bluuebunny/crossref_metadata_2025 huggingface dataset:
Feedback enhanced phonon lasing of a microwave frequency resonator
Authors: Parsa Peyman , Shandilya Prasoon Kumar , Lake David P. , Mitchell Matthew E. , Barclay Paul E.
Published: April 2024

The amplitude of self-oscillating mechanical resonators in cavity optomechanical systems is typically limited by nonlinearities arising from the cavity’s finite optical bandwidth. We propose and demonstrate a feedback technique for increasing this limit. By modulating the cavity input field with a signal derived from its output intensity, we increase the amplitude of a self-oscillating GHz frequency mechanical resonator by 22% (an increase in coherent phonon number of 50%), limited only by the achievable optomechanical cooperativity of the system. This technique will advance applications dependent on high dynamic mechanical stress, such as coherent spin-phonon coupling, as well as the implementation of sensors based on self-oscillating resonators.
Sliding limited penetrable visibility graph for establishing complex network from time series
Authors: Wang Shilin , Li Peng , Chen Guangwu , Bao Chengqi
Published: April 2024

This study proposes a novel network modeling approach, called sliding window limited penetrable visibility graph (SLPVG), for transforming time series into networks. SLPVG takes into account the dynamic nature of time series, which is often affected by noise disturbances, and the fact that most nodes are not directly connected to distant nodes. By analyzing the degree distribution of different types of time series, SLPVG accurately captures the dynamic characteristics of time series with low computational complexity. In this study, the authors apply SLPVG for the first time to diagnose compensation capacitor faults in jointless track circuits. By combining the fault characteristics of compensation capacitors with network topological indicators, the authors find that the betweenness centrality reflects the fault status of the compensation capacitors clearly and accurately. Experimental results demonstrate that the proposed model achieves a high accuracy rate of 99.1% in identifying compensation capacitor faults. The SLPVG model provides a simple and efficient tool for studying the dynamics of long time series and offers a new perspective for diagnosing compensation capacitor faults in jointless track circuits. It holds practical significance in advancing related research fields.
Zero-dimensional nano-carbons: Synthesis, properties, and applications
Authors: Kurniawan Darwin , Xia Zhenhai , Dai Liming , Ostrikov Kostya (Ken) , Chiang Wei-Hung
Published: April 2024

Zero-dimensional (0D) nano-carbons, including graphene quantum dots, nanodiamonds, and carbon dots, represent the new generation of carbon-based nanomaterials with exceptional properties arising from diverse quantum phenomena, such as the surface, size, and edge effects, which strongly depend on the carbon–carbon bond configuration (sp2, sp3, and a mixture of sp2 and sp3) and particle size. Their unique physicochemical properties, including the optical, electronic, magnetic, reactivity, and catalytic properties, are valuable for energy conversion and storage, sensing, catalysis, optoelectronic devices, modern nanotechnologies, biomedical, and many other applications. This review aims to provide insights into the distinctive effects of 0D nano-carbon microstructures on their physicochemical properties that are crucial for cutting-edge fundamental studies and a broad range of multifunctional applications. The key synthesis methods for different types of 0D nano-carbons and current advances of characterization and computational techniques to study the structures of 0D nano-carbons and their structure–property relationships are also discussed. The review concludes with the current status, challenges, and future opportunities in this rapidly developing research field.
Calculations of flow field and heat exchange properties in high-power high-enthalpy inductively coupled plasma generator
Authors: Jiang Qihao , Liu Zhenyu , Niu Yue , Xie Yanan , Liu Yanming
Published: April 2024

High-enthalpy and high-density inductively coupled plasmas (ICPs) have the capability to generate continuous, high-temperature, and high-enthalpy plasma gas flows. They find extensive applications in various fields including material processing and aerospace engineering. This work aims to provide a theoretical basis for the better utilization and improvement of high-power ICP plasma generation devices developed by the Xidian University. The discharge characteristics of argon gas, heat exchange properties, and flow field characteristics are investigated through modeling. According to the simulations (50–250 kW coil power input), the increase in ignition input power and the gas intake leads to an increase in the internal temperature of the generator, gas outlet velocity, and electron number density. A noticeable high-pressure region gradually forms in the middle of the pipeline during the ignition, which gradually controls the internal flow field. Surrounding this high-pressure region, thermal exchange recirculation vortices are formed inside the plasma tube, which damages the flow field quality at the generator outlet. We propose to use shrink nozzles to improve the outlet flow quality. The simulation of ICP generator can guide facility utilization and further development.
Charged particle dynamics in an elliptically polarized electromagnetic wave and a uniform axial magnetic field
Authors: Mishra Shivam Kumar , Sharma Sarveshwar , Sengupta Sudip
Published: April 2024

