Hasil untuk "Materials Science"

Ruijia Wang, Hongda Guo, Tao Zhang et al.

ABSTRACT Fixation of CO2 through photocatalytic cycloaddition with epoxides to synthesize cyclic carbonates is an important but challenging process. In this work, carbon dots (CDs) synthesized from gallic acid and polyethylenimine are used for the efficient catalytic cycloaddition of CO2 with epoxides in the absence of any solvent, additives, and halides, and importantly upon irradiation by natural sunlight. Specifically, carbon dots generated thermal energy and electrons upon solar irradiation, which together with their surface N‐sites activated the inert CO2. Meanwhile, epoxides were activated by the surface hydroxyl and carboxylic groups of the carbon dots, which reacted with activated CO2 at solar thermal‐induced high temperatures. The CDs shows excellent stability and recyclability during the catalysis. A 1000 mmol scale reaction for cyclic carbonate synthesis performed well upon irradiation with natural sunlight in the presence of CDs, showing great potential for the industrial application due to the simple, mild, and energy‐saving process.

Qian Tang, Fushen Zhang, Weiye Xu et al.

Background: Oral diseases, such as dental caries, periodontal diseases, and oral cancers, represent significant global public health challenges. With the COVID-19 pandemic, traditional diagnostic methods have limitations, thus highlighting the need for innovative, early, and non-invasive diagnostic approaches. Analyse and summarise publications globally through a comprehensive bibliometric study to help researchers suggest possible directions for future research. Objective: The purpose of the study was to evaluate global academic productivity, impact, and collaboration of electrochemical biosensors for oral diseases utilising bibliometrics based on annual number of publications, countries and regions, institution, authors, journals, citations and co-occurrences of author keywords over the last 20 years. Methods: This study employs bibliometric analysis to assess the research of electrochemical biosensors for oral diseases in the Web of Science from 2000 to 2023. Utilising VOSviewer, CiteSpace software, and Microsoft Excel, we conducted a bibliometric and visualised analysis of electrochemical biosensors for oral diseases. Results: The quantity of pertinent publications in this research domain displays a fluctuating but overall upward trend. In aggregate, there are 341 articles and 82 reviews, encompassing research contributions from 55 countries, 649 institutions, and involving 2068 authors. Among these publications, China, the USA, and India emerged as the predominant contributing nations. Predominantly, articles found their publication venue in “Biosensors & Bioelectronics.” Notably, the author with the highest number of publications and most influence is Wang, Joseph S. The top 3 keywords include “biosensor,”“sensor,”“saliva.” Conclusion: In this investigation, statistical analysis and network visualisation were conducted to reveal the research progress, trends, and trending topics on electrochemical biosensors for oral diseases via a thorough bibliometric analysis. We found that Despite these challenges, electrochemical biosensors hold significant promise for transforming oral disease diagnostics. Overcoming current technical barriers will improve both oral and systemic health outcomes.

J.P. Pollard, T. Zagyva, C.S.J. Pickles et al.

Thermophysical properties are reported on ε-HfH2 samples fabricated by powder metallurgy. Samples were heat treated in the range 300–550 °C to transform them from ε-HfH2 to δ-HfH1.6-x, allowing comparison of the properties of both phases. Higher molar heat capacity was found in stoichiometric ε-HfH2 compared to literature data on sub-stoichiometric ε-HfH1.83. The δ-phase undergoes a vacancy order–disorder transformation at ∼130 °C with a transformation enthalpy of ∼1.4 kJ mol−1. The room-temperature thermal diffusivity of the ε and δ phases were 0.11 and 0.09 cm2 s−1 respectively. These values are lower than those for literature bulk hydride materials, which is accounted for by pore-phonon scattering. Thermal expansion of ε and δ phases was measured by high-temperature X-ray diffraction to be 9.2 and 11 x10-6 K−1, respectively. The data on the ε phase is the first known in the literature. The thermal expansion was highly anisotropic, with a negative thermal expansion parallel to the a-axis (Ra = −8.7). Such extreme anisotropy has implications in controlling the microstructure for thermal damage tolerance.

