bluuebunny/crossref_metadata_2025 huggingface dataset:
Enzymatic and Bio-Inspired Enantioselective Oxidation of Non-Activated C(sp
3)–H Bonds
Authors: Bietti Massimo , Costas Miquel , Palone Andrea
Published: August 2024

The enantioselective oxidation of C–H bonds relies on two different approaches: the use of enzymes or bio-inspired transition metal catalysts. Both are powerful tools, as they transform ubiquitous C(sp3)–H bonds into valuable oxygenated building blocks. However, the reaction remains a challenge in synthetic chemistry, continuously demanding efficient catalytic systems to improve substrate scopes. Optimization of site- and enantioselectivities in bio-catalytic systems is underpinned by protein engineering, while ligand design and medium effects play crucial roles in bio-inspired synthetic complexes. In this Short Review, recent advances in the field are described, focusing on reactions that target strong, non-activated C–H bonds.

1 Introduction

1.1 Enantioselective Catalytic C–H Oxidation in Nature and Bio-Inspired Systems

1.2 Biological C–H Oxidation Mechanism and Challenges for the Implementation of Chirality with Synthetic Catalysts

1.3 Bio-Catalytic C–H Oxidation Systems: From Microorganism to Engineered Enzymes

1.4 Mimicking Nature: The Bio-Inspired C–H Oxidation Approach

1.5 Origin of Enantioselectivity

2 Enantioselective C–H Oxidation of Non-Activated C–H Bonds

2.1 Hydroxylation at Non-Activated C–H Bonds by Bio-Catalytic Systems

2.2 Enantioselective C–H Lactonization with Enzymatic Systems

2.3 Oxidation at Non-Activated C–H Bonds by Synthetic Catalysts

2.4 Enantioselective Lactonization with Small-Molecule Catalysts

3 Conclusions
Cuneanes as Potential Benzene Bioisosteres Having Chirality
Authors: Takebe Hiyori , Matsubara Seijiro
Published: August 2024

Cuneane, a structural isomer of cubane, possesses C
2v
symmetry, unlike the Oh
symmetry of cubane. It can exhibit chirality with only a single substituent, differentiating it from cubane. Consequently, cuneane is being explored as a potential benzene bioisostere in pharmaceutical molecules, adding complexity such as chirality through isomerization of the cubane skeleton. Although there has been limited research on the synthesis of cuneane, recent years have seen increased attention devoted to this cage hydrocarbon. In this short review, we will discuss recent advances in the synthesis, utilization, and transformations of the cuneane framework into other cage hydrocarbons.

1 Introduction: Absolute Configuration Notation

2 Preparation of 1,3- and 2,6-Disubstituted Cuneanes by Constitutional Isomerization of 1,4-Disubstituted Cubanes

3 Preparation of 1,2-Disubstituted Cuneanes from 1-Cuneanecarboxamide via Directed ortho-Metalation

4 Investigation of the Potential as a Benzene Bioisostere

5 Asymmetric Synthesis of Cuneanes

6 Cuneane Scaffold Editing

7 Conclusion
Improving the endoscopic recognition of early colorectal carcinoma using artificial intelligence: current evidence and future directions
Authors: Thijssen Ayla , Schreuder Ramon-Michel , Dehghani Nikoo , Schor Marieke , de With Peter H.N. , van der Sommen Fons , Boonstra Jurjen J. , Moons Leon M.G. , Schoon Erik J.
Published: August 2024

Background and study aims Artificial intelligence (AI) has great
potential to improve endoscopic recognition of early stage colorectal carcinoma (CRC). This
scoping review aimed to summarize current evidence on this topic, provide an overview of the
methodologies currently used, and guide future research.

Methods A systematic search was performed following the
PRISMA-Scr guideline. PubMed (including Medline), Scopus, Embase, IEEE Xplore, and ACM Digital
Library were searched up to January 2024. Studies were eligible for inclusion when using AI
for distinguishing CRC from colorectal polyps on endoscopic imaging, using histopathology as
gold standard, reporting sensitivity, specificity, or accuracy as outcomes.

Results Of 5024 screened articles, 26 were included.
Computer-aided diagnosis (CADx) system classification categories ranged from two categories,
such as lesions suitable or unsuitable for endoscopic resection, to five categories, such as
hyperplastic polyp, sessile serrated lesion, adenoma, cancer, and other. The number of images
used in testing databases varied from 69 to 84,585. Diagnostic performances were divergent,
with sensitivities varying from 55.0% to 99.2%, specificities from 67.5% to 100% and
accuracies from 74.4% to 94.4%.

