bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of Exclusive Choice Policies on Platform Supply Chains: When Both Same-Side and Cross-Side Network Effects Exist
Authors: Chen Haijun , Xu Qi
Published: May 2024

This research investigates the effects of “choose-one-over-another” monopolistic strategies on two-sided platforms, analyzing the implications of such practices on network effects and platform economics through the Hotelling model. Our key findings include the following: (1) “Choose-one-over-another” policies enhance positive network effects, increasing multi-homing on the demand side but reducing overall platform revenue. These policies also intensify negative network effects, leading to higher prices for supply-side users and thereby undermining the welfare of demand-side users. (2) After antitrust interventions, platforms adjust pricing dynamically, increasing for one side and decreasing for the other in response to changes in same-side network effects, which in turn influences multi-homing behaviors and revenue impacts differently before and after the enforcement of such policies. (3) Without exclusive selection mandates, platform pricing strategies tend to lower prices for supply-side users, especially under competitive pressures or weaker positive network effects, potentially increasing platform revenue and overall supply chain welfare under certain conditions. This study highlights the critical role of regulatory oversight in curbing monopolistic platform behaviors to protect user rights and ensure market health, offering strategic guidance for platform management amidst competitive and operational challenges.
Can Self-Presentation on Social Media Increase Individuals’ Conspicuous Consumption Tendency? A Mixed-Method Empirical Study on WeChat in China
Authors: Lu Yan , Zhao Taiyang , Song Siying , Song Wei
Published: May 2024

Previous studies have mainly focused on the impact of social media self-presentation on individuals’ happiness and mental health, whereas few have attended to its potential influence on consumer behavior. A mixed-method empirical study with an online survey (N = 408) and an experimental study (N = 160) investigated the effects of social media self-presentation on individuals’ conspicuous consumption in China. We found that consumers’ self-presentation behavior on social media promoted tendencies for social comparison, thereby enhancing their conspicuous consumption. However, compared with individuals using social media less often, self-presentation had a more significant impact on the social comparison tendencies of users who used social media more often. Our study explains why individuals’ self-presentation on social media increases their conspicuous consumption tendencies. The study results contribute to the existing knowledge of how consumers’ behavior on social media affects their product preferences.
Digital Wallet, Happy Heart: An Analysis Based on the Economic–Social–Environmental Perspective
Authors: Gong Xiaomei , Zhang Huirong , Zhang Jiaping
Published: May 2024

While the prior mobile payment−subjective well-being (SWB) literature has mainly discussed its economic and social impacts, the present study supplements this body of research by introducing an economic–social–environmental perspective. Using two waves of representative Chinese national surveys, the instrumental variable (IV) estimator suggests that mobile payment is positively and statistically significantly correlated with SWB. Furthermore, the results reveal that the positive correlation comes from the compound influence of economic, social, and environmental channels. Specifically, it shows that mobile payment not only affects people’s economic and social performance but also mitigates the adverse effects of poor environmental conditions on SWB. Additionally, a further disaggregated analysis shows that mobile payment exerts a stronger positive influence on SWB for people from underdeveloped areas within the economic–social–environmental framework. These findings shed light on the role of financial technology in facilitating sustainable development.
How the Character of the Narrator Constructs a Narratee and an Implied Reader in Philip Pullman’s Northern Lights
Authors: Grange Richard
Published: May 2024

The third-person omniscient narrator of fiction texts for children holds the ability to access characters’ thoughts, fly where they will within the story, and interact with time and tense. Philip Pullman characterises this kind of narrator as a multiscient sprite, not a human seeing and telling, but something else which possesses unhuman-like qualities. This paper uses an analysis of the narrator’s voice, character, and choices to access two other characters created by the story being told—the narratee and the implied reader, both of whom may well be thought of as child characters produced by the text. A profile of these two products is then presented. Through a close textual analysis, which draws out untagged parts of Northern Light’s narrator’s speech, an examination of the kinds of characters the narratee, and implied reader could be seen to be is gathered. The narrator’s ability to intensely empathise with characters is passed onto the narratee and also normalised by aspects of the story, including the alethiometer, a device from the created world of the story which is imbued with strikingly similar qualities to the narrator. Lyra, the book’s protagonist, and the instrument interact with each other in a manner akin to the narrator and narratee, both having an agency which the implied reader could be bestowed with from reading the text.
Hept-6-en-1-yl Furan-2-carboxylate
Authors: Wang Zhongwei , Song Lin , Qin Yukun
Published: May 2024

This study aims to develop an efficient and green one-pot method for the synthesis of 6-en-1-yl furan-2-carboxylic acid heptyl ester. Initially, using furfural as the starting substrate, hept-6-en-1-yl furan-2-carboxylate was prepared using a one-pot method. This study developed a new experimental scheme for preparing ester compounds, using cuprous chloride as a catalyst and tert butyl hydrogen peroxide as an oxidant to prepare furoic acid. Without the need for intermediate treatment, the target product can be directly obtained from furfural by adding 7-bromo-1-heptene, TBAB, and potassium carbonate. This method effectively utilizes furfural as a platform chemical, demonstrating its potential for synthesizing high-value chemicals. The entire synthesis process is simple and efficient, following the principles of green chemistry.
The Quest for High-Temperature Superconductivity in Nickelates under Ambient Pressure
Authors: Aggarwal Leena , Božović Ivan
Published: May 2024