Guosong Han, Huihui Zhang, Zhixiang Li

IntroductionSpinal cord injury (SCI) represents a severe traumatic disorder of the central nervous system, leading to potential loss of motor and sensory functions. Its intricate pathological mechanism renders its treatment a formidable challenge. Recently, hydrogels have emerged as promising materials for spinal cord repair due to their exceptional biocompatibility and biodegradability, garnering significant attention. Consequently, extensive research on hydrogel applications in spinal cord injuries aims to provide an in-depth understanding of this field’s current state and delineate future research trajectories.MethodsA thorough search was conducted using the Web of Science Core Collection (WoSCC). Bibliometric tools such as CiteSpace, VOSviewer, Scimago Graphica, R and Bibliometrix software were employed to construct a knowledge map regarding the application of hydrogel in SCI.ResultsA bibliometric analysis of 1,015 publications between 2000 and 2025 elucidates the current research landscape, developmental trends, academic impact, and emerging knowledge dissemination patterns in hydrogel applications for SCI. The international collaboration in hydrogels-based SCI research exhibits a China-U.S.-centered network structure: as the top two publishing countries (464 vs. 278 publications), they maintain the closest bilateral collaboration, collectively forming a prominent transnational research network. The journal Biomaterials boasts the highest number of publications with 58 articles. Among prolific authors, Shoichet, Molly S., has authored the most papers, totaling 38 articles. There is a notable collaboration among various countries and institutions, with current research predominantly focusing on inflammation, apoptosis, nanoparticles, and injectable hydrogels. These efforts aim to achieve functionalized hydrogel regulation of microenvironmental changes, emerging as a focal point in contemporary research. This research highlights the latest trend of hydrogels in the treatment of SCI, thus pointing out the direction for new treatment strategies.DiscussionThe current research focus, which include the integration of functionalized hydrogels with biological factors, are setting the stage for subsequent investigative endeavors and the eventual clinical application of hydrogel in the treatment of SCI. This comprehensive analysis not only delineates the current state and emerging frontiers of hydrogel-based treatments for SCI but also provides a roadmap for future innovation.

Chanhee Park, Joonho Lee, Woo-Sang Jung

This study investigated the microstructural evolution of the γ′′, γ′, and δ phases during creep for alloy 718. Creep tests on two-step aged samples were conducted under different stresses and temperatures ranging from 600 to 700 °C. Analysis of precipitates was performed on two-step aged and crept samples using scanning electron microscopy and transmission electron microscopy. The creep rupture lives were decreased with increasing stresses and temperatures and showed a linear correlation between experimental data and Larson-Miller parameter curve predictions. The γ′′ phase was formed as a disc shape in the grain interior and had an orientation relationship of (001)γ′′//{001}γ and [100]γ′′//<100>γ with γ matrix. The length of the γ′′ phases increased with increasing temperatures and creep exposure time. The activation energy for γ′′ lengthening was 323 kJ/mol, similar to that for lattice diffusion of Nb in Ni. It was found that the formation mechanisms of δ phase were different from temperatures. The δ phase was formed in grain interiors and grain boundaries and had a blocky shape during a sub-δ solvus annealing process. On the other hand, the δ phase was formed as a plate shape and had an orientation relationship of (010)δ//(111¯)γ and [102]δ//[011]γ with γ matrix at creep temperatures. The growth rates of plate δ phase were faster than blocky δ phase at all creep temperatures.

