bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of anharmonicity on local defect modes in a one-dimensional crystal
Authors: Kosevich A. M. , Kovalev A. S.
Published: November 2024

The effect of anharmonicity on the vibrational modes of an isotopic defect in a one-dimensional chain is considered. It is shown that the anharmonicity causes some qualitative changes in the vibrational modes of the isotope. In particular, modes localized close to the defect with frequencies close to the lower edge of the spectrum can exist for both signs of the defect mass. A similar situation also holds for modes whose frequencies are localized near the upper edge of the harmonic approximation spectrum. It is shown that when anharmonicity is taken into account the modes become quasilocal.
Magnetization distribution in uniaxial and cubic ferromagnets containing dislocations
Authors: Gann V. V. , Fel'dman É. P.
Published: November 2024

The magnetization distribution around dislocations is investigated in ferromagnets with uniaxial and cubic anisotropy by taking account of the energy of an inhomogeneous exchange interaction and the nonsymmetry of the distortion tensor. The distribution of deviations of the magnetic moments around screw and edge dislocations in iron is computed.
Ferromagnetic resonance linewidth in metals
Authors: Akhiezer I. A. , Belozorov D. P. , Chudnovskii E. M.
Published: November 2024

It is shown that the experimentally observed anomalous increase of the FMR linewidth at low temperatures in Ni might be related to the hydrodynamic nature of FMR in a system of collectivized electrons.
Viscosity of Ne-H2 and Ne-D2 solutions
Authors: Konareva V. G. , Finkil'shtein O. L. , Rudenko N. S.
Published: November 2024

The viscosity of Ne-H2 and Ne-D2 solutions is measured for the first time over a wide range of temperatures and concentrations in the homogeneous region. The measurements have been made by the method of damped torsional oscillations of a disk. The excess viscosity of the solution is found to have a complicated dependence (which alternates sign in the Ne-H2 system) on the concentration.
Effects of impurities on the residual electrical resistivity of indium and gallium
Authors: Aleksandrov B. N. , Dukin V. V.
Published: November 2024

The degree of the influence of 12 different impurities on the residual resistivity ρ0 of indium and gallium was investigated. The alloys were prepared from high-purity (∼99.9999%) solvent metals with relative resistance δ4.2 = R4.2/R293 equal to (5−6) × 10−5 and (3−3.5)×10−5 respectively, in the concentration interval 10−3−0.5 wt. % for indium and 3×10−3−0.4 wt. % for gallium. The measured values of Δρ0/c (the change of the residual resistivity of the alloy per at. % of dissolved impurity) for alloys with impurities belonging to the same period reveal a quadratic dependence on the valence difference between the impurity and matrix metals. The resistivities of alloys based on these metals, calculated by the phase-shift method with allowance for the distortion of the solvent metal lattice by the impurity atoms and with the aid of the pseudopotential theory (Ashcroft's model pseudopotential and the Appapillai form factors calculated from “first principles”) are in agreement with experimental values in the best case.
Spin waves in the superfluid B-phase of He3
Authors: Gongadze A. D. , Gurgenishvili G. E. , Kharadze G. A.
Published: November 2024

Based on the Larkin and Migdal method, spin-wave excitations in the superfluid B-phase of He3 are considered theoretically, with the s- and p-components of Landau's Fermi-liquid exchange interaction taken into account.
Resistance current states and the nonstationary properties of superconducting channels
Authors: Galaiko V. P. , Dmitriev V. M. , Churilov G. E.
Published: November 2024

An experimental and theoretical investigation of the supercritical current states in narrow superconducting films has been conducted near Tc. New physical aspects of superconductivity associated with the formation of superconducting nuclei for electric fields in the films that are less than the critical field Ec2, and also with the development of a microscopic “phase” stratification structure, are discussed. Features on the current-voltage characteristics of films that are associated with the stratification structure, its motion, and with oscillation of the electric potential on specimens of finite length have been investigated.
Use of nitrogen vapor pressure data to test the scaling theory
Authors: Zozulya V. N.
Published: November 2024

The vapor pressure of nitrogen has been measured in a temperature interval from 84°K to within 0.05°K of the critical temperature Tc. The data have been used to test the equations of the scaling theory. It has been shown that the measured data are best approximated by the “extended symmetric scaling” equation postulated earlier by V. L. Pokrovskii with the exponent α for the divergence of d2P/ dT2 as T approaches Tc being equal to 0.11 ± 0.03.
Effects of the dispersion law and diffuse quasiparticle scattering on oscillation processes in a cylindrical conductor in a weak magnetic field
Authors: Bogachek É. N. , Gogadze G. A. , Kulik I. O.
Published: November 2024

A study has been made of the oscillation effect in a cylindrical conductor in a weak magnetic field (effects of flux-quantization type) for an arbitrary quasiparticle dispersion law and weak diffuse electron scattering at the surface. The oscillation period is Δ Φ = h c/e; if the conditions (kFσ)2 > (1/3π)ln (π/6)kFR, л5/2 (kFσ)2l/2 R ≲ 1 are met, the main contribution to the oscillations in the thermodynamic quantities comes from glancing electrons (kF is the Fermi wave vector, σ is the height of the roughness, l is the roughness length, and R is the radius of the cylinder), whose wave functions are localized near the surface of the conductor.
ac Josephson current as a function of voltage
Authors: Akimenko A. I. , Solov’ev V. S. , Yanson I. K.
Published: November 2024

