bluuebunny/crossref_metadata_2025_split huggingface dataset:
A coaxial solid state nonlinear pulse forming line with an exponentially tapered ferrite composite core
Authors: Crawford Travis D. , Evers Sophia I. , Sapoff Bradley H. , Garner Allen L. 
Published: December 2024

The need to optimize size, weight, and power of high-power microwave (HPM) systems has motivated the development of solid-state HPM sources, such as nonlinear transmission lines (NLTLs), which utilize gyromagnetic precession or dispersion to generate RF. One recent development implemented the NLTL as a pulse forming line (PFL) to form a nonlinear pulse forming line (NPFL) system that substantially reduced the system’s size by eliminating the need for a separate PFL; however, matching standard loads can be challenging. This paper describes the development of a tapered NPFL using an exponentially tapered composite based ferrite core containing 60% nickel zinc ferrite (by volume) encased in polydimethylsiloxane (PDMS) and encapsulated in a 5% barium strontium titanate shell. The tapers exponentially change the line’s impedance from a 50 Ω standard HN connection to 25 Ω before tapering back to 50 Ω. We characterized the core behavior by obtaining magnetization curves and ferromagnetic resonance measurements. The rise time (10%–90%) of the pulse decreased from ∼6 ns for 5 kV charging voltage to 1.8 ns for 15 kV charging voltage. Under unbiased conditions, the system generated HPM with a center frequency of ∼850 MHz with a 3 dB bandwidth of 125 MHz. Magnetic biases of 15 and 25 kA/m increased the modulation depth and decreased the center frequency to ∼500 MHz for 15 kV charging voltage.
Nature of the carrier dynamics and contrast formation on the photoactive material surfaces: Insight from ultrafast imaging to DFT calculations
Authors: Nematulloev Sarvarkhodzha , Nughays Razan O. , Nematulloev Saidkhodzha , Thomas Simil , Naphade Dipti R. , Anthopoulos Thomas , Bakr Osman M. , Alshareef Husam N. , Mohammed Omar F. 
Published: December 2024

Precise material design and surface engineering play a crucial role in enhancing the performance of optoelectronic devices. These efforts are undertaken to particularly control the optoelectronic properties and regulate charge carrier dynamics at the surface and interface. In this study, we used ultrafast scanning electron microscopy (USEM), which is a powerful and highly sensitive surface tool that provides unique information about the photoactive charge dynamics of material surfaces selectively and spontaneously in real time and space in high spatial and temporal resolution. Here, time-resolved images of CdTe (110), CdSe (100), GaAs (110), and other semiconductors revealed that the presence of oxide layers on the surface of materials leads to an increase in the work function (WF) and trap state densities upon optical excitation, leading to the formation of dark image contrast in USEM experiments. These findings were further supported by ab initio calculations, which confirmed the reliability of the observed changes in the excited surface WFs. Besides enhancing our understanding of surface charge dynamics, it also offers valuable insights into manipulating these properties. This study paves the way for precise control and the potential to design highly efficient light-harvesting devices.
Predicting viscosities and thermal conductivities from dilute gas to dense liquid: Deriving fundamental transfer lengths for momentum and energy exchange in revised Enskog theory
Authors: Jervell Vegard G. , Wilhelmsen Øivind 
Published: December 2024

Chapman–Enskog theory has long provided an accurate description of the transport properties of dilute gas mixtures. At elevated densities, revised Enskog theory (RET) provides a framework for describing the departure of the transport properties from their dilute-gas values. Various methods of adapting RET for the description of real fluids have been proposed in the literature. The methods have in common that they incorporate one or more length scales to describe molecular interactions. With few exceptions, the required length scales have been estimated from experimental transport property data. In this work, we introduce two transfer lengths that describe the residual transport of momentum and energy. We derive a model called the exchange-weighted closest approach (EWCA), which links the transfer lengths to the intermolecular potential. Combining the EWCA model with Mie potentials fitted to experimental equilibrium properties yields accurate predictions for several real fluids, including a binary mixture. At higher temperatures, the theory is accurate at surprisingly high densities, even up to the liquid–solid transition of argon. We demonstrate how the transfer lengths can be computed from experimental data or correlations for the transport properties. The transfer lengths obtained in this manner are in good agreement with those obtained from the EWCA model paired with an accurate ab initio potential for argon. The results suggest that kinetic theory, after further developments, can become a predictive theory also for liquids.
Beyond the Debye–Hückel limit: Toward a general theory for concentrated electrolytes
Authors: Dinpajooh Mohammadhasan , Intan Nadia N. , Duignan Timothy T. , Biasin Elisa , Fulton John L. , Kathmann Shawn M. , Schenter Gregory K. , Mundy Christopher J. 
Published: December 2024