Conclusions This review highlights that using AI to improve
endoscopic recognition of early stage CRC is an upcoming research field. We introduced a
suggestions list of essential subjects to report in research regarding the development of
endoscopy CADx systems, aiming to facilitate more complete reporting and better comparability
between studies. There is a knowledge gap regarding real-time CADx system performance during
multicenter external validation. Future research should focus on development of CADx systems
that can differentiate CRC from premalignant lesions, while providing an indication of
invasion depth.
Visible-Light-Induced Iron(III)-Catalyzed Synthesis of Unsymmetrical Bis(indolyl)methanes through Hydrogen Atom Transfer
Authors: Mandal Kush , Rana Gopal , Nur Asadujjaman , Ghosh Sourav , Jana Umasish
Published: August 2024

We report a visible-light-mediated, FeCl3-catalyzed, one-pot tandem strategy for the regioselective synthesis of unsymmetrically substituted tertiary and quaternary carbon-containing 3,3′-bis(indolyl)methanes under aerobic conditions. This strategy involves the coupling of 3-arylideneindolines with indoles through a photoinduced chlorine-radical-mediated hydrogen-atom-transfer reaction. The present strategy features mild and environmentally benign reaction conditions, low cost, high yields, and tolerance of a wide range of functional groups. Furthermore, to demonstrate the synthetic value of the reaction, a naturally occurring bioactive bisindolyl(phenyl)methane was synthesized.
Characterisation of Aqueous Ultra-high Homeopathic Potencies: Nanoparticle Tracking Analysis
Authors: Van Wassenhoven Michel , Goyens Martine , Dorfman Pierre , Devos Philippe , Demangeat Jean-Louis
Published: August 2024

Background and Objectives Over the past decade, research using various methods has claimed the material nature, including nanoparticles (NPs), of high homeopathic potencies. The current study aims to verify these findings using NP tracking analysis (NTA).

Methods Six independent serial dilutions of commonly used homeopathic medicines—either soluble (Gelsemium, Pyrogenium, Kalium mur) or insoluble (Cuprum, Argentum, Silicea)—were prepared according to European Pharmacopoeia standards. We compared the homeopathic dynamisations (DYNs) in pure water with their potentised controls and with simple dilutions (DIL) up to 30cH/10−60. We also tested the influence of the container (glass or PET) on the solvent controls.

Results We observed the presence of particles from 20 to 300–400 nm in all DYNs, DILs and controls, except in pure unstirred water. The sizes and size distributions of NPs in high homeopathic potencies were smaller than those in controls for soluble sources and larger for insoluble sources, even above 11cH. The opposite behaviour was observed in the number of NPs. When comparing DYN and DIL, the number, size, presence of aggregates or chains and brightness of NPs increased with DYNs, which was also observed above 11cH. Many NPs scattered light of low intensity, indicating the presence of material particles. The container had a significant effect on the number and size of NPs, indicating the involvement of the atmosphere and leaching processes.

Conclusion Homeopathic medicines contain NPs with specific properties, even when diluted beyond Avogadro's number. Homeopathic potentisation is not a simple dilution. The starting material, the solvent used, the type of container and the manufacturing method influence the characteristics of these NPs. The nature of these NPs is not known, but most likely they are a mixture of nanobubbles and elements from the atmosphere and container, including insoluble ones.
Digital health in stroke: a narrative review
Authors: Silva Gisele Sampaio , Andrade João Brainer Clares de
Published: August 2024

Digital health is significantly transforming stroke care, particularly in remote and economically diverse regions, by harnessing mobile and wireless technologies, big data, and artificial intelligence (AI). Despite the promising advancements, a notable gap exists in the formal clinical validation of many digital health applications, raising concerns about their efficacy and safety in real-world clinical settings. Our review systematically explores the landscape of digital health in stroke care, assessing the development, validation, and implementation of various digital tools. We adopted a comprehensive search strategy, scrutinizing peer-reviewed articles published between January 2015 and January 2024, to gather evidence on the effectiveness of digital health interventions. A rigorous quality assessment was conducted to ensure the reliability of the included studies, with findings synthesized to underscore key technological innovations and their clinical outcomes. Ethical considerations were meticulously observed to maintain data confidentiality and integrity. Our findings highlight the transformative potential of mobile health technologies, AI, and telemedicine in improving diagnostic accuracy, treatment efficacy, and patient outcomes in stroke care. Our paper delves into the evolution and impact of digital health in cerebrovascular prevention, diagnosis, rehabilitation and stroke treatment, emphasizing the digital health's role in enhancing access to expert care, mitigating treatment delays and improving outcomes. However, the review also underscores the critical need for rigorous clinical validation and ethical considerations in the development and deployment of digital health technologies to ensure their safe and effective integration into stroke care practices.
Comparison of MRI Osteoarthritis Knee Score with Clinico-Radiological Grading
Authors: Halmandge Amul M. , Malik Rajesh , Sarawagi Radha , Sharma Jitendra
Published: August 2024

Background Knee joint osteoarthritis (OA) is among the most prevalent degenerative diseases of the joints in the body. Various scoring system exists for grading OA, such as (1) magnetic resonance imaging (MRI) Osteoarthritis Knee Score (MOAKS), (2) clinical grading by Western Ontario and McMaster Universities Arthritis Index (WOMAC), and (3) X-ray grading of the Kellgren–Lawrence grading system (K-L).

Objectives To study MRI findings and MOAKS scoring of knee OA and correlation with WOMAC and K-L scoring.

Setting and Design Cross-sectional study in hospital population.

Materials and Methods A total 40 knee OA cases underwent an MRI of the knee. MOAKS scoring was done and compared with K-L grading and WOMAC scores.

Statistical Analysis Collected data were compiled systematically and interpreted using IBM SPSS statistics software 25.0. A p-value of less than 0.05 was considered significant.

Results The mean total WOMAC score was 9. K-L grade 2 was the most prevalent X-ray grade. Bone marrow lesion (BML) and cartilage loss in MOAKS score were greater in the medial femorotibial region. A moderate positive correlation was noted between the WOMAC score and K-L grade; full-thickness articular cartilage loss score at the medial femorotibial joint (MFTJ) and WOMAC score; partial-thickness articular cartilage loss score at lateral femorotibial joint (LFTJ) and WOMAC total pain score. No correlation was found between BML and pain severity score.

