bluuebunny/crossref_metadata_2025_split huggingface dataset:
An ultra-high vacuum scanning tunneling microscope with pulse tube and Joule–Thomson cooling operating at sub-pm
z
-noise
Authors: Eßer Marcus , Pratzer Marco , Frömming Marc , Duffhauß Jonas , Bhaskar Priyamvada , Krzyzowski Michael A. , Morgenstern Markus 
Published: December 2024

Low-temperature scanning tunneling spectroscopy is a key method to probe electronic and magnetic properties down to the atomic scale, but suffers from extreme vibrational sensitivity. This makes it challenging to employ closed-cycle cooling with its required pulse-type vibrational excitations, albeit this is mandatory to avoid helium losses for counteracting the continuously raising helium prices. Here, we describe a compact ultra-high vacuum scanning tunneling microscope (STM) system with an integrated primary pulse tube cooler (PTC) for closed-cycle operation. It achieves temperatures down to 1.5 K via a secondary Joule–Thomson stage and a z-noise down to 300 fmRMS in the STM junction for the frequency range of 0.1 Hz–5 kHz (feedback loop off). This is better than many STMs cooled by an external supply of liquid helium. The challenge to combine an effective vibrational decoupling from the PTC with sufficient thermal conduction is tackled by using a multipartite approach including the concept of bellows with minimal stiffness to decouple the PTC vibrationally from the STM and an optimized STM design with minimal vibrational transfer to the STM junction. As important benchmarks, we could reduce the voltage noise in the tunnel junction down to 120 μV and supply radio frequency excitations up to 40 GHz with amplitudes up to 10 mV in the junction via a close-by antenna. The development principally enables other secondary cooling stages such that it opens the perspective for a helium conserving operation of STMs across the whole interesting temperature range.
Ultrafast photoconductivity dynamics in narrow-gap HgCdTe films
Authors: Refvik N. B. , Purschke D. N. , Jensen C. E. , Pan W. , Simpson H. R. J. , Lei W. , Gu R. , Antoszewski J. , Umana-Membreno G. A. , Faraone L. , Hegmann F. A. 
Published: December 2024

Mercury cadmium telluride (Hg1−xCdxTe or MCT) is the premier material for infrared detection. However, despite its importance, studies exploring the ultrafast photoresponse in this semiconductor alloy are limited. Here, we use time-resolved terahertz spectroscopy to perform a detailed study of the picosecond charge carrier dynamics in long-wave infrared Hg1−xCdxTe (x ∼ 0.2) films, providing insight into ultrafast carrier cooling and temperature-dependent scattering mechanisms. Due to the multilayer photoexcited sample geometry, an elementary thin-film analysis leads to a negative photoconductivity artifact. We, therefore, derive a modified thin-film photoconductivity formula to accurately extract a Drude photoconductivity spectrum. In our analysis, we include the effects of carrier diffusion and the conduction band non-parabolicity in Hg1−xCdxTe. We extract ultrahigh electron mobilities as large as 6 × 105 cm2 V−1 s−1 at 25 K. At cryogenic temperatures, we find the photoexcited electron mobility is up to four times larger than the dark mobility, which we attribute to suppression of ionized impurity scattering due to hole capture by acceptor-type Hg vacancies. In addition, after photoexcitation, we observe a relatively slow rise in photoconductivity over a 10 ps timescale with a monotonically increasing carrier scattering time and a carrier effective mass that decays exponentially with a time constant of 1.9 ps, which we attribute to hot-carrier cooling dynamics in the non-parabolic conduction band.
Unlocking n-type semiconductivity in diamond: A breakthrough approach via surface metal doping
Authors: Liu Defeng , Wu Guixuan , Luo Shulin , Wang Gangcheng , Wang Xiaowei , Wang Xueting 
Published: December 2024

