Hasil untuk "Materials Science"

Kanpatom Kasonsuwan, Yukinaga Miyashita, Suwicha Wannawichian

Abstract We studied the characteristics of ultra‐low‐frequency (ULF) waves associated with dipolarization in the near‐Earth plasma sheet for substorms and pseudosubstorms, employing superposed epoch analysis of data from the Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft. We find exponential intensification of ULF waves before dipolarization for both substorms and pseudosubstorms, highlighting Pi2 waves' appearance before Pi1 waves. After rapid growth, the high‐frequency portion of the Pi2 waves and the Pi1 waves in a tailward region for pseudosubstorms are notably weaker and decrease faster than those for substorms. These results suggest that instabilities related to high‐frequency Pi2 and Pi1 waves are essential for a full‐fledged substorm and auroral poleward expansion.

A. Salahi-Niri, M. Zali, A. Yadegar

Objective: Helicobacter pylori remains one of the most prevalent bacterial infections globally. While H. pylori eradication reduces gastric cancer risk, increasing antimicrobial resistance (AMR) impairs the effective treatment with major geographic variability. This systematic review summarizes the global epidemiology, mechanisms of resistance, clinical consequences, and emerging strategies to address H. pylori AMR. Materials and Methods: We systematically searched PubMed, Scopus, and Web of Science for articles published between 2000 and June 2025. Keywords included “Helicobacter pylori”, “antimicrobial resistance”, “clarithromycin”, “metronidazole”, “levofloxacin”, “children”, and “epidemiology”. Inclusion criteria comprised English-language studies in human subjects reporting prevalence, mechanisms, or treatment outcomes related to resistance. Excluded were case reports, animal studies, and small series (<20 patients). Emphasis was placed on multicenter trials, surveillance reports, and systematic reviews. Results: Analysis of included studies demonstrated that clarithromycin resistance exceeds 20-30% in many regions, particularly East Asia and Southern Europe, undermining traditional triple therapy. Metronidazole resistance is widespread, ranging from 30-70% globally, while levofloxacin resistance shows alarming upward trends. Amoxicillin and tetracycline resistance remain rare, while rifabutin retains activity against multidrug-resistant strains. Pediatric populations exhibit especially high clarithromycin and metronidazole resistance, with pooled prevalence exceeding 35% in some regions, limiting therapeutic options. Molecular mechanisms primarily involve point mutations in 23S rRNA, rdxA/frxA, and gyrA genes, while next-generation sequencing has identified additional candidate loci. Novel strategies, including bismuth-based quadruple therapy, vonoprazan-based dual regimens, and molecular-guided therapy improve outcomes. Adjunctive measures such as probiotics, antimicrobial peptides, and stewardship interventions offer further promise. Conclusions: H. pylori AMR represents a critical barrier to eradication worldwide. Expanded global surveillance, rapid molecular diagnostics, and personalized therapy are urgently needed. Future research should prioritize pediatric-focused strategies, non-antibiotic alternatives, and equitable access to optimized regimens. Coordinated international action is essential to contain resistance and preserve the benefits of eradication.

Wojciech Polkowski, Paolo Lai Zhong Lo Biundo, Jianmeng Jiao et al.

New ternary Fe-Si-B alloys were developed as potential metallic phase change materials (PCMs) for application in ultra-high temperature latent heat thermal energy storage systems (LHTES). By a thermodynamic re-assessment of the Fe-Si-B system, three new Si-rich (approx. 40–50 wt%) compositions were pre-selected for further analyses. The new alloys can provide very high energy density (even above 1 MWh/m3) at melting temperatures around 1150–1200 °C. Furthermore, new PCM candidates have twice lower B content than already developed Fe-26Si-9B alloy, what is beneficial from the economic point of view. For the sake of experimental validation, the PCM candidates were produced by the arc melting technique. The outputs of thermodynamic calculations were verified in detailed microstructural studies and differential scanning calorimetry experiments. In the case of the newly developed Fe-46Si-5B and already designed Fe-26Si-9B alloy, the energy density higher than 1 MWh/m3 was experimentally confirmed.

