bluuebunny/crossref_metadata_2025 huggingface dataset:
Reform and Practice of Hybrid Teaching Mode in Econometrics Course Based on OBE+SPOC
Authors: Wu Yan
Published: December 2023

This paper presents a study of the hybrid teaching mode for the Econometrics course based on Outcomes Based Education (OBE) and Small Private Online Courses (SPOC). Firstly, the paper by analyzed the issues present in Econometrics teaching. It focuses on the problem of limited course hours and incomplete understanding by beginners in the teaching process of Econometrics; Students lack a solid foundation in mathematics and statistics; Students will operate the software, but the results of the econometric model will not be explained; Insufficient autonomy of students in learning; The lack of up-to-date cases and data has been analyzed. Secondly, the paper proposes a hybrid teaching mode based on OBE+SPOC. Different from traditional MOOC, SPOC is not a "loose management of free range", but a hybrid teaching mode based on OBE+SPOC, which is formed on the MOOC platform and revolves around key links such as "course objectives, course content, classroom implementation, and course evaluation". Thirdly, the practice of the hybrid teaching mode of Econometrics course based on OBE+SPOC is presented.The hybrid teaching mode of Econometrics based on OBE+SPOC provides an effective way to solve the problems in traditional Econometrics teaching. Through the combination of online and offline learning, students can obtain a more flexible and personalized learning experience. Finally, the study concludes with insights into the effectiveness of this model.
The Research on the Ways of Chinese Social Media Bloggers Promoting the Spread of Hanfu Culture in China - The Case of Blogger Si Yue
Authors: Fang Yumo
Published: December 2023

This paper studies how Si Yue, as a Hanfu blogger, promotes the spread of Hanfu culture in the era of rapid development of social media. The research of this paper shows how bloggers use social media to output content to achieve the purpose of traditional culture transmission, which has a very important impact on the re-attention of ancient culture in the new Internet era. Through observation and analysis of the Douyin account of Si Yue, a well-known Hanfu blogger, it is found that the high quality of short video content and different types of content will make the audience have a sense of empathy. The success of combining traditional culture with new culture and the popularity of communication media have a very positive impact on the spread of Hanfu culture, although some negative effects are also included. For example, Hanfu culture has been abused by unscrupulous merchants to make profits. Cultural communication, social media, traditional Chinese culture, short videos.
Information Transmission and Visual Image System Construction on WeChat Public Accounts of Colleges and Universities -- A Case Study on Jiangsu University
Authors: Yang Xueyun , Zhou Yu
Published: December 2023

Objectives: This study aims to make the public platforms of modern colleges and universities more propagating and more accommodating to the use demand and psychological needs of the public. With the WeChat public account of Jiangsu University as an example, this study is based on the Customer Satisfaction Index (CSI) and combines the characteristics of the official WeChat public account of Jiangsu University. A Jiangsu University official WeChat public account customer satisfaction model was built according to the user evaluation of the usefulness, usability, enjoyment, appearance, and perceived information quality of WeChat public accounts. Methods: Focusing on vision and the readings of WeChat tweets from the Jiangsu University public account, we conducted two-factor analysis of variance to observe the participation behaviors of users. Thereby, the concrete strategies for Jiangsu University to build its vision system on its WeChat public account were systematically analyzed.
A Design and Framework for Measuring Social Media Cyberbullying: Based on Text Sentiment Analysis
Authors: Fang Zhou
Published: December 2023

Cyberbullying is a focal issue of public concern. This study focuses on cyberbullying and innovatively introduces text sentiment analysis techniques into the research of specific social behaviors. Through this technique, a research framework for a cyberbullying scale in social media will be designed to explore the dissemination mechanisms and characteristics of cyberbullying in Chinese social media, and to develop a cyberbullying scale that is in line with the cultural background and characteristics of Chinesespeaking countries.
Proxy Advisors: A Double-Edged Sword for Institutional Investors
Authors: Zhao Jiyang
Published: December 2023

Institutional investors who own shares in hundreds of companies and have heavily diversified portfolios face significant challenges. More importantly, investee companies usually organise their annual general meetings at the same time, which creates a huge logistical and administrative workload for institutional investors. Also, the “free riding” is also a frequent problem, which greatly reduces the incentive for institutional investors to participate in corporate governance. Hence, the proxy advisors were introduced because of two factors: regulatory policies demand and market demand. Proxy advisors do have a lot to offer to corporate governance, and many empirical studies have demonstrated that proxy advisors play an important role in director elections, say-on-pay and ESG. However, there are some negative effects, such as the multiple conflicts of interest, ineffective and incomplete information and insufficient transparency, institutional investors’ over-reliance on proxy advisors. In addition to having an impact on corporate governance, proxy advisors have a significant effect on the engagement of shareholders. There are three main points. Firstly, proxy advisors stimulate institutional investors' participation in corporate voting through lowering the costs. Secondly, proxy advisors mitigate the collective action dilemma of institutional investors, and the third one is about the robo-voting problem. From the discussion of the essay, the impact of proxy advisors on shareholder engagement is significant, and while there is a degree of negative impact, the positive impact of proxy advisors is more significant and should be sustained and improved.
Has aging reduced the impact of consumption on GDP? ——Empirical Testing Based on Threshold Regression
Authors: Xue Shuling , Zhao Minhui , Sun Cong
Published: December 2023