The superconductive current flowing through niobium point contacts was measured as a function of applied voltage using a bridge circuit. With the assumption that the de component of the superconductive current is proportional to the amplitude of the ac Josephson current, the latter was determined as a function of the voltage applied to the contact. For eV >2Δ the results agree qualitatively with theory. A maximum in the superconductive current (the Riedel peak) was observed in the superconducting current-voltage curves and in the curve of if signal amplitude versus voltage in experiments involving the mixing of two uhf signals.
Parametric excitation of “magnetic excitons” in singlet-triplet systems
Authors: Seidov Yu. M. , Suleimanov A. M.
Published: November 2024

Parametric excitation of “magnetic excitons” in a ferromagnet in a singlet state is considered with parallel orientation of stationary and variable magnetic fields. The Hamiltonian of the ferromagnet in the singlet state is represented in the pseudospin formalism. The multi-time Green's function is used for higher approximations to the problem of the reaction of the system to external perturbations. The critical pump field is estimated to be of the order of 10−102 Oe.
Tunable disorder on the S-state majority-voter model
Authors: do Nascimento Francisco I. A. , Sampaio Filho Cesar I. N. , Moreira André A. , Herrmann Hans J. , Andrade José S.
Published: November 2024

We investigate the nonequilibrium phase transition in the S-state majority-vote model for S=2,3, and 4. Each site, k, is characterized by a distinct noise threshold, qk, which indicates its resistance to adopting the majority state of its Nv nearest neighbors. Precisely, this noise threshold is governed by a hyperbolic distribution, P(k)∼1/k, bounded within the limits e−α/2<qk<1/2. Here, the parameter α plays a pivotal role as it determines the extent of disorder in the system through the spread of the threshold distribution. Through Monte Carlo simulations and finite-size scaling analyses on regular square lattices, we deduced that the model undergoes a continuous order–disorder phase transition at a specific α=αc. Interestingly, the critical threshold exhibits a power-law decay, αc∼Nv−δ, as the number Nv of neighboring sites increases. From the least square fits to the data sets results in δ=0.65±0.01 for S=2, δ=0.92±0.01 for S=3, and δ=0.93±0.01 for S=4. Furthermore, the critical exponents β/ν and γ/ν are consistent with those found in the S-state Potts model.
Thermal transport property of boron nitride nanosheets
Authors: Bhattacharjee Amrito , Jiang Hongbo , Li Lu Hua , Huang Shaoming , Chen Ying Ian , Cai Qiran
Published: November 2024

The rapid progress of high-performance microelectronic devices underscores the urgent necessity to develop materials possessing superior thermal conductivity for effectively dissipating heat in cutting-edge electronics. Boron nitride nanosheets (BNNSs) have garnered significant attention due to their exceptional thermal conductivity, combined with electrical insulation and low thermal expansion coefficient, offering a promising solution to heat-related challenges in electronic devices. While BNNSs share some common thermal behaviors with other two-dimensional (2D) materials, they also exhibit unique characteristics. For instance, BNNSs exhibit larger isotope disorders compared to graphene, yet their isotope enhancement in thermal conductivity is lower than that of their carbon counterpart. This review provides an overview of the thermal transport properties and mechanisms of BNNSs explored over the past decade, beginning with a brief introduction to the basic of thermal conductivity. It then delves into the thermal transport mechanisms in BNNSs, highlighting factors impacting the in-plane thermal conductivity of BNNSs, as well as the cross-plane thermal conductivity and the factors influencing it. Finally, the review discusses challenges associated with BNNS thermal conductivity measurement and outlines potential future research avenues.
Morse index for solutions of a nonlinear Kirchhoff equation
Authors: Pan Kefan , Wang Chunhua , Zhai Mingxue
Published: November 2024

In this paper, we study a perturbed nonlinear Kirchhoff equation with subcritical growth in R3. Although the existence of concentrated solutions with a single peak or multi peaks to the problem above has been obtained in Li et al. [J. Differ. Equations 268, 541–589 (2020)] and Luo et al. [Proc. R. Soc. Edinburgh, Sect. A 149, 1097–1122 (2019)], respectively, the Morse indices of them remain open. First, we compute the Morse index of single-peak solutions concentrated at a point P∈R3 by variational methods, which can also be applied to the case where P is a degenerate critical point of V. Then, we also study the Morse index of multi-peak solutions concentrated at the non-degenerate critical points of V. Here the main difficulty comes from the nonlocal term ∫R3|∇u|2dyΔu. In addition, since the estimates of the eigenvalues and the eigenfunctions of the linearized problem associated to the limit problem are unknown, we have to study them independently, which are quite interesting.
Uncertainty quantification of material parameters in modeling coupled metal and high explosive experiments
Authors: Nelms Matthew , Schill William , William Kuo I.-F. , Barton Nathan , Schmidt Kathleen
Published: November 2024