An analytical study of charged particle dynamics in the presence of an elliptically polarized electromagnetic wave and a uniform axial magnetic field is presented. It is found that a charged particle resonantly gains energy for gω0/ω′=±1, ω0, and ω′, respectively, being the cyclotron frequency of the charged particle in the external magnetic field and Doppler-shifted frequency of the wave seen by the particle, and g=±1, respectively, correspond to right and left-handedness of polarization. An explicit solution of the governing equation is also presented in terms of particle position or laboratory time, for the specific case of resonant energy gain in a circularly polarized electromagnetic wave. These explicit position- or time-dependent expressions are useful for better insight into various phenomena, viz., cosmic ray generation, microwave generation, plasma heating, and particle acceleration.
Boosting electron and x-ray emission from laser produced plasmas by doping liquid droplets
Authors: Sahu Deepak Kumar , Khanna Sonali , Sabui Ratul , Gopal Ram , Krishnamurthy M.
Published: April 2024

In recent studies, it has been shown that under optimal dual pulse irradiation, it is possible to generate anomalous relativistic temperature (>500 keV) electron emission even with mJ/pulse lasers at 1/100th of the relativistic intensity when micrometer droplets of methanol are used as a high repetition rate target. In this paper, we present the results of doping these droplets with CH3I to bring out a 30-fold enhancement in electron emission. Experiments and simulations presented here find a route to enhance electron emission driven by two plasmon decay instability. Improving compact laser plasma based sources of MeV electrons, x-ray emission schemes that use a high repetition rate, and mJ/pulse laser systems is important not only for basic science but also applications of imaging and radiography.
Fault response analysis and comprehensive modeling for renewable energy microgrids consisting of virtual synchronous generators
Authors: Chen Guozhen , Mu Longhua , Fang Chongkai , Zhang Mi
Published: April 2024

Virtual synchronous generators (VSGs) have considerable potential to be applied in renewable energy microgrid systems because they provide inertia and damping, thus improving system stability. However, the fault characteristics of renewable energy microgrids differ from those of conventional grids. Consequently, investigating the fault responses of VSGs and establishing the associated fault model would significantly enhance the fault calculation and protection mechanism design in renewable energy microgrids. This paper briefly introduces the VSG control principles and fault control strategy before establishing the corresponding transient- and steady-state VSG fault models and calculating the model parameters. For simplicity, the fault model is linearized at the steady-state estimation point and semi-decoupled for the computation of the voltage amplitude and power angle. Finally, the results from MATLAB/Simulink simulations are compared with those from the proposed fault models, and the influence of the system parameters on the model is discussed. The results demonstrate the validity, simplicity, intuitiveness, and broad applicability of our approach.
Implant biomechanics relating to the dental implant and prosthesis design: In-vitro strain gauge analysis and finite element analysis
Authors: Shaukat Aqsa , Zehra Nida , Kaleem Muhammad , Fareed Muhammad Amber
Published: April 2024

Background: Biomechanics of an implant-supported prosthesis play a key role in the success or failure of rehabilitation of missing teeth. This study aimed to analyze biomechanical factors, such as an implant design and prosthesis design for a single implant-supported prosthesis. An in-vitro strain gauge analysis and finite element analysis were performed to assess different implant thread shapes and prosthesis retention modes for their strain-producing property in the peri-implant region of bone. Methodology: Four study models were prepared. Two models were fitted with Bio Horizon Tapered-Pro implants having predominant buttress-shaped threads (BT) and then two models were fitted with Grande Morse Neo Dent implants having trapezoid-shaped threads (TT). Each design was used with two types of retention modes for prostheses, BP-C and TT-C for cement-retained prostheses and similarly BT-S and TT-S for screw-retained prostheses. The strain gauges were bonded to the models and connected to a strain meter. Using an opposing porcelain fused to a metal prosthesis, a combined (axial and non-axial) load of 50–300 N at a strain rate of 0.95 mm/s was applied stepwise to each prosthesis. The strain values were recorded, and the collected data were organized and analyzed using SPSS version 22. For the finite element analysis, four 3-D models were designed. The bone, dental implants, and prostheses for each group were designed using Solid Works. A static, linear simulation was conducted in Ansys software. Results and discussion: The strain values recorded were all less than 3000μɛ and within the physiological loading zone as per Frost’s theory. Statistically significant differences were found between all groups with p-values <0.05, suggesting that changes in implant design led to differences in peri-implant bone strains. At the maximum loading of 300 N, i.e., at the mean biting force of an individual adult, the maximum strain value of 1812 με was recorded for group TT-C. At the minimum loading, all strain values were less than 500 με except for group TT-C for which 518 με was recorded. The peri-implant bone next to the implant’s crest showed maximum strain, which means that this site is more subjected to the effects of overloading than any other part. The von Mises stress was seen concentrated at the implant neck. Conclusion: TT-C implant-supported prostheses give a high strain profile. In comparison, the BT-C implant-supported prostheses give a low strain profile at mean biting forces.
A robust balancing mechanism for spiking neural networks
Authors: Politi Antonio , Torcini Alessandro
Published: April 2024