Gareth S. Parkinson

Over the past decade, extensive research into single-atom catalysts (SACs) has revealed that the catalytic behavior of metal adatoms is highly dependent on how they interact with their support. A strong dependence on the local coordination environment has led to comparisons with metal-organic complexes, and there is growing excitement about the potential to fine-tune SACs by controlling the adsorption geometry. The rise of computational screening to identify the optimal support-metal combinations underscores the need for rigorous benchmarking of theoretical methods, to validate realistic geometries, mechanisms, and the impact of adsorption on stability and catalytic activity. The surface science approach is particularly well-suited for this task because it allows to precisely determine the geometry of the metal atom and interpret its catalytic behavior. Moreover, the effects of temperature and molecular adsorption on the model catalysts stability can be studied in isolation, and conclusions drawn from UHV studies tested in increasingly common near-ambient pressure and electrochemical setups. This perspective highlights recent breakthroughs and specific systems, including metal oxides, metal-organic frameworks, and carbon nitrides, where insights from surface science experiments can significantly advance understanding in this rapidly evolving field.

M. S. Rajeevan, B. Mini Devi

In an age of fast-paced technological change, patents have evolved into not only legal mechanisms of intellectual property, but also structured storage containers of knowledge full of metadata, categories, and formal innovation. This chapter proposes to reframe patents in the context of information science, by focusing on patents as knowledge artifacts, and by seeing patents as fundamentally tied to the global movement of scientific and technological knowledge. With a focus on three areas, the inventions of AIs, biotech patents, and international competition with patents, this work considers how new technologies are challenging traditional notions of inventorship, access, and moral accountability.The chapter provides a critical analysis of AI's implications for patent authorship and prior art searches, ownership issues arising from proprietary claims in biotechnology to ethical dilemmas, and the problem of using patents for strategic advantage in a global context of innovation competition. In this analysis, the chapter identified the importance of organizing information, creating metadata standards about originality, implementing retrieval systems to access previous works, and ethical contemplation about patenting unseen relationships in innovation ecosystems. Ultimately, the chapter called for a collaborative, transparent, and ethically-based approach in managing knowledge in the patenting environment highlighting the role for information professionals and policy to contribute to access equity in innovation.

Elizabeth Bradley, Adilson E. Motter, Louis M. Pecora

Nonlinear science has evolved significantly over the 35 years since the launch of the journal Chaos. This Focus Issue, dedicated to the 80th Birthday of its founding editor-in-chief, David K. Campbell, brings together a selection of contributions on influential topics, many of which were advanced by Campbell's own research program and leadership role. The topics include new phenomena and method development in the realms of network dynamics, machine learning, quantum and material systems, chaos and fractals, localized states, and living systems, with a good balance of literature review, original contributions, and perspectives for future research.

Shan Zhou, Jiahui Li, Jun Lu et al.

The unique topology and physics of chiral superlattices make their self-assembly from nanoparticles highly sought after yet challenging in regard to (meta)materials1–3. Here we show that tetrahedral gold nanoparticles can transform from a perovskite-like, low-density phase with corner-to-corner connections into pinwheel assemblies with corner-to-edge connections and denser packing. Whereas corner-sharing assemblies are achiral, pinwheel superlattices become strongly mirror asymmetric on solid substrates as demonstrated by chirality measures. Liquid-phase transmission electron microscopy and computational models show that van der Waals and electrostatic interactions between nanoparticles control thermodynamic equilibrium. Variable corner-to-edge connections among tetrahedra enable fine-tuning of chirality. The domains of the bilayer superlattices show strong chiroptical activity as identified by photon-induced near-field electron microscopy and finite-difference time-domain simulations. The simplicity and versatility of substrate-supported chiral superlattices facilitate the manufacture of metastructured coatings with unusual optical, mechanical and electronic characteristics. Chiroptically active pinwheel assemblies on substrates are formed by tetrahedral gold nanoparticles from the effective ‘compression’ of a perovskite-like, low-density phase, thereby enabling the manufacture of metastructured coatings with special chiroptical characteristics as identified by photon-induced near-field electron microscopy and chirality measures.

Kun Zhang, Yu Chang, Jingjing Lei et al.