Recently, superconductivity with Tc ≈ 80 K was discovered in La3Ni2O7 under extreme hydrostatic pressure (>14 GPa). For practical applications, we needed to stabilize this state at ambient pressure. It was proposed that this could be accomplished by substituting La with Ba. To put this hypothesis to the test, we used the state-of-the-art atomic-layer-by-layer molecular beam epitaxy (ALL-MBE) technique to synthesize (La1−xBax)3Ni2O7 films, varying x and the distribution of La (lanthanum) and Ba (barium). Regrettably, none of the compositions we explored could be stabilized epitaxially; the targeted compounds decomposed immediately into a mixture of other phases. So, this path to high-temperature superconductivity in nickelates at ambient pressure does not seem promising.
Effect of the Atmospheric Plasma Treatment Parameters on the Surface and Mechanical Properties of Carbon Fabric
Authors: Sampino Samuele , Ciardiello Raffaele , D’Angelo Domenico , Cagna Laura , Paolino Davide Salvatore
Published: May 2024

The use of Atmospheric Pressure Plasma Jet (APPJ) technology for surface treatment of carbon fabrics is investigated to estimate the increase in the fracture toughness of carbon-fiber composite materials. Nitrogen and a nitrogen–hydrogen gas mixture were used to size the carbon fabrics by preliminarily optimizing the process parameters. The effects of the APPJ on the carbon fabrics were investigated by using optical and chemical characterizations. Optical Emission Spectroscopy, Fourier Transform Infrared-Attenuated Total Reflection, X-ray Photoelectron Spectroscopy and micro-Raman spectroscopy were adopted to assess the effectiveness of ablation and etching effects of the treatment, in terms of grafting of new functional groups and active sites. The treated samples showed an increase in chemical groups grafted onto the surfaces, and a change in carbon structure was influential in the case of chemical interaction with epoxy groups of the epoxy resin adopted. Flexural test, Double Cantilever Beam and End-Notched Flexure tests were then carried out to characterize the composite and evaluate the fracture toughness in Mode I and Mode II, respectively. N2/H2 specimens showed significant increases in GIC and GIIC, compared to the untreated specimens, and slight increases in Pmax at the first crack propagation.
The Effect of Cr Addition on the Strength and High Temperature Oxidation Resistance of Y2O3 Dispersion Strengthened Mo Composites
Authors: Guan Haochen , Lv Chongshan , Ding Qingming , Wang Guangda , Xiong Ning , Zhou Zhangjian
Published: May 2024

Y2O3 dispersion-strengthened Molybdenum (Mo) composites were prepared by the mechanical alloying of Mo and Y powders then consolidation by spark plasma sintering. The effects of Chromium (Cr) addition (0 wt. %, 5 wt. %, 10 wt. % and 15 wt. %, respectively) on the mechanical performance and high-temperature oxidation resistance of Mo-Y2O3 were investigated. The introduction of Cr had a significant influence on the mechanical property and oxidation resistance of the Mo-Y2O3 composite. The highest bending strength reached 932 MPa when the addition of Cr content was 5 wt. % (Mo–5Cr–1Y sample). This improvement is likely attributable to the dual mechanism of grain refinement and solid solution strengthening. Moreover, the Mo–5Cr–1Y sample showed the thinnest oxide layer thickness after high-temperature oxidation tests, and exhibited the best oxidation resistance performance compared with the other samples. First principle calculation reveals that Cr could improve the Mo–MoO3 interface bonding to prevent rapid spalling of the oxide layer. Meanwhile, Cr also facilitates the formation of the dense Cr2(MoO4)3 layer on the surface, which can inhibit further oxidation.
Comparative Study of the Optical and Dielectric Anisotropy of a Difluoroterphenyl Dimer and Trimer Forming Two Nematic Phases
Authors: Zavvou Evangelia E. , Welch Chris , Mehl Georg H. , Vanakaras Alexandros G. , Karahaliou Panagiota K.
Published: May 2024

We present a comparative study of the optical and dielectric anisotropy of a laterally fluorinated liquid crystal dimer and its homologous trimer, both exhibiting two nematic phases. In the high-temperature nematic phase, both oligomers exhibit positive optical anisotropy with similar magnitude, which, however, is lower in comparison with the optical anisotropy of the monomer. In the same temperature range, the dielectric permittivity along and perpendicular to the nematic director, measured on magnetically aligned samples, reveals negative dielectric anisotropy for both oligomers, which saturates as the temperature approaches the N–N phase transition temperature. Comparison of the dielectric anisotropies of the oligomers with the corresponding anisotropy of the monomer indicates a systematic variation of its magnitude with the number of the linked mesogenic units. Results are compared with the corresponding anisotropies of the cyanobiphenyl dimers, the archetypal compounds with two nematic phases, and are discussed in terms of the dipolar structure of the mesogens and the dipolar correlations in their nematic phases.
Study on Shear Performance of Corroded Steel Fiber Reinforced Concrete Beams under Impact Load
Authors: Gu Jianxiao , Li Liancheng , Huang Xin , Chen Hui
Published: May 2024