Dynamical balance of excitation and inhibition is usually invoked to explain the irregular low firing activity observed in the cortex. We propose a robust nonlinear balancing mechanism for a random network of spiking neurons, which works also in the absence of strong external currents. Biologically, the mechanism exploits the plasticity of excitatory–excitatory synapses induced by short-term depression. Mathematically, the nonlinear response of the synaptic activity is the key ingredient responsible for the emergence of a stable balanced regime. Our claim is supported by a simple self-consistent analysis accompanied by extensive simulations performed for increasing network sizes. The observed regime is essentially fluctuation driven and characterized by highly irregular spiking dynamics of all neurons.
The influence of wall effects on self-propelled performance of brown trout swimming
Authors: Yang Guang , Li Wen-jie , Du Hong-bo , Wan Yu , Jia Rui , Yang Sheng-fa , Zhang Peng
Published: April 2024

When benthic fish engage in predation, they often swim near the riverbank or close to hard rocks, where they are subjected to the combined effects of side and benthic walls. This study focuses on the brown trout and employs a three-dimensional numerical model to simulate the process of brown trout accelerating from a stationary state to a cruising state under the influence of wall effects. A self-developed subroutine algorithm is applied to solve the various hydrodynamic parameters of brown trout swimming. By varying the distance between the fish's center of gravity and the wall, this study explores the self-propelled performance and efficiency of fish swimming affected by the sidewall as well as the combined influence of the side and benthic walls. This study also reveals the hydrodynamic mechanism of wall effects that impact the performance of fish swimming in the body/caudal fin (BCF) mode. The results demonstrate that when the distance is less than 0.5 times the body length of the fish, swimming near the sidewall can enhance speed and thrust, but the swimming efficiency will reduce. Closer proximity to the benthic wall leads to increased power consumption and decreased efficiency, which is disadvantageous for fish swimming. The findings of this study reveal the unstable wall effects experienced by fish and offer insights for designing biomimetic underwater vehicles that leverage wall effects as well as for creating habitats that support fish swimming in the BCF mode.
Study on flooding displacement based on the influence of fluid gravity differentiation
Authors: Yang Manping , Long Shiyu , Yang Chao , Li Bingfan , Zhang Zhi
Published: April 2024

In order to visualize multiphase fluid seepage in porous reservoir media due to gravitational differentiation, a series of innovative experimental devices for individual or composite repulsion were fabricated to study and analyze the effects of repulsion mode, glass bead diameter, inclination angle, settling time, and crude oil viscosity on the gravitational differentiation of oil, gas, and water. The results show that compared with the actual production process in the reservoir, which requires a long time for the transport and aggregation of multiphase fluids under the action of gravity, this device can make the oil, gas, and water to produce gravity differentiation quickly and obviously. Compared with water flooding and gas flooding, combination flooding mainly extracted the emulsion of the oil–water mixture. The gravity differentiation effect of the oil–water mixture is much more significant than that of the oil–gas mixture. Static treatment of the emulsion is also required for reading numbers and producing a clear oil–water interface by oil–water gravity differentiation. Neither too low nor too high, the bank angle of a pipe filled with sand is conducive to the oil–water gravity differentiation. The effect of gravity differentiation within a specific time is directly proportional to the standing time. The change in the displacement mode can further amplify the three-phase gravity differentiation of oil, gas, and water. The greater the viscosity of crude oil, the harder the displacement. Finally, the microscopic experiment witnessed the oil–water gravity differentiation process of the extracted emulation. This experimental study identifies the main factors affecting the gravitational differentiation of multiphase fluids and methods to improve the gravitational differentiation rate of oil and water or oil and gas. The findings provide a theoretical basis for the rational and effective development of oil reservoirs.
The center for nonlinear studies: A personal history
Authors: Ecke Robert E.
Published: April 2024

The Center for Nonlinear Studies (CNLS) was an integral part of my scientific career starting as a Postdoctoral Fellow in 1983 up to my tenure as CNLS Director from 2004 to 2015. As such, I experienced a number of scientific phases of CNLS through almost four decades of foundation, evolution, and transition. Throughout this entire interval, the inspiration and influence of David Campbell guided my way. A proper history of CNLS encompassing all of the many contributors to the CNLS story is beyond my means or purpose here. Instead, I present the history as I experienced it. I emphasize the main scientific accomplishments achieved at CNLS over more than 40 years, but I will also attempt to describe and quantify the attributes that made and continue to make the Center for Nonlinear Studies a special institution of remarkable impact and longevity. Throughout its existence, CNLS owes much to the enduring legacy of David Campbell who laid down the foundations and operating principles that have made it so successful.
Q&A: Asmeret Asefaw Berhe reflects on her tenure as DOE Office of Science director
Authors: Kramer David
Published: April 2024

As Berhe returns to academia, the soil biogeochemist discusses the federal agency’s work on major research facilities, AI algorithms, and training the next generation of scientists.
Supporting rehabilitation practice for COVID-19 recovery: a descriptive qualitative analysis of allied health perspectives
Authors: Van Laake Tanis , Hitch Danielle
Published: April 2024