Grain growth of magnesium (Mg) and its hydride is one of the main reasons for kinetic and capacity degradation during the hydrogen absorption and desorption cycles. To solve this problem, herein we propose a novel method involving synergistic effect of inside embedded metals and outside coated graphene to limit the growth of Mg and its hydride grains. The graphene coated Mg‒Y‒Al alloys were selected as a model system for demonstrating this positive effect where the Mg91Y3Al6 alloy was first prepared by rapidly solidified method and then high-pressure milled with 5 wt% graphene upon 5 MPa hydrogen gas for obtaining in-situ formed YAl2 and YH3 embedded in the MgH2 matrix with graphene shell (denoted as MgH2-Y-Al@GR). In comparison to pure MgH2, the obtained MgH2-Y-Al@GR composites deliver much better kinetics and more stable cyclic performance. For instance, the MgH2-Y-Al@GR can release about 6.1 wt% H2 within 30 min at 300°C but pure MgH2 only desorbs ∼1.5 wt% H2. The activation energy for desorption of MgH2-Y-Al@GR samples is calculated to be 75.3±9.1 kJ/mol that is much lower than approximately 160 kJ/mol for pure MgH2. Moreover, its capacity retention is promoted from ∼57% of pure MgH2 to ∼84% after 50th cycles without obvious particle agglomeration and grain growth. The synergistic effect of outside graphene coating with inside embedded metals which could provide a huge number of active sites for catalysis as well as inhibit the grain growth of Mg and its hydride is believed to be responsible for these.

Guohao Gao, Mitsuo Hara, Takahiro Seki et al.

In recent times, there has been a significant surge in research interest surrounding thermo-responsive water-soluble polyacrylamides, primarily due to their intriguing capability to undergo significant solubility changes in water. These polymers exhibit the remarkable ability to shift from a soluble to an insoluble state in response to temperature variations. The capacity of these polymers to dynamically respond to temperature changes opens up exciting avenues for designing smart materials with tunable properties, amplifying their utility across a spectrum of scientific and technological applications. Researchers have been particularly captivated by the potential applications of thermo-responsive water-soluble polyacrylamides in diverse fields such as drug delivery, gene carriers, tissue engineering, sensors, catalysis, and chromatography separation. This study reports the construction and functionalization of polymer gels consisting of a polymer network of polyacrylamide derivatives with nano-sized structural units. Specifically, thermo-responsive polymer gels were synthesized by combining well-defined star-shaped polymers composed of polyacrylamide derivatives with a multifunctional initiator and linking method through a self-accelerating click reaction. The polymerization system employed a highly living approach, resulting in polymer chains characterized by narrow molecular weight distributions. The method’s high functionality facilitated the synthesis of a temperature-responsive block copolymer gel composed of N-isopropyl acrylamide (NIPA) and N-ethyl acrylamide (NEAA). The resulting polymer gel, comprising star-shaped block copolymers of NIPA and NEAA, showcases smooth volume changes with temperature jumps.

Xin He, Xun Zhou, Ting Shang et al.

Sacrificial metallic coatings are an effective strategy for mitigating corrosion in steel operating in industrial environments. This review article focuses on examining the protection mechanism of zinc-aluminum-magnesium (Zn-Al-Mg) coatings on steel substrates. Specifically, it investigates the effects of various elements and their corrosion products on the corrosion resistance of Zn-Al-Mg coatings. Furthermore, this review summarizes the formation mechanisms of various specialized corrosion modes that occur following the corrosion of Zn-Al-Mg coatings, based on previous experimental findings. It also includes suggestions for further research areas that could contribute to the development of highly corrosion-resistant and long-lasting coatings. These suggestions are based on published laboratory and field test results available in literature.

Zhonglin Gao, Jie Wei, Hongyang Wang et al.

In the continuous scaling-up process of the separating system, a mechanism exists that transforms the behavior of the flow field, resulting in deviations from the original model and conclusions. The paper examined the effects of the scale up of a fluidized bed by CFD. It was observed that increasing the diameter reduces the amplitude of axial density fluctuations. Similarly, increasing the static height increases the amplitude. Moreover, increasing the static bed height enhances the visibility of the cyclic flow structure of gas and solid phases. The flow structure in large bed diameters is disrupted. The impact of changing the bed diameter on bed density is more significant than the static height. As the bed diameter increases, the bubble disturbance decreases and the aggregation phase gradually disappears while the proportion of the emulsified phase keeps increasing. This study will guide and assist in the future application of separated fluidized beds in industry.

L. Raki, J. Beaudoin, R. Alizadeh et al.

Concrete science is a multidisciplinary area of research where nanotechnology potentially offers the opportunity to enhance the understanding of concrete behavior, to engineer its properties and to lower production and ecological cost of construction materials. Recent work at the National Research Council Canada in the area of concrete materials research has shown the potential of improving concrete properties by modifying the structure of cement hydrates, addition of nanoparticles and nanotubes and controlling the delivery of admixtures. This article will focus on a review of these innovative achievements.

Joohwi Lee, Atsuto Seko, Kazuki Shitara et al.