With the growing use of steel-fiber-reinforced-concrete (SFRC) beams in environmentally friendly and rapid construction, it is essential to assess their impact performance. These beams may encounter unexpected impact loadings from accidents or terrorist attacks during service life. This study explored the impact of steel fiber content and drop hammer height on the impact load testing of corrosion-treated SFRC beams. Experiments were conducted with varying steel fiber contents (0%, 0.25%, 0.5%, 0.75%, and 1.0%), and drop hammer height (1 m, 2 m, and 3 m). The corrosion test demonstrates that SFRC beams supplemented with steel fibers showcase a diminished surface rust spot area in comparison to those lacking fibers. This improvement is ascribed to the bonding between fibers and the concrete matrix, along with their current-sharing properties. SFRC beams, subjected to impact testing, exhibit concrete crushing at the top without spalling, showcasing improved impact resistance due to increased fiber content, which reduces crack formation. Additionally, different fiber contents yield varied responses to impact loads, with higher fiber content notably enhancing overall beam performance and energy dissipation capacity. Energy dissipation analysis shows a moderate increase with higher fiber contents, and impulse impact force generally rises with fiber content, indicating improved impact resistance.
Applying a Tripodal Hexaurea Receptor for Binding to an Antitumor Drug, Combretastatin-A4 Phosphate
Authors: Kong Yu , Zhang Rong , Li Boyang , Zhao Wei , Wang Ji , Sun Xiao-Wen , Lv Huihui , Liu Rui , Tang Juan , Wu Biao
Published: May 2024

Phosphates play a crucial role in drug design, but their negative charge and high polarity make the transmembrane transport of phosphate species challenging. This leads to poor bioavailability of phosphate drugs. Combretastatin-A4 phosphate (CA4P) is such an anticancer monoester phosphate compound, but its absorption and clinical applicability are greatly limited. Therefore, developing carrier systems to effectively deliver phosphate drugs like CA4P is essential. Anion receptors have been found to facilitate the transmembrane transport of anions through hydrogen bonding. In this study, we developed a tripodal hexaurea anion receptor (L1) capable of binding anionic CA4P through hydrogen bonding, with a binding constant larger than 104 M−1 in a DMSO/water mixed solvent. L1 demonstrated superior binding ability compared to other common anions, and exhibited negligible cell cytotoxicity, making it a promising candidate for future use as a carrier for drug delivery.
Application of Digital Image Correlation for Strain Mapping of Structural Elements and Materials
Authors: Bogusz Paweł , Krasoń Wiesław , Pazur Kamil
Published: May 2024

The strain gauge method and the digital image correlation (DIC) method are commonly employed for measuring strain in tested objects, including material specimens and structural elements. The optical method enables the assessment of 3D strain fields across the entire area of interest, achieved through cameras and advanced software. The study investigates both quasi-static strength tests and more advanced research of structures. It explores full-scale construction testing, featuring highly stressed components of new wagon designs. The paper reviews the benefits and challenges of using the DIC method to measure large-scale elements. Conducting full-scale object testing is characterized by significant complexity, often involving interactions between elements, complex loading conditions, and the influence of friction. Numerous factors affect the measurements. Therefore, to compare both methods, an initially standard shear by tensile test of CFRP composite was analyzed. The analysis of strain maps provides valuable visualization of deformation patterns occurring during construction loading. The strain gauge method was crucial for verifying the quality of the DIC measurements. The results obtained provide a detailed understanding of how the components behave, highlighting the versatility of digital image correlation technology. For strain values of 0.3% and above, a good match was obtained between optical and strain gauge measurements. Below this value, the results have less accuracy. The results obtained provide a detailed understanding of how the components behave, highlighting the versatility of digital image correlation technology. The error comparison and discussion between different measurement scenarios were conducted. The paper presents a developed methodology for measuring strain and displacement state in complex and crucial structural elements. The method can be applied to measurements of heavily loaded components used in the transportation industry; for example, in railways.
Potential of Reusing 3D Printed Concrete (3DPC) Fine Recycled Aggregates as a Strategy towards Decreasing Cement Content in 3DPC
Authors: Skibicki Szymon , Federowicz Karol , Hoffmann Marcin , Chougan Mehdi , Sibera Daniel , Cendrowski Krzysztof , Techman Mateusz , Pacheco João Nuno , Liard Maxime , Sikora Pawel
Published: May 2024

