bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of the Resistance of Self-Compacting Concrete (SCC) with the Use of Granite Stone Waste to Alkali-Silica Reaction
Authors: Solikin Mochamad , Fatoni Rois , Pratiwi Indah , Setiawan Budi , Afani Iqbal Rahmad , Perdana Habdan Rizki , Sabrina Nindya
Published: April 2024

Aggregates occupy ±70% of the concrete volume and their quality must meet specifications. Concrete surfaces submerged in water for a long time cause concrete failure due to the reaction between aggregate and cement to form silica gel. The wear value of granite is less than gravel, so this study used granite as a substitute for coarse aggregate. This study was conducted to assess the resistance of SCC concrete with 0%, 25%, and 30% granite stone variations to alkali-silica reaction attack. The experimental method was applied to the study with ACI method mix design as well as 25 MPa plan fc'. Concrete cylinder samples 150 mm x 300 mm aged 28 days were used in the compressive strength test, alkali-silica reaction expansion test used mortar block samples 285 mm x 25 mm x 25 mm in 80±2˚C NaOH solution bath for 14 days. The optimum compressive strength of 32.17 MPa and the lowest percentage change in length of 0.04% was obtained by sample BG.25-SCC, indicating that granite stone is not reactive to silica alkali reaction because the percentage change in length <0.10%. This study concludes that granite stone can improve the resistance of concrete to silica alkali reaction.
Statement of the Uterus Commission of the Gynecological Oncology Working Group (AGO) on Neoadjuvant Chemotherapy Prior to Definitive Radiochemotherapy in Patients with Locally Advanced Cervical Cancer
Authors: Tempfer Clemens , Fehm Tanja , Vordermark Dirk , Marnitz-Schulze Simone , Beckmann Matthias W. , Denschlag Dominik , Brucker Sara , Wallwiener Markus , Eichbaum Michael , Ataseven Beyhan , Hillemanns Peter ,   für die Kommission Uterus der AGO
Published: April 2024

The presentation of the results of the prospective randomized international multicenter GCIG INTERLACE trial at the 2023 congress of the European Society of Medical Oncology (ESMO) is likely to change the therapy for locally advanced cervical cancer. In the GCIG INTERLACE trial, six cycles of neoadjuvant chemotherapy administered weekly and consisting of carboplatin AUC2 and paclitaxel 80 mg/m2 followed by definitive radiochemotherapy with pelvic radiotherapy (40 – 50.4 Gray) and cisplatin (40 mg/m2 once a week for 5 weeks) and brachytherapy (total dose EQD2 at least 78 Gy at point A) (experimental arm) were compared with definitive radiochemotherapy alone (standard arm) in patients with locally advanced cervical cancer (Fédération Internationale de Gynécologie et dʼObstétrique [FIGO] 2008 stage IB1/node positive, IB2, II, IIIB and IVA) and was found to be significantly superior with significantly longer recurrence-free survival (hazard ratio [HR] 0.65;
95% confidence interval [CI] 0.64 – 0.91; p = 0.013) and significantly longer overall survival rates (HR 0.61; 95% CI: 0.40 – 0.91; p = 0.04) after 5 yearsʼ follow-up. After considering the results of the GCIG INTERLACE trial published at the congress, the Uterus Commission of the AGO is of the opinion that neoadjuvant chemotherapy with carboplatin AUC2 and paclitaxel 80 mg/m2 d1, q7, x6 may be offered to patients with locally advanced cervical cancer (FIGO stage IB1/node positive, IB2, II, IIIB and IVA) in addition to the current standard therapy after the patient has been informed about the risks, with the decision taken on a case-by-case basis. However, before this approach can be discussed at guideline level or defined as the new therapy standard, it will be necessary to wait until the data from the full publication are available.
Dual-Catalysis-Enabled Construction of Vicinal Stereogenic Centers through Diastereo- and Enantioselective Allylic Substitution
Authors: Su Bo , Yang Kai , Chen Lu
Published: April 2024

Vicinal stereogenic centers represent prevalent structural motifs in organic synthetic chemistry, and their construction poses a longstanding challenge. Transition-metal-catalyzed asymmetric allylic substitution has become a well-established enantioselective C–C bond-forming reaction. When these reactions involve a prochiral nucleophile and an allylic electrophile with a terminal substituent, the creation of vicinal stereogenic centers becomes feasible. However, despite remarkable achievements having been accomplished, realizing this transformation with precise control over both the enantio- and diastereoselectivity remains a significant challenge. To address the stereoselective challenges, the introduction of a second catalyst to the transition-metal-catalyzed asymmetric allylic alkylation to control the diastereoselectivity during C–C bond formation has proven particularly fruitful. In this short review, we aim to highlight recent advances in dual catalysis that enable diastereo- and enantioselective allylic substitutions.