Experiments involving the coupling of metal and high explosives (HE) are of notable defense-related interest, and we seek to refine the uncertainty quantification associated with models of such experiments. In particular, our focus is on how uncertainty related to the metal constitutive model challenges our ability to infer high explosive model parameters when analyzing focused science experiments. We consider three focused experiments involving an HE accelerating metal: small plate tests with tantalum/LX-14 and tantalum/LX-17 pairings as well as a tantalum/LX-17 cylinder test. For all three models, we perform sensitivity analysis to ascertain the influence of metal strength on the coupled experimental response. Moreover, we calibrate each model in a Bayesian setting and study the quantification of metal strength on the inference of the HE parameters. Based on our results, we offer guidance for future metal/HE experiments.
Graphene/black phosphorus-based infrared metasurface absorbers with van der Waals Schottky junctions
Authors: Ogawa Shinpei , Fukushima Shoichiro , Shimatani Masaaki , Iwakawa Manabu
Published: November 2024

Black phosphorus (BP) is a promising candidate for fabricating infrared (IR) photodetectors because its bandgap in the IR region can be controlled by varying the number of layers. BP-based metasurfaces have attracted considerable attention for applications in wavelength-selective and/or polarization-selective IR absorbers. Graphene and BP (Gr/BP) van der Waals (vdW) heterostructures are expected to enhance the performance of BP-based IR photodetectors. However, the Gr/BP vdW heterostructure forms a Schottky junction; thus, the electron transfer between Gr and BP should be investigated to determine the precise optical properties of Gr/BP vdW heterostructure-based metasurfaces. In this study, the electron transfer in the Gr/BP vdW heterostructure is investigated theoretically. The metasurface absorber structure proposed based on the results comprises periodic Gr/BP vdW heterostructure strips on top, a middle dielectric layer, and a bottom reflector. Numerical calculations indicated that the Gr/BP vdW heterostructure has strong wavelength- and polarization-selective near-unity IR absorption. The absorbance is increased and absorption wavelength is shortened compared with those of the monolayer-BP-based metasurface. The absorption wavelength can be controlled by changing the width of the Gr/BP strips owing to the hybrid localized surface plasmons of Gr/BP. This is attributed to the electron transfer through the Schottky junction between Gr and BP with enhanced localized surface plasmon resonance. The results suggest that the Gr/BP vdW heterostructure is a promising platform for realizing wavelength-selective and/or polarization-selective IR photodetectors and IR absorbers/emitters. The resulting photodetectors exhibit high responsivity and low noise because the BP bandgap corresponds to the IR wavelength region.
Specific and high-affinity adsorption of volatile organic compounds on titanium dioxide surface
Authors: Liu Xinyi , Zhou Tao , Sheng Xinyue , Li Hui , Liu Wei-Tao
Published: November 2024

The interaction between metal oxides and volatile organic compounds (VOCs) from the ambient atmosphere plays an important role in environmental and catalytic applications. Previous scanning probe microscopy and x-ray spectroscopy studies revealed surprisingly that the TiO2 [rutile (110)] surface selectively adsorbed atmospheric carboxylic acids, which typically exist in only parts-per-billion concentrations. In this work, we used in situ sum-frequency vibrational spectroscopy to study the interaction between rutile (110) and typical VOC molecules, including formic acid, acetic acid, and formaldehyde. Spectra from all three adsorbed molecules on rutile (110) were similar to the rutile surface spectrum in the ambient atmosphere, showing a broad resonance near 2950 cm−1 that can be attributed to the bridging bidentate adsorption of corresponding compounds. In contrast, on a fused silica surface, a molecular monodentate adsorption configuration was observed for all the molecules, with aliphatic carbons appearing to be the dominant adventitious species.
Shrinking shrimp-shaped domains and multistability in the dissipative asymmetric kicked rotor map
Authors: Rolim Sales Matheus , Mugnaine Michele , Leonel Edson Denis , Caldas Iberê L. , Szezech José D.
Published: November 2024

An interesting feature in dissipative nonlinear systems is the emergence of characteristic domains in parameter space that exhibit periodic temporal evolution, known as shrimp-shaped domains. We investigate the parameter space of the dissipative asymmetric kicked rotor map and show that, in the regime of strong dissipation, the shrimp-shaped domains repeat themselves as the nonlinearity parameter increases while maintaining the same period. We analyze the dependence of the length of each periodic domain with the nonlinearity parameter, revealing that it follows a power law with the same exponent regardless of the dissipation parameter. Additionally, we find that the distance between adjacent shrimp-shaped domains is scaling invariant with respect to the dissipation parameter. Furthermore, we show that for weaker dissipation, a multistable scenario emerges within the periodic domains. We find that as the dissipation gets weaker, the ratio of multistable parameters for each periodic domain increases, and the area of the periodic basin decreases as the nonlinearity parameter increases.
Design, justification, and prototyping of the visible and infrared wide angle viewing system diagnostic for ITER equatorial port 12
Authors: Vives S. , Guillon C. , Letellier L. , Aumeunier M. H. , Courtois X. , Garitta S. , Grosy J. , Lapcevic N. , Lefevre N. , Peluso B. , Peneliau Y. , Medrano M. , Pastor C. , Mota F. , Martin V. , Poissy J. , Jouffroy G. , Lopez Heredero R. , Gonzalez-Fernandez L. M. , Fernandez-Rodríguez M. , Garcia-Lopez R. , Zamora M. J. , Belenguer T. , Le Guern F. , Piqueras J. , Fabbri M. , Testoni P.
Published: November 2024