This paper explores the new potential strategy of using fine recycled aggregates (fRA) derived from waste 3D printed concrete (3DPC) as a substitute for cement in additive manufacturing. This study hypothesizes that fRA can optimize mixture design, reduce cement content, and contribute to sustainable construction practices. Experimental programs were conducted to evaluate the fresh and hardened properties, printability window, and buildability of 3DPC mixes containing fRA. Mixes with replacement rates of cement with fRA by 10 vol%, 20 vol%, 30 vol%, 40 vol%, and 50 vol% were produced. A comprehensive experimental protocol consisting of rheological studies (static and dynamic yield stress), dynamic elastic modulus determination (first 24 h of hydration), flexural and compressive strengths (2 d and 28 d), and an open porosity test was performed. The obtained results were verified by printing tests. In addition, an economic and environmental life cycle assessment (LCA) of the mixes was performed. The results indicate that up to 50 vol% cement replacement with fRA is feasible, albeit with some technical drawbacks. While fRA incorporation enhances sustainability by reducing CO2 emissions and material costs, it adversely affects the printability window, green strength, setting time, and mechanical properties, particularly in the initial curing stages. Therefore, with higher replacement rates (above 20 vol%), potential optimization efforts are needed to mitigate drawbacks such as reduced green strength and buildability. Notably, replacement rates of up to 20 vol% can be successfully used without compromising the overall material properties or altering the mixture design. The LCA analysis shows that reducing the cement content and increasing the fRA addition results in a significant reduction in mix cost (up to 24%) and a substantial decrease in equivalent CO2 emissions (up to 48%). In conclusion, this study underscores the potential of fRA as a sustainable alternative to cement in 3D printed concrete.
Fine-Tuning Artificial Neural Networks to Predict Pest Numbers in Grain Crops: A Case Study in Kazakhstan
Authors: Anarbekova Galiya , Ruiz Luis Gonzaga Baca , Akanova Akerke , Sharipova Saltanat , Ospanova Nazira
Published: May 2024

This study investigates the application of different ML methods for predicting pest outbreaks in Kazakhstan for grain crops. Comprehensive data spanning from 2005 to 2022, including pest population metrics, meteorological data, and geographical parameters, were employed to train the neural network for forecasting the population dynamics of Phyllotreta vittula pests in Kazakhstan. By evaluating various network configurations and hyperparameters, this research considers the application of MLP, MT-ANN, LSTM, transformer, and SVR. The transformer consistently demonstrates superior predictive accuracy in terms of MSE. Additionally, this work highlights the impact of several training hyperparameters such as epochs and batch size on predictive accuracy. Interestingly, the second season exhibits unique responses, stressing the effect of some features on model performance. By advancing our understanding of fine-tuning ANNs for accurate pest prediction in grain crops, this research contributes to the development of more precise and efficient pest control strategies. In addition, the consistent dominance of the transformer model makes it suitable for its implementation in practical applications. Finally, this work contributes to sustainable agricultural practices by promoting targeted interventions and potentially reducing reliance on chemical pesticides.
Navigating Uncharted Waters: The Transformation of the Bank of Korea’s Monetary Policy in Response to Global Economic Uncertainty
Authors: He Yugang , Teng Zhuoqi
Published: May 2024

The evolving global economic landscape necessitates adaptive monetary policies, especially for economies like South Korea that are deeply integrated with global markets. This research explores the strategic recalibrations of the Bank of Korea’s monetary policy amid fluctuations in global economic uncertainty. Utilizing a sophisticated microeconomic theoretical framework, this study employs Bayesian estimation techniques and impulse response analysis to dissect the dynamic effects of these global shocks on South Korea’s macroeconomic stability and policy direction. Our findings reveal that the Bank of Korea has adeptly navigated through turbulent economic conditions induced by external shocks through well-coordinated policy adaptations. These adaptations, which include both traditional and innovative monetary tools, have been crucial in stabilizing the financial environment and promoting economic growth. By detailing the tailored application of the Taylor rule within the Korean context and strategic foreign exchange interventions by the central bank, this study contributes significantly to the broader discourse on the efficacy of monetary policy in open economies and offers insights on integrating advanced analytical methods into economic policy analysis.
Mathematical Logic Model for Analysing the Controllability of Mining Equipment
Authors: Shishkin Pavel V. , Malozyomov Boris V. , Martyushev Nikita V. , Sorokova Svetlana N. , Efremenkov Egor A. , Valuev Denis V. , Qi Mengxu
Published: May 2024

The issues of the evaluation and prediction of the reliability and testability of mining machinery and equipment are becoming particularly relevant, since the safety of technological processes and human life is reaching a new level of realisation due to changes in mining technology. The work is devoted to the development of a logical model for analysing the controllability of mining equipment. The paper presents a model of reliability of the operation of mining equipment on the example of a mine load and passenger hoist. This generalised model is made in the form of a graph of transitions and supplemented with a system of equations. The model allows for the estimation of the reliability of equipment elements and equipment as a whole. A mathematical and logical model for the calculation of the availability and downtime coefficients of various designs of mining equipment systems is proposed. This model became the basis for the methods to calculate the optimal values of diagnostic depth. At these calculated values, the maximum value of availability factor will be obtained. In this paper, an analytical study was carried out and dependences of the readiness factor of parameters of the investigated system such as the intensity of control of technical systems, intensity of failures, etc., were constructed. The paper proposes a mathematical model to assess the reliability of mine hoisting plants through its integration into the method of improving the reliability of mine hoisting plants.
Deterministic and Stochastic Nonlinear Model for Transmission Dynamics of COVID-19 with Vaccinations Following Bayesian-Type Procedure
Authors: Jeelani Mohammadi Begum , Din Rahim Ud , Alhamzi Ghaliah , Hleili Manel , Alrabaiah Hussam
Published: May 2024