1 Introduction

2 Construction of Vicinal Stereogenic Centers by Organo and Metal Dual Catalysis

2.1 Chiral Phase-Transfer Catalysis and Transition-Metal Dual Catalysis

2.2 Chiral Amine and Transition-Metal Dual Catalysis

2.3 NHC and Transition-Metal Dual Catalysis

2.4 Chiral Aldehyde and Transition-Metal Dual Catalysis

2.5 Chiral Lewis Base and Transition-Metal Dual Catalysis

3 Construction of Vicinal Stereogenic Centers by Metal and Metal Dual Catalysis

3.1 Lewis Acidic Metal and Iridium Dual Catalysis

3.2 Lewis Acidic Metal and Palladium Dual Catalysis

3.3 Palladium and Ruthenium Dual Catalysis

3.4 Other Advancements in the Construction of Vicinal Stereogenic Centers through Synergistic Bimetallic Catalysis Enabling Asymmetric Allylic Alkylation

4 Conclusions and Future Outlook
Synthesis of α-Phenyl β-Enamino γ-Sultims: the New Horizon of the CSIC Reaction
Authors: Dobrydnev Alexey V. , Chuchvera Yaroslav O. , Tararina Valentyna , Chuchvera Inna , Ostapchuk Eugeniy N. , Popova Maria V. , Shishkina Svitlana V. , Volovenko Yulian M.
Published: April 2024

Herein, we report the novel strategy for the synthesis of 4-enamino-5-phenyl-2,3-dihydroisothiazole 1-oxides (in other words α-phenyl β-enamino γ-sultims) based on the CSIC reaction. Particularly, readily available α-amino nitriles (the Strecker products) reacted with benzyl sulfinyl chloride to give the corresponding sulfinamides, which upon treatment with excess of LiHMDS converted into the target α-phenyl β-enamino γ-sultims. The method works well and tolerates strained 3- and 4-membered spirocyclic substituents. A preliminary in silico study indicated that the γ-sultim scaffold can be considered a promising pharmacophore template.
Numerical investigation of core plate of pyramid-type lattice sandwich with resonant rings
Authors: Li Chengfei , Chen Zhaobo
Published: April 2024

The pyramid-type lattice sandwich panel is known for its exemplary mechanical characteristics. In this study, we draw inspiration from the local resonance mechanisms observed in acoustic metamaterials and introduce a resonant ring to enhance the capabilities of the panel for damping low-frequency vibrations. We use the finite element method to develop a model to explore the band structure and the corresponding vibrational responses, with a particular emphasis on the significant influence of the bandgap. A comprehensive comparison between the results of experiments and those of simulations unequivocally validated our proposed model. Crucially, our findings underscore that the damping-related effect can be enhanced and the desired range of frequencies can be fine-tuned by appropriately selecting the geometric and periodic parameters of the lattice sandwich panel. These insights have important implications for tailoring materials to specific engineering applications.
On-chip topological phononic crystal acoustic waveguide based on lithium niobate thin films
Authors: Xu Xuankai , Liu Yushuai , Wu Tao
Published: April 2024

This Letter introduces an on-chip topological phononic crystal (PnC) acoustic waveguide employing lithium niobate thin films. Utilizing a C3v symmetry-breaking mechanism, the topological PnC acoustic waveguide is achieved, operating at frequencies exceeding 430 MHz. A SH0 mode acoustic transceiver is designed, enabling highly efficient on-chip acoustic wave transmission and reception. The fabricated topological PnC waveguide demonstrates a propagation loss of 11.3 dB/mm at the edge mode. An acoustic beam splitter utilizing topological edge mode has been demonstrated, showing the configurability of the topological PnC acoustic waveguide. These results offer significant promise for advancing the development of hybrid phononic circuits tailored for high-frequency acoustic information processing, sensing, and manipulation.
Femtosecond laser-textured superhydrophilic coral-like structures spread AgNWs enable strong thermal camouflage and anti-counterfeiting
Authors: Wu Tingni , Yin Kai , Pei Jiaqing , He Yuchun , Duan Ji-An , Arnusch Christopher J.
Published: April 2024

Modulating the thermal emission of a material in the infrared (IR) range can be essential for various practical applications such as smart textiles, camouflage, and anti-counterfeiting. Although many different materials or structures have been proposed, the complex manufacturing processes are still hindering their widespread use. Herein, a facile femtosecond laser processing technology and a drop-coating method are introduced to form a patternable low emissivity film. Laser-treated polyimide films resulted in superhydrophilic structured surfaces that are uniformly coated with silver-nanowires (AgNWs) in aqueous solutions for low emissivity surfaces. Furthermore, the emissivity of the samples is as low as ∼0.2 without deterioration over 800 bending-releasing cycles. The as-prepared films also display good thermal camouflage properties, namely, the films reduced the thermal radiation temperature of an object by 35.8 °C when the object temperature was ∼69.1 °C. Additionally, this IR camouflage effect of the AgNWs coated samples shows excellent stability even in harsh environments such as immersion in water, acid, alkali, and salt solution and applied voltage. We also show that information encryption was possible by adjusting the amount of AgNWs. The design of this programmable patterned low emissivity film indicates an idea for the thermal camouflage and anti-counterfeiting technology, which can carry more abundant application scenario and disguise them more complex and sophisticated.
Nitrogen vacancy–acceptor complexes in gallium nitride
Authors: Vorobiov Mykhailo , Demchenko Denis O. , Andrieiev Oleksandr , Reshchikov Michael A.
Published: April 2024

We used photoluminescence (PL) spectroscopy and first-principles calculations to investigate GaN doped with Mg, Be, and implanted with Ca. The PL spectra revealed distinct red emission bands (RLA, where A = Be, Mg, and Ca) with maxima between 1.68 and 1.82 eV, each associated with a specific impurity. These bands consistently appeared alongside the green GL2 PL band at 2.33 eV, attributed to nitrogen vacancy (VN). Our calculations suggest that these bands result from recombination via defect complexes of group-II acceptors substituting for Ga with VN (AGaVN, A = Be, Mg, and Ca). The experimental +/0 transition levels for these complexes were estimated to be 0.6, 0.8, and 1.0 eV above the valence band maximum for Mg-, Be-, and Ca-containing complexes, respectively. The radiative recombination is facilitated by excited donor states located close to the conduction band minimum. Furthermore, our theory predicts that ZnGaVN and CdGaVN are stable and possess similar properties, although, no PL was detected from these defect complexes. The presented findings shed light on the identity of compensating donor complexes that impede the efficiency of p-type doping in GaN.
Numerical investigation of induction of chaotic micromixing via vibration switching
Authors: Kaneko Kanji , Hasegawa Yosuke , Hayakawa Takeshi , Suzuki Hiroaki
Published: April 2024