Conclusion Higher WOMAC scores were associated with higher grades of K-L scoring and score of cartilage loss (partial and full thickness) of the MOAKS scoring system. The rest of the features of the MOAKS score (BML score, osteophyte, and synovitis) had no significant association with pain severity and K-L grading.
Ghost Sign on Diffusion-Weighted Imaging Generated Apparent Diffusion Coefficient Map: Additional MRI Diagnostic Marker for Extremity Osteomyelitis
Authors: He Angela , Guirguis Mina , Silva Flavio Duarte , Ashikyan Oganes , Pezeshk Parham , Rajamohan Naveen , Salhadar Karim , Xi Yin , Chhabra Avneesh
Published: August 2024

Objective The aim of this study was to determine the sensitivity and specificity and inter-reader reliability of previously known “ghost sign” and “penumbra sign” on T1-weighted (T1W) imaging and “ghost sign” on apparent diffusion coefficient (ADC) map in osteomyelitis (OM) of the extremities.

Materials and Methods In this cross-sectional retrospective study, two fellowship-trained musculoskeletal readers blinded to final diagnosis of OM versus no OM were asked to report the penumbra sign and ghost sign on T1W images and ghost sign on ADC map, as well as diagnosis of OM. Cohen's kappa was used. Diagnostic performance measures including sensitivity, specificity, and accuracy were calculated.

Results A sample of 178 magnetic resonance imaging (MRI) scans of pathology-proven cases were included in this study, with 41 being positive for OM and 137 being negative for OM. There was a fair inter-reader agreement for imaging signs, and moderate agreement of 0.60 for OM. The sensitivities of the penumbra sign on T1W imaging, ghost sign on T1W imaging, and ghost sign on ADC map for OM are 3.7, 9.8, and 19.5%, respectively, while their respective specificities are 98.9, 97.8, and 94.5%, respectively. All three imaging signs showed a similar (good) accuracy of 76 to 78%.

Conclusion The ghost sign on ADC can be used as an additional marker for OM and is a similarly highly specific but a more sensitive sign for OM than the conventionally used penumbra sign and ghost sign on T1W imaging.

Key Points
Update on the Role of Imaging in the Diagnosis, Staging, and Prognostication of Gallbladder Cancer
Authors: Rana Pratyaksha , Kalage Daneshwari , Soundararajan Raghuraman , Gupta Pankaj
Published: August 2024

Gallbladder cancer (GBC) is a highly aggressive malignancy with dismal prognosis. GBC is characterized by marked geographic predilection. GBC has distinct morphological types that pose unique challenges in diagnosis and differentiation from benign lesions. There are no specific clinical or serological markers of GBC. Imaging plays a key role not only in diagnosis and staging but also in prognostication. Ultrasound (US) is the initial test of choice that allows risk stratification in wall thickening and polypoidal type of gallbladder lesions. US findings guide further investigations and management. Computed tomography (CT) is the test of choice for staging GBC as it allows comprehensive evaluation of the gallbladder lesion, liver involvement, lymph nodes, peritoneum, and other distant sites for potential metastases. Magnetic resonance imaging (MRI) and magnetic resonance cholangiopancreatography allow better delineation of the biliary system involvement. Contrast-enhanced US and advanced MRI techniques including diffusion-weighted imaging and dynamic contrast-enhanced MRI are used as problem-solving tools in cases where distinction from benign lesion is challenging at US and CT. Positron emission tomography is also used in selected cases for accurate staging of the disease. In this review, we provide an up-to-date insight into the role of imaging in diagnosis, staging, and prognostication of GBC.
Venous Thromboembolism in Patients with Glioblastoma: Molecular Mechanisms and Clinical Implications
Authors: Versteeg Henri H. , Buijs Jeroen T. , Kapteijn Maaike Y. , Bakker Nina , Koekkoek Johan A. F.
Published: August 2024

Patients with glioblastoma are among the cancer patients with the highest risk of developing venous thromboembolism (VTE). Long-term thromboprophylaxis is not generally prescribed because of the increased susceptibility of glioblastoma patients to intracranial hemorrhage. This review provides an overview of the current clinical standard for glioblastoma patients, as well as the molecular and genetic background which underlies the high incidence of VTE. The two main procoagulant proteins involved in glioblastoma-related VTE, podoplanin and tissue factor, are described, in addition to the genetic aberrations that can be linked to a hypercoagulable state in glioblastoma. Furthermore, possible novel biomarkers and future treatment strategies are discussed, along with the potential of sequencing approaches toward personalized risk prediction for VTE. A glioblastoma-specific VTE risk stratification model may help identifying those patients in which the increased risk of bleeding due to extended anticoagulation is outweighed by the decreased risk of VTE.
Common organic compounds could enable artificial photosynthesis devices
Authors: Johnson-Groh Mara
Published: August 2024

Unique chemical and structural properties offer photocatalytic potential for porphyrin-based nanomaterials.
Unraveling hydrodynamic interactions in fish schools: A three-dimensional computational study of in-line and side-by-side configurations
Authors: Pan Yu , Zhang Wei , Kelly John , Dong Haibo
Published: August 2024