We develop a mathematical model for the SARAS-CoV-2 double variant transmission characteristics with variant 1 vaccination to address this novel aspect of the disease. The model is theoretically examined, and adequate requirements are derived for the stability of its equilibrium points. The model includes the single variant 1 and variant 2 endemic equilibria in addition to the endemic and disease-free equilibria. Various approaches are used for the global and local stability of the model. For both strains, we determine the basic reproductive numbers R1 and R2. To investigate the occurrence of the layers (waves), we expand the model to include some analysis based on the second-order derivative. The model is then expanded to its stochastic form, and numerical outcomes are computed. For numerical purposes, we use the nonstandard finite difference method. Some error analysis is also recorded.
Bifurcation Analysis in a Coffee Berry-Borer-and-Ants Prey–Predator Model
Authors: Trujillo-Salazar Carlos Andrés , Olivar-Tost Gerard , Sotelo-Castelblanco Deissy Milena
Published: May 2024

One of the most important agricultural activities worldwide, coffee cultivation, is severely affected by the Coffee Berry Borer (CBB), Hypothenemus hampei, considered the primary coffee pest. The CBB is a tiny beetle that diminishes the quantity and quality of coffee beans by penetrating them to feed on the endosperm and deposit its eggs, continuing its life cycle. One strategy to combat CBBs is using biological control agents, such as certain species of ants. Here, a mathematical model (consisting of a system of nonlinear ordinary differential equations) is formulated to describe the prey–predator interaction between CBBs and an unspecified species of ants. From this mathematical perspective, the model allows us to determine conditions for the existence and stability of extinction, persistence or co-existence equilibria. Transitions among those equilibrium states are investigated through the maximum per capita consumption rate of the predator as a bifurcation parameter, allowing us to determine the existence of transcritical and saddle-node bifurcations. Phase portraits of the system are presented for different values of bifurcation parameter, to illustrate stability outcomes and the occurrence of bifurcations. It is concluded that an increase in bifurcation parameters significantly reduces the CBB population, suggesting that ant predation is an effective control strategy, at least theoretically.
A Review on Large-Scale Data Processing with Parallel and Distributed Randomized Extreme Learning Machine Neural Networks
Authors: Gelvez-Almeida Elkin , Mora Marco , Barrientos Ricardo J. , Hernández-García Ruber , Vilches-Ponce Karina , Vera Miguel
Published: May 2024

The randomization-based feedforward neural network has raised great interest in the scientific community due to its simplicity, training speed, and accuracy comparable to traditional learning algorithms. The basic algorithm consists of randomly determining the weights and biases of the hidden layer and analytically calculating the weights of the output layer by solving a linear overdetermined system using the Moore–Penrose generalized inverse. When processing large volumes of data, randomization-based feedforward neural network models consume large amounts of memory and drastically increase training time. To efficiently solve the above problems, parallel and distributed models have recently been proposed. Previous reviews of randomization-based feedforward neural network models have mainly focused on categorizing and describing the evolution of the algorithms presented in the literature. The main contribution of this paper is to approach the topic from the perspective of the handling of large volumes of data. In this sense, we present a current and extensive review of the parallel and distributed models of randomized feedforward neural networks, focusing on extreme learning machine. In particular, we review the mathematical foundations (Moore–Penrose generalized inverse and solution of linear systems using parallel and distributed methods) and hardware and software technologies considered in current implementations.
The Association between Cafestol and Cardiovascular Diseases: A Comprehensive Review
Authors: Hao Wen-Rui , Cheng Chun-Yao , Chen Huan-Yuan , Chen Jin-Jer , Cheng Tzu-Hurng , Liu Ju-Chi
Published: May 2024

Cafestol, a bioactive compound found in coffee, has attracted considerable attention due to its potential impact on cardiovascular health. This review aims to comprehensively explore the association between cafestol and cardiovascular diseases. We delve into the mechanisms through which cafestol influences lipid metabolism, inflammation, and endothelial function, all of which are pivotal in cardiovascular pathophysiology. Moreover, we meticulously analyze epidemiological studies and clinical trials to elucidate the relationship between cafestol and cardiovascular outcomes. Through a critical examination of existing literature, we aim to provide insights into the potential benefits and risks associated with cafestol concerning cardiovascular health.
Surgery for Active Infective Endocarditis on Mitral Valve: Anatomical, Surgical, and Disease Factors as Long-Term Outcome Modifiers
Authors: Berretta Paolo , Bifulco Olimpia , Luthra Suvitesh , Tessari Chiara , Zingale Anna , Bergonzoni Emma , Galeazzi Michele , Lombardi Valentina , Malvindi Pietro Giorgio , Gerosa Gino , Ohri Sunil , Di Eusanio Marco
Published: May 2024

