bluuebunny/crossref_metadata_2025 huggingface dataset:
Navigating epoxidation complexity: building a data science toolbox to design vanadium catalysts
Authors: Ferraz-Caetano José , Teixeira Filipe , Cordeiro M. Natália D. S.
Published: February 2024

This communication presents a novel approach to set up a machine learning-ready database for epoxidation reactions, focusing on vanadium catalysts.
Palladium-catalyzed domino cyclization/direct functionalization involving the insertion of SO2
Authors: Zhang Xinwei , Lu Yaoyao , Zhang Shuoshuo , Lin Shuizhen , Chen Mengting , Huang Xiaolei
Published: February 2024

A reductive cross-coupling strategy for the synthesis of sulfone-containing oxindoles was presented. Moreover, using amines instead of alkyl bromides, a palladium-catalyzed domino cyclization/aminosulfonylation was also established.
Insights into the mechanical stability of tetrahydrofuran hydrates from experimental, machine learning, and molecular dynamics perspectives
Authors: Lin Yanwen , Zhou Ziyue , Song Zixuan , Shi Qiao , Hao Yongchao , Fu Yuequn , Li Tong , Zhang Zhisen , Wu Jianyang
Published: February 2024

The multi-scale approaches including experimentation, MD simulations and ML models improve the understanding of hydrate mechanics and provide a predictive framework for estimating the mechanical properties of hydrates under complex conditions.
Synthesis of anti-depressant molecules via metal-catalyzed reactions: a review
Authors: Kanwal Aqsa , Afzal Uzma , Zubair Muhammad , Imran Muhammad , Rasool Nasir
Published: February 2024

Depression is one of the most mutilating conditions in the world today.
Enhancement in the dielectric and magnetic properties of Ni2+–Cu2+ co-doped BaFe11Cu1−xNixO19 hexaferrites (0.0 ≤ x ≤ 1.0)
Authors: Atif M. , Husnain H. Ul , Rehman Atta Ur , Younas U. , Rafique T. , Khalid W. , Ali Z. , Nadeem M.
Published: February 2024

The coexistence of considerably high dielectric and magnetic characteristics in BaFe11Cu1−xNixO19 hexaferrites with x = 1.0 make them attractive as microwave absorbers.
PtIrFeCoNiMo high-entropy alloy nanodendrites for boosting the alkaline hydrogen oxidation performance
Authors: Ma Xiaolong , Zhang Shuang , Zhou Yaojiang , Lei Wenli , Zhai Yueming , Zhao Yuanmeng , Shan Changsheng
Published: February 2024

PtIrFeCoNiMo HEA NDs show excellent alkaline HOR performance due to optimizing the HBE and OHBE by the synergistic high-entropy effect.
Constructing a multivalent Co-confined N-doped C–Si hybrid hollow nanoreactor for synchronous pollutant mineralization and solar-driven interfacial water regeneration
Authors: Zhu Hongyang , Du Rongrong , Zhao Hongyao , Liu Mengting , Wang Yanyun , Yu Chao , Guo Zengjing , Tang Sheng , Ang Edison Huixiang , Yang Fu
Published: February 2024

A multivalent Co-confined N-doped C–Si hybrid hollow nanoreactor was anchored onto a tailored sponge acting as a monolith bifunctional evaporator, which enables the synchronous pollutant mineralization and solar-driven interfacial water regeneration.
Light-driven rotary polypyrrole/agar composite films
Authors: Wang Dan , Hou Zhen , Wang Fengling , Zhang Hui , Jiang Jiwei , Dong Bin
Published: February 2024

We report light-driven rotary photoactuator films consisting of an agar and polypyrrole composite, which could achieve ultrafast rotation and sliding upon sunlight irradiation.
Simultaneous production of hydrogen and chlorine through overall brine splitting with a particulate photocatalyst
Authors: Okada Takumi , Kodera Masanori , Miseki Yugo , Kusama Hitoshi , Gunji Takahiro , Sayama Kazuhiro
Published: February 2024

Pt-loaded TiO2 was shown to split brine into H2 and Cl2 in a stoichiometric manner under UV irradiation in a flow-type reactor.
CRISPR/Cas systems combined with DNA nanostructures for biomedical applications
Authors: Sun Shujuan , Yang Haoqi , Wu Ziyong , Zhang Shusheng , Xu Jingjuan , Shi Pengfei
Published: February 2024

DNA nanostructures are easy to design and construct, have good biocompatibility, and show great potential in biosensing and drug delivery when combined with CRISPR/Cas systems.
Correction: The route for commercial photoelectrochemical water splitting: a review of large-area devices and key upscaling challenges
Authors: Vilanova António , Dias Paula , Lopes Tânia , Mendes Adélio
Published: February 2024

Correction for ‘The route for commercial photoelectrochemical water splitting: a review of large-area devices and key upscaling challenges’ by António Vilanova et al., Chem. Soc. Rev., 2024, https://doi.org/10.1039/d1cs01069g.
Synthesis of monolayer SiP via chemical vapor transport toward superior optoelectronic and catalytic performance
Authors: Yu Tong , Qiu Hailong , Liu Hongjun , Hu Zhanggui , Wu Yicheng
Published: February 2024

Single-layer SiP crystals with excellent photoelectric detection and hydrogen evolution reaction properties were synthesized by the one-step CVT method.
Regioselective electrochemical cascade C–H sulfonylation–bromination of indolizines to access difunctionalized indolizines
Authors: Jiang Wenxuan , Liu Xiang , Zhu Chuanying , Chen Meiyi , Li Weidan , Cao Hua
Published: February 2024