Device applications of ultra-wide bandgap diamond rely on controlled carrier types and concentrations, yet conventional n-type doping in diamond has been challenging due to its strong covalent bonds. Surface charge transfer doping (SCTD) provides an effective alternative, utilizing energy level differences between surface dopants and semiconductors to modulate carrier properties. In this study, we examined n-type SCTD doping on oxygen- and fluorine-passivated diamond (100) surfaces [diamond(100):Y, where Y = O, F] using alkali metals (Na, K, Rb, and Cs) through first-principle calculations. Following surface metal doping of diamond(100):Y, electron enrichment shifted the Fermi level into the conduction band, confirming effective n-type doping. The maximum areal electron densities reached 2.50 × 1014 cm−2 for diamond(100):O and 2.00 × 1014 cm−2 for diamond(100):F, exceeding the previously reported optimal values for surface organic molecule doping. For diamonds of equal thickness and identical passivating atoms, charge transfer followed the trend Na &gt; K &gt; Rb &gt; Cs, inversely related to atomic radius. With increasing diamond thickness, charge transfer rose for oxygen-passivated surfaces and declined for fluorine-passivated ones before stabilizing, corresponding to the conduction band minimum (CBM) shift: downward for oxidization and upward for fluorination. For all alkali metal surface doping, charge transfer was greater in diamond(100):O than in diamond(100):F, owing to the lower CBM of oxidized diamond. Overall, effective n-type SCTD doping is critically influenced by diamond’s CBM levels—dependent on its thickness and surface passivation—and the metal atom’s radius. These findings provide theoretical insights into advancing diamond-based electronic and optoelectronic devices.
PAHs in protein matrix
Authors: Lobsiger Simon , Umbricht Gisela , Mallia Silvia , Bilsel Mine , Gökçen Taner , Akkuş Özen Şükran , Kaminski Martin , Zübner Isabella , Đokić Vasić Dragana , Bešter Erika , Valenčič Vasilij , Portesi Chiara , Schiavone Consolato , Romaniello Francesco 
Published: December 2024

Main text
This Supplementary Comparison, EURAMET.QM-S15 "PAHs in Protein Matrix", was organized by the Federal Institute of Metrology METAS. The target analytes were four PAHs: benz[a]anthracene (BaA); benzo[a]pyrene (BaP); benzo[b]fluoranthene (BbF); and chrysene (Chr), for which maximum limits are set in the European and Swiss food legislation. The measurands were the mass fractions (µg/kg) of these PAHs in a protein-rich matrix.
Six National Metrology Institutions (NMIs) and Designated Institutes (DIs) participated in EURAMET.QM-S15. The study required solvent extraction, separation of the target analytes from interfering matrix components (clean-up), analytical/chromatographic separation and selective detection of the target analytes.
Solvent extraction (ASE, PLE, HUPsSE, QuEChERS) followed by SPE cleanup was applied by the participants in the sample pretreatment and GC-IDMS/MS, GC-HR-IDMS and LC-FLD were applied for separation and detection.
The results for the determination of the four PAHs in EURAMET.QM-S15 ranged from 0.5 µg/kg to 5.3 µg/kg for BaA, 0.6 µg/kg to 13.3 µg/kg for BaP, 0.6 µg/kg to 7.0 µg/kg for BbF and 0.5 µg/kg to 5.0 µg/kg for Chr.
Due to poor extraction efficiencies, as a result of unfavorable choice of solvent and insufficient demonstration of metrological traceability of the calibrant, only the results of two participants were included in the evaluation of the Supplementary Comparison Reference Value (SCRV). The SCRV was assigned using the weighted mean of these two participants which agreed well with gravimetrically prepared mass fractions and evidence from an ancillary study performed with external expert laboratories. Four participant results were excluded from the SCRV for the technical reasons mentioned above. The SCRV (X ± u(X)) was 3.291 µg/kg ± 0.079 µg/kg for BaA, 4.28 µg/kg ± 0.10 µg/kg for BaP, 4.77 µg/kg ± 0.12 µg/kg for BbF and 2.967 µg/kg ± 0.070 µg/kg for Chr. The two institutes that were included in the assignment of consensus SCRV agreed within their standard uncertainties.
Successful participation in EURAMET.QM-S15 demonstrates the following measurement capabilities in determining the mass fractions of organic compounds, with a molecular mass between 150 g/mol and 500 g/mol, having a low polarity (pKow < -2), in a mass fraction range from 0.1 µg/kg to 100 µg/kg in a high protein food matrix.
To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.
The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Multi-frequency compact encoding metasurface for independent beam control
Authors: Huang Xiaojun , Li Wentao , Xue Qi , Gao Junfei , Wang Danqi , Xiang Mei 
Published: December 2024