Objective The study aimed to explore the perspective of healthcare workers on the resources they need to provide quality rehabilitation for people recovering from coronavirus disease 2019 (COVID-19) infection. Methods A descriptive qualitative approach using reflexive thematic analysis was employed. Focus groups and interviews were performed with nine healthcare workers (one intensive care unit physiotherapist, one respiratory therapist and seven occupational therapists) with experience treating patients recovering from COVID-19 infection within hospital and in the community. Verbatim transcripts were coded and analysed for themes. Results Healthcare workers perceive an urgent need for resources about recovery from COVID-19 infection to support quality care. They particularly want detailed guidance about potential trajectories of recovery, and what should be expected over time for people with long COVID. Many observed that this group of patients had higher oxygen requirement and experienced slower recovery than others with serious respiratory conditions. Supports for quality care do exist but were not perceived as sufficient by participants. They want any new resources developed to be accessible, quick to access and targeted to specific healthcare worker roles and services settings. Participants identified several barriers to accessing practice supports, including the time poor nature of health care and financial costs to both patients and healthcare workers. Conclusion Healthcare workers perceive an urgent need for the development of resources to support quality rehabilitation for people recovering from COVID-19 infection, to support best outcomes for this group of patients. Any resources developed must consider identified barriers to their access and use to maximise their impact.
The creation of Grampians Health – a case study focusing on lessons learned from a health service merger
Authors: Duckett Stephen , Grenfell Rob , Sykes Sharon
Published: April 2024

This case study of the merger of four hospitals in western Victoria reports on the views of participants affected by the merger – as staff or from the communities – about 2 years after the merger. Respondents reported that many of the sought-after benefits of the merger were being delivered. However, the merger process itself attracted criticism, and it is here that this merger can provide lessons for others. Although there was a long lead time of consultation prior to the formal decision to merge, there was very little time to plan the next steps of implementation – there were only days between the decision and the merger taking effect. Future mergers should manage that differently. There is also a lot of literature on mergers which might provide a check list to enhance the likelihood of success in future mergers.
Chemical and mineralogical factors affecting the kinetics of acid drainage in different geomaterials
Authors: Abrahão Walter A. P. , Vasques Isabela C. F. , Fabris José D. , de Mello Jaime W. V.
Published: April 2024

Context Acid drainage (AD) production from sulfide rich materials can impact the environment, particularly the surrounding mine areas. A suitable evaluation of AD is warranted to prevent and remediate its impacts. The methods that estimate AD and its kinetics are time consuming. Aims To identify chemical and mineralogical features that influence the AD dynamics, and propose a fast method to estimate the AD generation. Methods Chemical analyses of sulfides rocks and thiomorphic soil samples included pH, contents of major elements and the acid-base accounting (ABA). Mineral identification was performed by X-ray diffractometry (XRD) and scanning electronic microscopy (SEM). The rate of sulfide oxidation in samples was evaluated through simulated weathering (SW) tests performed with different contents of H2O2, with and without CaCO3. Supernatant was drained to determine pH, acidity and S-sulfate. Key results Generation of AD was affected by carbonates and sulfides contents in samples, crystal sizes and types. Coal and thiomorfic soil produces more AD, due to framboidal pyrites and small sized sulfides. Conclusions Sulfides oxidation rate and AD generation increased from the metamorphic and igneous intrusive rocks to sedimentary-volcanic and then the supergenic geomaterials, from bigger to smaller crystal sizes. Carbonates and arsenic inhibit AD kinetics. The ABA failed to predict the AD in geomaterials, especially the ultramafic. The SW dynamic tests were suitable to assess AD kinetics and the stoichiometry of acidity production. Implications Carbonates and sulfides are important features to predict AD in several geological environments. Using H2O2 can abreviate the time consuming tests to assess the AD kinetics.
3D Poissonian image deblurring via patch-based tensor logarithmic Schatten-p minimization
Authors: Lu Jian , Huang Lin , Liu Xiaoxia , Xie Ning , Jiang Qingtang , Zou Yuru
Published: April 2024

In medical and biological image processing, multi-dimensional images are often corrupted by blur and Poisson noise. In this paper, we first propose a new tensor logarithmic Schatten-p (t-log-Sp
) low-rank measure and a tensor iteratively reweighted Schatten-p minimization algorithm for minimizing such measure. Furthermore, we adopt this low-rank measure to regularize the non-local tensors formed by similar 3D image patches and develop a patch-based non-local low-rank model. The data fidelity term of the model characterizes the Poisson noise distribution and blur operator. The optimization model is further solved by an alternating minimization technique combined with variable splitting. Experimental results tested on 3D fluorescence microscope images show that the proposed patch-based tensor logarithmic Schatten-p minimization method outperforms state-of-the-art methods in terms of image evaluation metrics and visual quality.
Computational analysis of device-to-device variability in resistive switching through single-layer hexagonal boron nitride and graphene vertical heterostructure model
Authors: Turfanda Aykut , Ünlü Hilmi
Published: April 2024

We quantify the device-to-device variations in resistive switching by considering a single-layer hexagonal boron nitride and graphene junction as a model. Then, we mimic the variations in the surface of a two-dimensional material in terms of defects and interface states by changing the distance between single-layer hexagonal boron nitride and graphene. We use density functional theory as a methodology to perform simulations at the atomic scale. The results show that the distance affects the current–voltage characterization results and that creating ultra uniform structures is important to reduce the device-to-device variability. These results are crucial to understand the reliability and accuracy of device-to-device variations in memory devices and mimic the neural dynamics beyond the synaptic cleft.
Effects of