Regioselective electrochemical C–H sulfonylation–bromination between indolizines, sodium sulfinates, and KBr has been established in an undivided cell, in which KBr serves as both the brominating agent and electrolyte.
Preparation of bio-based porous material with high oil adsorption capacity from bio-polyurethane and sugarcane bagasse
Authors: Cuong Thai Dinh , Dien Le Quang , Hoang Phan Huy
Published: February 2024

A sugarcane bagasse-polyurethane composite (SC-PU composite) with highly efficient removal of oil from an oil/water system was fabricated by inserting sugarcane fiber filler into a bio-based PU matrix.
Langmuir–Blodgett assisted alignment of 2D nanosheets in polymer nanocomposites for high-temperature dielectric energy storage applications
Authors: Yu Cong , Wang Jian , Yan Jingjing , Xia Jianlong , Zhang Xin
Published: February 2024

The Langmuir–Blodgett deposition technique enables a precise in-plane alignment and a densely packed arrangement of CNO nanosheets within the PEI matrix, resulting in a significant enhancement of energy storage performance at 150 °C.
A target defence‐intrusion game with considering the obstructive effect of target
Authors: Wang Keyang , Zhou Shaobo , Yao Yao , Sun Qi , Wang Yintao
Published: February 2024

This paper considers the problem of a defender agent to guard the target area being attacked by a hostile agent. There are two different agents‐intruder and defender here. The purpose of the defender is to prevent the intruder from approaching the target and if possible, catch the intruder. As the guardian object of the defender, the target area also obstructs its free movement. Therefore, a new geometric method is proposed to solve the problem. Firstly, the winning zones are constructed for the agents using two different methods. When the defender's initial position is in the defender's winning zone, the defender can capture the intruder. When the initial position of the defender is in the winning zone of the intruder, the intruder can successfully attack the target. Subsequently, a method is proposed for determining the dominance region boundary under the influence of target obstruction. Also, the winner can be ascertained by observing whether the dominance region boundary intersects the target area. The optimal strategy is then given according to the different payoff functions. Finally, some examples show the effectiveness of the method. In addition, the conditions and limitations for applying this method to other convex targets are provided.
Adaptive total energy shaping of a class of manipulators
Authors: Harandi M. Reza J. , Taghirad Hamid D.
Published: February 2024

Point‐to‐point control of underactuated mechanical systems is a challenging problem, especially if some of the system's parameters are uncertain. A popular method to stabilize underactuated manipulators is total energy shaping, in which a new Hamiltonian function is assigned to the closed‐loop system while a set of partial differential equations (PDEs) should be solved. In this study, an adaptive total energy shaping controller based on the approach called interconnection and damping assignment passivity‐based control (IDA‐PBC) for some underactuated robots is designed. The proposed method can overcome uncertainties in the dynamical parameters and also the parameters of the input mapping matrix under the satisfaction of the PDEs. The stability of the desired pose is ensured by the Lyapunov approach via suitable design of adaptation laws without the requirement for the persistence of excitation condition or other similar conditions. The results are applied to a 3‐DOF underactuated manipulator and verified by simulations.
Gaia’s brightest very metal-poor (VMP) stars
Authors: Viswanathan Akshara , Starkenburg Else , Matsuno Tadafumi , Venn Kim A. , Martin Nicolas F. , Longeard Nicolas , Ardern-Arentsen Anke , Carlberg Raymond G. , Fabbro Sébastien , Kordopatis Georges , Montelius Martin , Sestito Federico , Yuan Zhen
Published: February 2024

Context. Gaia DR3 has offered the scientific community a remarkable dataset of approximately one million spectra acquired with the radial velocity spectrometer (RVS) in the calcium II triplet region, which is well suited to identify very metal-poor (VMP) stars. However, over 40% of these spectra have no released parameters by Gaia’s GSP-Spec pipeline in the domain of VMP stars, whereas VMP stars are key tracers of early Galactic evolution.

Aims. We aim to provide spectroscopic metallicities for VMP stars using Gaia RVS spectra, thereby producing a catalogue of bright VMP stars distributed over the full sky that can serve as the basis for studies of early chemical evolution throughout the Galaxy.

Methods. We selected VMP stars using photometric metallicities from the literature and analysed the Gaia RVS spectra to infer spectroscopic metallicities for these stars.

Results. The inferred metallicities agree very well with literature high-resolution metallicities, with a median systematic offset of 0.1 dex and standard deviation of ∼0.15 dex. The purity of this sample in the VMP regime is ∼80%, with outliers representing a mere ∼3%.

Conclusions. We have built an all-sky catalogue of ∼1500 stars available, featuring reliable spectroscopic metallicities down to [Fe/H] ∼ −4.0, of which ∼1000 are VMP stars. More than 75% of these stars have either no spectroscopic metallicity value in the literature to date or have been flagged as unreliable in their literature spectroscopic metallicity estimates. This catalogue of bright (G <  13) VMP stars is three times larger than the current sample of well-studied VMP stars in the literature in this magnitude range, making it ideal for high-resolution spectroscopic follow-ups and studies of the properties of VMP stars in different parts of our Galaxy.
Prediction model for sandstone strength based on Weibull distribution of micro-element strength and power-law distribution of crack length
Authors: SHI Hao , ZHANG Houquan , WU Jiangyu , SONG Lei , LI Ming , RONG Chuanxin , LU Pengju
Published: February 2024