Based on the threshold regression model, from the perspective of per capita consumption, this paper explores whether the degree of aging reduces the driving effect of consumption on China's GDP, and examines the impact of consumption structure on GDP. It is found that per capita consumption has a positive effect on regional GDP, and aging plays a threshold role in the impact. As the aging worsens, the driving effect of per capita consumption on GDP begins to strengthen, and the impact of the aging dependency ratio is the largest when it is between 10.44 and 13.10. The impact of per capita health consumption is not significant, and the per capita consumption of education, culture and entertainment has a restraining effect on GDP. Finally, this paper puts forward relevant suggestions based on the above conclusions.
Ethical Considerations in Artificial Intelligence: A Comprehensive Disccusion from the Perspective of Computer Vision
Authors: Li Ni
Published: December 2023

This paper delves deeply into the multifaceted ethical challenges within the realm of computer vision, focusing intently on various ethical dimensions inherent in this cutting-edge field. It emphasizes the pressing need to address ethical concerns related to AI technologies, including algorithmic fairness, informed consent, public engagement, robust privacy protocols, transparency, and the integration of human judgment through human-in-the-loop systems. The study underscores the vital importance of collaboration among diverse stakeholders, including governments, businesses, academia, and society, to promote responsible and equitable AI practices within computer vision.Through meticulous examination, the paper highlights the urgency of balancing technological advancement with ethical considerations. It advocates for the development and implementation of ethical principles, ensuring that AI technologies align with societal values and promote fairness, transparency, and accountability. The collaborative efforts among various sectors are crucial to fostering an ethical framework that guides the responsible deployment of AI in the field of computer vision. By integrating ethical consciousness into the core of technological innovation, this approach aims to create a symbiotic relationship between artificial intelligence and society, ultimately benefiting humanity as a whole.
Local University Cultivation Model Research on Specialized Software Engineering Talents Under Integration of Production and Education
Authors: Wei Le , Shu Hongping , Zhao Qiuyun , Cao Liang
Published: December 2023

In the context of the new era, cultivating high-quality innovative talents and technical skills has become an urgent requirement to promote the development of the software industry. There are some problems in the training of specialized software engineering talents in local universities in China, such as unclear orientation, ineffective practical teaching effect and shortage of professional teachers. Based on the issues mentioned above, it is advisable to establish a clear professional orientation aligned with industry demands and develop a curriculum system and content that are in line with this specialized focus. Establishing a collaborative industry-education-research practical teaching system and deepening the collaborative innovation capability development model between industry, education, and research. By solving the two core problems of 'what kind of professional talents to cultivate ' and 'how to cultivate '. It aims to provide suggestions for the professional cultivation of software engineering talents in local colleges and universities in the era of industry-education fusion.
The evaluation of marketing competitiveness of B2B E-commerce enterprises based on optimized deep learning networks
Authors: Zhang Zifeng
Published: December 2023

In the context of e-commerce trade between enterprises, there are problems such as price wars, false advertising, and unreasonable operations aimed at seizing market share. However, traditional estimation methods cannot provide a reasonable evaluation of the marketing competitiveness of e-commerce enterprises from an overall perspective. To help enterprises better clarify their own position and quantify their marketing competitiveness, a competitiveness evaluation model based on optimized deep learning networks is proposed. By combining subjective and objective evaluation methods, the indicators that affect the marketing competitiveness of enterprises are assigned to obtain the final competitiveness value. The research outcomes expressed that the max absolute error of the model constructed by the research institute was 0.0006, the max relative error was 0.0045, and the model accuracy was 99.85%. In the secondary indicator experiment of marketing competition, the model determined that the turnover rate of fixed assets had the greatest impact, with a weight value of 0.1263. Nine companies were randomly selected for market value estimation, and the average relative error of the model was 14.90%, which was lower than the mean relative error of the relative valuation, cash flow and absolute valuation methods, with numerical differences of 8.03%, 2.94%, and 0.12%, respectively. The research findings illustrated that the model constructed by the research institute had good performance and certain reference values for evaluating the marketing competitiveness of e-commerce enterprises.
Unintentional Suture Fistula Between the Proximal and Distal Esophagus in a Preterm Neonate with Type C Esophageal Atresia
Authors: Menso Julia E. , Reijntjes Maud A. , Mussies Carlijn M. , van Wijk Michiel P. , Zwaveling Sander
Published: December 2023