Background and Objectives: Determinants of long-term outcomes after surgery for native mitral valve endocarditis have not been thoroughly investigated. The aim of this study was to assess anatomical, disease, and surgical risk factors for long-term mortality and need of reintervention, in patients undergoing mitral valve surgery for active endocarditis. Materials and Methods: Patients who underwent surgery for active native mitral valve endocarditis at three academic centres, between 2000 and 2022, were analysed. The primary outcome was long-term survival. The secondary outcome was the freedom from mitral reoperation. Survival curves were constructed with Kaplan–Meier methodology. Multivariable Cox regression was used to identify demographic, anatomical, disease, and surgical factors associated with late mortality and reoperation. Results: 335 consecutive patients with active mitral endocarditis were analysed. Two hundred and one patients (70.5%) had infection confined to the valve cusp whereas 89 (25.6%) had invasive disease extended to the annulus and surrounding tissues. Preoperative neurological events occurred at the diagnosis in 52 cases. Streptococci were the most common causative organisms followed by Staphylococcus aureus, Coagulase-negative Staphylococcus, and Enterococcus. Valve repair was performed in 108 patients (32.2%). Survival at 5 and 10 years was 70.1% and 59.2%, respectively. Staphylococcus emerged as an independent predictor of late mortality, along with age, chronic obstructive pulmonary disease, and previous cardiac surgery. Survival was considerably reduced in patients with S. aureus compared with those without (log rank p < 0.001). The type of surgery (repair vs. replacement) did not emerge as a risk factor for late mortality and reoperation. Seventeen patients underwent mitral reoperation during the follow-up. The 5- and 10-year freedom from reoperation was 94.7% and 91.8%, respectively. Conclusions: Active mitral valve endocarditis remains a life-threatening disease with impaired survival. While lesion characteristics influenced surgical decision-making and intraoperative management, their impact on long-term survival and freedom from reintervention appears to be moderated by other factors such as infecting pathogens and patient comorbidities.
ACOM/TEM and EBSD Microstructure Characterization of ECAE-Processed Zirconium
Authors: Companhoni Mychelle Vianna Pereira , Gonçalves Além-mar Bernardes , Ferrante Maurizio , Sordi Vitor , Pinto André Luiz
Published: May 2024

Materials produced through equal channel angular extrusion (ECAE) may offer enhanced mechanical properties over classic thermomechanical processing like extrusion or rolling. Conventional techniques such as electron backscatter diffraction (EBSD) may be insufficient to properly characterize the microstructure of these materials. Darkfield (DF) transmission electron microscopy (TEM), on the other hand, may lead to erroneous conclusions with respect to grain size. In this work, zirconium was submitted to ECAE deformation through four passes in the Bc route at 350 °C. The microstructure was evaluated through FEG-SEM/EBSD (field emission gun–scanning electron microscopy), DF TEM, and ACOM/TEM (automated crystal orientation mapping in TEM). EBSD revealed that the microstructure was heterogeneous with a few large grains surrounded by a fine submicrometric structure, which was only partially resolved through this technique. The fine structure was, however, described through ACOM/TEM. DF TEM was revealed to be somewhat unreliable when the same region was evaluated through ACOM/TEM. Therefore, a combination of techniques seems to be required for proper characterization.
Precipitation Thermodynamics in an Al–Zn–Mg Alloy with Different Grain Sizes
Authors: Wang Zhen , Huang Siqi , Zhang Wenkai , Li Shunqiang , Liu Jizi
Published: May 2024

In order to gain insight into the influence of grain size on precipitation thermodynamics, bulk materials of coarse-grained (CG), ultrafine-grained (UFG) (with or without dislocations), and nanocrystalline (NC) 7075 Al alloy have been fabricated by solid solution treatment, equal-channel angular pressing (ECAP), or high-pressure torsion (HPT) processes. The precipitation behavior and the corresponding thermal phenomenon were studied by transmission electron microscopy (TEM) and differential scanning calorimetry (DSC) heating. The results indicated that there are significant differences in precipitation thermodynamics among the four bulk materials. In the CG and UFG materials without dislocations, homogeneous nucleation is the primary precipitation mechanism. However, the nucleation of the GP zones is suppressed at lower temperatures due to a reduction in the number of residual vacancies and the supersaturation in the UFG interiors. This is attributed to the absorption of vacancies and solute atoms by a greater volume of grain boundaries. It can be observed that the greater the excess of vacancies remaining in grain interiors, the lower the temperature at which nucleation of GP zones occurs. Defect-assisted heterogeneous nucleation was identified as the predominant precipitation mechanism in the UFG materials with dislocations and the NC materials. These defects encompass dislocations, lattice distortions, and grain boundaries. The decomposition processes of solid solutions were found to be almost complete at a lower temperature. The presence of dislocations, lattice distortions, and grain boundaries enables solute atoms to diffuse at a much faster rate, significantly enhancing the precipitation rate and reducing the nucleation and formation energies of various precipitate phases.
Effect of Al2O3 on Crystallization, Microstructure, and Properties of Glass Ceramics Based on Lead Fuming Furnace-Slag
Authors: Zhang Ning , Xie Feng , Wang Wei , Lu Diankun
Published: May 2024