It is of the great significance to construct the strength prediction model that considers the influence of the macro and micro defects in the rock in an overall manner to ensure the construction of smart mines and the safety of underground personnel and equipment. Based on the Weibull distribution of rock micro-element strength and the power-law distribution of crack length and the discrete element calculation model, the prediction model for strength of damaged rock specimens were established by numerical simulation and theoretical derivation respectively. Then the rationality of the model was verified by the calculated results. The results show that: 1) The weibull distribution of the micro-element strength and the power-law distribution of the crack length in the PFC2D calculation model are realized by programming, and the quantitative corresponding relationship between the macro, micro and micro damage in the rock and the corresponding distribution parameters is analyzed. 2) 400 sandstone specimens with macro, micro and micro damage are numerically established and loaded to achieve statistical analysis of the relationship between micro element strength, pre-crack information and rock strength. According to the simulation results, the four-dimensional space scatter points of uniaxial compressive strength of sandstone specimens are constructed, and the flow law of compressive strength of sandstone specimens under the influence of multiple damage parameters is obtained. 3) Combined with Mori Tanaka method and rock damage probability distribution theory, a 12 parameter rock strength prediction model is established. The model can both describe the influence of the micro-element strength and macroscopic crack information on the rock strength, and the model calculation results are highly consistent with the simulated results, with the correlation coefficient up to 0.991.
Application of covariance analysis method in design of modulated inertial navigation systems
Authors: GUAN Bofan , HU Wei , LI Sihai , YANG Xiaokang , LI Chirong
Published: February 2024

Error analysis of inertial navigation systems is one of the important tasks in inertial navigation research. Through error analysis, the contribution of each error in the system to the total error can be obtained. This work is particularly important in the rotary modulation inertial navigation system, because it is necessary to evaluate the suppression effect of the rotation strategy on various error sources through error analysis. Firstly, a state space model of the error has been established based on the system error model, and the total navigation error is divided into linear combinations of various error factors through recursion and decomposition. The derived covariance update equation can be used to quickly and accurately obtain the contribution of various errors including initial error and device error to the total system error. Simulation results of strapdown, single-axis and two-axis modulation systems verifies that the error propagation rules calculated by the proposed method are in agreement with the known conclusions. Simulation of different modulation strategies shows that the proposed method is fast and intuitive in evaluating rotation strategies.
Evaluating the suppression of Hydrilla verticillata by manual removal and planting natives for small-scale restoration efforts in a spring-fed river
Authors: Maroti Angela , Hutchinson Jeffrey T.
Published: February 2024

Hydrilla (Hydrilla verticillata) is an invasive aquatic macrophyte found on every continent except Antarctica. Due to the high number of federally listed species in the San Marcos River, Texas, management options for hydrilla are limited. We examined the ability of the two native macrophytes to suppress hydrilla in plots where 0 to 100% hydrilla was removed. In plots where 100% hydrilla was removed, Texas wild rice exhibited equal or greater coverage to hydrilla. Hydrilla was present in 100% of the plots at the end of the study, regardless of percent removal, while Texas wild rice (Zizania texana) and water stargrass (Heteranthera dubia) were present in 50 and 42% of the plots, respectively. While the overall survival percentage in plots was 50% for Texas wild rice, the mean root and shoot dry weights were significantly greater than hydrilla which occurred in all plots. However, hydrilla coverage was among the highest in plots where 100% of the hydrilla was removed at the start of the study, indicating its ability to quickly invade disturbed sites. The study results indicate morphological differences with hydrilla allocating greater biomass into its shoots while Texas wild rice allocates equal amounts of biomass into its shoots and roots.
Host shift to non-native species or ecological dead end? Endangered branchiobdellidans (Annelida: Clitellata) found on introduced Signal Crayfish in Japan
Authors: Konno Tomoaki , Tanaka Kazunori , Koizumi Itsuro
Published: February 2024

Symbionts, including parasites, are usually small and thus have been overlooked for their existence and scientific research. In the context of biological invasion, host shifts between native and non-native species occur. Since symbionts often affect host behaviour and survival, it is important to reveal the cryptic invasions and host shifts of such small symbionts. Here, we report the first evidence of the potential host shift of a native endangered branchiobdellidans, ectosymbiotic crayfish worms, to a non-native Signal Crayfish, Pacifastacus leniusculus (Dana 1852), in Hokkaido, Japan. Pacifastacus leniusculus is native to North America and was recently introduced to the Atsubetsu River system in Sapporo. In addition to the North American ectosymbiont, Sathodrilus tetrodonta (Pierantoni, 1906), we found an endangered Japanese species, Cirrodrilus cirratus complex on P. leniusculus. However, C. cirratus complex as well as S. tetrodonta were not found on the native Japanese Crayfish, Cambaroides japonicus (De Haan, 1841), in the same river system, indicating a host shift of the ectosymbiont to invasive crayfish. It remains unclear whether C. cirratus complex will persist for a long time with the non-native host or if this is only a transient leading to local extinction.
SATB2-associated syndrome: a case report
Authors: Issad Mehdi , Ahossi Victorin , Melli Emma , Hoarau David
Published: February 2024

Introduction: SATB2-associated syndrome is an extremely rare genetic disorder. It is characterized by delayed neurocognitive development, craniofacial anomalies and dental defects. Observation: This case report highlights the craniofacial and dental phenotype linked to a mutation resulting in SATB2-associated syndrome affecting a 13-year-old boy. Conclusion: The diagnosis of this syndrome is very difficult. The management using a multidisciplinary strategy includes among others, oral hygiene maintenance, orthodontic treatment and intensive speech therapy.
Developing an alternative crossbar material from jute/E-glass fiber hybrid reinforced polymer matrix composite
Authors: Gadisa Dejene Girma , Tesfay Abrha Gebregergs
Published: February 2024