We present the case of a patient with gross type C esophageal atresia in a preterm neonate (gestational age of 31 weeks + 1 day) with a birth weight of 1,470 g. The fistula was released via a thoracotomy, but no primary anastomosis could be made, due to an unexpected long gap. The distal esophagus was closed and approximated to the blind pouch using traction sutures until an adjacent position was reached. A gastrostomy was created for enteral feeding. Although a second attempt to make an anastomosis was unsuccessful, the patient unexpectedly developed a suture fistula 6 weeks after the first procedure, enabling feeding via a nasogastric tube. Over time, six dilations were necessary. Full enteral feeding was achieved at the age of 6 months. Our case confirms sparse reports that deliberately creating a suture fistula may be a solution in esophageal atresia patients when an unexpected long gap prohibits a primary anastomosis.
Missed Proximal Tracheoesophageal Fistula (TEF) in a Neonate with Type D Esophageal Atresia
Authors: Menso Julia E. , Reijntjes Maud A. , Oomen Matthijs W. , Rinkel Rico N.P.M. , Terheggen-Lagro Suzanne W.J. , Gorter Ramon R.
Published: December 2023

We present the case of a patient with the rare type D esophageal atresia (EA), diagnosed after correction of an EA initially diagnosed as type C. Routine postoperative contrast esophagogram showed a missed proximal tracheoesophageal fistula. This case report illustrates the potential difficulties to diagnose type D EA.
Polyampholyte Hydrogels with pH-Dependent Swelling for Controlled Catch and Release of Model Dyes
Authors: Çeper Tolga , Mohotti Supun W. , Lange Leon X. , Schacher Felix H.
Published: December 2023

Polyampholyte hydrogels with tunable charge are synthesized by a facile two-step approach including the free-radical crosslinking copolymerization of tert-butoxycarbonylaminomethylacrylate (tBAMA) with N,N′-methylenebisacrylamide and subsequent deprotection. Thermal, photo- and redox-initiating methods were utilized in the synthesis of crosslinked PtBAMA and the resulting polymer networks swell during deprotection in a mixture of trifluoro acetic acid/water. While the crosslinked PtBAMA forms organogels in various organic solvents such as chloroform, acetone and DMSO, polydehydroalanine (PDha) networks after deprotection form hydrogels with pH-dependent swelling and oscillatory swelling/deswelling depending on pH value and salinity. The tunable charge of the developed hydrogels was employed for a catch-and-release platform controlled by pH, in which methylene blue as a cationic model was adsorbed at pH 11 and desorbed at pH 2, whereas methyl blue as an anionic model dye was adsorbed at pH 2 and desorbed at pH 11.
Ligand-Free Copper(I) Chloride Catalyzed N-Arylation of 1,2,4-Triazole with Aryl Bromides
Authors: Teo Yong-Chua , Ang WeiZhi , Low Chloe Kah-Yee
Published: December 2023

An efficient protocol was developed for the N-arylation of 1,2,4-triazole by using substituted aryl bromides catalyzed by CuCl under ligand-free conditions. This method afforded the products in good to excellent yields (up to 88%) under the optimized conditions.
Evidence from the Use of Solvatochromic Dyes Indicates that Bulk Pure Water does not Potentise
Authors: Cartwright Steven J. , Pinkus Tony S.
Published: December 2023

Background Whilst it is assumed that water plays a crucial role in homeopathy, it is unclear what specific functions water has in the generation, propagation and maintenance of homeopathic potencies. Solvatochromic dyes have demonstrated themselves to be reliable indicators of the presence of potencies and so are well placed to begin to address these questions.

Objective The aim of the current study was to ascertain whether pure water could be potentised. If pure water can be potentised, this would indicate that water plays a crucial role in the generation of homeopathic potencies. If it cannot be potentised, then this result points to water being an inert carrier and medium for the potentisation of substances placed in it.

Methods A specially designed potentiser capable of consistently and reliably producing homeopathic potencies to rigorous standards (Pinkus Potentiser) was used to run up potencies of “Water 10M” and Arsenicum 10M in two interchangeable stainless-steel vials. “Water 10M” and Arsenicum 10M, along with unsuccussed control water, were then tested against solutions of the solvatochromic dye phenol blue by following the absorbance of the dye at 658 nm.

Results “Water 10M” gave results no different statistically from unsuccussed water (p > 0.05) with no change over the time course of the experiments, whereas Arsenicum 10M gave statistically different results (p < 0.001) with increasing divergence from both “Water 10M” and unsuccussed water over time. Similar results were obtained when the vials in which Arsenicum 10M and “Water 10M” were produced were exchanged, so that the vial in which Arsenicum 10M had been produced was then used to produce “Water 10M” and vice versa, indicating the results could not be explained by any anomalies in the production vials themselves.

Conclusion Results using the solvatochromic dye phenol blue to detect and measure homeopathic potencies indicate that bulk water itself does not potentise and that unsuccussed water and water that has been succussed are no different. This indicates that what is potentised during cycles of dilution and succussion are the substances placed in water and not the water itself. In turn, this indicates that water is simply a carrier for the homeopathic signal. Evidence from the practice of homeopathy supports this conclusion.
Efficacy and Safety of Holmium Laser Lithotripsy for Renal Calculi in Retrograde Intrarenal Surgery: A Comparative Study in Libyan Patients
Authors: Abushnaf Abubaker , Garta Ibrahim , Omran Ali bin , Aboshnaf Anas
Published: December 2023

Background Kidney stones are a common problem that can be treated by different surgical methods. The choice of treatment depends on the stone and patient characteristics and the local resources and skills of the urologists.