Niels Taubert

This paper reviews research literature on Diamond Open Access (DOA) journals - sometimes also called Platinum Open Access - that was produced after this journal segment started to become a priority in European research policy around 2020. It contextualizes the current science policy debate, critically examines different understandings of DOA, and reviews studies on the role of such journals in scholarly communication. Most existing research consists of quantitative studies focusing on aspects such as the number of DOA journals, their publication output, the diversity of the landscape in terms of subject areas, languages, publishing entities, indexing in major databases, awareness and perception among scholars, cost analyses, as well as insights into the internal operations of DOA journals. The review shows that research on DOA journals is partly influenced by the science policy discourse in at least two ways: first, through the normativity inherent in that discourse, and second, through the temporality of policy-driven research of practical relevance, which leaves important aspects of the phenomenon understudied. Moreover, research on the DOA journal landscape has implications beyond understanding this particular journal segment, as it also challenges established views of the global system of scholarly communication.

Hang Jiang, Tal August, Luca Soldaini et al.

The field of Computer science (CS) has rapidly evolved over the past few decades, providing computational tools and methodologies to various fields and forming new interdisciplinary communities. This growth in CS has significantly impacted institutional practices and relevant research communities. Therefore, it is crucial to explore what specific research values, known as basic and fundamental beliefs that guide or motivate research attitudes or actions, CS-related research communities promote. Prior research has manually analyzed research values from a small sample of machine learning papers. No prior work has studied the automatic detection of research values in CS from large-scale scientific texts across different research subfields. This paper introduces a detailed annotation scheme featuring ten research values that guide CS-related research. Based on the scheme, we build value classifiers to scale up the analysis and present a systematic study over 226,600 paper abstracts from 32 CS-related subfields and 86 popular publishing venues over ten years.

Kyle D. Miller, Michele Campbell, Danilo Puggioni et al.

We introduce decoratypes as a structure taxonomy that classifies compounds based on site decorations of specific structural prototypes. Building on this foundation, a ferroelectric materials discovery framework is developed, integrating decoratypes with an active learning approach to accelerate exploration. In addition, six novel ferroelectric candidates are predicted, including three strain-activated ferroelectrics and three strain-activated hyperferroelectrics. These findings highlight the potential of the decoratype taxonomy to enhance our understanding of structure-driven material properties and facilitate the discovery of promising yet underexplored regions of chemical space.

Chenhang Xu, Alfred Zong

Quantum materials hold immense promises for future applications due to their intriguing electronic, magnetic, thermal, and mechanical properties that often arise from a complex interplay between microscopic degrees of freedom. Important insights of such interactions come from studying the collective excitations of electrons, spins, orbitals, and lattice, whose cooperative motions play a crucial role in determining the novel behavior of these systems and offer us a key tuning knob to modify material properties on-demand through external perturbations. In this regard, ultrafast light-matter interaction has shown great potential in controlling the couplings of collective excitations, and rapid progress in a plethora of time-resolved techniques down to the attosecond regime has significantly advanced our understanding of the coupling mechanisms and guided us in manipulating the dynamical properties of quantum materials. This review aims to highlight recent experiments on visualizing collective excitations in the time domain, focusing on the coupling mechanisms between different collective modes such as phonon-phonon, phonon-magnon, phonon-exciton, magnon-magnon, magnon-exciton, and various polaritons. We introduce how these collective modes are excited by an ultrashort laser pulse and probed by different ultrafast techniques, and we explain how the coupling between collective excitations governs the ensuing nonequilibrium dynamics. We also provide some perspectives on future studies that can lead to discoveries of the emergent properties of quantum materials both in and out of equilibrium.

Felix Wetzler, Jan-Erik Nebel, Wei Zhang et al.