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structure formation on the surface morphology and internal microstructure of GaAs thin films
Authors: Tian Wenwen , Chen Qian , Bian Zhetian , Gao Yue , Xie Quan , Gao Tinghong
Published: April 2024

Gallium arsenide (GaAs) materials have the advantages of high electron mobility, electron saturation drift rate, and other irreplaceable semiconducting properties. They play an important role in the electronics, solar and other fields. However, during GaAs film sedimentary growth, As atoms can undergo segregation to form

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clusters because of the influence of external factors, which affect the surface morphology and internal structure of these films. In this study, a series of investigations on the deposition and growth of GaAs crystal films were performed. Additionally, the deposition and growth of GaAs thin films were simulated using molecular dynamics. The influence of As8 clusters on the surface morphology and internal structure of GaAs films at different incidence angles, velocities and substrate temperatures was studied by using ‘defect analysis technology’ and ‘diamond structure identification’ in open source software, along with surface roughness and radial distribution function. Results show that with increasing incident angle, the number of

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clusters decreases and film density increases. Increasing incident velocity increases the irregular movement of

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clusters in air, and their deposition on the film surface affects the morphology of the film, and the surface roughness increases first and then decreases. Additionally, we investigated the effect of different substrate temperatures on the film surface. Results show that at a substrate temperature of 1173 K, the number of

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clusters in the film decreases or the As8 clusters disappear, heterogeneous nucleation occurs in the film, and the crystallization rate increases. Although the dislocation line associated with nucleation may affect the mechanical and optical properties of the film, it considerably reduces the annealing effort after the deposition and growth.
Recent advances and understanding of high-entropy materials for lithium-ion batteries
Authors: Feng Songjun , Liu Hui
Published: April 2024

Lithium-ion batteries (LIBs) has extensively utilized in electric vehicles and portable electronics due to their high energy density and prolonged lifespan. However, the current commercial LIBs are plagued by relatively low energy density. High-entropy materials with multiple components have emerged as an efficient strategic approach for developing novel materials that effectively improve the overall performance of LIBs. This article provides a comprehensive review the recent advancements in rational design of innovative high-entropy materials for LIBs, as well as the exceptional lithium ion storage mechanism for high-entropy electrodes and considerable ionic conductivity for high-entropy electrolytes. This review also analyses the prominent effects of individual components on the high-entropy materials’ exceptional capacity, considerable structural stability, rapid lithium ion diffusion, and excellent ionic conductivity. Furthermore, this review presents the synthesis methods and their influence on the morphology and properties of high-entropy materials. Ultimately, the remaining challenges and future research directions are outlined, aimed at developing more effective high-entropy materials and improving the overall electrochemical performance of LIBs.
Cutting nanodisks in graphene down to 20 nm in diameter
Authors: Sakurai Makoto , Okano Ayako Omura , Iwasaki Takuya , Joachim Christian
Published: April 2024

A direct focused He+ beam direct machining is presented to fabricate solid-state nano-disk at the surface of a graphene multilayer micro-flake deposited on an Au/Ti/sapphire surface. At irradiation doses larger than 5.0 × 1017 ions cm−2 and with a beam size well below 1 nm, graphene disks down to 20 nm in diameter have been machined with for nano-disk down to 50 nm in diameter, a central hole for preparing the positioning of a rotation axle. The local heat generated by this irradiation is inducing a partial graphene amorphization and deformation, leading to a complete graphene nano-disk vaporization at doses larger than 5 × 1018 ions cm−2. A dry transfer printing technique followed by a graphene surface cleaning was used to transfer the nano-disks from its initial surface to a fresh and clean surface. Tapping mode atomic force micrograph have been recorded to follow the vaporization as a function of the He+ dose to confirm the graphene solid-state nano-disk fabrication limit to about 20 nm with this process.
Sonochemical synthesis of bioinspired graphene oxide–zinc oxide hydrogel for antibacterial painting on biodegradable polylactide film
Authors: Le Hon Nhien , Nguyen Thi Binh Yen , Nguyen Dac Thanh Tung , Dao Thi Bang Tam , Nguyen Trung Do , Ha Thuc Chi Nhan
Published: April 2024