The ITER equatorial visible and infrared Wide Angle Viewing System (WAVS) will play a major role in the protection of plasma facing components by providing surface temperature measurements of these components. It will also image the plasma emission in the visible range. The WAVS is composed of 15 lines of sight located in four Equatorial Ports (EPs) 3, 9, 12, and 17. Its development is being carried out by the Consortium constituted by CEA, CIEMAT, INTA, and Bertin Technologies, within grant contracts financed by F4E. In the EP12, the in-vessel and ex-vessel components of the WAVS are at their final design phase. This article presents an overview of the opto-mechanical design of the WAVS in the EP12 presented at the final design review.
Experimental study of streamer inception and transition characteristics for live working gap under switching impulse
Authors: Fang Yaqi , Yang Bingsen , Mao Suhan , Zeng Hao , Fang Junkang , Zhang Xiaoxing
Published: November 2024

The switching impulse discharge characteristics are the basis for determining the minimum approach distance in equipotential live working (EPLW) gap. The discharge mechanism of the EPLW gap is not fully deterministic currently. In this study, two actual EPLW gaps and two simplified gaps including sphere–plane gap and bundle conductor + rod-plane gap are established, and the discharge mechanism of these gaps is investigated. The result indicates that the discharge characteristics of sim-worker's back and feet are similar to the simplified electrode. For the sim-worker's back, the streamer inception time delay, inception voltage, injected charge, and transition time are 93.3 μs, 765 kV, 6.19 μC, and 44.7 μs, respectively. The current waveforms of the sim-worker's back and the sphere electrode (R = 0.3 m) exhibit similar characteristics, both containing single pulse, and streamer length nearly half the gap. For the sim-worker's feet, the corresponding values are 28.5 μs, 307 kV, 0.67 μC, and 81.6 μs, similar to the bundle conductor + rod electrode (R = 5 cm), with multiple pulse current waveforms and streamer length of 0.49 m, also similar to the bundle conductor + rod electrode (R = 5 cm). The result can contribute to lineman safety protection and simplified gap design for live working.
Model-free distributed state estimation with local measurements
Authors: Gao Kepan , Ran Chenyu , Wang Xiaoling , Liu Liu , Jiang Guo-Ping
Published: November 2024

In this paper, the state estimation problem of physical plants with unknown system dynamic is revisited from the perspective of limited output information measurement, which corresponds to those with characteristics of high-dimensional, wide-area coverage and scatter. Given this fact, a network of sensors are used to carry out the measurement with each one accessing only partial outputs of the targeted systems and a novel model-free state estimation approach, named distributed stochastic variational inference state estimation, is proposed. The key idea of this method is to compensate for the impacts of local output measurements by adding nearest-neighbor rule-based information interaction among estimators to complete the state estimation. It finds from the numerical experiments that the proposed method has clear advantages in both estimation accuracy and speed, and it also provides guidance on how to improve the efficiency of state estimation under local measurements.
Lift enhancement via leading edge vortex delay in flapping flight utilizing kinematic modifications
Authors: Nadig Sumukha V. , Ghosh Santanu
Published: November 2024

Flapping-winged micro aerial vehicles (MAVs) are an innovative approach to indoor flight, useful for reconnaissance. However, challenges remain in improving the maneuverability of these drones in low-speed flight, specifically using wing kinematics for different flight profiles. This work focuses on the plunge motion of the SD7003 airfoil in forward flight. Unsteady simulations are carried out at a Reynolds number of 10,000 in Ansys Fluent upon validation against experimental, theoretical, and numerical results from literature. Modification of the kinematics is performed by skewing the sinusoidal curve that dictates the effective angle of attack of the airfoil, leading to what is termed “peak-shifted” (PS) kinematics. The skewness of the curve is varied systematically to delay the peak of plunge velocity during the downstroke. Due to this, the leading edge vortex formation and shedding were also found to be delayed, with stronger vortex cores causing a surge in lift force. Results indicate that with the PS kinematics, mean lift increased by 4.5% and mean drag reduced by 7.9%, at the cost of an increase in power requirement of 42.9% compared to the baseline kinematics. Since lift augmentation and drag reduction are obtained with no change in plunge amplitude or frequency, this opens up opportunities in tail-less MAV design to use PS kinematics in short intervals for maneuvers or flight controls, including roll, pitch, and yaw.
Numerical analysis of the interaction between a droplet and an air boundary layer
Authors: Shi Z. Y. , Sun S. , Wu Z. L. , Tan H. J.
Published: November 2024

The deformation and movement of droplets are widely utilized in many industrial applications. The present work investigates the evolution of a single droplet interacting with an air boundary layer numerically and validated by wind tunnel experiments. The volume of fluid method is employed to study the interaction from the micro-perspective. The influences of airflow velocity, droplet size, and depression angle on interactions are comprehensively discussed. The outcomes indicate that droplet diameter and airflow velocity significantly influence the interaction. Based on the morphological evolution of the droplets, the regimes of the interaction can be classified into three categories. It is shown that the airflow velocity, depression angle, and droplet diameter influence the droplet maximum streamwise spreading length. Furthermore, only the airflow velocity and droplet diameter influence the maximum height. The scaling law for the maximum streamwise spreading factor is revealed. Finally, the velocity profile of the boundary layer above the droplet maximum height is also analyzed, revealing a power-law relationship in its curve. These results provide valuable insight for further investigation on the droplet–air boundary layer interaction.
The spectrum of experimentally accessible states for melting and freezing transitions in mesoporous materials
Authors: Alzaidi A. , Schneider D. , Kikkinides E. S. , Valiullin R.
Published: November 2024