When fabricating magnetic components for micro-electro-mechanical systems, the intrinsic material properties as well as the magnetic anisotropy of the deposited material and the fabricated devices must be adjusted to the application. This work focuses on electrochemically deposited cobalt phosphorus layers from a sulfate-based electrolyte to be used as hard magnetic scales in position measurement systems. In preliminary tests round discs (5 mm diameter, 20 or 10 μm height) were fabricated, showing the influence of three process parameters (current density, pH-value and temperature) on the chemical composition and the magnetic behavior of the deposited cobalt phosphorus. Hereby deposition parameters to produce hard magnetic cobalt phosphorus are defined. Deposits with up to 6 wt.-% phosphorus show hard magnetic behavior, whereas deposits with more than 6 wt.-% show soft magnetic behavior. This is correlated with a transition from crystalline to amorphous structures. In further investigations arrays of micro scales (40 μm width, 10 μm height) were fabricated to show the influence of direct current and pulsed current on the properties of the deposits. Pulsed current increases coercive field strength by about 40 %, resulting in maximum values of 23 kA/m (in-plane) and 14 kA/m (out-of-plane). Remanence increases by about 30 %, resulting in maximum values of 0.40 T (in-plane) and 0.2 T (out-of-plane). Pulse plating changes preferred orientation from (110) to (100) and slightly increases grain size by about 20 %, resulting in an average grain size of 25 nm.

Berhane Nugusse Zereay, Sándor Kálvin, György Juhász et al.

We developed and applied a new calibration method to make more accurate measurements with our multi-color ellipsometric mapping tool made from cheap parts. Ellipsometry is an optical technique that measures the relative change in the polarization state of the measurement beam induced by reflection from or transmission through a sample. During conventional ellipsometric measurement, the data collection is relatively slow and measures one spot at a time, so mapping needs a long time compared with our new optical mapping equipment made by an ordinary color LED monitor and a polarization-sensitive camera. The angle of incidence and the incident polarization state is varied point by point, so a special optical calibration method is needed. Three SiO₂ samples with different thicknesses were used for the point-by-point determination of the angle of incidence and rho (ρ) corrections. After the calibration, another SiO₂ sample was measured and analyzed using the calibrated corrections; further, this sample was independently measured using a conventional spectroscopic ellipsometer. The difference between the two measured thickness maps is less than 1 nm. Our optical mapping tool made from cheap parts is faster and covers wider area samples relative to conventional ellipsometers, and these correction enhancements further demonstrate its performance.

Qiu Yin, Yucheng Luo, Xianglin Yu et al.

Abstract Cell‐laden hydrogel fibers/tubules are one of the fundamentals of tissue engineering. They have been proven as a promising method for constructing biomimetic tissues, such as muscle fibers, nerve conduits, tendon and vessels, etc. However, current hydrogel fiber/tubule production methods have limitations in ordered cell arrangements, thus impeding the biomimetic configurations. Acoustic cell patterning is a cell manipulation method that has good biocompatibility, wide tunability, and is contact‐free. However, there are few studies on acoustic cell patterning for fiber production, especially on the radial figure cell arrangements, which mimic many native tissue‐like cell arrangements. Here, an acoustic cell patterning system that can be used to produce hydrogel fibers/tubules with tunable cell patterns is shown. Cells can be pre‐patterned in the liquid hydrogel before being extruded as cross‐linked hydrogel fibers/tubules. The radial patterns can be tuned with different complexities based on the acoustic resonances. Cell viability assays after 72 h confirm good cell viability and proliferation. Considering the biocompatibility and reliability, the present method can be further used for a variety of biomimetic fabrications.

Pengcheng Xiao, Yuxin Jin, Liguang Zhu et al.