Over the last three decades, the use of hybrid reinforced fiber composite materials for structural applications has increased. Minimizing the weight of vehicle components has been considered an important solution for improving fuel economy, increasing technical benefits, and reducing harmful emissions. This study used jute and E-glass fiber with a polyester matrix to develop the hybrid composite. Hand layups were employed for sample preparation of 40% fiber and 60% of the polyester matrix with four different stacking sequences. The mechanical property and water absorption test were influenced by fiber stacking sequences and jute fiber treatment. In this investigation, the result shows that the hybrid G-J-J-G hybrid of NaOH-treated jute fiber exhibited higher strength than a hybrid containing jute fiber at their outer layer and a hybrid of the same stacking sequence with untreated jute fibers. A hybrid with a G-J-J-G arrangement was used to develop alternative crossbar members by size optimization with a genetic algorithm. The sizing optimization of crossbar member results shows that the weight of the hybrid composite crossbar can be reduced by 46.47%, from 9.765 kg to 5.227 kg per single component of crossbar member, and comparatively, an average of 0.00544 L per 100 km of fuel was enabled to be saved. Thus, jute/E-glass hybrid reinforced polyester composite can effectively be an alternative to the current steel structure without compromising their application.
Konsum von Tabakzigaretten, E-Zigaretten und Wasserpfeifen bei Kindern und Jugendlichen. Ergebnisse des Präventionsradars von 2016 bis 2023
Authors: Hanewinkel Reiner , Hansen Julia
Published: February 2024

Fragestellung Trends der Nutzung verschiedener Rauchprodukte im Kindes- und Jugendalter von 2016–2023 sollen abgebildet werden.

Methode Datengrundlage bilden sieben Wellen des Präventionsradars, einer schulbasierten epidemiologischen Studie in den Klassenstufen 5–10. Primäre Endpunkte der Untersuchung waren die Lebenszeit- und die Monatsprävalenz des Konsums von Tabakzigaretten, E-Zigaretten, Wasserpfeifen sowie des Konsums von mindestens zwei dieser Rauchprodukte (kombinierter Konsum). Prävalenzschätzungen basieren auf logistischen Regressionsmodellen.

Ergebnisse Der Auswertung liegen 94.127 Fragebögen zugrunde. Das Geschlechtsverhältnis war ausgewogen (49% weiblich), das mittlere Alter betrug 13 Jahre (SD=1,8). 2022/2023 betrug die Lebenszeitprävalenz des Rauchens von Tabakzigaretten 18,8% (95%-KI 18,1–19,5), von E-Zigaretten 23,5% (95%-KI 22,8–24,3), von Wasserpfeifen 14,0% (95%-KI 13,4–14,7) und des kombinierten Konsums 19,0% (95%-KI 18,3–19,7). Die Monatsprävalenz des Rauchens von Tabakzigaretten betrug 5,9% (95%-KI 5,5–6,4), von E-Zigaretten 7,0% (95%-KI 6,5–7,4), von Wasserpfeifen 3,2% (95%-KI 2,8–3,5) und des kombinierten Konsums 4,8% (95%-KI 4,4–5,2). Seit 2016 zeichnen sich folgende Trends im Hinblick auf die Lebenszeitprävalenz ab: Tabakzigaretten (–3,0 Prozentpunkte), E-Zigaretten (+1,8 Prozentpunkte), Wasserpfeifen (–9,2 Prozentpunkte), kombinierter Konsum (–2,7 Prozentpunkte). In den Jahren der COVID-19-Pandemie rauchten weniger Jugendliche. Post-COVID stiegen die Prävalenzen mit Ausnahme der Wasserpfeife wieder an.

Diskussion Der Konsum von Rauchprodukten im Jugendalter tritt häufig auf. Über den Beobachtungszeitraum deutet sich eine Trendumkehr hin zur E-Zigarette als populärstem Produkt bei Kindern und Jugendlichen an. Zudem hat sich der kombinierte Konsum mehrerer Rauchprodukte als häufiges Konsummuster verfestigt. Konsequente verhältnis- und verhaltenspräventive Maßnahmen sind erforderlich, um das Ziel einer rauchfreien Gesellschaft im Jahr 2040 noch erreichen zu können.
Perivascular spaces and where to find them – MR imaging and evaluation methods
Authors: Seehafer Svea , Larsen Naomi , Aludin Schekeb , Jansen Olav , Schmill Lars-Patrick Andreas
Published: February 2024

Background Perivascular spaces (synonym: Virchow-Robin spaces) were first described over 150 years ago. They are defined as the fluid-filled spaces surrounding the small penetrating cerebral vessels. They gained growing scientific interest especially with the postulation of the so-called glymphatic system and their possible role in neurodegenerative and neuroinflammatory diseases.

Methods PubMed was used for a systematic search with a focus on literature regarding MRI imaging and evaluation methods of perivascular spaces. Studies on human in-vivo imaging were included with a focus on studies involving healthy populations. No time frame was set. The nomenclature in the literature is very heterogeneous with terms like “large”, “dilated”, “enlarged” perivascular spaces whereas borders and definitions often remain unclear. This work generally talks about perivascular spaces.