Structural disorder in mesoporous solids gives rise to complex phase behavior for materials confined within their pore spaces. As a result, a wide spectrum of possible phase configurations associated with spatial distributions of thermodynamic phases throughout the pore networks can be realized in experiments. Despite their importance, quantifying these states remains largely unaddressed. By considering solid–liquid equilibria as a representative example and using a simple random network model, we investigate the spectrum of such states accessible in real experiments and relate this spectrum to the structural characteristics of porous solids. We classify these states by their free energies and demonstrate how network effects break degeneracies for specific phase compositions and temperatures. Furthermore, we identify the experimental conditions that delineate boundary free energy states, differentiating accessible from inaccessible states. The insights from this study on solid–liquid equilibria are also equally applicable to gas–liquid equilibria in confined spaces and contribute to a deeper understanding of relaxation dynamics associated with hysteresis.
Mechanism of protofibril formation in aqueous collagen solutions
Authors: Bulavin Leonid A. , Cherevko Kostyantyn V. , Khorolskyi Oleksii V. , Svechnikova Oksana S. , Zabashta Yurii F.
Published: November 2024

The shear viscosity of aqueous collagen solutions was experimentally investigated over the temperature range of 303–353 K and collagen concentrations of 1–7 wt. %. A structural phase transition was observed at ∼315 K, corresponding to the onset of protofibril formation. It is shown that below this temperature, protofibrils containing both ordered and disordered segments are formed, with the proportion of ordered segments increasing as the temperature decreases, reaching ∼30% at 303 K. An analysis of the temperature dependence of the order parameter for the structural transition in the water–collagen system suggests that this transition exhibits characteristics of a second-order phase transition.
Domain switching and shear-mode piezoelectric response induced by cross-poling in polycrystalline ferroelectrics
Authors: Hall D. A. , Daniel L. , Watson M. , Condie A. , Comyn T. P. , Kleppe A. K. , Withers P. J.
Published: November 2024

The mechanisms contributing to the electromechanical response of piezoelectric ceramics in the shear mode have been investigated using high-energy synchrotron x-ray diffraction. Soft lead zirconate titanate ceramic specimens were subjected to an electric field in the range 0.2–3.0 MV m−1, perpendicular to that of the initial poling direction, while XRD patterns were recorded in transmission. At low electric field levels, the axial strains remained close to zero, but a significant shear strain occurred due to the reversible shear-mode piezoelectric coefficient. Both the axial and shear strains increased substantially at higher field levels due to irreversible ferroelectric domain switching. Eventually, the shear strain decreased again as the average remanent polarization became oriented toward the electric field direction. The lattice strain and domain orientation distributions follow the form of the total strain tensor, enabling the domain switching processes to be monitored by the rotation of the principal strain axis. Reorientation of this axis toward the electric field direction occurred progressively above 0.6 MV m−1, while the angle of rotation increased from 0° to approximately 80° at the maximum field of 3.0 MV m−1. A strong correlation was established between the effective strains associated with different crystallographic directions, which was attributed to the effects of elastic coupling between grains in the polycrystal.
Design and experimental demonstration of functional devices for energy manipulation in new analog acoustic computers
Authors: Zhang Long-Fa , Wang Chang-Chun , Pei Ning-Wo , Zou Xin-Ye , Cheng Jian-Chun
Published: November 2024

The development of new analog computers based on analog signals of electromagnetic or elastic waves has become a hot research topic in recent years. In this Letter, based on the concept of quantum state transfer, we study the process of energy transfer between acoustic cavities. Through the transformation from the temporal domain to the spatial domain, we further study the process of energy transfer between acoustic waveguides, and then we realize the applications of energy distributors and limiters in the acoustic system, which are the functional devices of wireless communication technology in new analog acoustic computers. We both simulationlly and experimentally demonstrate the effectiveness of the two applications. The energy distributor and limiter we proposed have the advantages of a relatively wide operating frequency range and adjustability. Our work shows the transfer mechanism of acoustic energy between different structures, which increases its potential application value in new analog acoustic computers.
A technical review on characterization methods for structures and properties of emulsion
Authors: Shi Xuncheng , Qi Dawei , Lin Caihong , Li Jianwei
Published: November 2024

Emulsions, particularly in the pharmaceutical, cosmetic, and food industries, are essential for the delivery and stabilization of active ingredients. Due to their structural complexity—including variations in droplet size, phase distribution, and interfacial properties—characterizing emulsions is essential for optimizing their performance and stability. Existing reviews tend to focus on specific emulsion types, properties, or individual characterization techniques, often failing to provide a holistic assessment. Consequently, there is a critical need for a comprehensive review that integrates various characterization methods. This review addresses this gap by systematically evaluating key techniques, including scattering methods (dynamic light scattering, small-angle x-ray scattering), spectroscopic techniques (Fourier transform infrared and nuclear magnetic resonance spectroscopy), microscopy methods (scanning electron microscopy, confocal laser scanning microscopy), and rheometry. By consolidating the strengths and limitations of each method, this review offers a unified framework to guide researchers in selecting appropriate techniques for characterizing emulsions, ultimately contributing to the optimization of their structure, properties, and performance across diverse applications.
Modeling and testing strategic interdependence and tipping in public policy implementation
Authors: Liu Lu , Cui Zhihan , Kunreuther Howard , Heal Geoffrey
Published: November 2024