Graphene oxide nanosheet (GO) is a multifunctional platform for binding with nanoparticles and stacking with two dimensional substrates. In this study, GO nanosheets were sonochemically decorated with zinc oxide nanoparticles (ZnO) and self-assembled into a hydrogel of GO–ZnO nanocomposite. The GO–ZnO hydrogel structure is a bioinspired approach for preserving graphene-based nanosheets from van der Waals stacking. X-ray diffraction analysis (XRD) showed that the sonochemical synthesis led to the formation of ZnO crystals on GO platforms. High water content (97.2%) of GO–ZnO hydrogel provided good property of ultrasonic dispersibility in water. Ultraviolet-visible spectroscopic analysis (UV–vis) revealed that optical band gap energy of ZnO nanoparticles (∼3.2 eV) GO–ZnO nanosheets (∼2.83 eV). Agar well diffusion tests presented effective antibacterial activities of GO–ZnO hydrogel against gram-negative bacteria (E. coli) and gram-positive bacteria (S. aureus). Especially, GO–ZnO hydrogel was directly used for brush painting on biodegradable polylactide (PLA) thin films. Graphene-based nanosheets with large surface area are key to van der Waals stacking and adhesion of GO–ZnO coating to the PLA substrate. The GO–ZnO/PLA films were characterized using photography, light transmittance spectroscopy, coating stability, scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopic mapping (EDS), antibacterial test and mechanical tensile measurement. Specifically, GO–ZnO coating on PLA substrate exhibited stability in aqueous food simulants for packaging application. GO–ZnO coating inhibited the infectious growth of E. coli biofilm. GO–ZnO/PLA films had strong tensile strength and elastic modulus. As a result, the investigation of antibacterial GO–ZnO hydrogel and GO–ZnO coating on PLA film is fundamental for sustainable development of packaging and biomedical applications.
Comment on ‘The spacecraft decompression problem’
Authors: Mungan Carl E
Published: April 2024

By combining the conventional form of the Bernoulli equation (which assumes isothermal and incompressible flow along a streamline) with the ideal gas law, good agreement between theory and experiment has been recently found for the time dependence of the pressure inside a two-liter plastic bottle initially pumped up to three atmospheres as the air subsequently leaks out of a small hole into the ambient surroundings. However, the predicted flow speed of the air out of the hole can exceed the speed of sound, casting doubt on the incompressible assumption. In this Comment, it is shown that the compressible and isothermal form of the Bernoulli equation gives similarly good agreement, provided that a reduced effective area for the size of the hole is adopted. This compressible model predicts a definite time at which all of the excess air in the bottle will have escaped. On the other hand, for air leaking out of a vessel (such as a spacecraft) into vacuum, one should instead use a compressible and adiabatic model, as has been previously demonstrated.
The effect of electron backscatter and charge build up in media on beam current transformer signal for ultra-high dose rate (FLASH) electron beam monitoring
Authors: Pageot Charles , Zerouali Karim , Guillet Dominique , Muir Bryan , Renaud James , Lalonde Arthur
Published: April 2024

Objective. Beam current transformers (BCT) are promising detectors for real-time beam monitoring in ultra-high dose rate (UHDR) electron radiotherapy. However, previous studies have reported a significant sensitivity of the BCT signal to changes in source-to-surface distance (SSD), field size, and phantom material which have until now been attributed to the fluctuating levels of electrons backscattered within the BCT. The purpose of this study is to evaluate this hypothesis, with the goal of understanding and mitigating the variations in BCT signal due to changes in irradiation conditions. Approach. Monte Carlo simulations and experimental measurements were conducted with a UHDR-capable intra-operative electron linear accelerator to analyze the impact of backscattered electrons on BCT signal. The potential influence of charge accumulation in media as a mechanism affecting BCT signal perturbation was further investigated by examining the effects of phantom conductivity and electrical grounding. Finally, the effectiveness of Faraday shielding to mitigate BCT signal variations is evaluated. Main Results. Monte Carlo simulations indicated that the fraction of electrons backscattered in water and on the collimator plastic at 6 and 9 MeV is lower than 1%, suggesting that backscattered electrons alone cannot account for the observed BCT signal variations. However, our experimental measurements confirmed previous findings of BCT response variation up to 15% for different field diameters. A significant impact of phantom type on BCT response was also observed, with variations in BCT signal as high as 14.1% when comparing measurements in water and solid water. The introduction of a Faraday shield to our applicators effectively mitigated the dependencies of BCT signal on SSD, field size, and phantom material. Significance. Our results indicate that variations in BCT signal as a function of SSD, field size, and phantom material are likely driven by an electric field originating in dielectric materials exposed to the UHDR electron beam. Strategies such as Faraday shielding were shown to effectively prevent these electric fields from affecting BCT signal, enabling reliable BCT-based electron UHDR beam monitoring.
On how structures convey non-diffusive turbulence spreading
Authors: Long Ting , Diamond P.H. , Ke Rui , Chen Zhipeng , Cao Mingyun , Xu Xin , Xu Min , Hong Rongjie , Tian Wenjing , Yuan Jinbang , Liu Yanmin , Yan Qinghao , Yang Qinghu , Shen Chengshuo , Guo Weixin , Wang Lu , Nie Lin , Wang Zhanhui , Hao Guangzhou , Wang Nengchao , Chen Zhongyong , Pan Yuan , Li Jiquan , Chen Wei , Zhong Wulyu
Published: April 2024