The phenomenon of underscreening in concentrated electrolyte solutions leads to a larger decay length of the charge–charge correlation than the prediction of Debye–Hückel (DH) theory and has found a resurgence of both theoretical and experimental interest in the chemical physics community. To systematically understand and investigate this phenomenon in electrolytes requires a theory of concentrated electrolytes to describe charge–charge correlations beyond the DH theory. We review the theories of electrolytes that can transition from the DH limit to concentrations where charge correlations dominate, giving rise to underscreening and the associated Kirkwood Transitions (KTs). In this perspective, we provide a conceptual approach to a theoretical formulation of electrolyte solutions that exploits the competition between molecular-informed short-range (SR) and long-range interactions. We demonstrate that all deviations from the DH limit for real electrolyte solutions can be expressed through a single function ΣQ that can be determined both theoretically and numerically. Importantly, ΣQ can be directly related to the details of SR interactions and, therefore, can be used as a tool to understand how differences in representations of interaction can influence collective effects. The precise function form of ΣQ can be inferred through a Gaussian field theory of both the number and charge densities. The resulting formulation is validated by experiment and can accurately describe the collective phenomenon of screening in concentrated bulk electrolytes. Importantly, the Gaussian field theory predictions of the screening lengths appear to be less than ∼1 nm at concentrations above KTs.
Systematic ab initio calculation of spectroscopic constants for A-reduced rotational effective Hamiltonians of asymmetric top molecules using normal ordering of cylindrical angular momentum operators
Authors: Krasnoshchekov Sergey V. , Efremov Ilya M. , Polyakov Igor V. , Millionshchikov Dmitry V. 
Published: December 2024

This research paper presents a new fundamental approach for evaluating accurate ab initio quartic, sextic, and octic centrifugal distortion parameters of A-reduced rotational effective Hamiltonians of asymmetric top molecules. In this framework, the original Watson Hamiltonian, expanded up to sextic terms of kinetic and potential energies, is subjected to a series of vibrational and rotational operator unitary transformations, leading to reduced Watson effective Hamiltonians for the equilibrium configuration, ground state, and weakly perturbed vibrationally excited states. The proposed scheme is based on a numerical-analytic implementation of the sixth-order Van Vleck operator perturbation theory with the systematic normal ordering of vibrational rising and lowering operators (a†, a) and cylindrical angular momentum operators (Jz, J+, J−). The efficiency of the developed theoretical model is demonstrated by the juxtaposition of predicted centrifugal distortion parameters for several three to eight atomic molecules, including H2S, CH2O, C2H4, CH2D2, CH2F2, CH2Cl2, and B2H6, using the coupled-cluster single double triple/quadruple-ζ level of quantum chemistry. In comparison with the values derived using the customary analytic expressions, the calculated quartic and sextic parameters may improve by an order of magnitude in the fourth and sixth orders, respectively, reaching an accuracy of about 1%. Predicted octic constants can serve as an excellent starting point for fitting to experimental spectra.
Linguistic complexity development in the writings of Chinese EFL
learners across three proficiency levels
Authors: Wang Zhihong , Yang Lianrui , Chen Ying , Li Xukui 
Published: December 2024