Enhanced mixing in microfluidic systems is necessary in many applications such as chemical processing, biological assays, and diagnosis. We are developing a microfluidic system to efficiently mix minute reagents (down to several microliters) using vibration-induced flow (VIF), in which a net flow is generated around a micropillar by applying periodic vibration. In this study, we numerically investigate the enhancement in chaotic mixing using the VIF technique and periodic switching of vibrations. By extending our previous numerical simulation model, we investigate the flow field and trajectories of fluid particles in three-dimensional space. We demonstrate that chaotic advection characteristics can be observed by periodically switching the vibrational direction of a substrate using simple cylindrical pillars. In addition, using an appropriate interval for switching the vibration axes yields better mixing performance. The extent of chaotic advection is evaluated quantitatively using the Lyapunov exponent considering various vibration parameters, such as the vibration amplitude, separation distance between each pillar and pillar shape. The flow field induced by a large-amplitude and sharp-edged wall pillar provides excellent mixing results. Thus, VIF is successfully applied to obtain an efficient mixing strategy with the aid of the chaotic theory.
Photogalvanic spectroscopy on MnBi2Te4 topological insulator thin films
Authors: Takagi Tsubasa , Watanabe Ryota , Yoshimi Ryutaro , Tsukazaki Atsushi , Takahashi Kei S. , Kawasaki Masashi , Tokura Yoshinori , Ogawa Naoki
Published: April 2024

We demonstrate zero-bias mid-infrared photocurrent generation in topological insulator MnBi2Te4 thin films. The symmetry breakings at the surface and interfaces lead to the coexistence of Dirac and Rashba band states, which enable two kinds of photogalvanic responses. One is the magneto-photogalvanic effect in the presence of an external in-plane magnetic field perpendicular to photocurrent direction, and the other is the light-polarization-dependent linear photogalvanic effect arising from in-plane symmetry breakings, both observed up to room temperature. We disentangle these contributions by light-polarization and temperature dependent spectroscopy under the varying magnetic field.
MesoHOPS: Size-invariant scaling calculations of multi-excitation open quantum systems
Authors: Citty Brian , Lynd Jacob K. , Gera Tarun , Varvelo Leonel , Raccah Doran I. G. B.
Published: April 2024

The photoexcitation dynamics of molecular materials on the 10–100 nm length scale depend on complex interactions between electronic and vibrational degrees of freedom, rendering exact calculations difficult or intractable. The adaptive Hierarchy of Pure States (adHOPS) is a formally exact method that leverages the locality imposed by interactions between thermal environments and electronic excitations to achieve size-invariant scaling calculations for single-excitation processes in systems described by a Frenkel–Holstein Hamiltonian. Here, we extend adHOPS to account for arbitrary couplings between thermal environments and vertical excitation energies, enabling formally exact, size-invariant calculations that involve multiple excitations or states with shared thermal environments. In addition, we introduce a low-temperature correction and an effective integration of the noise to reduce the computational expense of including ultrafast vibrational relaxation in Hierarchy of Pure States (HOPS) simulations. We present these advances in the latest version of the open-source MesoHOPS library and use MesoHOPS to characterize charge separation at a one-dimensional organic heterojunction when both the electron and hole are mobile.
Advances in the development of few-cycle gigawatt-peak-power mid-IR optical parametric amplifiers pumped by Cr:Forsterite laser using non-oxide nonlinear crystals
Authors: Suleimanova D. Z. , Migal E. A. , Badikov D. V. , Potemkin F. V.
Published: April 2024

We demonstrate an experimental and theoretical comparison of non-oxide LiGaS2, HgGa2S4, and AgGaS2 crystals performance for wavelength conversion into the near and mid-IR range 1.5–8 μm in optical parametric amplifier pumped by Cr:Forsterite laser, delivering 100 fs pulses at 1.24 μm. It is shown that exceptionally high total energy conversion efficiency into the idler (4–5 μm) and signal (1.65–1.8 μm) waves up to 18% can be achieved using the HGS crystal, providing high nonlinearity, while the LGS crystal is more preferable for generating few-cycle mid-IR pulses due its unique dispersive properties. Our source features high peak power in gigawatt regime (0.4–2.4 GW) with pulse duration below 80 fs and optical synchronization with high harmonic generation (HHG) and THz beamlines, which is ideal for pump-probe experiments of nonlinear and strong-field physics.
Experimental demonstration of complex four-wave mixing processes with pump of orbital-angular-momentum superposition mode
Authors: Pan Xiaozhou , Yu Sheng , Zhang Kai , Jing Jietai
Published: April 2024

