
Simulation-free determination of microstructure representative volume element size via Fisher scores
Authors: Liu Wei , Mojumder Satyajit , Liu Wing Kam , Chen Wei , Apley Daniel W.
Published: April 2024

A representative volume element (RVE) is a reasonably small unit of microstructure that can be simulated to obtain the same effective properties as the entire microstructure sample. Finite element (FE) simulation of RVEs, as opposed to much larger samples, saves computational expenses, especially in multiscale modeling. Therefore, it is desirable to have a framework that determines the RVE size prior to FE simulations. Existing methods select the RVE size based on when the FE-simulated properties of samples of increasing sizes converge with insignificant statistical variations, with the drawback being that many samples must be simulated. We propose a simulation-free alternative that determines the RVE size based only on a micrograph. The approach utilizes a machine learning model trained to implicitly characterize the stochastic nature of the input micrograph. The underlying rationale is to view RVE size as the smallest moving window size for which the stochastic nature of the microstructure within the window is stationary as the window moves across a large micrograph. For this purpose, we adapt a recently developed Fisher score-based framework for microstructure nonstationarity monitoring. Because the resulting RVE size is based solely on the micrograph and does not involve any FE simulation of specific properties, it constitutes an RVE for any property of interest that solely depends on the microstructure characteristics. Through numerical experiments of simple and complex microstructures, we validate our approach and show that our selected RVE sizes are consistent with when the chosen FE-simulated properties converge.
A multilayer network model of interaction between rumor propagation and media influence
Authors: Zhai Shidong , Li Haolin , Zhu Shuaibing , Ma Jun
Published: April 2024

Rumors spread among the crowd have an impact on media influence, while media influence also has an impact on rumor dissemination. This article constructs a two-layer rumor media interaction network model, in which the rumors spread in the crowd are described using the susceptibility-apathy-propagation-recovery model, and the media influence is described using the corresponding flow model. The rationality of the model is studied, and then a detailed analysis of the model is conducted. In the simulation section, we undertake a sensitivity analysis of the crucial parameters within our model, focusing particularly on their impact on the basic reproduction number. According to data simulation analysis, the following conclusion can be drawn: First, when the media unilaterally influences the crowd and does not accept feedback from the crowd, the influence of the media will decrease to zero over time, which has a negative effect on the spread of rumors among the crowd (the degree of rumor dissemination decreases). Second, when the media does not affect the audience and accepts feedback from the audience, this state is similar to the media collecting information stage, which is to accept rumors from the audience but temporarily not disclose their thoughts. At this time, both the media influence and the spread of rumors in the audience will decrease. Finally, the model is validated using an actual dataset of rumors. The simulation results show an R-squared value of 0.9606, indicating that the proposed model can accurately simulate rumor propagation in real social networks.
Experimental testing of the Prandtl–Tomlinson model: Molecular origin of rotational friction
Authors: Zheng Weichao
Published: April 2024

Structural superlubricity, one of the most important concepts in modern tribology, has attracted lots of interest in both fundamental research and practical applications. However, the underlying model, known as the Prandtl–Tomlinson (PT) model, is oversimplified and not for real processes, despite its prevalence in frictional and structural lubricant studies. Here, with a realistic system, cholesteric liquid crystals confined between two atomically smooth surfaces, we measure both the surface torque during rotational friction and the molecular rotation from the commensurate to incommensurate configuration at the onset of structural lubricity. Furthermore, by changing the surface potential or the strain, the Aubry transition is confirmed. The results agree well with the description by a quasi-one-dimensional version of the PT model and provide molecular evidence for rupture nucleation during static friction. Our study bridges the gap between theories and experiments and reinforces the connection between friction and fracture.
Structural relaxation of amorphous phase change materials at room temperature
Authors: Pries Julian , Stenz Christian , Wei Shuai , Wuttig Matthias , Lucas Pierre
Published: April 2024

Owing to their ability for fast switching and the large property contrast between the crystalline and amorphous states that permits multi-level data storage, in-memory computing and neuromorphic computing, the investigation of phase change materials (PCMs) remains a highly active field of research. Yet, the continuous increase in electrical resistance (called drift) observed in the amorphous phase has so far hindered the commercial implementation of multi-level data storage. It was recently shown that the resistance drift is caused by aging-induced structural relaxation of the glassy phase, which is accompanied by a simultaneous decrease in enthalpy and fictive temperature. This implies that resistance is related to enthalpy relaxation. While the resistance is known to drift even at room temperature and below, evidence for enthalpy relaxation at room temperature in amorphous PCMs is still missing. Here, we monitor changes in enthalpy induced by long-term room-temperature aging in a series of PCMs. Our results demonstrate the simultaneity of resistance drift and enthalpy relaxation at room temperature, and thus provide further insights into the mechanism of resistance drift and its possible remediation.
Sodium chloride crystallization in a model porous medium during drying with a receding sharp front
Authors: Fekih Oumayma , Sghaier Nour , Amara Mohamed El Amine Ben , Prat Marc
Published: April 2024

Visualization experiments in a model porous medium are presented in this work to study the interplay between salt precipitation and gas–liquid displacement during evaporation for the drying situation characterized by a receding sharp drying front. Various types of salt subflorescence are distinguished depending on the location of the subflorescence growth, namely, away from the drying front in the region predominantly occupied by gas or in the liquid-saturated region. A distinction is also made regarding the subflorescence that develops in the predominantly gaseous region depending on the degree of occupation of the pores by the subflorescence structure. The experiment confirms that the capillary liquid films can be a pathway for the dissolved salt transport. As a result of the capillary film effect, the evaporation front must be distinguished from the drying front and subflorescence structures can develop in the vicinity of the evaporation front away from the drying front. It is also shown that the pinning of the evaporation front leads to an anomalous drying front kinetics with a drying front position varying linearly with time and not according to the classical scaling with the square root of time.
Hydrodynamic performance of shallow-water waveguides subject to nonlinear waves
Authors: Cen Yuhao , Liang Dongfang , Cheng Qian , Liu Xiaodong , Zou Siyuan
Published: April 2024

The idea of water wave control for ease of shipping or energy exploitation has been the subject of extensive research. Yet, most studies are limited to two-dimensional simulations focusing primarily on transformations of small-amplitude linear waves. This paper presents a theoretical and numerical investigation of the hydrodynamic performance of a type of shallow-water waveguides. The concept of an effective refractive index for water waves is proposed through analogy with electromagnetic waves, based on which the wave-controlling mechanism is explained. The precise wave field is revealed using computational fluid dynamics simulations. The numerical model is validated by comparing the numerical predictions with experimental data. Subsequently, the nonlinear wave fields around the waveguide are systematically studied by increasing the incident wave height. The numerical results confirm the significant increase in the wave height above the waveguide platform, as a result of wave refraction and reflection. Such an amplification effect slightly reduces as the nonlinearity of the incident wave increases.