bluuebunny/crossref_metadata_2025 huggingface dataset:
Fall detection and notification system to fast emergency management for the elderly
Authors: Goldwin Ivan , Gunadhi Albert , Lestariningsih Diana , Pranjoto Hartono , Angka Peter Rhatodirdjo , Agustine Lanny
Published: January 2024

An elderly person needs special attention from his family environment; however, in general elderly people still want to live independently and not depend on their family. On the other hand, elderly people have a high risk of falling accidents because they experience a decline in health, especially physical health, which can result in serious injury or death if treatment cannot be done immediately. To overcome this, a tool is needed that can detect falls in the elderly so that it is hoped that the elderly can be treated immediately. The elderly fall detection tool is designed using accelerometer, gyroscope and GPS sensors. The function of the tool is to detect an elderly person's fall and then respond by sending information to family members from the mobile phone number that has been stored in the tool's programming. The tool has dimensions of 3.4 x 7 x 3 cm which can be put into an elderly person's pocket. Testing of the tool was carried out by the subject performing a falling movement 10 times. The tool succeeded in detecting and sending fall information to Telegram 9 times so that the success rate of the fall detection tool was 90%.
The performance of DST-Wavelet feature extraction for guitar chord recognition
Authors: Sumarno Linggo
Published: January 2024

Small systems can be designed to be more energy-efficient compared to larger systems. On small systems, the need for data processing with small data sizes becomes a necessity. In the context of small systems for guitar chord recognition, there are indications that further efforts can be made to reduce the size of feature extraction data. This paper introduces DST (Discrete Sine Transform)-Wavelet feature extraction to achieve this reduction. Basically, this work evaluated the frame blocking length, the number of DST cutting factors, and the type of wavelet filters (Daubechies and biorthogonal families) to obtain the optimal number of feature extraction data. Based on the evaluation, the optimal result obtained was a number of four feature extraction data. This optimal result was obtained by using a frame blocking length of 512 points, a DST cutting factor of 0.5, and a biorthogonal 3.3 wavelet filter. Testing with 140 test chords using these four feature extraction data could give an accuracy of up to 92.86%.
Using a stepper motor as a low-power, low-rotation DC generator for renewable energy harvesting
Authors: Suwarno Djoko Untoro
Published: January 2024

Currently, the need for renewable energy is getting bigger; studying renewable energy generation requires a small-scale or miniature generator with a low rotation that can produce power for lamp loads. The selection of generators is not as appropriate as using DC motors with high rpm, as generators still produce a small voltage (<12V) and a small current. The use of DC motors equipped with gears requires a large torque to rotate the rotor. The solution offered to overcome this problem is the use of stepper motors as a DC generator with low rotation. The stepper motor has a multi-pole coil and permanent magnet that qualify it as a generator. This study uses the nema23 stepper motor as a DC generator. The stepper motor used is a 6-wire stepper motor (two pairs of coils), a half-wave rectifier, and a capacitor to buffer the voltage. The load is a 12VDC lamp. The results obtained indicate that the stepper motor generator can turn on the lights with a manual hand rotation.
Techno-economic analysis of hybrid PV-Battery-diesel system for isolated Dockyard In West Papua
Authors: Saputra Azis , Setyawan Aji , Chairiman  , Putri Adinda Ihsani , Diguna Lina Jaya
Published: January 2024

An isolated dockyard located in West Papua currently relies on two diesel generators (DGs) with a total capacity of 1,100 kW to fulfil its energy demand. However, these DGs operate at low efficiency, resulting in a high levelized cost of energy (LCOE) of Rp9,064 /kWh and generating 496 metric tons CO2 emissions equivalent per year. On the other hand, the dockyard holds significant solar energy potential. There is opportunity to utilise solar photovoltaic (PV) since its LCOE is also decreasing. This study aims to determine the optimal configuration and sizing of a PV-battery-diesel to minimise LCOE, considering CO2 emissions and a maximum capital expenditure (CAPEX) constraint of Rp 16.4 billion. Four topologies are evaluated: DG, PV-DG, PV-battery, and PV-battery-DG topology. The results highlight the PV-battery-DG topology as the lowest LCOE of Rp3,185 /kWh while adhering to the CAPEX constraint. The PV-battery topology is the most effective in reducing emissions by 100%. Both the PV-battery-DG and PV-battery topologies are less sensitive to fuel price volatility but are more influenced by changes in inflation rates. In contrast, the DG and PV-DG topologies are relatively less responsive to inflation changes but significantly responsive to variations in fuel prices.
SCADA for waste sorting system as an environmental conservation effort
Authors: Loblobly Thomas Eryanto , Gunawan Ridowati , Sriwindono Haris , Setiyani Theresia Prima Ari
Published: January 2024