We numerically investigate the hydrodynamic interactions between a pair of three-dimensional (3D) fish-like bodies arranged in both in-line and side-by-side configurations. The morphology and kinematics of these fish-like bodies are modeled on a live rainbow trout (Oncorhynchus mykiss) observed during steady swimming in the laboratory. An immersed-boundary-method-based incompressible Navier–Stokes flow solver is employed to capture the flow dynamics around the fish-like bodies accurately. Our findings indicate that hydrodynamic performance of individual fish in both arrangements is influenced by their spatial separation when in close proximity as well as by the relative phase difference between the two fish. In the case of in-phase in-line schools, the leading fish experiences up to 5.3% increase in propulsive efficiency, attributed to the water blockage effect caused by the following fish. In comparison, the following fish experiences an increase in drag and power consumption along its body. Detailed analysis reveals that this rise in drag primarily results from an increase in friction drag (89%), driven by the amplified velocity field around the fish's body. Furthermore, altering the phase difference between the fish can help reduce pressure drag on the following fish by affecting the interaction between incoming vortex rings and its trunk. In side-by-side schools with in-phase swimming, a reduction of 6.8% in power consumption on the caudal fin is achieved for each fish when the transverse distance is maintained at 0.25 body lengths. Flow analysis reveals that the decrease in power usage is attributed to a diminished velocity field between the caudal fins, facilitating flow separation and subsequently reducing energy expenditure required for generating comparative thrust. For the out-of-phase swimming, the side-by-side school system experiences enhanced thrust production, owing to a wake energy recapture mechanism. The degree of enhancement varies for each fish and is determined by the specific phase difference. These insights obtained from our study hold the potential to inform the design and navigation strategies of underwater robotic swarms.
The revised Riemann–Hilbert approach to the Kaup–Newell equation with a non-vanishing boundary condition: Simple poles and higher-order poles
Authors: Zhang Yongshuai , Qiu Deqin , Shen Shoufeng , He Jingsong
Published: August 2024

With a non-vanishing boundary condition, we study the Kaup–Newell (KN) equation (or the derivative nonlinear Schrödinger equation) using the Riemann–Hilbert approach. Our study yields four types of Nth order solutions of the KN equation that corresponding to simple poles on or not on the ρ circle (ρ related to the non-vanishing boundary condition), and higher-order poles on or not on the ρ circle of the Riemann–Hilbert problem (RHP). We make revisions to the usual RHP by introducing an integral factor that ensures the RHP satisfies the normalization condition. This is important because the Jost solutions go to an integral factor rather than the unit matrix when the spectral parameter goes to infinity. To consider the cases of higher-order poles, we study the parallelization conditions between the Jost solutions without assuming that the potential has compact support, and present the generalizations of residue conditions of the RHP, which play crucial roles in solving the RHP with higher-order poles. We provide explicit closed-form formulae for four types of Nth order solutions, display the explicit first-order and double-pole solitons as examples and study their properties in more detail, including amplitude, width, and exciting collisions.
Sensitivity and heat penalty in all-optical quantum thermometry with Germanium-vacancy color centers in diamond
Authors: Dharmasiri A. , Vincent C. , Rajib T. I. , Pochechuev M. , Liu X. , Verhoef A. J. , Agarwal G. S. , Zheltikov A. M.
Published: August 2024

All-optical thermometry based on laser-driven photoluminescence (PL) of germanium–vacancy (GeV−) centers in diamond is quantified in terms of a trade-off between temperature sensitivity and laser-induced heating. We show that the noise-floor sensitivity ηT of the temperature readout from the GeV− PL return scales as (pΔt)−1/2 with the laser power p and detection time Δt, allowing the temperature uncertainty to be reduced by increasing p and Δt. This noise-floor reduction is, however, never penalty-free. Specifically, higher laser powers translate into higher temperatures of the diamond crystal. We demonstrate that the noise-floor as low as ηT = 37.5 mK/Hz can be achieved with the laser power set at p = 6.30 mW. We also show that a further reduction of ηT is possible at higher p. The experimental setting implemented in this study helps keep the level of heat released in a diamond crystal well below the typical level of microwave-induced heating in nitrogen-vacancy center-based thermometry, thus offering an advantageous approach for diamond-based thermometry in biological systems.
Air-coupled ultrasound using broadband shock waves from piezoelectric spark igniters
Authors: Scheuer K. G. , DeCorby R. G.
Published: August 2024

We used an optomechanical sensor to study the ultrasound generated by manually operated piezoelectric spark igniters. These low-energy sparks produce short-duration acoustic shock-wave pulses, with sub-microsecond rise times and frequency content extending well beyond 2 MHz in air. The same source–receiver combination was then used to demonstrate broadband characterization of solid (polymer and glass) plates in a simple setup, where single spark events yielded high signal-to-noise ratio data without the need for critical alignment. This setup also enabled us to estimate pressure excursions approaching 105 Pa at millimeter-scale distances from the spark. The results are in large part made possible by the small size, wide bandwidth, and high sensitivity of the optomechanical sensor and might be of interest for air-coupled ultrasound applications in nondestructive testing.
Magnon excitation-induced spin memory loss in epitaxial L10-FePt/MgO/L10-FePt magnetic tunnel junctions
Authors: Yang Guang , Zhao Yunchi , Qi Jie , Zhang Yi , Shao Bokai , Wang Shouguo
Published: August 2024