Orbital angular momentum (OAM), characterized by a topological charge ℓ (ℓ integer), serves as a promising vehicle for carrying quantum information. Generating a nonclassical field involving two or more OAM modes can largely enhance the data-carrying capacity of quantum information processing. In this Letter, we present the implementation of a four-wave mixing (FWM) process, featuring a pump beam of a coherent OAM superposition mode and a probe beam of a single OAM mode. We generate twin beams encompassing multiple OAM modes and illustrate their quantum correlation when the pump beam assumes different coherent OAM superposition modes. Furthermore, we analyze the OAM mode components in each output field to deepen our understanding of the nonlinear interaction among different OAM modes. The obtained results show the rich structure of the nonlinear interaction of OAM modes in the FWM process and provide a perspective to study quantum information protocols.
Synthesis and resistive switching performance of lead-free double perovskite Cs2AgBiBr6 films
Authors: Zeng Fanju , Tan Yongqian , Hu Wei , Tang Xiaosheng , Yin Haifeng , Jing Tao , Huang Lianshuai , Yang Yi , Liao Juan , Zhou Changmin
Published: April 2024

In recent years, the lead-free double perovskite Cs2AgBiBr6 has emerged as an appealing alternative to lead-based perovskites due to its nontoxicity and long-term stability. In this study, we employed methyl acetate as an antisolvent and prepared high-quality Cs2AgBiBr6 films by a facile one-step spin-coating method. The prepared films exhibited excellent crystallinity with densely packed crystal grains. The root mean square roughness and average roughness of the obtained Cs2AgBiBr6 perovskite films were 6.69 and 5.43 nm, respectively. Furthermore, the memory device based on the Cs2AgBiBr6 perovskite films exhibited uniform and repeatable bipolar resistive switching performance with an ON/OFF ratio of 15, an endurance of 80 cycles, and a retention time of 104 s. This work showcases a simple and convenient one-step spin-coating method for depositing high-quality Cs2AgBiBr6 thin films while highlighting their potential application in resistive switching memories based on lead-free double perovskites.
Metasurface-enhanced photochemical activity in visible light absorbing semiconductors
Authors: Paudel Yamuna , Chachayma-Farfan Diego J. , Alù Andrea , Sfeir Matthew Y.
Published: April 2024

Heterogeneous photocatalysis is an important research problem relevant to a variety of sustainable energy technologies. However, obtaining high photocatalytic efficiency from visible light absorbing semiconductors is challenging due to a combination of weak absorption, transport losses, and low activity. Aspects of this problem have been addressed by multilayer approaches, which provide a general scheme for engineering surface reactivity and stability independent of electronic considerations. However, an analogous broad framework for optimizing light–matter interactions has not yet been demonstrated. Here, we establish a photonic approach using semiconductor metasurfaces that is highly effective in enhancing the photocatalytic activity of GaAs, a high-performance semiconductor with a near-infrared bandgap. Our engineered pillar arrays with heights of ∼150 nm exhibit Mie resonances near 700 nm that result in near-unity absorption and exhibit a field profile that maximizes charge carrier generation near the solid–liquid interface, enabling short transport distances. Our hybrid metasurface photoanodes facilitate oxygen evolution and exhibit enhanced incident photon-to-current efficiencies that are ∼22× larger than a corresponding thin film for resonant excitation and 3× larger for white light illumination. Key to these improvements is the preferential generation of photogenerated carriers near the semiconductor interface that results from the field enhancement profile of magnetic dipolar-type modes.
Study on the film thickness and surface wave velocity of the thin liquid film formed by a round jet obliquely impinging on a horizontal plate
Authors: Zhang Hongzhou , Huang Yong , Yuan Weiwei , Wang Donghui
Published: April 2024

For a thin liquid film (in a supercritical flow) prior to the formation of a non-circular hydraulic jump formed by a round jet obliquely impinging on a horizontal plate, the time-averaged film thickness and the surface wave velocity are extracted based on the measured transient film thickness. On the one hand, the effect of many factors, including the jet velocity, impingement angle, azimuthal angle, liquid viscosity, and surface tension, on the time-averaged film thickness and surface wave velocity are discussed. When the jet Reynolds number increases to about 1.4×104, the film thickness profile suddenly increases, and the transition of liquid flow from laminar to turbulent occurs. Meanwhile, a rapid increase is observed downstream of the turbulent film thickness profile. The influence of surface tension on the time-averaged film thickness and surface wave velocity is negligible for thin liquid films before non-circular hydraulic jumps. Nonetheless, the surface tension has a significant influence on the interface profile of non-circular hydraulic jumps. Furthermore, a “crescent” kink region upstream of the jump can be identified when the surface tension is lower than 40.6 mN/m. On the other hand, experimental results are used to verify the prediction accuracy of existing approximate solutions. The laminar approximate solution with a quadratic boundary layer velocity profile can accurately predict the film thickness distribution of most laminar thin liquid films, except downstream of the thin liquid films with a dynamic viscosity higher than 9.71 mPa s. The surface wave velocities are found to be close to the predicted surface velocities of the approximate solutions.
Three-metal ion mechanism of cross-linked and uncross-linked DNA polymerase β: A theoretical study
Authors: Chu Wen-Ting , Suo Zucai , Wang Jin
Published: April 2024