Abstract
Encoding metasurfaces, as innovative materials that facilitate the integration of the physical and digital realms, offer engineers a more streamlined and effective approach to manipulating electromagnetic waves. In order to modulate electromagnetic waves at multiple frequencies with a single metasurface as much as possible, researchers adopt methods such as mechanical stretching and multilayer stacking to design a variety of structures. However, these works all have problems like complex structures and inconvenience in use. Therefore, it is still a challenge to design a metasurface that can flexibly modulate electromagnetic waves at multiple frequencies by using a simple structure. In this paper, we present a reflective encoding metasurface capable of independently modulating the phase at two disparate frequencies. This is achieved through the manipulation of octagonal copper rings and copper patches on the meta-atom. To enhance and achieve more precise beam control accuracy, a genetic algorithm is utilized to optimize the arrangement of low-frequency and high-frequency structures individually, which are then integrated to facilitate beam deflection at both frequencies. The simulation results demonstrate that the proposed compact dual-frequency coded metasurface effectively controls the incident electromagnetic waves at 6 GHz and 19 GHz, and realizes the beam deflection within the range of elevation angles from 0° to 45° and azimuth angles from 0° to 360° in the half-space. Measurements are performed in a microwave anechoic chamber to verify the simulations, and the measurement results are consistent with the simulations. The proposed metasurface has potential applications in compact space and multi-channel communication services due to its good beam control capability.
Dynamics of a single anisotropic particle under various resetting protocols
Authors: Chaki Subhasish , Olsen Kristian Stølevik , Löwen Hartmut 
Published: December 2024

Abstract
We study analytically the dynamics of an anisotropic particle subjected to different stochastic resetting schemes in two dimensions. The Brownian motion of shape-asymmetric particles in two dimensions results in anisotropic diffusion at short times, while the late-time transport is isotropic due to rotational diffusion. We show that the presence of orientational resetting promotes the anisotropy to late times. When the spatial and orientational degrees of freedom are reset, we find that a non-trivial spatial probability distribution emerges in the steady state that is determined by the initial orientation, particle asymmetry and the resetting rate. When only spatial degrees of freedom are reset while the orientational degree of freedom is allowed to evolve freely, the steady state is independent of the particle asymmetry. When only particle orientation is reset, the late-time probability density is given by a Gaussian with an effective diffusion tensor, including off-diagonal terms, determined by the resetting rate. Generally, the coupling between the translational and rotational degrees of freedom, when combined with stochastic resetting, gives rise to unique behavior at late times not present in the case of symmetric particles. Considering recent developments in experimental implementations of resetting, our results can be useful for the control of asymmetric colloids, for example in self-assembly processes.
Chiral effects at the metal center in Fe(III) spin crossover coordination salts
Authors: Zaz M Zaid , Chin Wai Kiat , Viswan Gauthami , Subedi Arjun , Mishra Esha , McElveen Kayleigh A , Tamang Binny , Shapiro David , N’Diaye Alpha T , Lai Rebecca Y , Dowben Peter A 
Published: December 2024

Abstract
Evidence of chirality was observed at the Fe metal center in Fe(III) spin crossover coordination salts [Fe(qsal)2][Ni(dmit)2] and [Fe(qsal)2](TCNQ)2 from x-ray absorption (XAS) spectroscopy at the Fe 2p3/2 core threshold. Based on the circularly polarized XAS data, the x-ray natural circular dichroism for [Fe(qsal)2][Ni(dmit)2] and [Fe(qsal)2](TCNQ)2 is far stronger than seen for [Fe(qsal)2]Cl suggesting this natural circular dichroism signature is a ligand effect rather than a result of just a loss of octahedral symmetry on the Fe core. The larger the chiral effects in the Fe 2p core to bound XAS, the greater the perturbation of the Fe 2p3/2 to 2p1/2 spin–orbit splitting seen in the XAS spectra.
Application of three-dimensional point cloud technology based on spectral confocal in FPC welding inspection
Authors: Wang Tianle , Chen Fei , Chen Xiaobo , Zhu Zhisong 
Published: December 2024