Results This review article discusses the morphologic MRI characteristics in different sequences. With the continual improvement of image quality, more and tinier structures can be depicted in detail. Visual analysis and semi or fully automated segmentation methods are briefly discussed.

Conclusion If they are looked for, perivascular spaces are apparent in basically every cranial MRI examination. Their physiologic or pathologic value is still under debate.

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Citation Format
Improving the use of LLMs in radiology through prompt engineering: from precision prompts to zero-shot learning
Authors: Russe Maximilian Frederik , Reisert Marco , Bamberg Fabian , Rau Alexander
Published: February 2024

Purpose Large language models (LLMs) such as ChatGPT have shown significant potential in radiology. Their effectiveness often depends on prompt engineering, which optimizes the interaction with the chatbot for accurate results. Here, we highlight the critical role of prompt engineering in tailoring the LLMs’ responses to specific medical tasks.

Materials and Methods Using a clinical case, we elucidate different prompting strategies to adapt the LLM ChatGPT using GPT4 to new tasks without additional training of the base model. These approaches range from precision prompts to advanced in-context methods such as few-shot and zero-shot learning. Additionally, the significance of embeddings, which serve as a data representation technique, is discussed.

Results Prompt engineering substantially improved and focused the chatbot’s output. Moreover, embedding of specialized knowledge allows for more transparent insight into the model’s decision-making and thus enhances trust.

Conclusion Despite certain challenges, prompt engineering plays a pivotal role in harnessing the potential of LLMs for specialized tasks in the medical domain, particularly radiology. As LLMs continue to evolve, techniques like few-shot learning, zero-shot learning, and embedding-based retrieval mechanisms will become indispensable in delivering tailored outputs.

Key Points 

Citation Format
Stereochemical Aspects of the C-Glycosylation of Pyranosides and Furanosides
Authors: Achanta Srinivas , Bandichhor Rakeshwar , Sasikala Ch. V. A. , Basu Debjit , Nahide Pradip D.
Published: February 2024

The stereoselective synthesis of α- and β-C-glycosides is one of the most challenging areas of research in the field of glycoside chemistry. In this review, we summarize the various methods available for stereocontrolled glycosylation and also discuss the predictive models available to explain the stereochemical outcome of six- and five-membered-ring oxocarbenium ions with allyltrimethylsilane nucleophile under Lewis acid conditions.

1 Introduction

2 Stereochemical Aspects during Glycoside Bond Formation in Pyranosides

2.1 Lewis Acid Mediated Nucleophilic Addition to Six-Membered-Ring Oxocarbenium Ions

2.2 Arylalane Addition to Anhydroglucose

2.3 Glucal Epoxide Method

2.4 Glycosyl Leaving Group Substitution Method

2.5 Glycosylation via Transition-Metal-Mediated Cross-Coupling

3 Stereochemical Aspects during Glycoside Bond Formation in Furanosides­

3.1 Lewis Acid Mediated Nucleophilic Addition to Five-Membered-Ring Oxocarbenium Ions

4 Summary and Conclusion
Assessing the effect of urban digital infrastructure on green innovation: mechanism identification and spatial-temporal characteristics
Authors: Li Chengming , Wen Meiyu , Jiang Shaoxiang , Wang Huaxing
Published: February 2024

Under the background of digitization and greening in China, digital infrastructure offers new opportunities for developing green innovation. This paper investigates the effect of digital infrastructure on urban green innovation using panel data from 285 Chinese prefecture-level cities between 2011 and 2020, and explains the mechanism and its spatial-temporal dynamic effect. The results demonstrate that digital infrastructure promotes urban green innovation. Talent agglomeration, R&D investment increase, and industrial structure upgrading are crucial channels. Furthermore, depending on a city’s size, human capital, environmental regulations, and financial subsidies, digital infrastructure contributes to urban green innovation differently. Also, there is not only a positive spatial spillover effect of digital infrastructure but a threshold effect that presents a nonlinear trend of rising marginal effect. This study provides a new perspective for promoting digital infrastructure and urban green innovation, which makes a difference in facilitating its high-level development collaboratively.
The effect of caring ethical climate on employees’ knowledge-hiding behavior: evidence from Chinese construction firms
Authors: Chen Zhen , Tang Zixin
Published: February 2024

This research aims to explore the influencing mechanism of a caring ethical climate on knowledge-hiding behavior in large construction firms according to the reciprocity principle of social exchange theory. This is an empirical study based on the analysis of survey data collected from 413 employees working in large construction firms in China. Hierarchical regression is applied to test the research model. This research finds: (1) Caring ethical climate has a negative influence on knowledge-hiding behavior; (2) Caring ethical climate has a positive influence on psychological contract; (3) Psychological contract has a negative influence on knowledge-hiding behavior; (4) Psychological contract mediates the relationship between caring ethical climate and knowledge-hiding behavior; (5) Task interdependence positively moderates the relationship between psychological contract and knowledge-hiding behavior. Based on the social exchange theory, this study provides significant contributions to the theory and practice of knowledge management in large construction firms by highlighting the influence of a caring ethical climate on knowledge hiding among employees. This paper provides suggestions for reducing knowledge hiding and enhancing knowledge sharing among employees in large construction firms, so as to improve the knowledge management ability of large construction firms and enhance their competitive advantages.
A pressure-free long-time stable reduced-order model for two-dimensional Rayleigh–Bénard convection
Authors: Chand K. , Rosenberger H. , Sanderse B.
Published: February 2024