Aim The aim of this study was to evaluate the outcomes regarding the safety and effectiveness of retrograde intrarenal surgery (RIRS) using holmium laser lithotripsy for kidney stones sizes of less than or equal to 20, and more than 20 mm.

Methods The study was conducted on 54 patients with renal calculi at a single center using RIRS and holmium lithotripsy from April 2022 to April 2023. Stone size was calculated by summing up the diameters of all renal calculi, and stone-free rate (SFR) was defined as no stone or stone fragment less than 1 mm in the kidney. Results are described as mean ± standard deviation, frequency, and percentages. Chi-squared or unpaired t-tests are used for comparison between different groups as appropriate. A p-value less than 0.05 is considered significant.

Results The mean intrarenal stone size was 17.8 ± 7.6 mm, with a significant difference in stone size less than or equal to 20 mm and stone size more than 20 mm (19 ± 4.7 and 35 ± 4 mm, respectively). The main operation time was 66 ± 36.5 minutes, with significantly longer operation time for patients with kidney stones more than 20 mm (94.9 ± 34.5 vs. 49 ± 26 for stone size ≤20 mm). There was no difference in the length of stay after operation between the two different stone sizes. The overall immediate SFR was 64.4%, where stone size less than or equal to 20 mm showed a significantly higher SFR (83%) than SFR for stone size more than 20 mm (31%). This SFR increased to 91.1% 1 month later, with 100% clearance for stones size less than or equal to 20 mm compared with only 68% for stones size more than 20 mm. The overall complication rate was 9.2%, most of them were due to urinary tract infections (5 cases) that required intravenous antibiotics. Stone size had no significant effect on the complication rate. There was no significant difference in SFR between lower calyceal stone and other sites of stone.

Conclusion RIRS combined with holmium laser lithotripsy is a valuable treatment option for patients with renal stones particularly for patients with stones size of less than or equal to 20 mm with a relatively low rate and severity of complications.
Unraveling the Impact of Sperm DNA Fragmentation on Reproductive Outcomes
Authors: Nielsen Jeanett L.M. , Majzoub Ahmad , Esteves Sandro , Humaidan Peter
Published: December 2023

In recent years, there has been a growing interest in identifying subcellular causes of male infertility, and sperm DNA fragmentation (SDF) research has been at the forefront of this focus. DNA damage can occur during spermatogenesis due to faulty chromatin compaction or excessive abortive apoptosis. It can also happen as sperm transit through the genital tract, often induced by oxidative stress. There are several methods for SDF testing, with the sperm chromatin structure assay, terminal deoxynucleotidyl transferase d-UTI nick end labeling (TUNEL) assay, comet assay, and sperm chromatin dispersion test being the most commonly used. Numerous studies strongly support the negative impact of SDF on male fertility potential. DNA damage has been linked to various morphological and functional sperm abnormalities, ultimately affecting natural conception and assisted reproductive technology outcomes. This evidence-based review aims to explore how SDF influences male reproduction and provide insights into available therapeutic options to minimize its detrimental impact.
Gender Representation on North American Ophthalmology Societies' Governance Boards
Authors: Bondok Mostafa , Selvakumar Rishika , Khan Muhammad , Bondok Mohamed S. , Nguyen Anne Xuan-Lan , Ing Edsel , Law Christine
Published: December 2023

Purpose We examined the gender distribution and academic productivity of North American ophthalmology societies' board members.

Methods Cross-sectional and retrospective study of board members on American and Canadian ophthalmology societies. In December 2022, data was gathered from society webpages, online archives, and the Scopus database for publication information.

Results Of the identified 73 board presidents and 876 other board members, 49 (67.1%) board presidents were men and 24 (32.9%) were women, while 554 (63.2%) other board members were men and 322 (36.8%) were women (p = 0.53). Overall, board members who were men had significantly higher median h-indexes (men vs. women: 10 [interquartile range [IQR] = 22] vs. 7 [IQR = 12], p = 0.03) and median publication numbers (men vs. women: 23 [IQR = 84] vs. 14 [IQR = 52.3], p = 0.01). However, m-quotients (h-index divided by length of academic career) were not significantly different (men vs. women: 0.46 [IQR = 0.74] vs. 0.50 [IQR = 0.55], p = 0.67). Overall, a significant increase in the proportion of women board presidents comparing periods 1942 to 1961 and 2002 to 2021 was observed for all societies combined (3.1% [2/65] to 23.6% [210/888], p < 0.001).