Improperly managed household waste has led to environmental pollution. The methods of reducing, reusing, and recycling are effective in reducing waste volume. Therefore, waste needs to be sorted by type. Automated waste sorting using the SCADA (Supervisory Control and Data Acquisition) system consists of Capacitive Proximity Sensors, Inductive Proximity Sensors, and Infrared Proximity Sensors to detect the types of waste, a PLC TM221CE40R as the controller, and an Android-based HMI (Human Machine Interface) to monitor real-time waste bin fill levels. The types of waste to be sorted are organic, inorganic, and metal. The system comprises 1 main bin for users to deposit waste and 3 waste bins for the sorted materials. When users deposit a certain type of waste, the sensors detect the type of waste. This information triggers the motors of the 3 waste bins to rotate and stop right beneath the main bin, matching the waste type. The bottom of the main bin opens, allowing the waste to enter the appropriate container. Test results have shown that the system is capable of correctly sorting all types of organic and metal waste. However, for inorganic waste, the system correctly sorts only when the waste is clear in color.
Les virus influenza, une écologie complexe
Authors: Bessière Pierre
Published: January 2024

La diversité génétique des virus influenza A est considérable : les oiseaux aquatiques sauvages, considérés comme le réservoir de ces virus, hébergent dans leur tube digestif de très nombreux sous-types. Au fil des années, ils ont franchi la barrière d’espèce à de multiples occasions, et circulent aujourd’hui de manière pérenne chez plusieurs espèces. Ce sont les oiseaux domestiques qui paient le plus lourd tribut, du fait de l’existence de virus dits hautement pathogènes. Si notre territoire a connu par le passé plusieurs épizooties dévastatrices pour la filière volaille, jamais les virus influenza aviaire hautement pathogènes n’ont autant circulé en Europe. Au travers des différents articles de ce numéro, nous allons faire un état de l’art des connaissances actuelles sur ces virus.
Vers le déploiement de la vaccination contre l’IAHP
Authors: Bessière Pierre
Published: January 2024

Les virus influenza aviaires hautement pathogènes (VIAHP) de clade 2.3.4.4b se sont propagés dans le monde entier, faisant courir une menace perpétuelle pour les oiseaux sauvages et domestiques, mais également pour les mammifères. Les mesures de biosécurité ne sont désormais plus suffisantes pour prévenir l’introduction des virus dans les élevages et les flambées épizootiques à partir des élevages infectés. La vaccination contre ce virus, interdite jusqu’à il y a peu dans l’Union Européenne, est désormais obligatoire en France dans les élevages de canard. Deux vaccins DIVA ont montré leur efficacité vis-à-vis des virus de ce clade chez les canards : ils diminuent fortement l’excrétion virale et protègent contre la transmission. Ainsi, depuis l’automne 2023, la vaccination est obligatoire pour tous les canards de l’étage production et est basée sur du volontariat pour l’étage multiplication. Afin de s’assurer que les virus ne circulent pas à bas bruit chez les animaux vaccinés, des plans de surveillance virologique active et passive seront mis en place. Les mouvements d’animaux vaccinés au sein du territoire national et de l’Union Européenne seront soumis à une nouvelle réglementation.
Un microbiote en bonne santé : un prérequis à la bonne régulation d’une infection par un VIAHP
Authors: Bessière Pierre
Published: January 2024

Dès les premiers instants de la naissance, le microbiote, ce vaste écosystème microbien, colonise toutes les muqueuses. Il est désormais bien établi qu’il joue un rôle majeur dans la régulation du système immunitaire : en stimulant en permanence à bas bruit ce dernier, il le maintient dans un état de réactivité optimale. En ce qui concerne les virus influenza, cela avait été démontré chez la souris, mais jamais chez le canard. Grâce à une étude de l’ENVT, c’est maintenant chose faite : les canards dont le microbiote est profondément déstabilisé peinent à réguler la réplication virale, du fait d’une réponse immunitaire antivirale innée diminuée. La préservation du microbiote, via une utilisation raisonnée des antibiotiques, une ration alimentaire équilibrée et une limitation du stress, fait donc partie des mesures de prévention vis-à-vis des infections virales.
Einmal tief durchatmen – Atemtherapie mit dem Turbofaktor
Therapiebegleithund
Authors: Contreras Kelly Cruz , Del Carpio Catalan Maria Elena , Taphya Esperanza , Klingler Werner , Naber Kurt G. , Försterling Horst-Dieter , Sommer Andrei P.
Published: January 2024

Dieser Beitrag lässt uns weit über den üblichen
Hands-on-Tellerrand hinausblicken. Er ist zum einen ein kleines
Plädoyer für die besondere Verbindung von Mensch und Hund. Er
gibt dabei Einblick in den Arbeitsalltag eines Therapiebegleithundes –
voller Bewunderung für das Können, die Empathie und die
Intelligenz des Hundes sowie den enormen Einfluss, den dieser auf die Patienten
haben kann. Zum anderen ist es eine inspirierende Geschichte über
interdisziplinäre Zusammenarbeit und wie aus der Not heraus eine
hoffnungsgebende Behandlungsmethode aus Techniken des Atem- und Stimmtrainings
entwickelt werden konnte.
Die Vielschichtigkeit von Gangstörungen – Ursachen im
Fokus
Authors: Klein Ruth
Published: January 2024