In our recent publication, we have proposed a revised base excision repair pathway in which DNA polymerase β (Polβ) catalyzes Schiff base formation prior to the gap-filling DNA synthesis followed by β-elimination. In addition, the polymerase activity of Polβ employs the “three-metal ion mechanism” instead of the long-standing “two-metal ion mechanism” to catalyze phosphodiester bond formation based on the fact derived from time-resolved x-ray crystallography that a third Mg2+ was captured in the polymerase active site after the chemical reaction was initiated. In this study, we develop the models of the uncross-linked and cross-linked Polβ complexes and investigate the “three-metal ion mechanism” vs the “two-metal ion mechanism” by using the quantum mechanics/molecular mechanics molecular dynamics simulations. Our results suggest that the presence of the third Mg2+ ion stabilizes the reaction-state structures, strengthens correct nucleotide binding, and accelerates phosphodiester bond formation. The improved understanding of Polβ’s catalytic mechanism provides valuable insights into DNA replication and damage repair.
Thick crack-free {113} epitaxial boron-doped diamond layers for power electronics—Deposition with nitrogen addition and high microwave power
Authors: Alam Mahebub , Hubik Pavel , Gedeonova Zuzana , Fekete Ladislav , Kopecek Jaromir , Taylor Andrew , Mortet Vincent
Published: April 2024

In this work, first, we investigate the effect of nitrogen addition in microwave plasma enhanced chemical vapor deposition on the growth of thick {113} epitaxial diamond layers. We identify a narrow range of nitrogen concentrations for the growth of crack-free thick epitaxial layers with a smooth surface morphology. Without nitrogen, cracks start to appear after a layer thickness of 7–10 μm due to elastic energy stored in the epitaxial layer, but the addition of nitrogen stabilizes layer growth. We also investigate the use of low microwave power density growth conditions to produce thick boron-doped epitaxial layers. We observe a very high boron incorporation efficiency using these growth conditions. Finally, we demonstrate the fabrication of a thick (>200 μm) {113} p+ monocrystal plate. The concentration of boron in heavily doped diamond with metallic conductivity has been investigated by the Hall effect measurement technique, Raman spectroscopy, and secondary ion mass spectroscopy. The growth of high quality thick {113} oriented epitaxial layer with high boron concentration (>1020 cm−3) and low resistivity and the fabrication for the freestanding p+ substrates are necessary steps for the fabrication of vertical electronic devices such as high power Schottky diodes.
Chiral structure induces spatial spiral arrangement of Fe3O4 nanoparticles to optimize electromagnetic wave dissipation
Authors: Zhao Yongpeng , Wang Nan , Wang Huaifeng , Yuan Shenglin , Liu Mengmeng , Huang Hui , Zhao Yang , Wang Yuchao , Wu Zhijun , Guo Xin , Xu Lijia
Published: April 2024

The spatial anisotropic arrangement of magnetic particles is expected to increase the magnetic resonance frequency of magnetic particles and optimize the magnetic loss. Herein, helical carbon nanocoils were used as a chiral template to induce the spatial spiral distribution of Fe3O4 particles. Meanwhile, a linear control group was constructed with carbon nanofibers as a template. The three-dimensional spiral structure promotes the confined growth and uniform distribution of Fe3O4 particles. Due to the enhanced magnetic property, chiral samples exhibited superior impedance matching compared to linear samples. Experimental tests and theoretical simulation confirm that the spatial anisotropic distribution helps to increase magnetic loss and optimize impedance matching. This work illustrates the important role of chiral structure in improving the magnetic anisotropy of magnetic nanoparticles and provides an effective strategy for optimizing electromagnetic wave dissipation.
Coexistence of passive vortex-induced vibrations and active pitch oscillation triggered by a square cylinder attached with a deformable splitter plate
Authors: Venkatesh Aravindhan , Niu Jiqiang , Xue Xiao , Chen Zheng-Wei , Yao Hua-Dong
Published: April 2024

To understand passive vortex-induced vibrations (VIV) coexisting with active structure motions, this paper numerically investigates the use of pure pitch oscillation to control a square cylinder mounted with a deformable splitter plate at the Reynolds number of 333. The oscillation is enforced with an amplitude of 3° and different frequencies from 0 to 6 Hz. Direct numerical simulations using a partitioned method with a semi-implicit coupling algorithm are performed. According to the trajectories of the splitter-plate tip displacement with respect to the lift or drag force coefficient, a specific lock-in regime determined by the frequency of the enforced pitch oscillation is identified. Further spectral analyses of the tip displacement and lift force show that the lock-in frequencies are equal to the enforced frequencies. Next to the lock-in regime, semi-lock-in regimes with narrow bandwidths are distinguished, exhibiting both lock-in and non-lock-in features. In the non-lock-in regimes, the frequencies of the most predominant peaks in the spectra are found near the natural frequency of the splitter plate of 3.236 Hz, and the frequencies of the two secondary peaks are distributed along the characteristic lines following the ratios of these frequencies to the enforced frequency, which are ±1. Thus, the interaction is dependent on the combined effects of the passive VIV and the actively enforced pitch oscillations. Moreover, the intersection points of the characteristic lines are located close to the upper and lower frequency limits of the lock-in regime, inferring the conditions for the lock-in onset.
Ultrafast restricted intramolecular rotation in molecules with aggregation induced emission
Authors: Hu Xiao , Wang Dongdong , Wang Yanmei , Wang Ye , Zhang Song
Published: April 2024

In this work, the ultrafast intramolecular rotation behavior of 1,1,2,3,4,5-hexaphenylsilole has been investigated in several solutions with different viscosities using femtosecond transient absorption spectroscopy combined with density functional theory and time-dependent density functional theory calculations. It is demonstrated that the nonradiative process, which competes with radiative decay, involves two main stages, namely the restricted intramolecular rotation and internal conversion processes. The intramolecular rotation depends on viscosity and presents a significant restriction. The restricted rotational rate is determined to be dozens of picoseconds. The following nonradiative process is strongly dominated by intramolecular rotation. The nonradiative decay rate will decrease with the increase in viscosity, leading to a rise in the radiative probability and photoluminous yield. These results have borne out the mechanism of ultrafast restricted intramolecular rotation of aggregation induced emission and provided a detailed photophysical picture of nonradiative processes.
Rapid and sparse reconstruction of high-speed steady-state and transient compressible flow fields using physics-informed graph neural networks
Authors: Peng Jiang-Zhou , Wang Zhi-Qiao , Rong Xiaoli , Mei Mei , Wang Mingyang , He Yong , Wu Wei-Tao
Published: April 2024