The materials charged into a converter comprise molten iron and scrap steel. Adjusting the ratio by increasing scrap steel and decreasing molten iron is a steelmaking raw material strategy designed specifically for China’s unique circumstances, with the goal of lowering carbon emissions. To maintain the converter tapping temperature, scrap must be preheated to provide additional heat. Current scrap preheating predominantly utilizes horizontal tunnel furnaces, resulting in high energy consumption and low efficiency. To address these issues, a three-stage shaft furnace for scrap preheating was designed, and Fluent software was used to compare and study the preheating efficiency of the new three-stage furnace against the traditional horizontal furnace under various operational conditions. Initially, a three-dimensional transient multi-field coupling model was developed for two scrap preheating scenarios, examining the effects of both furnaces on scrap surface and core temperatures across varying preheating durations and gas velocities. Simulation results indicate that, under identical gas heat consumption conditions, scrap achieves markedly higher final temperatures in the shaft furnace compared to the horizontal furnace, with scrap surface and core temperatures increasing notably with extended preheating times and higher gas velocities, albeit with a gradual decrease in heating rate as the scrap temperature rises. At a gas velocity of 9 m/s and a preheating time of 600 s, the shaft furnace achieves the highest waste heat utilization rate for scrap, with scrap averaging 325 °C higher than in the horizontal furnace, absorbing an additional 202 MJ of heat per ton. In the horizontal preheating furnace, scrap steel exhibits a heat absorption efficiency of 35%, whereas in the vertical furnace, this efficiency increases notably to 63%. In the vertical furnace, the waste heat recovery rate of scrap steel reaches 57%.

Manish Parashar

Emerging data-driven scientific workflows are seeking to leverage distributed data sources to understand end-to-end phenomena, drive experimentation, and facilitate important decision-making. Despite the exponential growth of available digital data sources at the edge, and the ubiquity of non trivial computational power for processing this data, realizing such science workflows remains challenging. This paper explores a computing continuum that is everywhere and nowhere -- one spanning resources at the edges, in the core and in between, and providing abstractions that can be harnessed to support science. It also introduces recent research in programming abstractions that can express what data should be processed and when and where it should be processed, and autonomic middleware services that automate the discovery of resources and the orchestration of computations across these resources.

Michiko Yoshitake, Yuta Suzuki, Ryo Igarashi et al.

A college-level benchmark dataset for large language models (LLMs) in the materials science field, MaterialBENCH, is constructed. This dataset consists of problem-answer pairs, based on university textbooks. There are two types of problems: one is the free-response answer type, and the other is the multiple-choice type. Multiple-choice problems are constructed by adding three incorrect answers as choices to a correct answer, so that LLMs can choose one of the four as a response. Most of the problems for free-response answer and multiple-choice types overlap except for the format of the answers. We also conduct experiments using the MaterialBENCH on LLMs, including ChatGPT-3.5, ChatGPT-4, Bard (at the time of the experiments), and GPT-3.5 and GPT-4 with the OpenAI API. The differences and similarities in the performance of LLMs measured by the MaterialBENCH are analyzed and discussed. Performance differences between the free-response type and multiple-choice type in the same models and the influence of using system massages on multiple-choice problems are also studied. We anticipate that MaterialBENCH will encourage further developments of LLMs in reasoning abilities to solve more complicated problems and eventually contribute to materials research and discovery.

Kh. Zamani, M. Tavoosi, A. Ghasemi et al.

In this study, the effect of partial addition of silicon on the structural behavior and electromagnetism of TiC/Ti3AlC2 ceramic matrix composites has been investigated. In this regard, the mechanical alloying and annealing processes were used for the synthesis of the desired composite. Structural and phase investigations were performed using scanning electron microscope, differential thermal analysis, and X-ray diffractometer, and electromagnetic behavior was investigated by network analyzer. The results showed that it was possible to synthesize TiC/Ti3AlC2 composite structure with in-situ partial addition of silicon. 2TiC-Al-Ti-0.2Si system showed the best absorption behavior of electromagnetic waves with reflection loss of about -30.10 dB at matching frequency of 15.1 GHz. It was found that the TiC/Ti3AlC2 composite structure obtained from the mechanical alloying was stable after annealing at 1400 °C. However, the electromagnetic absorption behavior was affected. Thus, the reflection loss of the annealed samples was obtained about -1dB.

David Nugroho, Won-Chun Oh, Saksit Chanthai et al.