Die Ursachen von Gangstörungen bzw. pathologischen Bewegungsmustern
können vielfältig sein und beschränken sich nicht
notwendigerweise auf muskuloskelettale oder neurologische Probleme. Was kann
ggf. noch alles dahinterstecken? Die Ursachensuche bei Gangstörungen
kann sich daher oft als herausfordernd und langwierig erweisen. Wir zeigen, wie
sich die Diagnosesicherung mithilfe von passenden Laboruntersuchungen und
patientenorientierten Befundinterpretationen unterstützen
lässt.
Licht ins Dunkel: Die wichtigsten Parameter für die
therapeutische Anwendung von Laser und LED
Authors: Sommer Andrei P. , Mester Adam R. , Trelles Mario A.
Published: January 2024

Das Angebot an therapeutischen Laser- und LED-Geräten ist groß
und unübersichtlich. Doch welches ist für welche Zwecke am
besten geeignet und vor allem: Wie und warum wirkt es? Um sich im Dschungel an
unterschiedlichen Informationen und Angeboten zurechtzufinden, ist es hilfreich,
auf ein fundiertes Verständnis der physikalischen Grundlagen sowie
Kenntnisse über die aktuelle Evidenzlage zurückgreifen zu
können. Damit legt man eine solide Basis für informierte
Entscheidungen. Der nachfolgende „Kompass“ erklärt die
wichtigsten Parameter und Hintergründe.
The impact of a social and emotional learning programme to improve pupils’ educational inclusion in vocational education and training
Authors: Fernández-Martín Francisco D. , Aznar-Díaz Inmaculada , Cáceres-Reche María-del-Pilar , Trujillo-Torres Juan-Manuel
Published: January 2024

The purpose of this study was to assess the effectiveness of a programme aimed at improving social and emotional competencies among pupils registered in Basic Vocational Education and Training (VET) from disadvantaged contexts. The sample consisted of 110 first-year pupils (55 experimental group and 55 control group) from three Basic VET programmes delivered in an educational centre. Social and emotional learning was assessed using the Social and Emotional Learning Scale. After assigning each classroom group of each Basic VET programme to the experimental or control condition, the programme was implemented during a whole scholar year. This intervention was carried out by a team of previously trained teachers and educators and embedded in the school curriculum. The results show large effect sizes and statistically significant differences in favour of the experimental group in social and emotional competencies. These promising results suggest considering this SEL intervention as an example of an evidence-based programme.
Affect in science communication: a data-driven analysis of TED Talks on YouTube
Authors: Fischer Olivia , Jeitziner Loris T. , Wulff Dirk U.
Published: January 2024

Science communication is evolving: Increasingly, it is directed at the public rather than academic peers. Understanding the circumstances under which the public engages with scientific content is therefore crucial to improving science communication. In this article, we investigate the role of affect on audience engagement with a modern form of science communication: TED Talks on the social media platform YouTube. We examined how two aspects of affect, valence and density are associated with public engagement with the talk in terms of popularity (reflecting views and likes) and polarity (reflecting dislikes and comments). We found that the valence of TED Talks was associated with both popularity and polarity: Positive valence was linked to higher talk popularity and lower talk polarity. Density, on the other hand, was only associated with popularity: Higher affective density was linked to higher popularity—even more so than valence—but not polarity. Moreover, the association between affect and engagement was moderated by talk topic, but not by whether the talk included scientific content. Our results establish affect as an important covariate of audience engagement with scientific content on social media, which science communicators may be able to leverage to steer engagement and increase reach.
COVID-19 containment policies, digitalization and sustainable development goals: evidence from Alibaba’s administrative data
Authors: Zhou Xiaolan , Sawada Yasuyuki , Shum Matthew , Tan Elaine S.
Published: January 2024

The impact of digital platforms on the implementation of the United Nations’ (UN) Sustainable Development Goals (SDGs), especially the business sustainability of micro, small and medium-sized enterprises (MSMEs), under different containment policies during and after the COVID-19 pandemic has not yet been studied in detail. Using detailed administrative data from Alibaba Group’s online on-demand food delivery platform, we found that the digital platform contributed to the food security, wellbeing, employment and business sustainability of MSMEs both during and after the pandemic. We uncovered merchants’ heterogeneous responses to the COVID-19 pandemic during and after the implementation of different containment policies in China. On the extensive margin, the period of complete lockdown left long-term scarring on online merchants by decreasing the number of entrants, especially in the cooked food industry. In contrast, on the intensive margin, chain stores, especially those with large chain networks or multiapp stores, exhibited stronger resilience than their counterparts during and after lockdown. Thus, specialization (at the outlet level) and wider coverage (at the network level) emerged as key factors that enable business sustainability under challenging economic circumstances.
How deep is your trust? A comparative user requirements’ analysis of automation in medical and mobility technologies
Authors: Hick Sophia , Biermann Hannah , Ziefle Martina
Published: January 2024