Explosion flow fields are characterized by shock waves with varying intensity and position (i.e., explosive loads), which are the primary causes of structural damage. Accurate and rapid prediction of explosive loads is crucial for structural blast-resistant design and daily security management. While existing empirical models and numerical simulation methods can capture the propagation characteristics of explosive shock waves, high-precision simulation requires a massive computational workload, which is insufficient to meet the fast computational demands of various explosive scenarios. To address this contradiction, this study constructed a sparse reconstruction model for two-dimensional explosion fields based on machine learning algorithms. The model utilizes sparse observational data to establish a mapping relationship to the distribution of the entire flow field. The model is built by a physics-informed graph neural network (PIGN). The graph neural network is employed to associate node features, while the physical network is utilized to control model convergence, aiming to enhance model performance. Using the constructed dataset, the PIGN model was tested. Performance and generalization capabilities of the model were assessed by comparing its results with numerical simulation. This evaluation analyzed the relative error distribution and error statistical results of the reconstructed flow field. The results indicate that the PIGN model can effectively reconstruct explosion fields, with an average error in the reconstructed flow field below 4%. Furthermore, when the number of probe points reaches 10, the average error of the flow field reconstructed by the model is close to 6%. This model not only provides a highly reliable distribution of explosion overpressure and pressure-time variations but also, with a well-trained model, accomplishes flow field reconstruction within 1 ms. It offers a novel approach for achieving rapid and reasonable prediction of explosion fields or two-dimensional compressible flow fields.
Confined and spontaneously transformed oxidation structures due to the intrinsic heterogeneous surface morphology of C3N monolayer
Authors: Luo Wenjin , Zhao Liang , Huang Zhijing , Ni Junqing , Tu Yusong
Published: April 2024

Identifying the oxidation structure of two-dimensional interfaces is crucial to improve surface chemistry and electronic properties. Beyond graphene with only phenyl rings, a novel carbon-nitrogen material, C3N, presents an intrinsic heterogeneous surface morphology where each phenyl ring is encircled by six nitrogen atoms, yet its atomistic oxidation structure remains unclear. Here, combining a series of density functional theory calculations and ab initio molecular dynamics simulations, we demonstrate that thermodynamically favorable oxidation loci are confined to the phenyl ring, and kinetic transformations of oxidation structures are feasible along the phenyl ring, whereas those toward nitrogen atoms are proven to be extremely difficult. These results are attributed to the lower barrier of oxygen atom migration along the phenyl ring, while the significantly high barriers toward nitrogen atoms are due to the heterogeneous potential energy surface for oxygen–C3N interaction. This work highlights the significance of surface morphology on the characteristics of oxidation structure, offering insights into tunable electronic properties via confined interfacial oxidation.
TD-graphene: Theoretical prediction of a high-performance anode material for sodium-ion batteries with intrinsic metallicity, high capacity, and fast ion mobility
Authors: Zou Ru-Feng , Wu Zhi-Hui , Ma Tian-Ci , Zheng Xiao-Hong , Ye Xiao-Juan , Lin He , Liu Chun-Sheng
Published: April 2024

The utilization of pristine graphene as an anode material in sodium-ion batteries (SIBs) is limited by its inherent chemical inertness toward Na-ions. To address this issue, we propose a two-dimensional carbon allotrope (named as TD-graphene) by assembling tricyclo[4.4.1.11,6]dodecane (C12H20) skeleton. The topological non-hexagonal feature of C12H20 increases the degree of local carbon-ring disorder and introduces additional electron-deficient regions on the surface, thus enhancing the adsorption capability of Na. TD-graphene demonstrates exceptional stability across the energetic, thermodynamic, dynamic, and mechanical aspects. As a promising anode for SIBs, it exhibits an intrinsic metallicity, an ultra-high storage capacity (1487.58 mA h g−1), a low diffusion barrier (0.20 eV), a low average open-circuit voltage (0.33 V), and a small lattice expansion (0.6%). The presence of solvents with high dielectric constants improves the adsorption and migration capability of Na. Furthermore, taking into account the limitation of single-layer materials in practical applications, we employ h-BN as a promising substrate for TD-graphene, which can boost the Na adsorption and diffusion performance. These results render TD-graphene as a promising high-performance anode material for SIBs.
The photochemistry of Rydberg-excited cyclobutanone: Photoinduced processes and ground state dynamics
Authors: Eng J. , Rankine C. D. , Penfold T. J.
Published: April 2024