The present work presents a stable proper orthogonal decomposition (POD)-Galerkin based reduced-order model (ROM) for two-dimensional Rayleigh–Bénard convection in a square geometry for three Rayleigh numbers: 104 (steady state), 3×105 (periodic), and 6×106 (chaotic). Stability is obtained through a particular (staggered-grid) full-order model (FOM) discretization that leads to a ROM that is pressure-free and has skew-symmetric (energy-conserving) convective terms. This yields long-time stable solutions without requiring stabilizing mechanisms, even outside the training data range. The ROM’s stability is validated for the different test cases by investigating the Nusselt and Reynolds number time series and the mean and variance of the vertical temperature profile. In general, these quantities converge to the FOM when increasing the number of modes, and turn out to be a good measure of accuracy. However, for the chaotic case, convergence with increasing numbers of modes is relatively difficult and a high number of modes is required to resolve the low-energy structures that are important for the global dynamics.
Superparamagnetic properties of metal-free nitrogen-doped graphene quantum dots
Authors: Sultan Muhammad Shehzad , Makarov Vladimir I. , Mendoza Frank , Sajjad Muhammad , Barrionuevo Diestra Danilo G. , Inbanathan Flavia P. N. , Skelton Eli , Premadasa Uvinduni I. , Cimatu Katherine Leslee A. , Habiba Khaled , Jadwisienczak Wojciech M. , Weiner Brad R. , Morell Gerardo
Published: February 2024

This article reports the superparamagnetic behavior of metal-free nitrogen-doped graphene quantum dots (N-GQDs). The pulsed laser ablation (PLA) method was utilized to synthesize N-GQDs with an average diameter of 3.45 nm and a high doping level (N/C) of 1.4. Magnetic properties of as-synthesized N-GQDs were explored by performing magnetization vs magnetic field (M–H) and magnetization vs temperature (M–T) measurements. M–H plots measured in a temperature range of 2–300 K revealed the superparamagnetic behavior of N-GQDs. The value of saturation magnetization was found to be directly correlated to nitrogen concentration and a saturation magnetization up to 28.7 emu/g was obtained at room temperature (300 K). M–T measurements with zero-field-cooled (ZFC) and field-cooled (FC) conditions were employed to study anisotropy energy barriers and blocking temperature. A variation in the blocking temperature (TB) from 288 to 61 K was observed when the external magnetic field (H) was changed from 0.1 to 0.6 T. The origin of superparamagnetism was attributed to the presence of graphitic nitrogen bonding configuration and defect states. The observed superparamagnetic properties along with the optical properties of N-GQDs create an opportunity for developing materials for biomedical applications and data recording devices.
Tracking dynamo mechanisms from local energy transfers: Application to the von Kármán sodium dynamo
Authors: Creff M. , Faller H. , Dubrulle B. , Guermond J.-L. , Nore C.
Published: February 2024

Motivated by the observation that dynamo is a conversion mechanism between kinetic and magnetic energy, we develop a new approach to unravel dynamo mechanism based on local (in space, scale, and time) energy budget describing dissipation and scale-by-scale energy transfers. Our approach is based upon a new filtering approach that can be used effectively for any type of meshes, including unstructured ones. The corresponding formalism is very general and applies to any geometry or boundary conditions. We further discuss the interpretation of these energy transfers in the context of fast dynamo and anomalous dissipation. We apply it to the results from direct numerical simulations of the von Kármán Sodium setup (referred to as VKS) using a finite element code, showing dynamo action for two types of impellers (steel or soft iron) in the magnetic field growth and saturation phases. Although the two types of dynamo hardly differ from the mean-field theory point of view (the velocity fields are the same in both cases), the locality of our formalism allows us to trace the origin of the differences between these two types of dynamo: for steel impellers, the dynamo is due to the transfer of velocity energy both in the bulk and in the vicinity of the impellers, whereas for soft iron impellers, the dynamo effect mainly comes from the rotation of the blades. We finally discuss possible signatures of precursors to anomalous dissipation and fast dynamo, which could become relevant in the inviscid limit.
A sequency match filtering algorithm based on the generalized Walsh transform for processing rectangular wave signals
Authors: Li Bin , Zhang Sheng-Nan , Chen Jie , Zhao Wang-Cheng
Published: February 2024

The conventional Walsh function just takes values of +1 and −1 and can only track limited signal states. However, based on the characteristics of Walsh functions that can capture the frequency of square wave signals, this article proposes a generalized Walsh transform algorithm to process multi-valued rectangular wave signals. As an extension of the traditional Walsh functions, generalized Walsh functions have advantages in signal frequency matching and sequency spectrum amplitude extraction, which makes them well suited to express the valuable signal. First, we infer the invariance displacement theory in the time and sequency domains, limiting the value of a circular time shift to ensure the concentrated distribution of the signal sequency energy. This limitation lays a good foundation for constructing generalized Walsh functions. Then, two types of generalized Walsh functions are built by combining the characteristics of different periodic rectangular waves. We deduce two properties of orthogonality and completeness to prove the ability of the constructed functions to match the frequency and the extracted energy. Finally, we compare multiple filtering methods to verify the reliability of the proposed method.
A grid-independent dispersion approach for large-eddy simulation of spray
Authors: Shao Shujing , Lu Hao , Wang Zhaowen , Cheng Xiaobei
Published: February 2024