In this study, carbon quantum dots (CQDs) from Magnolia Grandiflora flower as a carbon precursor were obtained using a hydrothermal method under the optimized conditions affected by various heating times (14, 16, 18, and 20 min) and various electric power inputs (900–1400 W). Then, hydrogen sulfide (H₂S) was added to dope the CQDs under the same manner. The aqueous solution of the S-CQDs were characterized by FTIR, XPS, EDX/SEM, and TEM, with nanoparticle size at around 4 nm. Then, the as-prepared S-CQDs were successfully applied with fine corn starch for detection of minutiae latent fingerprints on non-porous surface materials. It is demonstrated that the minutiae pattern is more clearly seen under commercial UV lamps with a bright blue fluorescence intensity. Therefore, this research has proved that the S-CQDs derived from plant material have a better potential as fluorescent probes for latent fingerprint detection.

Guangyao Liu, Yongqi Yang, Chao Zheng et al.

Abstract P (N,N‐Dimethylacrylamide) ‐b‐P (2‐methoxyethyl acrylate) (PDMA‐b‐PMEA) and Poly (poly (ethylene glycol) methyl ether methacrylate) ‐b‐P (2‐methoxyethyl acrylate) (PPEGMA‐b‐PMEA) di‐block copolymer nanoparticles are prepared by RAFT dispersion polymerization in water at 35°C. By changing the degree of polymerization (DP) of PMEA and the solid content of the reaction solution, only spherical nanoparticles are obtained. Using PDMA and PPEGMA as macromolecular chain transfer agents (Macro‐CTA), the actual DP of PMEA block can be up to 11,520 and 17,000, respectively, the size of the obtained spherical nanoparticles can be close to 600 nm, and the molecular weight of the block copolymer can reach 106. Such large spheres may serve as model sterically stabilized particles for analytical centrifugation studies. In the mixed solvent of ethanol and water (1:1, v/v), we synthesize ultra‐high molecular weight CCS polymer by the arm‐first method. Star polymer with such high molecular weight and small particle size can be used for emulsification.

Dennis Wawrzik, Jorge I. Facio, Jeroen van den Brink

In recent years it has become clear that electronic Berry curvature (BC) is a key concept to understand and predict physical properties of crystalline materials. A wealth of interesting Hall-type responses in charge, spin and heat transport are caused by the BC associated to electronic bands inside a solid: anomalous Hall effects in magnetic materials, and various nonlinear Hall and Nernst effects in non-magnetic systems that lack inversion symmetry. However, for the largest class of known materials -- non-magnetic ones with inversion symmetry -- electronic BC is strictly zero. Here we show that precisely for these bulk BC-free materials, a finite BC can emerge at their surfaces and interfaces. This immediately activates certain surfaces in producing Hall-type transport responses. We demonstrate this by first principles calculations of the BC at bismuth, mercury-telluride (HgTe) and rhodium surfaces of various symmetries, revealing the presence of a surface Berry curvature dipole and associated quantum nonlinear Hall effects at a number of these. This opens up a plethora of materials to explore and harness the physical effects emerging from the electronic Berry curvature associated exclusively to their boundaries.

Davide Grassano, Davide Campi, Antimo Marrazzo et al.

Quantum spin Hall insulators are a class of topological materials that has been extensively studied during the past decade. One of their distinctive features is the presence of a finite band gap in the bulk and gapless, topologically protected edge states that are spin-momentum locked. These materials are characterized by a $\mathbb{Z}_2$ topological order where, in the 2D case, a single topological invariant can be even or odd for a trivial or a topological material, respectively. Thanks to their interesting properties, such as the realization of dissipationless spin currents, spin pumping and spin filtering, they are of great interest in the field of electronics, spintronics and quantum computing. In this work we perform an high-throughput screening of Quantum spin Hall insulators starting from a set of 783 2D exfoliable materials, recently identified from a systematic screening of the ICSD, COD, and MPDS databases. We find a new $\mathbb{Z}_2$ topological insulator (HgNS) as well as 3 already known ones and 7 direect gap metals that have the potential of becoming Quantum spin Hall insulators under a reasonably weak external perturbation.