In a changing world full of innovative technologies, trust and trust requirements are increasingly important for designing user-centred systems and ensuring their long-term implementation. In this study, we explored and compared the requirements of future users to build trust in the two contexts of medical and mobility technology by considering Ambient Assisted Living technologies (AAL) and Shared Autonomous Vehicles (SAV). We conducted an online survey study with N = 143 participants. The results show significant differences in the evaluation of individual trust requirements in the two contexts about data sharing, data privacy and security as well as customization. Using a cluster analysis, we identified distinct user groups and trust personalities in both contexts (medicine and mobility). The clusters differ in terms of innovation openness and risk readiness, initial trust, and presence of chronic illness. Correlation analyses revealed significant relationships between people’s initial perceived trust in technology in the two contexts and their assessment of trust requirements, as well as their behavioural intentions to use SAV or AAL systems. Our findings indicate that trust requirements are context-specific and influenced by individual characteristics. This knowledge can be used to inform developers and distributors of technologies to design, build, and manage systems that meet the needs of future users.
What shapes the financial capabilities of young adults in the US and Asia-Pacific region? A systematic literature review
Authors: Muat Susnaningsih , Mahdzan Nurul Shahnaz , Sukor Mohd Edil Abd
Published: January 2024

Young adults today face greater financial difficulties than previous generations as they transition from financial dependence to financial independence and require sufficient financial capabilities to overcome financial setbacks. Few studies, however, have conducted a detailed analysis of the literature on young adults’ financial capabilities in the Asia-Pacific region, home to over 1.1 billion young adults, and the US. Thus, this study systematically reviewed the literature addressing the factors affecting young adults’ financial capabilities in the US and the Asia-Pacific region, in accordance with the RepOrting standards for Systematic Evidence Syntheses (ROSES) publication standard and employing multiple research designs. The articles for this study were selected from two authoritative databases, Scopus and Web of Science, and a supplementary database, Google Scholar. Twenty-four articles were included for quality appraisal and qualitative synthesis based on predetermined criteria, including articles with empirical evidence published in English, with the US and Asia-Pacific countries as context and published after 2006. This review was divided into six major themes: (1) financial knowledge/literacy and education, (2) financial behaviour, (3) financial attitude, (4) financial inclusion, (5) financial socialisation, and (6) demographic characteristics. Eleven sub-themes were developed from the six major themes. The findings of this review identify three approaches to enhance the financial capability of young adults: (1) early financial education with practical simulations, which can promote positive financial attitudes and healthy financial behaviour; (2) assisting parents with adequate financial education given their role as the primary financial socialisation agents for young adults; and (3) coupling financial education with access to formal financial institutions. Additionally, this study provides insight into the directions that should be taken by future research endeavours.
Addition of Laponite to gelatin methacryloyl bioinks improves the rheological properties and printability to create mechanically tailorable cell culture matrices
Authors: Davern Jordan W. , Hipwood Luke , Bray Laura J. , Meinert Christoph , Klein Travis J.
Published: January 2024

Extrusion-based bioprinting has gained widespread popularity in biofabrication due to its ability to assemble cells and biomaterials in precise patterns and form tissue-like constructs. To achieve this, bioinks must have rheological properties suitable for printing while maintaining cytocompatibility. However, many commonly used biomaterials do not meet the rheological requirements and therefore require modification for bioprinting applications. This study demonstrates the incorporation of Laponite-RD (LPN) into gelatin methacryloyl (GelMA) to produce highly customizable bioinks with desired rheological and mechanical properties for extrusion-based bioprinting. Bioink formulations were based on GelMA (5%–15% w/v) and LPN (0%–4% w/v), and a comprehensive rheological design was applied to evaluate key rheological properties necessary for extrusion-based bioprinting. The results showed that GelMA bioinks with LPN (1%–4% w/v) exhibited pronounced shear thinning and viscoelastic behavior, as well as improved thermal stability. Furthermore, a concentration window of 1%–2% (w/v) LPN to 5%–15% GelMA demonstrated enhanced rheological properties and printability required for extrusion-based bioprinting. Construct mechanical properties were highly tunable by varying polymer concentration and photocrosslinking parameters, with Young's moduli ranging from ∼0.2 to 75 kPa. Interestingly, at higher Laponite concentrations, GelMA cross-linking was inhibited, resulting in softer hydrogels. High viability of MCF-7 breast cancer cells was maintained in both free-swelling droplets and printed hydrogels, and metabolically active spheroids formed over 7 days of culture in all conditions. In summary, the addition of 1%–2% (w/v) LPN to gelatin-based bioinks significantly enhanced rheological properties and retained cell viability and proliferation, suggesting its suitability for extrusion-based bioprinting.
Temperature-dependent Raman spectral evidence of local structural changes in BiFeO3 thin films: Influence of substrate and oxygen vacancies
Authors: Nandy Subhajit , Mocherla Pavana S. V. , Sudakar C.
Published: January 2024