Abstract
This study uses a corpus-based method to analyze the
developmental paths of syntactic and lexical complexity in Chinese EFL learners
across three proficiency levels. It examines six pieces of English essays
written in one semester under school instruction. The goal is to identify both
group results and individual developmental paths. The results show that both
groups and individuals at the same level follow a dynamic, nonlinear development
path, but with different trajectories. The development of syntactic complexity
in their writings is marked by variability and interaction between different
linguistic complexity subsystems. Chinese EFL learners at three proficiency
levels are each in a different stage of L2 development. The study concludes with
important and practical pedagogical implications for L2 instruction.
Falling, slipping, and stumbling backwards
Authors: Jackson Sinéad 
Published: December 2024

Abstract
This paper identifies how experiences of alcohol use disorder (AUD) are metaphorically framed in online alcohol
support materials, using a dataset curated to isolate the language individuals seeking support may encounter. Individuals affected
by AUD face barriers including self-stigma, shame, and a perceived lack of agency, which have been shown to inhibit help-seeking
behaviours. Framings of alcohol use may challenge or reinforce stigmatising perceptions, in ways which may empower or disempower
those affected. There has been little research examining how metaphor is used to communicate perceptions surrounding AUD,
particularly at crucial access points such as the language of support materials. This paper applies the Metaphor Identification
Procedure (Pragglejaz Group, 2007) to identify how metaphor use frames four key aspects
of AUD: lived experience; coping strategies; the disorder; treatment options. The findings show that Journey framings dominate in
this context, highlighting both the long-term nature and potential impermanence of recovery. Individuals are represented with
varying degrees of agency at different stages of dependence, and framings acknowledging mitigated agency tend to anthropomorphise
AUD itself in violent and highly agentive terms. The discussion examines the implications of the identified framings for
support-seeking individuals, highlighting the need for further research exploring how those individuals may respond to and
evaluate these framings.
Claims of not-knowing as patients’ responses in psychodynamic psychotherapy
Authors: Fenner Carolina 
Published: December 2024

Abstract
A fundamental aspect of psychotherapeutic conversation is the joint work of therapist and patient on articulating
something previously hidden or repressed. If the patient refuses to comply with the therapist’s questions or suggestions, such
cooperative work is limited. A possible non-cooperative response by the patient is the claim of not-knowing. This study examines
conversation analytically, using video recordings of German-speaking outpatient psychodynamic psychotherapies, how patients
express two different claims of not-knowing (German ich weiß nicht (‘I don’t know’) and keine
Ahnung (‘no idea’)) as a response to a question. The analysis results in four different functions: refusing
to answer, indexing difficulties, projecting continuation, and
disconfirming, which can only be determined by means of the context and not the structure of ich weiß
nicht or keine Ahnung. Some of the outlined functions might be context-specific for (psychodynamic)
psychotherapy.
A cylindrical microfluidic centrifuge for high-efficient blood separation
Authors: Miao Ying , Shan Liqing 
Published: December 2024

Abstract
In this paper, a new type of microfluidic centrifuge for plasma separation was presented. The main body of the centrifuge is cylindrical, consisting of a sample chamber and two automatic pressure-opening structures, with microchannels spiraling upward along the cylinder. Firstly, Comsol software was adapted to determine the microchannel parameter. The results showed that the centrifugal efficiency (CE) was proportional to the cylinder diameter, the loop number and the rotational speed. Therefore, 2 loops and 30 mm diameter were selected as the structural parameters. Then, polystyrene microspheres were employed to study the centrifuge performance. The experimental results showed that the centrifuge could effectively separate the particles in the suspension, and the centrifuge CE was inversely proportional to the initial concentration and proportional to the outlet ratio. Then, the ability of the centrifuge to separate plasma had been verified by experiments, and when the blood volume was diluted to three times, the CE was 97.4% with the 1:1 outlet ratio. Finally, the centrifuge was compared with other blood centrifuges. It can be seen that the cylindrical centrifuge has the advantages of low cost, simple operation, high separation efficiency, wide sample volume range and high separation rate.
Exploring the focusing system and evaluating structures through proton beam writing
Authors: Mongwaketsi Nametso , Khumalo Zakhelumuzi , Mtshali Christopher , Machethe Katlego , Mokoena Thabang , Barnard Hugo 
Published: December 2024