This work investigates the interplay between interfacial spin–orbit coupling (SOC) and magnon excitation-induced spin memory loss in epitaxial L10-FePt/MgO/L10-FePt magnetic tunnel junctions, which is crucial for advancing spintronic technologies. By employing systematic temperature-dependent transport measurements and inelastic electron tunneling spectroscopy, our study reveals that interfacial SOC at the Pt-terminated FePt/MgO interface significantly enhances magnon excitation during electron tunneling. This process results in a pronounced loss of spin memory in the spin-polarized current, diminishing the tunnel magnetoresistance ratio. Our findings provide critical insights into the mechanisms of spin memory loss, offering directions for optimizing spintronic device performance in the context of pronounced SOC environments.
Optimization of self-rectifying analog memristors by insertion of an interfacial layer
Authors: Zhao Xianyue , Li Kefeng , Chen Ziang , Dellith Andrea , Dellith Jan , Hübner Uwe , Bengel Christopher , Liu Feng , Menzel Stephan , Schmidt Heidemarie , Du Nan
Published: August 2024

Self-rectifying analog memristors have emerged as promising components for neuromorphic computing systems due to their inherent rectifying behavior and analog resistance states. Among these devices, BiFeO3 (BFO) memristors have shown exceptional performance, attributed to the accumulation and migration of oxygen vacancy (Vo··). However, the movement of Vo·· within the structure of the device presents challenges in optimizing their performance. To address this, the insertion of an interfacial layer has been proposed as a strategy to change the movement of Vo·· and enhance the behavior of memristor. In this study, we investigate the optimization of self-rectifying analog memristors by inserting an interfacial layer in BFO memristors. The more significant nonlinearity in high resistance state branch we observed in the current–voltage relationship leads to better rectifying behavior and a larger on/off ratio at room temperature, which indicates that the interfacial layer improves rectifying behavior. Moreover, we propose a model based on the modulation of the interfacial barrier to elucidate the impact of the interfacial layer on the BFO memristor. These findings provide insight into the design principles for optimizing self-rectifying analog memristors, with potential applications in neuromorphic computing.
Cavity-enhanced photo-thermoelectric response in graphene under cyclotron resonance
Authors: Park Sabin , Moriya Rai , Hayashi Kenjiro , Fushimi Naoki , Onodera Momoko , Zhang Yijin , Watanabe Kenji , Taniguchi Takashi , Kondo Daiyu , Sato Shintaro , Machida Tomoki
Published: August 2024

We investigated the photo-thermoelectric response of Landau-quantized graphene in an infrared optical cavity structure. High-quality graphene/h-BN heterostructure was fabricated on a TiO2/Au optical cavity. We observed a large enhancement of the photo-thermoelectric voltage when the energy of the inter-Landau-level optical absorption, so-called cyclotron resonance, was coincident with that of the cavity mode. This is due to cavity-enhanced cyclotron resonance absorption of mid-infrared light. A maximum photovoltage responsivity of ∼107 V/W was obtained at a wavelength of 9.27 μm under a magnetic field as low as ∼1 Tesla. The obtained responsivity was significantly higher than that of conventional graphene devices. Our results provide an efficient photo-thermoelectric conversion scheme that utilizes Landau-quantized graphene and an optical cavity.
Study of peak velocity of blasting vibration for raft foundation demolition based on MEA-BP algorithm
Authors: Wang Haojie , Li Shiquan , Zhen Shuai , Liu Jun , Peng Xianbing , Yi Yongsheng
Published: August 2024

In order to solve the problem of poor accuracy of blasting vibration prediction by the traditional Sadowski empirical formula and BP neural network, a model based on the mind evolutionary algorithm (MEA) is proposed for the first time to optimize the BP neural network. The blasting demolition of a raft slab foundation of an underground garage in Shenyang City, Liaoning Province, China, is taken as a research object, and the effects of the horizontal distance between different monitoring points, demolition area, elevation difference, the maximum amount of a single section of the charge, and the horizontal angle between the measurement point and the minimum resistance line on the peak velocity of vibration are taken into account. The empirical Sadowski formula, the MEA-BP algorithm, and the GA-BP algorithm were introduced to randomly train the 40 sets of data monitored at the site and to predict the eight sets of data outside the training, respectively. The results showed that the maximum relative errors of the results predicted by the MEA-BP model, the GA-BP model, and the empirical Sadowski formula were 14.94%, 19.36%, and 22.81%, respectively, and the average relative errors were 8.88%, 10.79%, and 16.84%, respectively. The prediction results corroborate that the MEA-BP algorithm has high adaptability in blasting vibration prediction for raft foundation demolition and provides reference for the prediction of vibration peak velocity in similar blasting projects.
Development and test of the laser blow-off impurity injection system in experimental advanced superconducting tokamak
Authors: Shen Y. C. , Fan Y. , Zhang H. M. , Lyu B. , Lin Z. C. , Yin X. H. , Wang F. D. , Fu J. , Ji H. J. , Zeng C. , Sun B. , Mao L. Y.
Published: August 2024