This study proposes a subgrid-scale (SGS) dispersion approach for large-eddy simulation (LES) of spray. Rather than associating the turbulence correlation timescale used in the dispersion approach with the computational grid, we put forward an approximation of this timescale proportional to the Kolmogorov timescale. The Kolmogorov scale kinetic energy is added to the variance of the stochastic part of the SGS dispersion velocity to account for the effects of micro-scale flows on droplets. The proposed approach supports the notion of grid-independent LES and is illustrated for two benchmark Engine Combustion Network's Spray-A cases, including a vaporizing spray case and a non-vaporizing spray case. We investigate the performance of the approach in LESs of two cases by comparing it with other dispersion approaches. In particular, the investigation mainly covers spray structures, vapor and liquid penetrations, and mass fraction profiles. Results obtained using the proposed approach shows the statistics of the simulated spray cases that exhibit both good agreement with measurements and a noticeable improvement over simulations based on other tested approaches. The approach also yields more consistent results under different grid resolutions, which shows its ability to achieve LESs in non-uniform grids.
Experimental and numerical study of different wing number and flapping-rotation decomposition of a flapping wing rotor unmanned aerial vehicle
Authors: Wang Ziyu , Kan Zi , Li Huadong , Zhao Shiwei , Li Daochun , Xiang Jinwu
Published: February 2024

The flapping wing rotor (FWR) is a novel aerial vehicle that combines the aerodynamic benefits of both a flapping wing and a rotary wing. By utilizing the passive rotation effect resulting from the flexible deformation of the center symmetric flapping wing, the FWR can enhance its lift force. However, previous research has neglected to explore the mechanism behind the flapping-rotation motion of a flyable FWR, which elucidates its lift advantage compared to conventional flapping motion. Additionally, the impact of varying wing number on the flapping-rotation motion and performance of the FWR has not been taken into consideration. Therefore, it is imperative to conduct an experimental analysis to ascertain the impact of flapping-rotation decomposition and varying wing quantities on FWR. In this study, our prior vehicle design, which exhibited consistent stable hovering and maneuvering capabilities, is employed to construct the flapping wing rotor experiment system. Through this unique experimental system, the effects of flapping-rotation decomposition and different wing quantities on FWR are individually investigated. Additionally, computational fluid dynamics simulation is utilized as an auxiliary and supplementary approach to analyze the aerodynamic characteristics of the flapping-rotation motion. The result proves that the stable flapping-rotation motion does produce a more significant lift increase than the normal flapping motions. Under the premise of stable flapping-rotation motion, more wings will not only produce more lift but also require more driving power. The interactions between the wings also affect the flapping-rotation motion.
An efficient discrete unified gas-kinetic scheme for compressible thermal flows
Authors: Wen Xin , Wang Lian-Ping , Guo Zhaoli
Published: February 2024

In this paper, an efficient discrete unified gas-kinetic scheme (DUGKS) is developed for compressible thermal flows based on the total energy kinetic model for natural convection with a large relative temperature difference. A double distribution function model is designed with the second distribution representing the total energy. This efficient DUGKS enables the simulation of compressible thermal flows, governed by the compressible Navier–Stokes–Fourier system, using only a seventh-order, off-lattice Gauss–Hermite quadrature (GHQ) D3V27A7 combined with a fifth-order GHQ D3V13A5. The external force is included by truncated Hermite expansions. Based on the Chapman–Enskog approximation and Hermite projection, we propose a systematic approach to derive the discrete kinetic boundary conditions for the density and total energy distribution functions. The discrete kinetic boundary treatments are provided for the no-slip boundary condition, Dirichlet boundary condition and Neumann boundary condition. To validate our scheme, we perform simulations of steady natural convection (Ra=103−106) in two- and three-dimensional cavities with differentially heated sidewalls and a large temperature difference (ε=0.6), where the Oberbeck–Boussinesq approximation is invalid. The results demonstrate that the current efficient DUGKS is robust and accurate for thermal compressible flow simulations. With the D3V27A7 and D3V13A5 off-lattice discrete particle velocity model, the computational efficiency of the DUGKS is improved by a factor of 3.09 when compared to the previous partial energy kinetic model requiring the ninth-order Gauss–Hermite quadrature.
Characterization and evolution of local streamline geometry in an incompressible turbulent channel flow
Authors: Wu Geyi , Xu Chunxiao
Published: February 2024

We investigated the statistical characterization and time evolution of local streamline geometry in typical regions of an incompressible turbulent channel flow at the friction Reynolds number Reτ∼1000. Local streamline structure is completely and uniquely determined by one magnitude factor—the magnitude of velocity gradient tensor (VGT) A—and four shape parameters—the second and third invariants of normalized VGT q and r, the intermediate eigenvalue of normalized strain-rate tensor a2, and the cosine of the angle between vorticity and the intermediate eigendirection of normalized strain-rate tensor | cos β|. As the distance to the wall decreases, the joint probability distribution function of q and r becomes more symmetrical and concentrated, while outside the viscous sublayer, the distribution of A in q–r plane gets dispersed. Interestingly, the inertial conditional mean trajectories (CMTs) exhibit a symmetrical picture only in the buffer layer, and outside the viscous sublayer, the pressure CMTs contributing to slow evolution from unstable focus compression geometry to stable focus stretching geometry tend to dominate the q–r plane as getting closer to the wall. Due to combined effects of inertia and pressure, the origin of the q–r plane (pure-shear geometry) acts as an attractor in the central region, the logarithmic region, and the upper part of the buffer layer while acts as a repeller in the lower part of the buffer layer and the viscous sublayer.
Integration method of compressed sensing with variational mode decomposition based on gray wolf optimization and its denoising effect in mud pulse signal
Authors: Yan Zhidan , Jiao Le , Sun Hehui , Sun Ruirui , Zhang Junzhuang
Published: February 2024