Temperature-dependent Raman spectral studies of BiFeO3 (BFO) films coated on three different substrates, viz., conducting Si (BFO-Si), sapphire (BFO-SAP), and fluorine-doped tin oxide (BFO-FTO), are reported between 123 and 773 K. The activity of Bi–O and Fe–O modes in these samples as a function of temperature shows different spectral features despite having synthesized from the same precursor. To understand the source of these variations, the spectra obtained on the above films were compared with those of bulk BiFeO3 (BFO-bulk) prepared via spark-plasma sintering. As the temperature increases, modes corresponding to the Bi–O activity at low frequency (120–180 cm−1) exhibit a redshift in their positions in all the samples. Between 350 and 550 K, BFO-SAP and BFO-Si samples show discernible anomalies in the positions of modes corresponding to the Fe–O activity (200–500 cm−1), which is not observed in the BFO-bulk and BFO-FTO samples. These anomalies are more pronounced for the modes between 350 and 500 cm−1, suggesting alterations in the Néel transition temperature (∼643 K for BiFeO3). Concurrently, another composite film of BiFeO3–CoFe2O4 coated on the Si substrate is explored. Raman studies on the composite film are used to compare and verify the influence of the substrate and defects on the magnetic ordering as a function of temperature. Our study highlights the significance and relevance of using Raman spectroscopy as a tool to discern various factors leading to local structural and magnetic variation in a given compound.
Low-frequency noise in InSnZnO thin film transistors with high-quality SiO2 gate oxide stacks
Authors: Chen Yayi , Liu Yuan , Deng Sunbin , Chen Rongsheng , Zhang Jianfeng , Kwok Hoi-Sing , Zhong Wei
Published: January 2024

Low-frequency noise (LFN) in InSnZnO (ITZO) thin-film-transistors (TFT) with high-quality SiO2 gate oxide (GO) stacks is studied. This stack is fabricated by the plasma enhanced chemical vapor deposition (PECVD) and comprises two single layers. One layer is deposited by a SiH4 source (SiH4–SiO2), and the other uses a tetraethyl-orthosilicate precursor (TEOS-SiO2). The drain current noise power spectral densities follow the typical 1/f rule, and the main origin of LFN changes with the variation of drain current intensities. At low drain current intensities, LFN is affected by grain boundaries in the channel. As the drain current intensities increase, LFN originates from the carrier number fluctuations in devices with single TEOS-SiO2 GOs and from the carrier number with correlated mobility fluctuations in devices with SiO2 stacks GOs. At extremely high drain current intensities, the contact noise acts as a significant source of LFN in devices with SiO2 GO stacks. According to the carrier number with correlated mobility fluctuation (ΔN−Δμ) model, the devices with optimal stacks GOs exhibit a relatively low trap density near the ITZO/SiO2 interface. Additionally, these devices have a lower border trap density in GOs compared to those with single compositions. It demonstrates that high-quality SiO2 stacks reduce traps near the SiO2/ITZO interface, leading to enhanced devices performance. This work provides a precise and efficient method to evaluate the quality of GOs in metal oxide TFTs.
Simulations of disordered matter in 3D with the morphological autoregressive protocol (MAP) and convolutional neural networks
Authors: Madanchi Ata , Kilgour Michael , Zysk Frederik , Kühne Thomas D. , Simine Lena
Published: January 2024

Disordered molecular systems, such as amorphous catalysts, organic thin films, electrolyte solutions, and water, are at the cutting edge of computational exploration at present. Traditional simulations of such systems at length scales relevant to experiments in practice require a compromise between model accuracy and quality of sampling. To address this problem, we have developed an approach based on generative machine learning called the Morphological Autoregressive Protocol (MAP), which provides computational access to mesoscale disordered molecular configurations at linear cost at generation for materials in which structural correlations decay sufficiently rapidly. The algorithm is implemented using an augmented PixelCNN deep learning architecture that, as we previously demonstrated, produces excellent results in 2 dimensions (2D) for mono-elemental molecular systems. Here, we extend our implementation to multi-elemental 3D and demonstrate performance using water as our test system in two scenarios: (1) liquid water and (2) samples conditioned on the presence of pre-selected motifs. We trained the model on small-scale samples of liquid water produced using path-integral molecular dynamics simulations, including nuclear quantum effects under ambient conditions. MAP-generated water configurations are shown to accurately reproduce the properties of the training set and to produce stable trajectories when used as initial conditions in quantum dynamics simulations. We expect our approach to perform equally well on other disordered molecular systems in which structural correlations decay sufficiently fast while offering unique advantages in situations when the disorder is quenched rather than equilibrated.
Effects of Al doping concentration and top electrode on the ferroelectricity of Al-doped HfO2 thin films
Authors: Feng Li , Li Yu-Chun , Huang Teng , Lu Hong-Liang , Zhang David Wei
Published: January 2024

Al-doped HfO2 (HAO) is regarded as one of the potential HfO2 ferroelectric materials owing to its compatibility with the front end of the line process in integration circuits. In this work, atomic layer deposited (ALD) HAO thin films with different Al-doping concentrations and the corresponding devices with Ti or W top electrodes have been explored. It is found that the HAO film properties and corresponding ferroelectric device performances depend greatly on the doping concentration. In the concentration range of 3.0%–5.0%, 4.5% is the most proper doping concentration to induce the ferroelectricity of the thin film. It is revealed by x-ray diffraction and photoelectron spectroscopy that the oxygen vacancies can be modulated by doping, thereby contributing to the formation of the ferroelectric orthorhombic phase. A high remnant polarization (2Pr) of 36.8 ± 0.7 μC/cm2 under 5 mV/cm sweeping is observed through electrical measurement in the device with a 4.5% HAO and W top electrode. In addition, it was found that the choice of W or Ti top electrodes would affect the leakage and breakdown characteristics of the device. This work reveals the mechanism of Al doping and electrode modulation of HfO2 device performance and promotes the development of HAO ferroelectric thin film devices.
Effect of hot-electron preheating on the multimode bubble-front growth of the ablative Rayleigh–Taylor instability
Authors: Li Jun , Yan Rui , Zhao Bin , Wu Junfeng , Wang Lifeng , Zou Shiyang
Published: January 2024