The Laser Blow-Off (LBO) impurity injection system is a crucial tool for studying impurity transport and plasma behavior. Conducting proactive impurity transport research is challenging on experimental advanced superconducting tokamak (EAST) due to the uncontrollable generation of impurity sources; therefore, it is necessary to develop a laser blow-off impurity injection system for injecting controlled trace impurity particles. This study presents the design and test results of an LBO system for the EAST. The system aims to provide precise and repeatable control over the timing and quantity of impurity injection. The system primarily consists of a laser source, two mirrors, a moveable focusing lens, a target material, and a vacuum system. The movement of the focusing lens is achieved by a three-dimensional displacement system. The operation of the system is completed by a remote control system. With the accurate control system, the laser spot diameter is adjustable, allowing for modification of impurity injection quantity. The test results demonstrate that the system can rapidly detect external trigger signals and ensure precise timing for the impurity injection. Furthermore, this system can also quickly change the focal point of the laser spot, addressing the requirements for impurity injections during the experiments with less than 0.4 mm position error for laser spot focusing. Test results have shown that the aluminum film material can be peeled off by the LBO system when the laser energy exceeds 650 mJ and the smallest ablation spot is about 1 mm. This study is of significant importance for conducting plasma impurity transport research on the EAST.
Low contact resistivity at the 10−4 Ω cm2 level fabricated directly on n-type AlN
Authors: Cao Haicheng , Nong Mingtao , Li Jiaqiang , Tang Xiao , Liu Tingang , Liu Zhiyuan , Sarkar Biplab , Lai Zhiping , Wu Ying , Li Xiaohang
Published: August 2024

Ultrawide bandgap aluminum nitride (AlN) stands out as a highly attractive material for high-power electronics. However, AlN power devices face performance challenges due to high contact resistivity exceeding 10−1 Ω cm2. In this Letter, we demonstrate achieving a low contact resistivity at the 10−4 Ω cm2 level via refined metallization processes applied directly to n-AlN. The minimum contact resistivity reached 5.82 × 10−4 Ω cm2. Our analysis reveals that the low contact resistance primarily results from the stable TiAlTi/AlN interface, resilient even under rigorous annealing conditions, which beneficially forms a thin Al–Ti–N interlayer, promotes substantial nitrogen vacancies, enhances the net carrier density at the interface, and lowers the contact barrier. This work marks a significant milestone in realizing superior Ohmic contacts for n-type AlN, paving the way for more efficient power electronic and optoelectronic devices.
Numerical simulation of wind–snow flow on a roof considering time-varying snow phase boundaries
Authors: He Yanli , Lai Guangxin , Guo Xingyu , Zhang Cong
Published: August 2024

Large-span roofs can be damaged by uneven snow loads caused by snow drifting. To predict wind-induced snow loads more accurately, this paper proposes a numerical simulation method. The method considers the interaction of wind and snow, the changing characteristics of snow phase boundaries over time, and corrects for snow deposition and erosion flux. The effectiveness of the method was confirmed by simulating wind–snow flow on a three-centered cylindrical shell and comparing the results with wind tunnel measurements. The simulation considered different snowfall conditions and time-varying snow phase boundaries on a large-span shell-shaped roof. The study investigated the influence of snowfall conditions and dynamic changes in snow phase boundaries on snow cover distribution by comparing simulation results.
Reducing the coupling of metamaterial via random configuration
Authors: Huang Wei , Yu Jiahe , Huang Zijie , Cao Shi-Ting , Jiang Huan , Zhao Feng , Yin Shan , Zhang Wentao , Han Jiaguang
Published: August 2024

In this paper, we demonstrate the Anderson localization effect in coupled metamaterial structures. We introduce the random variables by randomly choosing the geometrical parameter of structures and randomly choosing the distance between structures to reduce the coupling of metamaterial and this decoupling effect is equivalent to Anderson localization effect, which can reduce the coupling without enlarging the area of unit cell. We demonstrate our idea by employing the experiments. Furthermore, we present an example of deflector to see how this decoupling effect can help us design functional devices.
Statistical description of interacting multistream quantum systems
Authors: Akbari-Moghanjoughi M.
Published: August 2024

In this research, the electrostatically coupled multistream quasiparticle excitations are studied in the framework of the Wigner distribution function. It is remarked that the Wigner distribution of coupled multistream collective quantum excitations satisfies a simple Liouville-like evolution equation from which a generalized distribution function for multistream quasiparticle excitations is deduced. The phase-space structure of collective quantum excitations in counter-stream electron and two-stream electron–positron gas with their evolution is calculated and electron/positron hole formation due to the onset of quantum stream instability is studied in connection with the energy band structure of the multistream quantum system, for the first time. The quantum stream instabilities in symmetric and asymmetric stream systems are studied and compared. It is found that the presence of opposite-charge streams leads to overall stability due to lowering the interaction potential effect. The generalized Wigner theory is also applied to study the electron transport in a one-dimensional periodic lattice using the concept of virtual streams. Current generalized statistical formalism may be used to model different quantum phenomena in the linear excitations limit with collective electrostatic interactions. The applications extend to the stream instability in quantum charge transport in metals, semiconductors, plasmonic devices, phase-space structure of charge carriers in periodic lattices interacting with the external potential of arbitrary shape and the dynamic evolution of dense electron–positron jets in active galactic nuclei or within the extremely dense astrophysical objects.
Equilibrium atmospheric boundary layer model for numerical simulation of urban wind environment
Authors: Shen Lian , Han Yan , Cai C. S. , Hu Peng , Lei Xu , Zhou Pinhan , Deng Shuwen
Published: August 2024