We develop a game-theoretic model of strategic interdependence and tipping in public policy choices and show that the model can be estimated by probit and logit estimators. We test its validity and applicability by using daily data on state-level COVID-19 responses in the United States. Social distancing via shelter-in-place (SIP) strategies and wearing masks emerged as the most effective nonpharmaceutical ways of combatting COVID-19. In the United States, choices about these policies are made by individual states. We develop a game-theoretic model of such choices and test it econometrically, confirming strong interdependence in the implementation of these policies. If enough states engage in social distancing or mask wearing, others will be tipped to follow suit. Policy choices are influenced mainly by the choices of other states, especially those of similar political orientation and to a lesser degree by the number of new COVID-19 cases. The choice of mask-wearing policies is more sensitive to peer choices than the choice of SIP policies, and Republican states are much less likely than Democratic to introduce mask-wearing policies. The choices of policies are influenced more by political than public health considerations. These findings emphasize strategic interdependence in policy choice and offer an analytical framework for these complex dynamics.
First-Principles Study on Thermal and Electrical Transport Properties of NbGe2 and NbSi2: The Role of Electron–Phonon Coupling
Authors: Zhu Gui-Lin , Shang Man-Yu , Lü Jing-Tao
Published: November 2024

We investigate coupled electron and phonon transport in NbX
2 with X=Ge, Si, where experimental evidence of strong electron–phonon coupling and hydrodynamic transport has been reported. Based on first-principles density functional theory calculations, we measured the thermal and electrical transport properties of the compounds. We found that phonon–electron scattering strongly affects phonon thermal conductivity (κ
ph) and leads to a weak temperature dependence of κ
ph instead of a normal inverse temperature dependence when anharmonic three-phonon scattering dominates. In addition, κ
ph contributes to a quarter of the total thermal conductivity, which differs from typical metals in which the total thermal conductivity is predominantly derived from electrons. In contrast to previous numerical research, our electrical resistivity results agree well with the experimental measurements. The anisotropic properties of the transport coefficients are attributed to the electron–phonon dispersion relation. In addition, we found a negligible effect of electron–phonon drag on the transport properties, contrary to the expectation from a strongly coupled electron–phonon fluid.
Controllable switching based on vortex–antivortex pairs in exciton–polariton condensates
Authors: Wang Bin , Wu Kexin , Li Zhifeng , Wang Gang , Xue Yan
Published: November 2024

Vortex–antivortex pairs hold significant prospect for applications in high-capacity optical communications, multiparticle manipulations, and data processing systems. In this work, based on vortex–antivortex pairs, we explore a straightforward method to produce a 1–4 optical switch in a polariton condensate with a C-shaped potential. The switch, seeded by a degenerate state containing two vortex–antivortex pairs, can selectively target four objective states: two orthogonal states with a single vortex–antivortex pair and two concentric vortices with opposite circulations. All these topological states are stable states with the application of a single incoherent pump, while the switch is activated by an additional coherent control pulse.
A general strategy for enhancing the performance of Ga2O3-based self-powered solar-blind photodetectors through band structure engineering
Authors: He Huaile , Liu Jinsong , Chen Shiwei , Niu Changsheng , Zhang Xuehua , Jia Jinhua , Wu Chao , Hu Haizheng , Wu Fengmin , Guo Daoyou , Wang Shunli
Published: November 2024

The spectral response of Ga2O3 almost perfectly covers the 200–280 nm solar-blind ultraviolet wavelength range, making it an ideal semiconductor material for fabricating solar-blind ultraviolet photodetectors. However, due to the considerably deep valence band energy of Ga2O3 the construction of heterojunctions typically induces a significant valence band offset (ΔEv). Herein, we present a band engineering approach to improve the performance of Ga2O3 bases photodetectors. This pronounced valence band barrier can strongly influence the transport of photo-generated charge carriers, especially the extraction of holes in the depletion region. By introducing nitrogen (N) during the growth process, we elevated the valence band of Ga2O3 by 0.43 eV. The organic high-molecular-weight material of PEDOT:PSS has been utilized in conjunction with Ga2O3 to construct heterojunction photodetectors. The photodetectors exhibit excellent self-powered characteristics, with responsivity, detectivity, and response time being nearly ten times higher than those of Ga2O3 photodetectors before band structure modulation. The investigation into modulating the band structure of Ga2O3 carried out in this study will lay the theoretical foundation and provide technical solutions for developing satisfactory self-powered photodetectors.
OLM-SLAM: online lifelong memory system for simultaneous localization and mapping
Authors: Lu Haoran , Shen Yehu , Zhang Qingkui , Jiang Quansheng , Zhu Qixin , Fu Guizhong , Niu Xuemei , Li Jingbin
Published: November 2024