Hot electrons (HEs) generated via parametric instabilities at high laser intensities are a critical concern of laser-driven inertial confinement fusion (ICF), which can significantly impact the ICF performance by preheating the target. In this paper, the effects of HE preheating with moderate HE energy on the evolution of two-dimensional multimode ablative Rayleigh–Taylor instability (ARTI) up to the self-similar growth stage are studied through numerical simulations with a multigroup diffusion model. It is found that HE preheating stabilizes the linear growth of multimode ARTI and delays the onset of the self-similar growth regime. This time delay is more significant for the short-wavelength mode ARTI and higher energy HE cases. It is also shown that the variation of self-similar growth coefficients under HE preheating is not very significant. The delay to the onset of the nonlinear stage of multimode ARTI by HE preheating with moderate energy may be beneficial to ICF implosions.
Dense random packing of disks with a power-law size distribution in thermodynamic limit
Authors: Cherny Alexander Yu. , Anitas Eugen M. , Vladimirov Artem A. , Osipov Vladimir A.
Published: January 2024

The correlation properties of a random system of densely packed disks, obeying a power-law size distribution, are analyzed in reciprocal space in the thermodynamic limit. This limit assumes that the total number of disks increases infinitely, while the mean density of the disk centers and the range of the size distribution are kept constant. We investigate the structure factor dependence on momentum transfer across various number of disks and extrapolate these findings to the thermodynamic limit. The fractal power-law decay of the structure factor is recovered in reciprocal space within the fractal range, which corresponds to the range of the size distribution in real space. The fractal exponent coincides with the exponent of the power-law size distribution as was shown previously by the authors of the work of Cherny et al. [J. Chem. Phys. 158(4), 044114 (2023)]. The dependence of the structure factor on density is examined. As is found, the power-law exponent remains unchanged but the fractal range shrinks when the packing fraction decreases. Additionally, the finite-size effects are studied at extremely low momenta of the order of the inverse system size. We show that the structure factor is parabolic in this region and calculate the prefactor analytically. The obtained results reveal fractal-like properties of the packing and can be used to analyze small-angle scattering from such systems.
In situ tracking the phase change in metastable copper oxide thin film via thermal oxidation
Authors: Kenzhebayeva Yuliya , Migot Sylvie , Boulet Pascal , Milichko Valentin A. , Pierson Jean-François
Published: January 2024

Phase change (PC) materials, such as metal oxides, possess high fundamental and applied importance for modern memory, sensor, and photonic devices. However, revealing the kinetics and mechanisms of PC and achieving the reversible and irreversible PC regimes are still a challenge. Here, we report on 200 nm films of metastable Cu4O3 obtained by magnetron sputtering. In situ structural and optical analyses during air annealing revealed the thermal induced PC from Cu4O3 to CuO. Combination of x-ray diffraction and optical transmittance with heating up to 450 °C allowed us to explore the PC rate and then to correlate it with classical nucleation and crystal growth mechanism. We have also revealed two regimes of PC, possessing reversible 12% (1.42–1.25 eV) and irreversible 220% (1.25–2.75 eV) direct bandgap tuning by temperature. The results, thereby, pave the way for controllable transformation of copper oxide thin films to achieve the desired microstructure and its functionality.
Influence of the porosity pattern on the aerodynamics of a square-shaped fly-swatter
Authors: Gayout A. , Bourgoin M. , Plihon N.
Published: January 2024

The evolution of the normal aerodynamic coefficient of 19 configurations of square plates with various porosity patterns, ranging from solid plate to homogeneous porous plate, is experimentally characterized. The variation of the porosity pattern is obtained by partially covering the holes of a commercial fly-swatter using adhesive tape. Evolution of the normal aerodynamic coefficient is assessed from the measurement of the angular position of the porous plate, placed as a freely rotating pendulum swept by a flow in a wind tunnel. These angular measurements are also supported by particle image velocimetry (PIV) measurements of the structure of the wake. We show that the porosity pattern determines whether or not an abrupt stall occurs. In particular, the details of the porosity pattern on the edges of the plate are decisive for the existence of abrupt stall.
Analyzing the early impact dynamics of single droplets impacting onto wetted surfaces
Authors: Geppert A. K. , Stober J. L. , Steigerwald J. , Schulte K. , Tonini S. , Lamanna G.
Published: January 2024