Abstract
In response to welding quality inspection challenges in new energy vehicle battery systems, a fusion detection method based on two-dimensional (2D) and three-dimensional (3D) data is proposed. Initially, the point cloud data of the region of interest (ROI) were extracted with point cloud percentile filtering. Subsequently, the processed point cloud data were projected onto a 2D plane, and the coordinate data of the ROI was obtained by virtue of 2D image-processing techniques. This data was back-projected into a 3D space to retrieve the corresponding depth data. Finally, the depth value of the weld pit was determined by computing the vertical distance between the bottom of the weld pit and a predefined reference plane from the obtained depth data. Experimental results indicate that when detecting workpieces containing 50 valid weld pits, compared with traditional 3D detection methods, the detection time of this method is reduced from 6.70 s to 1.18 s. Additionally, the depth measurement error and variance are reduced by 39.24% and 59.46%. This method significantly improves the detection efficiency and accuracy, enabling an efficient analysis of the welding quality.
Review and novel formulae for transmittance and reflectance of wedged thin films on absorbing substrates
Authors: Ballester Manuel , Marquez Emilio , Bass John , Würsch Christoph , Willomitzer Florian , Katsaggelos Aggelos K 
Published: December 2024

Abstract
Historically, spectroscopic techniques have been essential for studying the optical properties of thin solid films. However, existing formulae for both normal transmission and reflection spectroscopy often rely on simplified theoretical assumptions, which may not accurately align with real-world conditions. For instance, it is common to assume (1) that the thin solid layers are deposited on completely transparent thick substrates and (2) that the film surface forms a specular plane with a relatively small wedge angle. While recent studies have addressed these assumptions separately, this work presents an integrated framework that eliminates both assumptions simultaneously. In addition, the current work presents a deep review of various formulae from the literature, each with their corresponding levels of complexity. Our review analysis highlights a critical trade-off between computational complexity and expression accuracy, where the newly developed formulae offer enhanced accuracy at the expense of increased computational time. Our user-friendly code, which includes several classical transmittance and reflectance formulae from the literature and our newly proposed expressions, is publicly available in both Python and Matlab at this link.
Electrochemical deposition of Ni on arrays of GaAs nanowires with n-type channels
Authors: Kuzmin V , Mokhov D , Berezovskaya T , Monastyrenko A , Bouravleuv A 
Published: December 2024

Abstract
The processes of electrochemical deposition of Ni on vertically aligned GaAs nanowires (NWs) grown by molecular-beam epitaxy (MBE) using Au as a growth catalyst on n-type Si(111) substrates were studied. Based on the results of electrochemical deposition, it was concluded that during the MBE synthesis of NWs the self-induced formation of conductive channels can occur inside NWs, thereby forming quasi core–shell NWs. Depending on the length of the channel compare to the NW heights and the parameters of electrochemical deposition, the different hybrid metal-semiconductor nanostructures, such as Ni nanoparticles on GaAs NW side walls, Ni clusters on top ends of GaAs NWs, core–shell GaAs/Ni NWs, were obtained.
Singular solutions for the conformal Dirac–Einstein problem on the sphere
Authors: Maalaoui Ali , Martino Vittorio , Xu Tian 
Published: December 2024

Abstract
In this paper we investigate the existence of singular solutions to the conformal Dirac–Einstein system. Because of its conformal invariance, there are many similarities with the classical construction of singular solutions for the Yamabe problem. We construct here a family of singular solutions, on the three dimensional sphere, having exactly two singularities.
Structural damage diagnosis of a cable-stayed bridge based on VGG-19 networks and Markov transition field: numerical and experimental study
Authors: Lu Naiwei , Liu Zengyifan , Cui Jian , Hu Lian , Xiao Xiangyuan , Liu Yiru 
Published: December 2024

Abstract
Traditional physical-driven modal methods are inappropriate for damage diagnosis of long-span flexible structures with complex mechanical behaviour. This study develops a deep Convolutional Neural Network-based damage diagnosis method for in-service bridges by using dynamic responses under moving loads. The dynamic responses were collected from the critical points on the girders of a cable-stayed bridge specimen under vehicle loading. These collected data was transformed into images based on Gramian Angular Field and Markov Transition Field (MTF). A deep learning algorithm based on VGG-19 was used to extract the damage feature from the data images associated with the structural responses. Finally, the unlabelled vibration data were input into the VGG-19 model for structural damage diagnosis. An experimental study was conducted for the damage diagnosis of a scale specimen of a cable-stayed bridge under moving loads. The acceleration signals of the main girder of the cable-stayed bridge under several damage conditions were monitored. The numerical results show the training accuracy of the deep learning method based on VGG-19 with MTF is up to 88%, and the average accuracy of the test dataset is 86.46% for each classification label. The transfer learning method can increase the classification accuracy up to 97.89%, indicating the advantage of intergrating transfer learning and VGG-19 network for structural damage diagnosis. The combination of VGG-19 and MTF algorithm provides a better solution for structural damage diagnosis of in-service infrastructures with long-term monitoring data.
HAIL: a family of high-diffusion lightweight block ciphers for internet of things security
Authors: Deng ChuTian , Li Lang , Feng JiaYi , Yan LiuYan 
Published: December 2024