We report on comprehensive experimental studies of turbulence spreading in edge plasmas. These studies demonstrate the relation of turbulence spreading and entrainment to intermittent convective density fluctuation events or bursts (i.e. blobs and holes). The non-diffusive character of turbulence spreading is thus elucidated. The turbulence spreading velocity (or mean jet velocity) manifests a linear correlation with the skewness of density fluctuations, and increases with the auto-correlation time of density fluctuations. Turbulence spreading by positive density fluctuations is outward, while spreading by negative density fluctuations is inward. The degree of symmetry breaking between outward propagating blobs and inward propagating holes increases with the amplitude of density fluctuations. Thus, blob-hole asymmetry emerges as crucial to turbulence spreading. These results highlight the important role of intermittent convective events in conveying the spreading of turbulence, and constitute a fundamental challenge to existing diffusive models of spreading.
Exploring the potential of olive pomace derived activated charcoal as an efficient adsorbent for methylene blue dye: a comprehensive investigation of isotherms, kinetics, and thermodynamics
Authors: Alouiz Imad , Benhadj Mohssine , Dahmane Elmontassir , Mouadili Abdeslam , Sennoune Mohamed , Amarouch Mohamed Yassine , Mazouzi Driss
Published: April 2024

Methylene blue (MB) is a heterocyclic aromatic chemical compound used as a dye in various dyeing processes. The accumulation of such an organic compound poses a significant threat to both the environment and human health. Therefore, numerous biological, physical, and chemical processes have been established to remove MB dye, with adsorption being the most predominant dye-based treatment technology. In this context, the aim of this work was to evaluate the adsorption properties of activated carbon derived from olive pomace against methylene blue. To this end, scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), and Fourier transform infrared spectroscopy (FT-IR) analyses were carried out to confirm the adsorption of MB on carbon structures. In addition, the effect of contact time, pH, initial dye concentration, adsorbent dose, and temperature on the adsorption efficiency of MB was investigated. On the other hand, kinetic and isothermal models were used to further understand the adsorption mechanism, which showed a good correlation with the pseudo-second-order kinetic model and the Langmuir isotherm. Finally, thermodynamic analysis showed favorable conditions for physisorption, with the process being both endothermic and spontaneous.
Design of an add-on ceramic composite armour against 14.5 × 114 mm API/B32 projectile for the armoured vehicles and investigation of the ballistic performance of the armour
Authors: Teoman Atanur , Göde Engin , Çetin Barış , Tonbul Kürşat , Çalışkan Umut , Öğünç Gökhan İbrahim
Published: April 2024

A ceramic/composite add-on armour system with innovative ceramic geometry (cylindrical) against 14.5 × 114 mm API/B32 projectile was developed and ballistic performance of the armour was investigated both experimentally and numerically. Numerical analysis was used to calculate exit velocities of the projectile after passing through the ceramic/composite layer (before penetrating the Armox 500T which simulates hull structure of an armoured vehicle) and also contributed to the selection of optimum ceramic thickness. The calculated projectile velocity-time curves (from numerical analysis) for three different ceramic thicknesses are given comparatively in the study. The curve characteristics are the same for three different analyses. The duration of the total absorption of the projectile energy is about 0.2 microseconds (ms). There were differences in the transmission of the stress wave and the delamination in the Ultra-High-Molecular-Weight Polyethylene (UHMWPE) layers differed as ceramic thickness increases. The separation between the layers varied with the change in projectile energy. As a result of the ballistic test, the armour prevented 14.5 × 114 mm API/B32 ammunition with desired damage mechanisms. In the x-ray image taken after the shootings, it was seen that the ceramic damage was local which enhanced multi-hit resistance capability and the geometry of the cylindrical alumina played an important role in the localization of the ceramic zone damage during the projectile penetration process. Due to this cylindrical ceramic geometry, the projectile moving on after the moment of impact constantly encounters a curved and new surface, and thus it is deflected and exposed to more wear. The areal density of the armour was also reduced by using the UHMWPE (which is one of the composite material whose fibres have the lowest density and good mechanical properties) composite plate as the backing plate.
Preparation and characterisation of polyvinyl alcohol/glycerol blend thin films for sustainable flexibility
Authors: Jamali Abdul Rauf , Shaikh Asif Ahmed , Dad Chandio Ali
Published: April 2024

Petroleum-based polymers pose significant environmental challenges; this prompts researchers to seek alternatives for the same. The foremost solution to replace petroleum-based packaging lies in bio-based polymers that can degrade with water, soil, and the environment. The most common and economical bio-based polymer today is polyvinyl alcohol (PVA), however, it has certain limitations such as brittleness, hydrophilic nature, etc. The primary objective of this study is to enhance the flexibility, transparency, barrier properties, and thermal stability of PVA by incorporating glycerol as a plasticizer. In this regard, thin films were prepared by utilizing a solution-casting technique (blade coating) upon the addition of numerous concentrations of glycerol ranging from 1 to 5 wt%. Here two sets of thin films were prepared i.e., with glycerol (modified) and without glycerol (pure PVA). Results suggest exceptional mechanical flexibility and enhanced optical properties in terms of improved transmittance (>90%) upon incorporation of glycerol into PVA. The modified films also demonstrated a significant increase in their water barrier capabilities in comparison to pure PVA films. When the concentration of glycerol reached to 5 wt%, a substantial increase in biodegradability and flexibility was witnessed resulting in reduced brittleness. Thus, the mechanical properties of the modified thin films exceeded that of pure PVA counterparts. The prepared thin films unveil exciting possibilities to be used in diverse applications; such as food packaging, membranes, biodegradable materials, etc,. The extensive discussion is presented in the light of observed results.
Triple-band transparency effect by multiple couplings based on toroidal dipole resonance
Authors: Li Jie , Chang Shiqi , Wang Yinghua , Wang Yongjin
Published: April 2024