Abstract
The Tandetron laboratory at iThemba LABS has been performing proton beam writing (PBW) with a beam spot size of approximately 3 × 3 μm2 for the fabrication of microstructures. Successful fabrication of structures measuring about 10–15 μm2 has been achieved. To further optimize the PBW system and enhance the spot size, TRANSPORT measurements were conducted to ensure the feasibility of focusing the beam to less than 1 µm, crucial for achieving high-resolution PBW. Additionally the capabilities of the new PBW in-house developed LabVIEW software to fabricate the ‘sun’ pattern was explored. The TRANSPORT calculations revealed that the quadrupole lenses exhibit a stronger beam focus in the Y axis and a comparatively weaker focus in the X axis. To validate and establish a correlation between the measured spot size of 3.2 μm × 580 nm and its morphology, PBW with raster scanning of the beam over polymethylene methacrylate (PMMA) was performed. Furthermore, the observed PMMA peeling during PBW and identified parameters influencing this behaviour will be considered in future. This research aims to optimize the PBW technique by improving the beam focus and structure resolution.
Orientation dependence of residual current in graphene by few-cycle linearly polarized light
Authors: Zhang Xiaoxue , Zhan Qiang , Liu Chengpu 
Published: December 2024

Abstract
The orientation dependence of residual current in graphene using linearly polarized light is theoretically investigated by numerically solving the time-dependent Schrödinger equation. We find that the residual current exhibits an unexplored small-period sinusoidal modulation in addition to a large-period sinusoidal modulation as a function of polarization angle. Via decomposing the residual current into two components, parallel and perpendicular to the laser polarization direction, we confirm that the large-period modulation comes from the parallel current component, while the small-period modulation is from the perpendicular component. These two current components are both influenced by the asymmetric population distribution as a consequence of the Landau–Zener–Stückelberg interference. The result here demonstrates a strong link between graphene symmetry and residual current and provides some insights into the development of light-field-driven petahertz information technology.
The dynamics of Tonks–Girardeau gas excited by a pulse drive
Authors: Li 李 Jia 佳 , Hao 郝 Yajiang 亚江 
Published: December 2024

Abstract
In this paper we study the dynamics of Tonks–Girardeau (TG) gases in a harmonic potential driven by a Gaussian pulse, which is in correspondence with the excitation dynamics of electrons in matter driven by an ultrashort laser pulse. The evolving dynamics of the TG gas are obtained with a Bose–Fermi mapping method combined with numerical techniques. We calculate the evolving dynamics of the occupation distribution of single-particle energy levels, the density distribution and the momentum distribution of the system. It is shown that the system arrives at a dynamically stable state at the end of driving. In the high-frequency regime, TG gases return back to the ground state, while in the low-frequency regime the population inversion exhibits that all atoms occupy high levels.
Editorial for design of nanocluster-based functional materials
Authors: Wang Guangzhao , Xu Wen Wu , Su Yan , Chen Hongshan , Yuan Hongkuan 
Published: December 2024

Abstract
Ultrasmall nanoparticles, universally recognized as nanoclusters, exhibit distinctive physical and chemical properties that are typically unobservable in bulk materials, stemming from the profound quantum confinement effects. With significant breakthroughs in crystal structure determination and atomically precise synthesis, nanoclusters have garnered increasing attention due to their intriguing luminescence properties, electronic transitions between the highest occupied molecular orbital and lowest unoccupied molecular orbital, chirality, quantized charging capabilities, and magnetic behaviors, along with their promising applications in diverse fields such as energy storage and conversion, catalysis, environmental remediation, and biological medicine. Furthermore, cluster assembly offers a promising route to fabricate innovative materials endowed with captivating properties, thereby offering novel approaches for designing nanocluster-based functional materials. Combining nanoclusters with one-dimensional (1D), two-dimensional (2D), and three-dimensional substrates to form composites usually introduces unusual physicochemical properties that are notably distinct from individual substrates and nanoclusters. Notably, the physicochemical properties of composites constructed from nanoclusters and 1D (or 2D) substrates can be readily tuned by the application of strain or an electric field, offering another additional avenue for designing nanocluster-based functional materials. In the Special Issue of Journal of Physics D: Applied Physics, entitled ‘Design of Nanocluster-Based Functional Materials’, we have compiled a comprehensive collection of 17 articles, showcasing the latest advancements in the field of cluster design and assembly, cluster adsorption and catalysis, and low-dimensional material devices. In the following, we concisely summarize the key research highlights of these studies.
Gallium nitride ultra-wideband terahertz absorber based on periodic pyramidal array
Authors: Qin Mingfei , Ji Shijun , Zhao Ji , Li Jingjin 
Published: December 2024