Conclusion The fraction of women on the academic boards in North American ophthalmology societies has increased sevenfold over the past 83 years. The gender composition of ophthalmology society boards is consistent with the gender composition of practicing ophthalmologists in the United States. Women in board or society positions have comparable academic output to men. Existing and new efforts to sustain progress in promoting women's representation and leadership opportunities must continue.
Comparing machine learning algorithms for non-invasive detection and classification of failure in piezoresistive bone cement via electrical impedance tomography
Authors: Keiderling L. , Rosendorf J. , Owens C. E. , Varadarajan K. M. , Hart A. J. , Schwab J. , Tallman T. N. , Ghaednia H.
Published: December 2023

At an estimated cost of $8 billion annually in the United States, revision surgeries to total joint replacements represent a substantial financial burden to the health care system and a tremendous mental and physical burden on patients and their caretakers. Fixation failures, such as implant loosening, wear, and mechanical instability of the poly(methyl methacrylate) (PMMA) cement, which bonds the implant to the bone, are the main causes of long-term implant failure. Early and accurate diagnosis of cement failure is critical for developing novel therapeutic strategies and reducing the high risk of a misjudged revision. Unfortunately, prevailing imaging modalities, notably plain radiographs, struggle to detect the precursors of implant failure and are often interpreted incorrectly. Our prior work has shown that the modification of PMMA bone cement with low concentrations of conductive fillers makes it piezoresistive and therefore self-sensing. When combined with a conductivity imaging modality such as electrical impedance tomography (EIT), it is possible to monitor load transfer across the PMMA using cost-effective, physiologically benign, non-contact, and real-time electrical measurements. Despite the ability of EIT for monitoring load transfer across self-sensing PMMA bone cement, it is unable to accurately characterize failure mechanisms. Overcoming this challenge is critical to the success of this technology in practice. Therefore, we herein expand upon our previous results by integrating machine learning techniques with EIT for cement condition characterization with the goal of establishing the feasibility of even off-the-shelf machine learning algorithms to address this important problem. We survey a wide variety of different machine learning algorithms for application to this problem, including neural networks on voltage readings of an EIT phantom for tracking the spatial position of a sample, specifying defect orientation within a sample, and classifying defect types, including cracks and delaminations. In addition, we explore the utilization of principal component analysis (PCA) for pre-treating impedance signals in each of these problems. Within the tested algorithms, our results show clear advantages of neural networks, support vector machines, and K-nearest neighbor algorithms for interpreting EIT signals. We also show that PCA is an effective addition to machine learning. These preliminary results demonstrate that the combination of smart materials, EIT, and machine learning may be a powerful instrumentation tool for diagnosing the origin and evolution of mechanical failure in joint replacements.
Construction of free quantum fields on nested fractal space-times
Authors: Ni Tianjia , Wen Zhiying
Published: December 2023

Free boson quantum fields on unbounded nested fractal space-times are constructed with mathematical rigour. We verify analogous properties to the Wightman’s axioms except for those involving Poincaré invariance.
Enhanced soft-to-hard magnetic switching ratio in grain-oriented Fe–Si cores induced by helical anisotropy
Authors: Dobák S. , Füzer J. , Petryshynets I. , Kollár P. , Kováč F.
Published: December 2023

The non-segmented shifted design of magnetic cores made of grain-oriented electrical steels, which induces the helical anisotropy, has been highly effective in reducing magnetic losses and minimizing acoustic noise in rotating machines. In order to address the challenges associated with precise theoretical modeling of complex underlying magnetization process, we have introduced angle-dependent first-order reversal curve diagrams. These diagrams offer significant insights into the microscopic properties of magnetization switching. By analyzing the distribution of coercive and interaction fields, we can identify distinct features that correspond to different domain wall processes and local coercivities, highlighting the magnetic behavior's heterogeneity. Through experimental measurements and theoretical analysis, we have gained quantitative understanding of the competing contributions from 90° and 180° domain wall processes in shifted structures. At shifting angles near the location of the hard magnetization axis, a notable transition in the magnetization process is observed by promoting the activation of the softer 180° domain wall processes. Among the different shifting angles tested, the structure with a shifting angle of 90° exhibits the highest ratio of soft-to-hard magnetization switching.
Spectra scaling of velocity components and pressure–strain correlations for hypersonic boundary layers at a range of wall-to-recovery temperatures
Authors: Liu Wanting , Huang Ranran , Wu Jie
Published: December 2023

Flow similarity is one of the most desirable features for turbulence under different conditions. For hypersonic boundary layers, different wall temperatures are known to change the turbulence evolution by influencing the intercomponent energy transfer, while the flow similarity has received less attention. Based on direct numerical simulations, this work investigates the spectral distribution of velocity components and pressure–strain correlations for hypersonic boundary layers at Mach 6 and wall-to-recovery temperature ratios equal to 0.3, 0.5, 0.76, and 1. The wall-normal evolution of turbulent structures is compared by the spectra peak scale λSP, wall-normal location ySP, and the vertical profiles of peak scale λP. For all cases, the peak scale profiles exhibit linear increases with a height of 0.1≤y/δ≤0.25. The linear growth of the turbulence scale in the logarithmic region indicates the existence of self-similar structures, and the agreement of peak scales in the outer scaling suggests the flow similarity under different wall temperatures. Likewise, the streamwise pressure–strain term has the peak scale profile linearly dependent on the height for the same vertical range 0.1≤y/δ≤0.25 with velocity components, while the wall-normal and spanwise terms exhibit both linear and constant vertical dependence depending on the wall temperatures. With the increase in wall temperature, the peak scale exhibits broader constant vertical dependence and narrower linear vertical dependence. The cospectral analysis further confirms that the pressure–strain correlations are maximized at different spanwise-vertical aspect ratios of turbulence structures.
The effect of the diamagnetic drift on geodesic acoustic modes in tokamak plasmas
Authors: Zhou Deng
Published: December 2023