In the paper, glass ceramics used as architectural materials were prepared based on lead fuming furnace-slag (LFFS) by a synergistic sinter-crystallization method. The effects of Al2O3 addition on the crystallization phase, crystallization kinetics, and mechanical performance of glass ceramics were investigated. The results showed that the phases of the glass ceramics prepared were composed of gehlenite and wollastonite, and crystallization kinetics analysis showed that bulk crystallization dominated the overall crystallization process in the Al2O3 content range from 2% to 8%. The glass transition temperature and the crystallization peak temperature of the glass ceramics generally increased with the increase in the Al2O3 content. Additionally, the crystalline morphology gradually developed from sheet-like to spherical, while the number of pores increased and the bulk density gradually decreased. When the Al2O3 content was 2%, the bending strength of glass ceramics reached its maximum, 75.1 MPa, corresponding to a bulk density of 2.24 g·cm−3. Owing to the high strength and relatively low bulk density, the sintered glass ceramics appear promising for potential applications in lightweight construction tiles.
Microstructure Tailoring for High Strength Ti-6Al-4V without Alloying Elements through Optimized Preheating and Post-Heating Laser Scanning in Laser Powder Bed Fusion
Authors: Tanrikulu Ahmet Alptug , Ganesh-Ram Aditya , Hekmatjou Hamidreza , Durlov Sadman Hafiz , Salehin Md Najmus , Amerinatanzi Amirhesam
Published: May 2024

Ti-6Al-4V with its eclectic array of excellent properties along with the combination of meticulous precision and flexibility offered by the laser powder bed fusion (LPBF) technology makes it a strong proponent in the field of engineering applications. As a substantial amount of research has paved the way to fabricate Ti-6AL-4V more effectively and efficiently, researchers are becoming more adventurous in finding out the optimal techniques to get better yields in terms of mechanical responses. This includes post-processing techniques i.e., heat treatment (HT) or introducing various alloying elements. Nevertheless, these techniques not only make the overall fabrication more expensive and time-consuming but also contradict the simplistic notion of additive manufacturing (AM) by imparting multistage fabrication without a considerable improvement overall. Here, we propose an innovative breakthrough in the field of Ti-6AL-4V fabrication with LPBF by introducing an in-situ approach to tackle the handicap mentioned in contemporary studies. By imparting multiple laser scans prior to and after the melting scan at each layer, a remarkable 37% improvement in yield strength (YS) can be achieved with higher elongation, while also maintaining a high relative density of around 99.99%.
Separation of Zr and Si in Zirconium Silicate by Sodium Hydroxide Sub-Molten Salt
Authors: Sun Hongqian , Song Jing , Qi Tao
Published: May 2024

In order to cleanly and efficiently extract zirconium from zircon sand (the main component is ZrSiO4), sodium hydroxide sub-molten salt was used to decompose ZrSiO4 in this study. When ZrSiO4 reacts with sodium hydroxide sub-molten salt, the formation of Na2ZrSiO5 (a water-insoluble product) considerably affects the separation efficiency of Zr and Si and increases production cost. Thus, it is necessary to control the formation of Na2ZrSiO5. The influence of NaOH content, reaction temperature, reaction time, and NaOH/ore mass ratio on the formation of Na2ZrSiO5 were systematically investigated. The optimum reaction parameters for the inhibition of Na2ZrSiO5 formation were as follows: 80% NaOH content, 245 °C reaction temperature, 4:1 NaOH/ore mass ratio, 10 h reaction time, and 400 r/min agitation speed. These results indicate that ZrSiO4 is decomposed to Na2ZrO3 and Na2SiO3 by reacting with NaOH, realizing the separation of Zr and Si, and then the reactions between Na2ZrO3 and Na2SiO3 result in the formation of Na2ZrSiO5, during the decomposition of ZrSiO4 using NaOH sub-molten salt. The sub-molten salt decomposition process can realize the clean extraction of zirconium, which is conducive to the sustainable development of zirconium resources.
Loss-Optimized Design of Magnetic Devices
Authors: Zhao Yuhu , Ming Zhengfeng , Du Chaofan
Published: May 2024

Maximizing efficiency, power density, and reliability stands as paramount objectives in the advancement of power electronic systems. Notably, the dimensions and losses of magnetic components emerge as primary constraints hindering the miniaturization of such systems. Researchers have increasingly focused on the design of loss minimization and size optimization of magnetic devices. In this paper, with the objective of minimizing the loss of magnetic devices, an optimal design method for the winding structure of devices is proposed based on the coupling relationship between the loss prediction model and the design variables. The method examines the decoupling conditions between the design variables and the loss model, deriving optimized design closure equations for the design variables. This approach furnishes a technical foundation for the miniaturized design of miniature apparatuses incorporating magnetic components, offering a straightforward and adaptable design methodology. The finite element method simulation results and experimental measurement data verify the accuracy of the prediction of the proposed method and the validity of the optimal design theory of device loss.
Constrained Volume Micro- and Nanoparticle Collection Methods in Microfluidic Systems
Authors: Wells Tanner , Schmidt Holger , Hawkins Aaron
Published: May 2024

Particle trapping and enrichment into confined volumes can be useful in particle processing and analysis. This review is an evaluation of the methods used to trap and enrich particles into constrained volumes in microfluidic and nanofluidic systems. These methods include physical, optical, electrical, magnetic, acoustic, and some hybrid techniques, all capable of locally enhancing nano- and microparticle concentrations on a microscale. Some key qualitative and quantitative comparison points are also explored, illustrating the specific applicability and challenges of each method. A few applications of these types of particle trapping are also discussed, including enhancing biological and chemical sensors, particle washing techniques, and fluid medium exchange systems.
Bidirectional Optical Neural Networks Based on Free-Space Optics Using Lens Arrays and Spatial Light Modulator
Authors: Ju Young-Gu
Published: May 2024