Single droplet impacts onto thin wall-films are a common phenomenon in many applications. For sufficiently high impact velocities, the droplet impact process consists of three phases, i.e., initial contact stage, droplet deformation with radial momentum transfer inducing an upward rising lamella, and crown propagation. Here, we present the results of a combined numerical and experimental study focusing on the early dynamics of the impact process. Specifically, the effects of the initial droplet shape, wall-film thickness, and contact line motion are analyzed. Prior to impact, an oblate spheroidal droplet shape was observed. Using direct numerical simulation, we show that the droplet shape affects the impact dynamics only during the first two phases, as it is one of the key parameter influencing the correct prediction of the impact zone. The contact line propagation is described by a square-root-time dependence R¯CL=ατ for both, dry and wetted surfaces. On dry surfaces, the advancement of the contact line is determined by the rolling motion of the truncated droplet. On wetted surfaces, the value of the α-parameter is controlled by two concurrent effects, namely, rolling motion and wall-film inertia. For impact onto thin films, the rolling motion prevails. With increasing wall-film height, the droplet penetrates into the soft substrates and wall-film inertia becomes the controlling factor. These insights into the early impact dynamics on wetted surface are important for the formulation of a unified modeling approach.
Pore-scale investigation on the effect of capillary barrier on two-phase displacement in dual-structure porous media
Authors: Meng Wei , Zhang Yunwei , Pei Haokang , Yu Jinbao , Hu Yingxue , Gu Zhaolin , Su Junwei
Published: January 2024

Although immiscible fluid–fluid displacement in porous media has received extensive attention, understanding the dynamics behavior within complex structures remains elusive. This study utilizes the direct numerical simulation by solving the Navier–Stokes equations and coupling with the volume of fluid method to examine oil–water flow in porous media across various contact angles θ and capillary number Ca. Three kinds of artificial porous media were generated with designed opening angle β, including single-structure and dual-structure models. A theoretical analysis of the capillary barrier phenomenon, as well as its occurrence conditions, is identified under water-wet conditions. Generally, when θ + β < 90°, the capillary force consistently drives oil displacement from throats to pores. Conversely, if θ + β > 90°, the direction of the capillary force can move toward the water phase side and prevent the fluid interface from continuing to move. For a single-structure porous medium, the dynamics behavior of fluids is controlled by the capillarity, wettability, and geometric structures. The greatest efficiency occurs when the condition θ + β = 90° is met, particularly at an intermediate Ca. For a dual-structure porous medium with smaller opening angles inside, the water phase tends to infiltrate the embedded pore structure due to weaker capillary barrier effects. Conversely, larger opening angles within the embedded structure lead to stronger capillary barrier effects, hindering water entry into the interior porous medium. This obstruction forces the water phase to bypass and traverse longer flow paths, resulting in the formation of a large amount of residual oil.
Lyotropic liquid crystal phases of monoolein in protic ionic liquids
Authors: Paporakis Stefan , Brown Stuart J. , Darmanin Connie , Seibt Susanne , Adams Patrick , Hassett Michael , Martin Andrew V. , Greaves Tamar L.
Published: January 2024

Monoolein-based liquid crystal phases are established media that are researched for various biological applications, including drug delivery. While water is the most common solvent for self-assembly, some ionic liquids (ILs) can support lipidic self-assembly. However, currently, there is limited knowledge of IL-lipid phase behavior in ILs. In this study, the lyotropic liquid crystal phase behavior of monoolein was investigated in six protic ILs known to support amphiphile self-assembly, namely ethylammonium nitrate, ethanolammonium nitrate, ethylammonium formate, ethanolammonium formate, ethylammonium acetate, and ethanolammonium acetate. These ILs were selected to identify specific ion effects on monoolein self-assembly, specifically increasing the alkyl chain length of the cation or anion, the presence of a hydroxyl group in the cation, and varying the anion. The lyotropic liquid crystal phases with 20–80 wt. % of monoolein were characterized over a temperature range from 25 to 65 °C using synchrotron small angle x-ray scattering and cross-polarized optical microscopy. These results were used to construct partial phase diagrams of monoolein in each of the six protic ILs, with inverse hexagonal, bicontinuous cubic, and lamellar phases observed. Protic ILs containing the ethylammonium cation led to monoolein forming lamellar and bicontinuous cubic phases, while those containing the ethanolammonium cation formed inverse hexagonal and bicontinuous cubic phases. Protic ILs containing formate and acetate anions favored bicontinuous cubic phases across a broader range of protic IL concentrations than those containing the nitrate anion.
A modular table-top setup for ultrafast x-ray diffraction
Authors: Lu W. , Nicoul M. , Shymanovich U. , Tarasevitch A. , Horn-von Hoegen M. , von der Linde D. , Sokolowski-Tinten K.
Published: January 2024

We present a table-top setup for femtosecond time-resolved x-ray diffraction based on a Cu Kα (8.05 keV) laser driven plasma x-ray source. Due to its modular design, it provides high accessibility to its individual components (e.g., x-ray optics and sample environment). The Kα-yield of the source is optimized using a pre-pulse scheme. A magnifying multilayer x-ray mirror with Montel–Helios geometry is used to collect the emitted radiation, resulting in a quasi-collimated flux of more than 105 Cu Kα photons/pulse impinging on the sample under investigation at a repetition rate of 10 Hz. A gas ionization chamber detector is placed right after the x-ray mirror and used for the normalization of the diffraction signals, enabling the measurement of relative signal changes of less than 1% even at the given low repetition rate. Time-resolved diffraction experiments on laser-excited epitaxial Bi films serve as an example to demonstrate the capabilities of the setup. The setup can also be used for Debye–Scherrer type measurements on poly-crystalline samples.
Improvement of the two-fluid momentum equation for turbulent bubbly flows
Authors: Sadeghi Ali , Ejtehadi Omid , Yoon Sang Hee , Kim Byoung Jae
Published: January 2024