Owing to ring strain, cyclic ketones exhibit complex excited state dynamics with multiple competing photochemical channels active on the ultrafast timescale. While the excited state dynamics of cyclobutanone after π* ← n excitation into the lowest-energy excited singlet (S1) state has been extensively studied, the dynamics following 3s ← n excitation into the higher-lying singlet Rydberg (S2) state are less well understood. Herein, we employ fully quantum multiconfigurational time-dependent Hartree (MCTDH) simulations using a model Hamiltonian as well as “on-the-fly” trajectory-based surface-hopping dynamics (TSHD) simulations to study the relaxation dynamics of cyclobutanone following 3s ← n excitation and to predict the ultrafast electron diffraction scattering signature of these relaxation dynamics. Our MCTDH and TSHD simulations indicate that relaxation from the initially-populated singlet Rydberg (S2) state occurs on the timescale of a few hundreds of femtoseconds to a picosecond, consistent with the symmetry-forbidden nature of the state-to-state transition involved. There is no obvious involvement of excited triplet states within the timeframe of our simulations (<2 ps). After non-radiative relaxation to the electronic ground state (S0), vibrationally hot cyclobutanone has sufficient internal energy to form multiple fragmented products including C2H4 + CH2CO (C2; 20%) and C3H6 + CO (C3; 2.5%). We discuss the limitations of our MCTDH and TSHD simulations, how these may influence the excited state dynamics we observe, and—ultimately—the predictive power of the simulated experimental observable.
Experimental study of sealing mechanism and sealing performance of symmetric magnetic fluid seal with occlusal pole teeth
Authors: Dou Xuankai , Yang Xiaolong , Liu Yang , Liu Enchen
Published: April 2024

To investigate the sealing mechanism and performance of the symmetric magnetic fluid seal (SMFS) with occlusal pole teeth (OPT), an experimental device was designed. The impact of magnetic fluid volumes and groove widths on the sealing mechanism and performance of the SMFS-OPT was investigated under different environments. Combining experimental results and numerical analyses, the applicability of the magnetic fluid sealing theoretical pressure resistance formula to SMFS-OPT is verified. The results show that low magnetic fluid volume and a large groove width prolong the differential pressure reduction process, thereby reducing the pressure resistance of the sealing device. Increasing the volume of the magnetic fluid increases the sealing device's self-healing rate but does not change the trend of the number of ruptures' impact on the pressure resistance.
Write error rate analysis of field-free spin-orbit torque switching in conically magnetized free layer nanomagnet
Authors: Mishra Pinkesh Kumar , Bhuktare Swapnil
Published: April 2024

Enhancing the performance of magnetic random access memories (MRAMs) is crucial, considering speed, energy efficiency, and endurance. Spin-orbit torque-based MRAMs offer ultrafast operation and enhanced reliability. Still, the energy efficiency and external magnetic field requirement for deterministic switching of nanomagnets with perpendicular magnetic anisotropy (PMA) are a significant hurdle. To address these issues, one of the proposed solutions employs a conically magnetized free layer magnetic tunnel junction device featuring second-order PMA. This approach can minimize the required switching current density by leveraging the interplay between first- and second-order PMA energies. Additionally, coupling with exchange bias from the antiferromagnet can eliminate the need for an external field entirely. Our analysis investigates the impact of current density (magnitude and rise/fall time), first- and second-order PMA fields, exchange bias, and field-like torque on the device's switching performance. By optimizing the perpendicular magnetic anisotropies, we report improvement in the write error rate from 10−4 to 10−7. Our findings hold promise for magnetic memory applications.
Transparent and flexible thermoelectric thin films based on copper sulfides
Authors: Ruan Siyuan , Wang Liangjun , Ouyang Yuzhao , Yang Jialin , Kang Xiaowan , Chen Xiaojian , Yang Chang
Published: April 2024

As a promising thermoelectric material, CuS has attracted significant attention due to its high conductivity, abundance of elements, and eco-friendliness. However, the study on CuS-based thermoelectric thin films is still lacking, impeding the advancement of CuS-based thermoelectric devices. Herein, high-quality CuS thin films have been fabricated through a facile vulcanization process. The effects of vulcanization temperature and film thickness on the thermoelectric properties of CuS thin films have been investigated. An optimal high power factor of 73.25 μW/m−1 K−2 is found at 400 K for a 20 nm-thick sample, and the optical transmittance is over 80% in the visible light spectrum. Meanwhile, excellent flexibility of the CuS thin films has been demonstrated. These results demonstrate the high promise of CuS thin films for transparent and flexible thermoelectric device applications.
Janus tetragonal Mn2BN monolayer: A 2D polar half-metal with coexistent ferroelectricity and magnetism
Authors: Yan Xu , Wang Junyuan , Wang Sheng , Liu Yong , Kou Liangzhi , Yang Guochun
Published: April 2024

The integration of ferroelectricity, ferromagnetism, and half-metallicity in two-dimensional (2D) materials is pivotal for advancing spintronic device technologies. However, the progress in identifying such materials is limited, and we here propose a compelling approach by constructing asymmetry structures (Janus) based on known 2D magnets, namely, the Janus tetragonal Mn2BN monolayer as a promising polar half-metal. The asymmetric arrangement of B and N atoms, coupled with comparable atomic sizes and evident electronegativity, ensures structural stability and inherent polarization, while the dominance of Mn atoms governs magnetism. The robust ferromagnetic order stems from a strong super-exchange interaction, evident in the significant hybridization between Mn d and B/N p orbitals. The Mn2BN monolayer exhibits a wide spin bandgap (1.09 eV), a substantial electric polarization (9.15 μC cm−2), and a sizable magnetic anisotropic energy (238 μeV/Mn) and maintains stable ferromagnetic order to ∼800 K. These properties position it as a promising candidate for next-generation multifunctional devices in spintronics.
Splashing and sealing of an ejecta sheet induced by a cavitation bubble close to a water surface
Authors: Wang Jingzhu , Wang Guanghang , Wang Yiwei
Published: April 2024