This paper introduces a novel architecture—bidirectional optical neural network (BONN)—for providing backward connections alongside forward connections in artificial neural networks (ANNs). BONN incorporates laser diodes and photodiodes and exploits the properties of Köhler illumination to establish optical channels for backward directions. Thus, it has bidirectional functionality that is crucial for algorithms such as the backpropagation algorithm. BONN has a scaling limit of 96 × 96 for input and output arrays, and a throughput of 8.5 × 1015 MAC/s. While BONN’s throughput may rise with additional layers for continuous input, limitations emerge in the backpropagation algorithm, as its throughput does not scale with layer count. The successful BONN-based implementation of the backpropagation algorithm requires the development of a fast spatial light modulator to accommodate frequent data flow changes. A two-mirror-like BONN and its cascaded extension are alternatives for multilayer emulation, and they help save hardware space and increase the parallel throughput for inference. An investigation into the application of the clustering technique to BONN revealed its potential to help overcome scaling limits and to provide full interconnections for backward directions between doubled input and output ports. BONN’s bidirectional nature holds promise for enhancing supervised learning in ANNs and increasing hardware compactness.
Research on the Coupling Effect of NBTI and TID for FDSOI pMOSFETs
Authors: Wei Hao , Liu Hongxia , Wang Shulong , Chen Shupeng , Yin Chenyv , Chen Yaolin , Gao Tianzhi
Published: May 2024

The coupling effect of negative bias temperature instability (NBTI) and total ionizing dose (TID) was investigated by simulation based on the fully depleted silicon on insulator (FDSOI) PMOS. After simulating the situation of irradiation after NBT stress, it was found that the NBTI effect weakens the threshold degradation of FDSOI PMOS under irradiation. Afterward, NBT stress was decomposed into high gate voltage stress and high-temperature stress, which was applied to the device simultaneously with irradiation. The devices under high gate voltage exhibited more severe threshold voltage degradation after irradiation compared to those under low gate voltage. Devices at high temperatures also exhibit more severe threshold degradation after irradiation compared to devices under low temperatures. Finally, the simultaneous effect of high gate voltage, high temperature, and irradiation on the device was investigated, which fully demonstrated the impact of the NBT stress on the TID effect, resulting in far more severe threshold voltage degradation.
Wideband Terminal Antenna System Based on Babinet’s Principle for Sub-6 GHz and Wi-Fi 6E/7 Applications
Authors: Han Chong-Zhi , Gong Guji , Wang Yan , Guo Jie , Zhang Liang
Published: May 2024

In this paper, a novel input impedance analysis methodology based on Babinet’s principle to broaden bandwidth is proposed, and a broadband multiple-input and multiple-output (MIMO) antenna system is designed, fabricated, and measured for fifth-generation (5G) and Wireless Fidelity (Wi-Fi) 6E/7 mobile applications. By analyzing the input impedance of open-slot antennas and planar monopole antennas using numerical calculations, the characteristics of the input impedance can be obtained. We find that combining the two antenna types in parallel can significantly enhance the bandwidth. Then, the four-dimensional image calculated by MATLAB based on the parallel impedance formula is processed to validate the methodology. Thus, a broad antenna element based on the impedance property analysis methodology is achieved, which operates ranging from 2.6 GHz to 7.46 GHz. Moreover, the equivalent circuit of the antenna element is established to further verify the validity of the methodology. Finally, a broadband MIMO antenna system consisting of eight antenna elements is designed, fabricated, and measured, and the isolation performance is better than 12 dB. Acceptable total efficiency higher than 45% is also obtained with envelope correlation coefficients (ECCs) lower than 0.05. The proposed impedance property analysis methodology innovatively proposes a new way to increase bandwidth, which can be widely applied in various antenna designs. Also, reasonable results show that the proposed MIMO antenna system is a good candidate for 5G and Wi-Fi 6E/7 mobile applications.
Dynamic Loading Characteristics of Cemented Paste Backfill with Recycled Rubber
Authors: Li Yang , Wang Xiaolong , Song Xiaobo , Yang Jie
Published: May 2024

The purpose of this study was to investigate the effect of the use of rubber powder from tire recovery on the dynamic loading performance of CPB. Finally, it is concluded that using recycled rubber material to backfill mine paste is helpful in reducing waste tire pollution and improving the impact resistance of the backfill body. The dynamic compressive strength, Dynamic Increase Factor (DIF), peak dynamic load strain, and dynamic load elastic modulus of the samples composed of slag, Portland cement, wastewater, and rubber powder were determined. Through the analysis of the experimental data, it can be seen that the recycled rubber reduces the dynamic compressive strength and DIF of the specimen but increases the peak dynamic load strain and dynamic load elastic modulus and other characteristics, and enhances the ability of the filled body to absorb elastic strain energy. The results show that recycled rubber can increase the deformation ability of the filler and improve the impact resistance of the filler. The results of this study provide valuable information and industrial applications for the effective management of solid waste based on sustainable development and the circular economy.