The effect of the radial derivative of the equilibrium particle distribution, i.e., the diamagnetic drift effect, on geodesic acoustic modes is taken into account in this work. The effect was routinely neglected in the previous studies on the geodesic acoustic mode since the dominant mode number is m/n=0/0. However, for finite electron temperatures, small m ≠ 0 side bands are present and the diamagnetic drift effect enters through these side bands. In this work, we find that the mode frequencies increase with the particle density gradient. The temperature ratio between electrons and ions, i.e., τ=Te/Ti, is a key parameter influencing this effect. The effect is more prominent for higher τ values. Another effect is the symmetry breaking of the propagating direction of the sideband potentials. In contrast to the pure standing wave form, the potential perturbation consists of a standing wave superimposed with a small amplitude traveling wave, which is nearly proportional to the density gradient.
Unveiling the role of chemical pressure on antiferroelectricity in NaNbO3-based antiferroelectric ceramics
Authors: Luo Gengguang , Yang Kaihua , Fu Xinyang , Ma Li , Che Zhiyi , Chen Xiyong , Cen Zhenyong , Feng Qin , Luo Nengneng
Published: December 2023

Chemical pressure is widely applied to antiferroelectrics (AFEs) as a criterion to enhance their antiferroelectricity. However, NaNbO3 (NN)-based ceramic with well-defined double polarization hysteresis (P–E) loops was rarely reported based on this strategy, and the effect of chemical pressure on antiferroelectricity remains to be understood. In this work, the Me cations (Me is Ti, Sn, Zr) with different ionic radii were introduced into the component system 0.76NaNbO3–0.20AgNbO3–0.04CaMeO3 to tune the negative chemical pressure and investigate its effect on antiferroelectricity. The enhancement of negative chemical pressure can effectively stabilize the AFE phase and reduce hysteresis, as revealed by the P–E loops and dielectric properties, which is further confirmed by the change in crystal lattice parameters and in situ Raman spectra. Rietveld refinement of x-ray powder diffraction reveals that the enhanced negative chemical pressure mainly reduces the cation off-centering displacement and [BO6] octahedral tilting angles. As a result, the 0.76NaNbO3–0.20AgNbO3–0.04CaZrO3 exhibits good reversibility of the electric field-induced antiferroelectric–ferroelectric phase transition and well-defined double P–E loops. This work reveals the underlying mechanism of chemical pressure and provides an effective way of discovering new NN-based AFEs.
SOS1-RSX-QIDH: A spin-opposite-scaled range-separated-exchange quadratic-integrand double-hybrid density functional
Authors: Brémond Éric , Pérez-Jiménez Ángel José , Sancho-García Juan Carlos , Adamo Carlo
Published: December 2023

We develop and validate the SOS1-RSX-QIDH density functional, a one-parameter spin-opposite-scaled variant of the range-separated-exchange quadratic-integrand double-hybrid (RSX-QIDH) model. By entering into the family of spin-biased double hybrids, this new density functional benefits from an improved computational scaling that rivals with the one of hybrids, still conserving the accuracy of its RSX-QIDH version. As part of the latter family, this density functional is well-adapted to treat molecular systems that are particularly prone to self-interaction errors in their ground and excited states. In particular, we show that the SOS1-RSX-QIDH model is a good compromise to treat ground-state problems dealing with kinetics and has a real added value when applied to the evaluation of the excited-state properties of equilibrium and out-of-equilibrium molecular complexes. Even if spin-biased double hybrids are recognized to strongly underestimate noncovalent interactions, we notice and recommend coupling SOS1-RSX-QIDH with a nonlocal van der Waals potential, a combination that is here proved to compete with the best density-functional approximations currently in use.
Simulation of thin-film detectors of ionizing radiation and thermal neutrons based on CdTe
Authors: Kosinov A. V. , Pudov A. O. , Sokolov S. A. , Rybka A. V. , Kutny V. E. , Davydov L. N. , Abyzov A. S.
Published: December 2023

The article is dedicated to the numerical simulations of thin-layer structures based on CdTe semiconductors, which can be fabricated by using low-cost technologies. Structures Mo/Au/CdS/CdTe/Au, and their modifications, with different thicknesses of the main layers are investigated. The possibility of creating a detector of ionizing radiation based on these structures, which has selective properties with respect to the radiation type, and very low operation voltage, is shown. The detection efficiencies of α-, β-, and γ-radiation in different energy ranges were calculated based on the obtained values of energy losses of ionizing particles, which are proportional to the output signal of the detector. The use of such detectors, together with a solid-state converter made of boron carbide containing either natural boron natB or boron enriched with the 10B isotope up to 95%, for the detection of thermal neutrons was also studied. It was shown that the structures could be used to create α-particle spectrometers, given that the CdTe thickness is tailored to the highest expected α-particle energy. Detectors with thin CdTe (1–5 μm) can be successfully used in the counting mode. For neutron detection, stacking multiple single structures into sandwich structures was proposed and investigated. In such a configuration, the detector qualities were markedly improved: the efficiency of neutron detection reached ∼60%, while the sensitivity to the background γ- and β-radiation was ∼100 times lower than that for neutrons. The very low sensitivity of the simulated neutron detectors to the neutron incidence angle was shown.
Experimental and theoretical analysis of pulsatile flow in elastic tubes: Wave propagation and attenuation
Authors: Roknujjaman Md. , Kyotoh Harumichi , Yohei Asada , Yasuhisa Adachi
Published: December 2023