Simultaneous Localization and Mapping is a fundamental task for robots in unknown environments. However, the poor generalization ability of learning-based algorithms in unknown environments hinders their widespread adoption. Additionally, artificial neural networks are subject to catastrophic forgetting. We propose a lifelong SLAM framework called OLM-SLAM that effectively solves the neural network catastrophic forgetting problem. To ensure the generalization of the neural network, this paper proposes a method for the sensitivity analysis of the network weight parameters. Meanwhile, inspired by human memory storage mechanisms, we design a dual memory storages mechanism that retains dynamic memory and static memory. A novel memory filtering mechanism is proposed to maximize image diversity within a fixed-size memory storage area addressing the problem of limited storage capacity of embedded devices in real-world situations. We have extensively evaluated the model on a variety of real-world datasets. Compared with CL-SLAM, the overall translation error of the test sequence is improved by 44.9%. The translation and rotation errors of Retention Ability (RA) were improved by 111.6% and 66.7%, respectively. The results demonstrate that OLM-SLAM can outperform previous methods of the same type, and OLM-SLAM has high RA when facing different sequences of the same type of environment.
Mechanical, electronic, optical, and thermoelectric properties of Rb2TlGaX6 (X = F, I) lead-free double perovskites: a first-principles study
Authors: Razzaq Md Abdur
Published: November 2024

Halide perovskites play an important role in the renewable energy industry and are the top substitutes for Pb-halide perovskites. This study investigates the structural, mechanical, electronic, optical, and thermoelectric properties of the double halide perovskites Rb2TlGaX
6 (X = F, I) using density functional theory (DFT) at WIEN2k interfaces. The structural, mechanical, and thermal stabilities are evaluated using the tolerance factor, Born–Huang criteria, and negative formation energy. The obtained lattice constants are 9.31 Å and 24.93 Å, for Rb2TlGaF6 and Rb2TlGaI6 respectively. Rb2TlGaF6 is brittle and Rb2TlGaI6 is ductile. Both compounds exhibit anisotropic behavior. The indirect semiconducting nature (L-W) is demonstrated by the estimated bandgap values of 6.05 eV (4.31 eV) and 1.06 eV (0.52 eV), for Rb2TlGaF6 and Rb2TlGaI6 respectively, using the TB-mBJ (PBE-GGA) potential. Distinctive optical characteristics are studied, including the dielectric function, loss function, conductivity, reflectivity, refractive index, and absorption coefficient. Based on the investigation, both materials exhibit excellent optical conductivity, high light absorption throughout the UV–visible spectrum, and low reflection (within 20% for Rb2TlGaF6 and 40% for Rb2TlGaI6). Lastly, various thermoelectric properties are explored by varying the temperature. Both compounds show a high Seebeck coefficient and low thermal conductivity. The maximum figure of merit (ZT) obtains of 0.61 and 0.81, for Rb2TlGaF6 and Rb2TlGaI6, respectively. These results demonstrate the suitability of Rb2TlGaF6 and Rb2TlGaI6 for thermoelectric and photovoltaic applications.
High gain and circularly polarised metasurface suspended twin port Al2O3 based antenna for mm-wave 5 G communication system
Authors: Shukla Pawan Kumar , Sigroha Deepak , Tripathi Vijay Shanker , Sharma Anand
Published: November 2024

This article discusses design and analysis of two-port alumina ceramic based aerial in mm-wave spectrum. Aperture coupling stimulate ceramic and produce dual fundamental orthogonal field i.e.

HEM

11
δ

x

and

HEM

11
δ

y

mode. Important features of structured aerial are: (i) designed antenna produces the circular wave within 32.65–33.25 GHz; (ii) double negative unit cell based metasurface suspension enhances the antenna’s broadsided gain to 9.0 dBi; and (iii) orthogonal arrangement of aerial ports improve the separation to over 25 dB. Experimental outcomes confirm the working spectrum of design aerial in between 32.21–33.55 GHz. Directional pattern and decent assessment of diversity parameters prepares the planned aerial appropriate for 5 G communication in mm-wave regime (n260/n511 frequency bands).
Observation of momentum-induced broadening of width in narrow Feshbach resonances of ultracold 133Cs atoms
Authors: Liu 刘 Zhennan 震南 , Zhao 赵 Hongxing 宏星 , Wang 王 Yunfei 云飞 , Li 李 Yuqing 玉清 , Wu 武 Jizhou 寄洲 , Liu 刘 Wenliang 文良 , Li 李 Peng 鹏 , Fu 付 Yongming 永明 , Xiao 肖 Liantuan 连团 , Ma 马 Jie 杰 , Jia 贾 Suotang 锁堂
Published: November 2024

Interactions between atoms in ultracold quantum gases play an important role in the study of the quantum simulation of many-body physics. Feshbach resonance is a versatile tool to control atomic interactions, where the atom-loss spectra are widely used to characterize Feshbach resonances of various atomic species. Here, we report the experimental observation of momentum-induced broadening of widths in atom-loss spectra of narrow 133Cs Feshbach resonances. We drive Bragg excitation to kick the Bose–Einstein condensate of Cs atoms in a cigar-shaped optical trap, and measure the atom-loss spectra of narrow Feshbach resonances of moving ultracold atoms near the magnetic fields 19.84 G and 47.97 G. We show that the widths of the atom-loss spectra are broadened for the atoms with the momenta of 2ħk and 4ħk, and even observe splitting in the Feshbach resonance of the atoms with momentum 4ħk. Our work may open the way for exploring the interesting physical phenomena arising from the collective velocity of colliding atoms that have been ignored in general.
Group cohesion and passive dynamics of a pair of inertial swimmers with three-dimensional hydrodynamic interactions
Authors: Mabrouk Mohamed Niged , Floryan Daniel
Published: November 2024