A two-fluid model is widely employed to predict gas–liquid two-phase flows. Conventional two-fluid equations, derived by assuming that all phases are interpenetrating continua, occasionally yield impractical results. For example, the bubble velocity is predicted to be higher than the water velocity for a horizontal fully developed bubbly flow. One solution for this irrational result is two-fluid momentum equations based on the motion of fluid particles. This study revisits the particle-motion-based two-fluid equations. Previously, it was validated only with respect to the difference between the bubble and liquid velocities. Recently, we observed an erroneous prediction of the void fraction distribution by the existing particle-motion-based momentum equations. This study, through rigorous analysis, discovered that this error could be resolved by neglecting the turbulent kinetic energy term in the particle-motion-based equation for the gas phase. Subsequently, the revised momentum equations were applied to the vertical and horizontal air–water bubbly flows. The conventional and revised momentum equations produced similar results for upward bubbly flows because the relative velocity between the bubble and water phases was mainly governed by buoyancy. For horizontal bubbly flows, the revised momentum equations led to a downward shift in the liquid velocity distributions, which was attributed to the modified momentum diffusion term. At a higher modification factor of turbulent dispersion, the velocity distributions exhibited an upward shift. We conclude that the optimization of physical models should be based on the revised two-fluid momentum equations.
Nonlinear magnetoelectric effects in layered multiferroic composites
Authors: Fetisov Y. K. , Srinivasan G.
Published: January 2024

Magnetoelectric (ME) effects in a ferromagnetic and piezoelectric composite are the changes in the polarization caused by a magnetic field or the changes in the magnetization caused by an electric field. These effects are aided by the mechanical deformation in the ferroic phases caused by the combination of magnetostriction and piezoelectricity. Interest in ME effects is due to a variety of physical phenomena they exhibit, as well as their potential applications in the creation of highly sensitive magnetic field sensors and other electronic devices. Linear ME effects in structures with layers of different ferroic materials have been studied extensively. However, nonlinear ME effects, which are caused by the nonlinearity of the magnetic, dielectric, and acoustic properties of ferromagnets and piezoelectrics, are less well understood. The purpose of this review is to summarize the current state of knowledge on nonlinear ME (NLME) effects in composite heterostructures and to discuss their potential applications. The review begins by discussing the characteristics of materials that are conductive to the occurrence of NLME effects and ferromagnetic-piezoelectric materials that are most commonly used to study such effects. The review then provides details on theoretical approaches to the description of NLME effects in heterostructures and experimental methods for studying these effects. Finally, the review presents a chronological overview of the experimentally observed NLME effects in composite structures excited by low-frequency and pulsed magnetic or electric fields. The review concludes with a discussion on the potential applications of NLME effects for highly sensitive magnetic field sensors.
Transmission–reflection-integrated multifunctional metasurfaces for multiplexed acoustic wave manipulation
Authors: Cheng Haoyi , Guo Jingwen
Published: January 2024

Considering the extraordinary wavefront modulation properties, acoustic metasurfaces have been extensively utilized to achieve powerful wave-manipulation functionalities. The next-generation acoustic metasurfaces are urgently required to encode more information capacity and process an increasing number of signal channels in a compact device, which needs more degrees of freedom for multifunctional wavefront modulation. In this study, subwavelength monolayer transmission–reflection-integrated metasurfaces (TRIMs) are systemically designed through a gradient-free topology optimization method to simultaneously realize diverse acoustic functions, such as beam steering, focusing, splitting, and diffusion, in reflection mode and transmission mode. Both numerical and experimental results demonstrate the desired wave-manipulation performance of the metasurfaces. In addition, a dual-frequency multiplexed TRIM is also numerically achieved for exploring the integration of multiple degrees of freedom and tunable function switching, which promise many unprecedented applications in integrated medical imaging, underwater wireless telecommunications, on-chip signal processing, etc.
Electrolyte design for reversible metal electrodeposition-based electrochromic energy-saving devices
Authors: Wang Jinhui , Lv Ying , Zhou Yiping , Jia Sensen , Zhu Feng , Schmidt Oliver G. , Cai Guofa
Published: January 2024

Reversible metal electrodeposition (RME)-based electrochromic devices have been attracting significant research interest due to their merits of low cost, simple configuration, and high extinction coefficients. As the key component in the electrochromic system, RME electrolytes with various metal ions and additives have endowed the RME device with flexible functionalities in energy-saving applications such as energy-efficient displays, smart windows, and camouflages. However, it is still challenging to research a widespread commercial application before some critical issues can be solved such as poor reversibility, low optical memory of the mirror state, and slow switching speed. Here, we offer a critical review of the recent progress of RME electrochromic devices based on aqueous, organic, ionic liquid, and eutectic electrolytes. Furthermore, the main challenges and perspectives for RME electrolytes are highlighted and discussed.