The objective of this study was to comprehensively examine the pulsatile flow behavior within an elastic tube using experimental and theoretical approaches. This work is an extension of our earlier report [Roknujjaman et al., Phys. Fluids, 34, 123612 (2022)]. In this paper, we adapted a quasi-one-dimensional model to elucidate the wave propagation and pulse attenuation phenomena in an elastic tube and compared with experimental findings. According to our investigation, the key findings were as follows: the experimental and predicted flow wave propagation trend agreed well. Additionally, because of the silicon tubes greater deformation than the urethane tubes, the pulsation was decreased farther in the silicon tubes than in the urethane ones. Furthermore, because of the reflected wave near the tube exit, the pulsations amplitude significantly increased, but it did not enlarge when the resistance was installed at the exit. Finally, we infer that the quasi-one-dimensional model is a better fit for experimental results compared to the two-dimensional model.
Synaptic plasticity emulation by natural biomaterial honey-CNT-based memristors
Authors: Templin Zoe , Tanim Md Mehedi Hasan , Zhao Feng
Published: December 2023

Artificial synaptic devices made from natural biomaterials capable of emulating functions of biological synapses, such as synaptic plasticity and memory functions, are desirable for the construction of brain-inspired neuromorphic computing systems. The metal/dielectric/metal device structure is analogous to the pre-synapse/synaptic cleft/post-synapse structure of the biological neuron, while using natural biomaterials promotes ecologically friendly, sustainable, renewable, and low-cost electronic devices. In this work, artificial synaptic devices made from honey mixed with carbon nanotubes, honey-carbon nanotube (CNT) memristors, were investigated. The devices emulated spike-timing-dependent plasticity, with synaptic weight as high as 500%, and demonstrated a paired-pulse facilitation gain of 800%, which is the largest value ever reported. 206-level long-term potentiation (LTP) and long-term depression (LTD) were demonstrated. A conduction model was applied to explain the filament formation and dissolution in the honey-CNT film, and compared to the LTP/LTD mechanism in biological synapses. In addition, the short-term and long-term memory behaviors were clearly demonstrated by an array of 5 × 5 devices. This study shows that the honey-CNT memristor is a promising artificial synaptic device technology for applications in sustainable neuromorphic computing.
Smooth transformations and ruling out closed orbits in planar systems
Authors: Pedergnana Tiemo , Noiray Nicolas
Published: December 2023

This work deals with planar dynamical systems with and without noise. In the first part, we seek to gain a refined understanding of such systems by studying their differential-geometric transformation properties under an arbitrary smooth mapping. Using elementary techniques, we obtain a unified picture of different classes of dynamical systems, some of which are classically viewed as distinct. We specifically give two examples of Hamiltonian systems with first integrals, which are simultaneously gradient systems. Potential applications of this apparent duality are discussed. The second part of this study is concerned with ruling out closed orbits in steady planar systems. We reformulate Bendixson’s criterion using the coordinate-independent Helmholtz decomposition derived in the first part, and we derive another, similar criterion. Our results allow for automated ruling out of closed orbits in certain regions of phase space and could be used in the future for efficient seeding of initial conditions in numerical algorithms to detect periodic solutions.
Exponential distribution functions for positivity-preserving lattice Boltzmann schemes: Application to 2D compressible flow simulations
Authors: Thyagarajan Karthik , Coreixas Christophe , Latt Jonas
Published: December 2023

A family of positivity-preserving lattice Boltzmann methods (LBMs) is proposed for compressible flow simulations in the continuum regime. It relies on the efficient collide-and-stream algorithm with a collision step based on exponential distribution functions. The latter serves as a generalization of Grad's post-collision distribution functions for which here (1) the linearized non-equilibrium contributions are replaced by their exponential forms and (2) the number of these contributions can be chosen arbitrary. In practice, post-collision moments of our exponential formulation are enforced through an iterative moment-matching approach to recover any macroscopic physics of interest, with or without external forces. This methodology directly flows from the extended framework on numerical equilibria [J. Latt et al., Philos. Trans. R. Soc. A 378, 20190559 (2020)] and goes one step further by allowing for the independent relaxation of hydrodynamic and high-order modes in a given moment space, notably, making the Prandtl number freely adjustable. The model is supplemented by a shock-capturing technique, based on the deviation of non-equilibrium moments from their equilibrium counterparts, to ensure good numerical properties of the model in inviscid and under-resolved conditions. A second exponential distribution accounts for extra degrees of freedom of molecules and allows for the simulation of polyatomic gases. To validate this novel approach and to quantify the accuracy of different lattices and moment closures, several 2D benchmark tests of increasing complexity are considered: double shear layer, linear wave decay, Poiseuille flow, Riemann problem, compressible Blasius flow over a flat plate, and supersonic flow past an airfoil. Corresponding results confirm the accuracy and stability properties of our approach for the simulation of compressible flows with LBMs. Eventually, the performance analysis further highlights its efficiency on general purpose graphical processing units.
Analytic expressions for correlations in coarse-grained simple fluids
Authors: Luo Siwei , Thachuk Mark
Published: December 2023