When swimming animals form cohesive groups, they can reap several benefits. Our understanding of collective animal motion has traditionally been driven by models based on phenomenological behavioral rules, but more recent work has highlighted the critical importance of hydrodynamic interactions among a group of inertial swimmers. To study how hydrodynamic interactions affect group cohesion, we develop a three-dimensional, inviscid, far-field model of a swimmer. In a group of two model swimmers, we observe several dynamical phases, including following, divergence, collision, and cohesion. Our results illustrate when cohesive groups can passively form through hydrodynamic interactions alone, and when other action is needed to maintain cohesion. We find that misalignment between swimmers makes passive cohesion less likely; nevertheless, it is possible for a cohesive group to form through passive hydrodynamic interactions alone. We also find that the geometry of swimmers critically affects the group dynamics due to its role in how swimmers sample the velocity gradient of the flow.
A Bowen ratio-informed method for coordinating the estimates of air–sea turbulent heat fluxes
Authors: Wang Yizhe , Tang Ronglin , Huang Lingxiao , Liu Meng , Jiang Yazhen , Li Zhao-Liang
Published: November 2024

Accurate quantification of turbulent heat fluxes [THF, comprising sensible heat flux (SHF) and latent heat flux (LHF)] and Bowen ratio (β, ratio of SHF and LHF) is essential for understanding the air–sea interaction. However, the biased estimates of SHF and LHF by widely applied bulk aerodynamic models, and the separate estimates of SHF and LHF by data-driven models, both may result in unrealistic β estimates. This study for the first time innovatively proposes a Bowen ratio-informed data-driven model (BrTHF) for coordinating the estimations of THF and β using the multivariate random forest (RF) technique and a combination of eddy covariance flux observations and meteorological and oceanic observations collected from 53 historical cruises. The result shows that the BrTHF model could not only achieve high-accuracy SHF and LHF estimates, but also avoid the outliers of β estimates that were commonly found in un-synergistic RF and well-known Coupled Ocean Atmosphere Response Experiment 3.5 models.
Fabrication of superhydrophobic transparent coatings prepared by spraying dual-sized silica particles
Authors: Yang Yue-Xin , Wang Bing-Bing , Wang Xin , Liu Yu
Published: November 2024

Photovoltaic modules exposed to severe wind and sand conditions over extended periods often accumulate dust, significantly impacting their power generation efficiency. Superhydrophobic self-cleaning coatings present a promising solution to mitigate this issue. In this study, a SiO2/PU coating was applied to glass substrates using a combined sol–gel spraying technique. The sol system comprised a mixture of SiO2 particles with diameters of 20 nm and 200 nm, enabling the construction of a micro-nano structure that enhances surface hydrophobicity. The SiO2/PU coatings prepared with mixed particle sizes demonstrated significant improvements in contact angle, rolling angle, self-cleaning, and antifouling properties compared to those made with a single particle size, achieving a water contact angle of 164.52°. Furthermore, the prepared SiO2/PU coatings possess excellent stability and transmittance. It is anticipated that this superhydrophobic SiO2/PU coating will be a candidate for anti- dust applications in photovoltaic modules.
Evaluating machine learning-based elephant recognition in complex African landscapes using drone imagery
Authors: McCarthy Chris , Banda Lumbani Benedicto , Kachamba Daud Jones , Emmanuel Junior Zuza , Chisambi Cornelius , Kumanga Ndaona , Lawrence Luciano , Sternberg Troy
Published: November 2024

This paper evaluates a machine learning-based approach for identifying and analyzing African bush elephants within complex terrains using high-resolution drone imagery. With human-wildlife conflict posing a significant threat to elephants worldwide, accurate and efficient monitoring techniques are crucial, yet challenging in diverse landscapes. Our study utilizes approximately 3,180 drone-captured images from Kasungu National Park in Malawi, encompassing various terrains including dense forests and open bushlands. These images were systematically preprocessed and analyzed using three distinct ML algorithms: Faster R-CNN, RetinaNet, and Mask R-CNN, each fine-tuned for identification of elephants across different age groups. Comparative performance metrics revealed nuanced strengths and limitations: Faster R-CNN showed notable proficiency in detecting adult elephants, particularly in dense foliage. Mask R-CNN, while less precise overall, demonstrated increased effectiveness in identifying juveniles and infants. RetinaNet, optimized for larger images, showed particular adeptness with adult elephants but less so with younger ones. Despite these promising results, overall recognition rates were lower than ideal, highlighting the complexities of wildlife identification in natural settings. This study not only facilitates the identification and counting of individual elephants but also provides insights into the challenges of applying ML in complex ecological contexts. The derived insights can assist conservationists and park officials in making informed decisions related to wildlife protection and habitat preservation. Furthermore, the study offers a valuable blueprint for integrating AI and machine learning technology into wildlife conservation strategies, presenting a scalable model with potential applications for different species and geographic regions, while acknowledging the need for further refinement to enhance accuracy and reliability in diverse ecological settings.