Abstract
Gallium nitride (GaN) has garnered significant attention due to its unique properties. Here, we present, for the first time, a polarization-independent ultra-wideband absorber in the terahertz band, consisting of a pyramidal GaN array and a GaN substrate. Numerical simulation results indicate that the designed absorber exhibits excellent absorption performance in the range of 0.39–1.98 THz, with a center frequency of 1.185 THz. The relative bandwidth ratio is 134.2%, and the absorption exceeds 90%. The equivalent circuit model further illustrates the ultra-wideband strong absorption characteristics of the proposed absorber. The simulated electromagnetic field distribution indicates that the perfect absorption of the designed absorber is attributed to the excitation of electromagnetic resonance. Additionally, due to the high structural symmetry, the absorber exhibits polarization-independent properties and maintains high absorption performance at large incidence angles. In the future, the proposed absorber will have a wide range of applications in optical applications, including detector devices, light detection equipment and solar energy collection systems.
Investigation of deep trap states at the negative polarization interface of N-polar HEMT through capacitance–conductance measurements
Authors: Lingaparthi R , Lili H , Dharmarasu N , Radhakrishnan K , Zhang J 
Published: December 2024

Abstract
N-polar high electron mobility transistors (HEMTs) will play a crucial role in the future high frequency and high power GaN based technology due to their inherent advantages over Ga-polar technology. However, still, there are some fundamental questions about N-polar technology that need to be addressed. One of the questions that remained unanswered or regaining interest recently is the nature of the negative polarization interface of N-polar HEMTs. Two contradicting views exist regarding the nature of the negative polarization interface at the barrier/buffer interface of N-polar HEMT: one view suggests that hole-like trap states exist at this interface while the other view suggests that two-dimensional hole gas exists at this interface. To give a possible solution to this fundamental question, in this study, two N-polar HEMT heterostructures were investigated, one without any Si δ-doping at the barrier/buffer interface and the other with Si δ-doping at the same interface. Through capacitance–conductance measurements, existence of deep trap states at the negative polarization interface at barrier/buffer interface is demonstrated for the sample without Si δ-doping, which indirectly contradicts the idea of existence of hole gas at this interface. Moreover, in the capacitance–conductance measurements, Si δ-doping is shown to eliminate the presence of deep trap states.
Crossover in atomic mobility underlying the glass transition in inorganic glasses
Authors: Cockrell C , Grimes R W 
Published: December 2024

Abstract
While the glass transition is easy to identify macroscopically, the underlying atomic mechanisms which facilitate the transition from amorphous solid to fluid are still poorly understood. We conduct classical molecular dynamics simulations on a variety of inorganic glasses in order to identify these mechanisms. While also modelling larger systems, we find that the essential qualities which constitute a glass and its transition to a liquid are present even in systems containing only a few hundred atoms. The transition is therefore a local phenomenon. Atomic mobility, the ability of an atom to escape its local coordination environment, is identified as a universal marker of the glass transition. In the solid state, the fraction of mobile atoms is negligible, whereas in the liquid state, effectively all atoms are mobile. The glass transition is continuous between these limiting states, with half of the network forming atoms attaining mobility exactly at the glass transition temperature, over a specific mobility half life, informed by thermodynamics. Over time, network forming atoms which were immobile may swap to become mobile and vice versa, though the population of mobile atoms remains a half.