The numerical simulation of urban wind environments faces difficulties in capturing the turbulent characteristics due to the large computational domain. Traditional Reynolds-averaged methods (RANS) can effectively capture the average wind characteristics of urban areas. However, due to the significant dissipation and attenuation of turbulent energy in the downstream direction, this method fails to provide accurate turbulent characteristics after time-averaging processing. Therefore, in order to obtain a higher-precision turbulent wind field distribution within urban areas, this paper proposed a new numerical method named an equilibrium atmospheric boundary layer model (EABL) by modifying the control equation of the shear stress transport k–ω model. During the process, the equilibrium atmospheric boundary layer was achieved successfully, and the attenuation problem of the turbulent kinetic energy and dissipation rate during the computational fluid dynamics numerical simulation was resolved. Simultaneously, a wind tunnel experiment and six turbulence models [standard k–ε, realizable k–ε, renormalization group k–ε, large eddy simulation—narrowband synthesis random flow generator (LES-NSRFG) and LES vortex method and EABL] were employed to simulate the wind field characteristics in an actual residential area. The simulation results demonstrate that, relative to traditional RANS models, the EABL model enhances the simulation accuracy of turbulence characteristics by over two times. Furthermore, compared to LES models, the EABL model can reduce computational time by threefold.
Cavitating flow control and noise suppression using air injection
Authors: Hilo Ali Kareem , Go Yeong-Ju , Hong Ji-Woo , Ahn Byoung-Kwon , Park Cheolsoo , Kim Gun-Do , Moon Il-Sung
Published: August 2024

The cavitation phenomenon not only reduces hydrodynamic performance but also generates vibrations and noise, significantly compromising the operational stability of the system. In this study, we investigate the efficiency of air injection in controlling cavitation patterns and reducing noise on hydrofoil, both experimentally and numerically. The focus is to assess how the location of air injection on the suction side of the hydrofoil, the rate of air injection, and the cavitation number affect the cavitating flow. The hydrofoil has a span and chord length (C) of 100 mm. The air is injected from a column of multi-holes positioned at x/C = 0.05, 0.10, 0.30, and 0.40 separately and controlled through a flow meter. The cavitation number ranges from 3.65 to 1.62, while the air injection rates are set at 1, 3, and 5 standard liters per minute. The experiments are conducted at Chungnam National University's high-speed cavitating tunnel. Simultaneously, a high-speed camera is used to observe cavitating flow, and a pressure transducer is employed to measure noise levels. The results indicate that injecting air closer to the leading edge has the most significant impact on reducing vapor cavitation and noise. Injecting air at x/C = 0.05 reduces the length of the vapor sheet cavity by 27% compared to cases without air injection. Increasing the air injection rate increased the volume of ventilated cavitation. Noise reduction is primarily noticeable in the high-frequency region (>2 kHz) at a high cavitation number of 2.22. As the cavitation number decreases to 1.62, the noise reduction shifts mainly to the low-frequency region, and the effectiveness of air injection in suppressing noise is reduced.
High-topological-number skyrmions with tunable diameters in two-dimensional frustrated J1−J2 magnets
Authors: Hu Hongliang , Shen Zhong , Chen Zheng , Wu Xiaoping , Zhong Tingting , Song Changsheng
Published: August 2024

Skyrmions are intriguing quasiparticles in the field of condensed matter due to their unique physics and promising applications in spintronic devices. However, despite abundant studies on skyrmions with a topological charge of Q = 1, there have been only few on those with higher Q (≥2) due to their intrinsic instability in Dzyaloshinskii–Moriya interaction (DMI) systems. In this work, applying the frustrated J1−J2 Heisenberg spin model, we investigate the stability of high-Q skyrmions and the manipulation of their diameters in a hexagonal close-packed lattice through atomistic simulations and first-principles calculations. First, three spin textures, called spiral, skyrmion, and ferromagnetic, are identified by varying (J1, J2), and it is shown that skyrmions with higher Q can occupy a wider range of (J1, J2) values. The diameter of the skyrmions can then be finely tuned using the frustration strength (|J2/J1|), the single-ion anisotropy (K), and an external magnetic field (B). As B increases, the high-Q skyrmions split into skyrmions with smaller Q and can be annihilated by a larger B. Furthermore, we find that the CoCl2 monolayer satisfies the criteria for a frustrated J1−J2 magnet, and its magnetic behaviors align with the aforementioned conclusions. In addition, high-Q skyrmions are identified in the CoCl2 monolayer, and the corresponding energy barriers for skyrmion collapse are investigated. Our findings pave the way for prospective spintronic applications based on high-Q and nanoscale skyrmionic textures.
Study on debris flow discharge characteristics of check dam spillway
Authors: Zhang Wen-tao , Liu Jin-feng , Xu Zheng-xuan , He Ping , You Yong , Sun Hao , Yang Hua-quan
Published: August 2024