Abstract
The accelerated evolution of Internet of Things (IoT) technology has made it crucial to secure information from resource-constrained devices. Therefore, a high-diffusion lightweight block cipher family, called HAIL, is proposed in this work to provide higher security for IoT devices while minimizing area and power consumption. In more detail, HAIL constructs an improved Lai-Massey structure with the high diffusion of the SPN structure and the symmetry of the Feistel structure. Additionally, the differential probability of 1 in the Lai-Massey structure is successfully avoided by introducing additional nonlinear operations. Compared to traditional ciphers employing the Lai-Massey structure, HAIL significantly reduces area consumption by discarding the modular component and adding shift operations into the Lai-Massey branch, thereby enhancing security. Moreover, HAIL selects an involutive, low-area S-box using Genetic Programming (GP) and combines it with an S-box that exhibits strong side-channel resistance, making the nonlinear part of HAIL advantageous for side-channel protection. Detailed testing verifies that HAIL64 and HAIL128 achieve full diffusion and avalanche effect within one and three rounds, respectively, showcasing effective diffusion properties. The throughput-to-area ratios of HAIL64 and HAIL128 at 100 kHz are 0.202 and 0.234 (SMIC 0.18 μm) respectively. Experimental results indicate that HAIL is immune to both linear and differential cryptanalysis. Finally, HAIL demonstrates high security redundancy against impossible differential attacks and Meet-In-The-Middle (MITM) attacks, among others, while its low power and area requirements address critical IoT constraints.
Modified Klein–Gordon oscillator in Ellis-Bronnikov-type wormhole spacetime with cosmic string and global monopole
Authors: de Oliveira M D , Schmidt Alexandre G M 
Published: December 2024

Abstract
In this paper, we investigate the modified relativistic oscillator with the Cornell potential via the quadri-potential given by X

μ
= (0, mωr + A/r, 0, 0) in the Ellis-Bronnikov-type wormhole spacetime with a global monopole and a cosmic string. We obtain the angular and radial wave functions exactly, as well as the eigenenergies. The radial wave function is expressed in terms of Heun polynomials, involving the quantum number n and the eigenenergies. By setting the value of n incrementally, the oscillation frequency ω is quantized with respect to l and m. Finally, as an example, we analyze the ground state and graphically investigate the influence of the global monopole, cosmic string, and A on the oscillator frequency, eigenenergies, and radial probability density, as well as the effect of the wormhole curvature on the radial probability density.
Dynamical insights into bifurcation, chaos and solitons in the space-time fractional symmetric regularized long wave equation
Authors: Younas Tayyaba , Ahmad Jamshad 
Published: December 2024

Abstract
The nonlinear conformable time-fractional Symmetric Regularized Long Wave (SRLW) equation is a significant model in physics, particularly for describing ion acoustic and space charge waves with weak nonlinearity. In this study, we apply the modified Sardar sub equation method and the modified extended auxiliary equation method to solve the SRLW equation. We effectively manage the fractional derivatives in the equation by employing Jumarie’s modified Riemann-Liouville derivative. Various types of soliton solutions, including kink, periodic, dark, bright, and singular solitary waves, are obtained in forms such as rational, hyperbolic, trigonometric, and exponential functions. A comparative analysis of the methods and the results is conducted, along with an exploration of fractional derivative effects by varying their values. The study also includes 2D and 3D plots that show how the solutions behave over time. It demonstrates that the methods used can be applied to other nonlinear models in mathematical physics. The research looks closely at the model’s behavior, including bifurcation, chaos, and stability. Phase portrait analysis at key points shows changes in the system’s behavior, and adding an external periodic force leads to chaotic patterns. The stability analysis proves that these methods&#xD;are reliable for studying phase portraits and soliton solutions in different nonlinear systems.