Coarse-graining of fluids is challenging because fluid particles are unbound and diffuse long distances in time. One approach creates coarse-grain variables that group all particles within a region centered on specific points in space and accounts for the movement of particles among such regions. In our previous work, we showed that in many cases, potential interactions for such a scheme adopted a generalized quadratic form, whose parameters depend on means, variances, and correlation coefficients among the coarse-grain variables. In this work, we use statistical mechanics to derive analytic expressions for these parameters, using properties of the fluid, including pair distribution functions. These expressions are compared against simulation-derived values and shown to be in good agreement. This approach can be used to calculate a priori the potential for any homogeneous, simple fluid, without the need for fitting procedures or matching, thus increasing the ease of use of this coarse-grain scheme and creating a foundation for large-scale bottom-up simulations. Furthermore, these expressions provide a quantitative way of studying the boundary between discrete (atomic) and continuum models of fluids.
Protein stability in a natural deep eutectic solvent: Preferential hydration or solvent slaving?
Authors: Gomes Inês , Galamba Nuno
Published: December 2023

Deep eutectic solvents (DESs) emerged as potential alternative solvent media in multiple areas, including biomolecular (cryo)preservation. Herein, we studied the stability of a small protein (ubiquitin) in water and a betaine-glycerol-water (B:G:W) (1:2:ζ; ζ = 0, 1, 2, 5, 10) DES, through molecular dynamics. An AMBER-based model that accurately describes the density and shear viscosity of the DES is proposed. We find that water molecules are largely trapped in the solvent, precluding the formation of a full hydration layer, seemingly opposite to osmolytes’ preferential exclusion/preferential hydration mechanism. Although the protein is stable in the DES, structural fluctuations are largely suppressed and only recovered upon sufficient hydration. This is explained by a solvent-slaving mechanism where β-fluctuations are key, with the non-monotonic hydration of some amino acids with the water content providing an explanation to the non-monotonic folding of some proteins in aqueous DESs. A major thermal stability enhancement in the DES is also observed, caused by a similar slowdown of the backbone torsional dynamics. Our results support a kinetic stabilization of the protein in the DES, whereas a possible thermodynamic stabilization does not follow a preferential hydration or water entrapment mechanism.
Spacing effects on blast loading characteristics of two tandem square columns under planar shock waves
Authors: Qiu Tao , Cheng Shuai , Du Xiaoqing , Zhang Dezhi
Published: December 2023

To effectively evaluate the structural responses, it is crucial to possess relevant knowledge regarding the blast load on the structure. The loading characteristics of two columns differ from those of a single column due to complex flow-field interference. The spacing effect on blast loading characteristics of two tandem rigid square columns is examined numerically and experimentally for different center spacing between the columns (L = 1.2B–12B, where B represents the side length of a column). This includes studying drag characteristics, distribution patterns of reflection overpressure and impulse, and understanding the physical mechanism under blast load. The experimental tests use a shock tube device powered by high-pressure gas, while numerical simulations solve Euler equations using computational fluid dynamics techniques. Our findings reveal that spacing cases can be categorized into four situations: small and medium spacings (L/B = 1.2–2 and 2.5–4), where the upstream column exhibits a significant shielding effect on the downstream column, resulting in the reduced drag coefficient for the downstream column; large spacings (L/B = 5–7), where drag coefficient improves but remains lower than that of a single column; superlarge spacings with negligible shielding effect (L/B = 8–12), leading to similar blast loading for the downstream column compared to a single column.
Influence of deformed parent vessel on rupture risk of micro cerebral aneurysm: Numerical study
Authors: Kang Kang , Ji Shujuan , Aminian Saman
Published: December 2023

One of significant impact of stent usage for the treatment of the saccular aneurysm is deformation of the parent vessel. Present study demonstrates the influence of the aneurysm deformation caused by the stent on the risk of aneurysm rupture. Computational fluid dynamic is applied for the modeling of the blood flow inside three internal carotid artery (ICA) aneurysms with different neck angles. One-way fluid–structure interaction model is applied for the interaction of the blood and vessel. Two stage of deformation is applied on the parent vessel to analyze the influence of deformation on the hemodynamic factors of wall shear stress and oscillatory shear index. Achieved results indicate that the deformation of the aneurysm by the stent significantly reduce wall shear stress is on the sac wall and decrease the risk of internal carotid artery ICA aneurysm rupture. Our finding confirm that the main effect of aneurysm deformation is reduction of the blood velocity near ostium region.