After a check dam is filled with sediment, the debris flow will flow out from the spillway. Insufficient discharge capacity of the spillway can lead to debris flow scouring the dam's shoulder and foundation. Therefore, it is necessary to study the discharge capacity of the spillway. It is of great importance for further optimizing the structural design of the check dam. This article analyzes discharge characteristics of debris flow of a spillway through a series of flume experiments. According to the motion states, it can be divided into five stages: contact stage of the spillway, flushing and climbing stage, increasing and reflux stage, stable discharge stage, and final discharge stage. We analyzed the influencing factors of the discharge capacity, including the type of spillway, bulk density of debris flow, scale of debris flow, flume gradient, and effective opening width of the spillway. Furthermore, we derived a calculation formula of discharge for the spillway based on Bernoulli's principle. Finally, we considered the influence of the ratio of flow area and Froude number to the discharge coefficient and established a calculation method of discharge. Consequently, we compared the calculated results with the measured results and found them to be in good agreement. Our research results provide a quantitative calculation method for the design of spillways and energy dissipation and erosion prevention projects under check dams, which is beneficial for improving engineering value and for better serving disaster prevention and reduction efforts.
Enhanced microwave absorption in GaFeO3 coated CoFe2O4 nano-hollowsphere
Authors: Jana Ishita , Hait Swarnali , Gorai Anupam , Mandal Kalyan
Published: August 2024

As a multiferroic material with substantial magnetoelectric coupling, gallium ferrite (GaFeO3, GFO) has been intensively studied in recent years. Cobalt ferrite (CoFe2O4, CFO) nano-hollowsphere (NHS), on the other hand, is found to be an efficient material for electromagnetic (EM) wave absorption. In this work, a composite consisting of magnetostrictive CFO NHS coated with GFO nanoparticles [(1−x)CoFe2O4 – xGaFeO3, for x = 0.0, 0.9, 0.7, 0.5, 0.3, and 1.0] is prepared as an effective strategy to develop highly efficient microwave material. The EM wave absorption properties of the samples are thoroughly investigated across a widely used frequency range of 1–20 GHz. Remarkable performance of the x = 0.7 composite is evident by its effective bandwidth of approximately 3 GHz and a minimum reflection loss of approximately −63.26 dB. Moreover, the excellent impedance matching, with |Zin/Z0| ≅ 1.00, observed in the aforementioned composite, satisfies well with the required characteristics for a superior microwave absorber. Therefore, a core–shell nanostructure consisting of CFO NHS as core and GFO with optimized shell thickness can be used successfully in microwave devices.
A wall-boundary-natural transitional Reynolds-stress model for high-order wing-body simulations
Authors: Wang Shunshun , Wang Shengye , Fu Xiang , Deng Xiaogang
Published: August 2024

The precise simulation of full-size wing-body configuration in real flight conditions is still a challenge in computational fluid dynamics in which transition and flow separation are the most crucial issues. To predict these problems robustly by high-order numerical methods, this paper proposes a new transitional Reynolds-stress model, which combines λ-scale (λ=τ8)-based SSG (Speziale, Sarkar, and Gatski)/LRR (Launder, Reece, and Rodi) model with γ−Reθt transition model. Compared with the ω-scale, the λ-scale variable has a natural boundary condition on the wall (helpful for numerical stability) and avoids an additional modification during the transition from laminar to turbulent flow. The T3 series plates with/without pressure gradient, 30P-30N multi-element airfoil, and DLR (German Aerospace Center) 6:1 prolate spheroid are carried out to validate the reliability of the new nine-equation transition model. Furthermore, the new model is applied to the analysis of National Aeronautics and Space Administration juncture flow . Numerical results show that the new transitional model has an obvious advantage in the prediction of Reynolds stresses over the traditional γ−Reθt SST(shear stress transport) k−ω (k is the turbulence kinetic energy, ω is the specific dissipation rate) model, and then, more physical junction separation as well as transition onset can be obtained.
Exploring the potential of Sn–Ge based hybrid organic–inorganic perovskites: A density functional theory based computational screening study
Authors: Tekin Adem , Kalpar Merve , Tekin Emine
Published: August 2024

Hybrid organic–inorganic perovskite solar cells have attracted significant attention in the field of optoelectronics due to their exceptional photovoltaic and optoelectronic properties. Although lead (Pb)-based perovskites exhibit the highest power conversion efficiencies, concerns about their toxicity and environmental impact have prompted significant research activities to explore alternative compositions. In this regard, a special emphasis has been devoted to tin (Sn) and germanium (Ge) based perovskites. In order to reveal the full potential of Sn–Ge based perovskites, we computationally screened perovskites with a general formula of A0.5A0.5′SnyGe1−yX3 (y = 0.00, 0.25, 0.50, 0.75, 1.00) at the density functional theory level, particularly using the HSE06 hybrid functional. By using 18 A/A′-cations, four X-anions, and five different y compositions, a total of 7695 perovskites in cubic (C), orthogonal (O), and tetragonal (T) phases were considered, and the most promising ones have been filtered out based on their formation energy and bandgap. More specifically, 596, 525, and 542 C-, O-, and T-phase perovskites have been identified with a HSE06 bandgap range of 1.0–2.0 eV. While the Sn1.00Ge0.00 composition was dominated for both C- and O-phases, for the T-phase, a higher number of promising perovskites were obtained with the Sn0.75Ge0.25 composition. It has also been found that Sn-rich perovskites exhibit more favorable bandgap characteristics compared to Ge-rich ones. FA, MS, MA, K, Cs, and Rb are the most favored A/A′-cations in these promising perovskites. Moreover, I− overwhelmingly prevails as the dominant anion. Further experimental validation may uncover the true capabilities and practical applicability of these promising perovskites.