An ejecta sheet is commonly formed when a cavitation bubble bursts into the air, creating an open cavity. The evolution of the sheet has been studied independently, with limited focus on the interaction between the ejecta sheet and the cavity. This study offers insights into the splashing and sealing of a laser-induced ejecta sheet. An object-distance compensation method is developed to capture clear images of the phenomena both above and below the water surface simultaneously. The ejecta sheet exhibits two patterns: an open splash and a sealed splash. In the case of an open splash, the cavity seals quasistatically, whereas in the case of a sealed splash, the cavity type transitions from shallow sealing to surface sealing as the dimensionless standoff distance γ increases. An axisymmetric model is proposed for analyzing how the ejecta sheet evolves during the sealing process. Since the sealing process is dominated by suction pressure resulting from rapid expansion of the cavity, we obtain the cross-sectional area As of the ejecta sheet as a function of the rates of change of the bubble volume (V̇b) and the sheet cross-sectional area (Ȧinn), and this function is shown to be independent of time. Remarkably, as γ increases, As decreases and increases in the regimes of shallow sealing and surface sealing, respectively. This tendency is induced by the significant difference in V̇b due to the initial state of the cavity. Our findings offer a new understanding of the dynamics of laser-induced ejecta sheets.
Acoustic and optical phonons in quasi-two-dimensional MPS3 antiferromagnetic semiconductors
Authors: Wright Dylan , Ebrahim Nataj Zahra , Guzman Erick , Polster Jake , Bouman Menno , Kargar Fariborz , Balandin Alexander A.
Published: April 2024

We report the results of the investigation of the acoustic and optical phonons in quasi-two-dimensional antiferromagnetic semiconductors of the transition metal phosphorus trisulfide family with Mn, Fe, Co, Ni, and Cd as metal atoms. The Brillouin–Mandelstam and Raman light scattering spectroscopies were conducted at room temperature to measure the acoustic and optical phonon frequencies close to the Brillouin zone center and the Γ−A high symmetry direction. The absorption and index of refraction were measured in the visible and infrared ranges using the reflectometry technique. We found an intriguing large variation, over ∼28%, in the acoustic phonon group velocities in this group of materials with similar crystal structures. Our data indicate that the full-width-at-half-maximum of the acoustic phonon peaks is strongly affected by the optical properties and the electronic bandgap. The acoustic phonon lifetime extracted for some of the materials was correlated with their thermal properties. The results are important for understanding the layered van der Waals semiconductors and assessing their potential for optoelectronic and spintronic device applications.
An innovative method of pressure measurement inside a laser-induced cavitation bubble
Authors: Uehara Satoshi , Sato Takehiko , Kamata Sayaka , Kanazawa Seiji , Iga Yuka , Nakajima Tomoki , Farhat Mohamed
Published: April 2024

This study proposes a novel method for measuring the pressure inside a laser-induced cavitation bubble during its expansion. Based on Paschen's theory, which relates electrical breakdown to gas pressure, applied voltage, and electrode distance, our approach uses two electrodes to estimate the cavitation bubble pressure at different expansion stages by noting the breakdown time at varying voltages. This method offers a high temporal resolution owing to its rapid electrical discharge response. The unveiled pressure during the expansion phase was approximately 0.4 atm. This value contradicts previous reports that assumed that the minimum pressure was close to the water vapor pressure.
Angle selectivity of liquid crystal superstructure and applications in bio-detection
Authors: Zhang Ting-Hao , Wan Bao-Fei , Sui Jun-Yang , Zhang Hai-Feng
Published: April 2024

In this paper, a temperature-controlled angle selection device based on a photonic bandgap is proposed, consisting of MLC-6608 liquid crystal (MLC) and common electrolytes stacked in layers. This device has an angular transmission stability for electromagnetic waves over a wide frequency band (600–660 THz). A high transmissivity (T>0.85) area, also called an angle window, is formed at 25° and 75°, and an area of zero transmissivity is formed beyond the angle window. The MLC is temperature-responsive, and the range of angle selection can be expanded or narrowed by temperature adjustment. When the MLC is replaced by the biological sample, it shows good sensing performance. It can be used to detect in vitro dermis, in vivo stratum corneum, and in vivo epidermis and it is of great significance in medicine, with a sensing sensitivity of 90.91°/refractive index unit.
Erratum: “Fractional Brownian motion with random Hurst exponent: Accelerating diffusion and persistence transitions” [Chaos 32, 093114 (2022)]
Authors: Balcerek Michał , Burnecki Krzysztof , Thapa Samudrajit , Wyłomańska Agnieszka , Chechkin Aleksei
Published: April 2024

We point out a minor mistake in Fig. 10 in the published version of our paper [M. Balcerek et al., Chaos 32, 093114 (2022)]. The conclusions drawn from the illustration remain the same.
Efficiency of diode effect in asymmetric inline long Josephson junctions
Authors: Guarcello C. , Pagano S. , Filatrella G.
Published: April 2024

An effective superconducting diode—that is an element whose critical current depends upon the polarity—is achieved with a special configuration of a long Josephson junction and a control line. The proposed geometry is simple, based on the well-established asymmetric inline long Josephson junction, and can be realized using traditional superconductors without the need of magnetic materials. The performance of the diode, as measured by the efficiency, only depends on the normalized length and the control current intensity. At the optimal working point, the efficiency reaches about 76% and could be further improved at the expenses of the circuit simplicity. Finally, when a sinusoidal current is applied to the device, calculations with realistic fabrication parameters show the rectification of a sinusoidal current with a frequency in the MHz region.