We explored multiple couplings properties in composite metastructure. One part is the asymmetric double rings, supporting the narrow toroidal dipole resonance, and the other component is an upright rod that excites the broad electric dipole resonance. When these two resonant modes coincide in the spectrum, dual-band plasmon induced transparency (PIT) behavior can be obtained, which is attributed to in-phase and out-of-phase couplings between the toroidal dipole and electric dipole modes. Meanwhile, the dual-band features will become a single PIT band by varying the rotation offset angle between the upper- and lower-rings. Moreover, by introducing lateral displacement of the rod with respect to the toroidal component, a triple-band PIT effect can be achieved. In particular, under a large lateral displacement, a broadband transparency window appears across a wavelength range greater than 120 nm, where the transmission exceeds 0.9. It is derived from the hybrid coupling between toroidal dipole, electric dipole and induced high-order resonance modes. The toroidal-based PIT metamaterials not only promote the understanding of toroidal dipole moment but also provide a positive reference for toroidal-based meta-devices.
The role of beat-by-beat cardiac features in machine learning classification of ischemic heart disease (IHD) in magnetocardiogram (MCG)
Authors: Senthilnathan S , Shenbaga Devi S , Sasikala M , Satheesh Santhosh , Selvaraj Raja J
Published: April 2024

Cardiac electrical changes associated with ischemic heart disease (IHD) are subtle and could be detected even in rest condition in magnetocardiography (MCG) which measures weak cardiac magnetic fields. Cardiac features that are derived from MCG recorded from multiple locations on the chest of subjects and some conventional time domain indices are widely used in Machine learning (ML) classifiers to objectively distinguish IHD and control subjects. Most of the earlier studies have employed features that are derived from signal-averaged cardiac beats and have ignored inter-beat information. The present study demonstrates the utility of beat-by-beat features to be useful in classifying IHD subjects (n = 23) and healthy controls (n = 75) in 37-channel MCG data taken under rest condition of subjects. The study reveals the importance of three features (out of eight measured features) namely, the field map angle (FMA) computed from magnetic field map, beat-by-beat variations of alpha angle in the ST-T region and T wave magnitude variations in yielding a better classification accuracy (92.7 %) against that achieved by conventional features (81 %). Further, beat-by-beat features are also found to augment the accuracy in classifying myocardial infarction (MI) Versus control subjects in two public ECG databases (92 % from 88 % and 94 % from 77 %). These demonstrations summarily suggest the importance of beat-by-beat features in clinical diagnosis of ischemia.
Analysis of the effect of landscape component classification on landscape diversity index
Authors: Ma Biao , Li Quanxi , Mao Zixuan , Liu Xuelu
Published: April 2024

The landscape diversity index (LDI) is an important level in biodiversity conservation, and its scale dependence has an important role in regional landscape planning and biological conservation. The aim of this study is to analyze in depth the effects of spatial scale changes in the classification of different landscape components on LDI and to explore the thresholds of LDI. The classification of landscape components was accomplished in the ArcMap environment using fusion and merging tools, and the LDI thresholds and scale changes were quantitatively assessed by LDI values. The results show that there are differences in LDI values for different classifications, and the threshold for LDI without considering scale changes can be interpreted as: 0.4215 ≤ LDI ≤ 1.9754. The grain sizes suitable for landscape diversity analysis are 160m and 1280 m, and the effective amplitude range of the I, II and III land type is 9~31 km, while the effective amplitude of three land use types is 20∼31 km, relatively lagging behind. However, when considering amplitude changes, the LDI threshold can be interpreted as 0.3027 ≤ LDI ≤ 2.0947, which is suitable for large-scale regional landscape diversity studies when the grain size is large. In conclusion, the essence of landscape diversity change with scale is caused by changes in the number and area of landscape components, and the threshold analysis should not only take into account the grain size and amplitude, but also consider the landscape background of the study area.
Filamentary-based organic memristors for wearable neuromorphic computing systems
Authors: Beak Chang-Jae , Lee Jihwan , Kim Junseok , Park Jiwoo , Lee Sin-Hyung
Published: April 2024

A filamentary-based organic memristor is a promising synaptic component for the development of neuromorphic systems for wearable electronics. In the organic memristors, metallic conductive filaments (CF) are formed via electrochemical metallization under electric stimuli, and it results in the resistive switching characteristics. To realize the bio-inspired computing systems utilizing the organic memristors, it is essential to effectively engineer the CF growth for emulating the complete synaptic functions in the device. Here, the fundamental principles underlying the operation of organic memristors and parameters related to CF growth are discussed. Additionally, recent studies that focused on controlling CF growth to replicate synaptic functions, including reproducible resistive switching, continuous conductance levels, and synaptic plasticity, are reviewed. Finally, upcoming research directions in the field of organic memristors for wearable smart computing systems are suggested.