The continuous wave mud pulse transmission holds great promise for the future of downhole data communication. However, significant noise interference during the transmission process poses a formidable challenge for decoding. In particular, effectively eliminating random noise with a substantial amplitude that overlaps with the pulse signal spectrum has long been a complex issue. To address this, an enhanced integration algorithm that merges variational mode decomposition (VMD) and compressed sensing (CS) to suppress high-intensity random noise is proposed in this paper. In response to the inadequacy of manually preset parameters in VMD, which often leads to suboptimal decomposition outcomes, the gray wolf optimization algorithm is designed to obtain the optimal penalty factor and decomposition mode number in VMD. Subsequently, the optimized parameter combination decomposes the signal into a series of intrinsic modes. The mode exhibiting a stronger correlation with the original signal is retained to enhance signal sparsity, thereby fulfilling the prerequisite for compressed sensing. The signal is then observed and reconstructed using the compressed sensing method to yield the final signal. The proposed algorithm has been compared with VMD, CS, and CEEMD; the results demonstrate that the method can enhance the signal–noise ratio by up to ∼20.55 dB. Furthermore, it yields higher correlation coefficients and smaller mean square errors. Moreover, the experimental results using real field data show that the useful pulse waveforms can be recognized effectively, assisting surface workers in acquiring precise downhole information, enhancing drilling efficiency, and significantly reducing the risk of engineering accidents.
Many-body theory calculations of positronic-bonded molecular dianions
Authors: Cassidy J. P. , Hofierka J. , Cunningham B. , Green D. G.
Published: February 2024

The energetic stability of positron–dianion systems [A−; e+; A−] is studied via many-body theory, where A− includes H−, F−, Cl−, and the molecular anions (CN)− and (NCO)−. Specifically, the energy of the system as a function of ionic separation is determined by solving the Dyson equation for the positron in the field of the two anions using a positron–anion self-energy as constructed in Hofierka et al. [Nature 606, 688 (2022)] that accounts for correlations, including polarization, screening, and virtual-positronium formation. Calculations are performed for a positron interacting with H22−, F22−, and Cl22− and are found to be in good agreement with previous theory. In particular, we confirm the presence of two minima in the potential energy of the [H−; e+; H−] system with respect to ionic separation: a positronically bonded [H−; e+; H−] local minimum at ionic separations r ∼ 3.4 Å and a global minimum at smaller ionic separations r ≲ 1.6 Å that gives overall instability of the system with respect to dissociation into a H2 molecule and a positronium negative ion, Ps−. The first predictions are made for positronic bonding in dianions consisting of molecular anionic fragments, specifically for (CN)22− and (NCO)22−. In all cases, we find that the molecules formed by the creation of a positronic bond are stable relative to dissociation into A− and e+A− (positron bound to a single anion), with bond energies on the order of 1 eV and bond lengths on the order of several ångstroms.
Revealing defect centers in PbWO4 single crystals using thermally stimulated current measurements
Authors: Isik M. , Gasanly N. M.
Published: February 2024

The trap centers have a significant impact on the electronic properties of lead tungstate (PbWO4), suggesting their crucial role in optoelectronic applications. In the present study, we investigated and revealed the presence of shallow trap centers in PbWO4 crystals through the utilization of the thermally stimulated current (TSC) method. TSC experiments were performed in the 10–280 K range by applying a constant heating rate. The TSC spectrum showed the presence of a total of four peaks, two of which were overlapped. As a result of analyzing the TSC spectrum using the curve fit method, the activation energies of revealed centers were found as 0.03, 0.11, 0.16, and 0.35 eV. The trapping centers were associated with hole centers according to the comparison of TSC peak intensities recorded by illuminating the opposite polarity contacts. Our findings not only contribute to the fundamental understanding of the charge transport mechanisms in PbWO4 crystals but also hold great promise for enhancing their optoelectronic device performance. The identification and characterization of these shallow trap centers provide valuable insights for optimizing the design and fabrication of future optoelectronic devices based on PbWO4.
Unusual anomalous Hall effect in SrRuO3 films with linear out-of-plane Ru vacancies gradient
Authors: Luo Yanli , Huang Haoliang , Zhang Jian , Wang Lenan , Shan Zheling , Zhu Mo , Gong Nanqi , Huang Jun , Cui Zhangzhang , Wang Jianlin , Huang Qiuping , Fu Zhengping , Lu Yalin
Published: February 2024

The manipulation of magnetic transport properties has been one of the central problems in spintronics. However, the modulation of Hall signals in thin films has stringent requirements on their thickness and means of growth. Here, a series of inhomogeneous SrRuO3 thin films with different paths of linear out-of-plane Ru vacancies gradient was designed to generate an unusual anomalous Hall effect (UAHE) under broad growth conditions. Combining x-ray diffraction and magnetic data, it was concluded that the appearance of UAHE was not a simple superposition of AHE caused by multiple magnetic phases. The interaction between these magnetic phases in the linear-vacancies-gradient SrRuO3 films was analyzed by the first-order reversal curve (FORC) method, and it was found that the change trend of FORC was the same as that of UAHE. Such out-of-plane linear-vacancies-gradient thin film provides a way to regulate the different phases by introducing the cation vacancies distribution in an orderly way to control their magnetic and transport properties in oxide films. Furthermore, a distinctive perspective on the origin of UAHE was obtained by combining FORC with UAHE.