Machine learning techniques are applied to make prediction models of the ${G}_{0}{W}_{0}$ band gaps for 270 inorganic compounds using Kohn-Sham (KS) band gaps, cohesive energy, crystalline volume per atom, and other fundamental information of constituent elements as predictors. Ordinary least squares regression (OLSR), least absolute shrinkage and selection operator, and nonlinear support vector regression (SVR) methods are applied with two levels of predictor sets. When the KS band gap by generalized gradient approximation of Perdew-Burke-Ernzerhof (PBE) or modified Becke-Johnson (mBJ) is used as a single predictor, the OLSR model predicts the ${G}_{0}{W}_{0}$ band gap of randomly selected test data with the root-mean-square error (RMSE) of 0.59 eV. When KS band gap by PBE and mBJ methods are used together with a set of predictors representing constituent elements and compounds, the RMSE decreases significantly. The best model by SVR yields the RMSE of 0.24 eV. Band gaps estimated in this way should be useful as predictors for virtual screening of a large set of materials.

Tamer A. Al-Shafie, Engy A. Mahrous, Mustafa Shukry et al.

Increasing cancer cell sensitivity to chemotherapy by amending aberrant metabolism using plant extracts represents a promising strategy to lower chemotherapy doses while retaining the same therapeutic outcome. Here, we incubated HepG2 cells with four plant extracts that were selected based on an earlier assessment of their cytotoxicity, viz asparagus, green tea, rue, and avocado, separately, before treatment with doxorubicin. MTT assays elucidated a significant decrease in doxorubicin-IC₅₀ following HepG2 incubation with each extract, albeit to a variable extent. The investigated extract’s ultra-performance liquid chromatography and gas chromatography coupled with mass spectrometry (UPLC/MS and GC/MS) revealed several constituents with anticancer activity. Biochemical investigation displayed several favorable effects, including the inhibition of hypoxia-inducible factor1α (HIF1α), c-Myc, pyruvate kinase-M2 (PKM2), lactate dehydrogenase-A (LDH-A), glucose-6-phosphate dehydrogenase (G6PD), and glutaminase by asparagus and rue extracts. To less extent, HIF1α, c-Myc, PKM2, and LDH-A were partially inhibited by green tea extract, and HIF1α and glutaminase activity was inhibited by avocado oil. Undesirably, green tea extract increased glutaminase; avocado oil rose c-Myc, and both increased G6PD. In conclusion, our study confirms the potential cytotoxic effects of these plant extracts. It highlights a strong association between the ability of asparagus, green tea, rue, and avocado to sensitize HepG2 cells to doxorubicin and their power to amend cell metabolism, suggesting their use as add-on agents that might aid in clinically lowering the doxorubicin dose.

S Suneetha, I Dinesh, S Ravindrakishore et al.

Background:  Anatomy is a very essential science. Knowledge of anatomy is significantly associated in situations with nearly every characteristic of medical modules. Therefore, it is required to be educated and mastered competently by medical students. Aim: The chief objective of this research is to note and examine the outcome of teaching methods for example problem-based learning and seminars when integrated with educational lectures by first-year UG students. Materials and Methods:  This is a cross-sectional study carried out at Andhra Medical College, Visakhapatnam, Andhra Pradesh, India in which 150 students from the first year were included. They were divided into 2 categories, 75 students in each category. Categories 1 and 2 are again subdivided into three categories. Both of the categories undergo seminar and problem-based learning in four chosen topics in the anatomy of the abdomen. An autonomous assessment was done to acknowledge the desired methods. Results:  In topic 1 the average difference between the case-based learning and lecture in both categories is 4 ± 1.18 and 3.4 ± 1.4 respectively. In topic 2, the average difference between the case-based learning and lecture in both categories is 3.9 ± 1.7 and 1.8 ± 1.3 respectively. Conclusion:  In this study, it was evaluated that problem-based learning is more efficacious in relating to critical thinking. However, problem-based learning and seminars both are required with didactic lectures. Recommendation:  Problem-based learning and tuition classes along with conventional lecture sessions are very effective in helping students understand anatomy in a better manner.

K. Espoir N'souglo, Katarzyna Kowalczyk-Gajewska, Mohammad Marvi-Mashhadi et al.

In this paper, we have investigated, using finite element calculations, the effect of initial texture on the formation of multiple necking patterns in ductile metallic rings subjected to rapid radial expansion. The mechanical behavior of the material has been modeled with the elasto-viscoplastic single crystal constitutive model developed by \citet{marin2006}. The polycrystalline microstructure of the ring has been generated using random Voronoi seeds. Both $5000$ grain and $15000$ grain aggregates have been investigated, and for each polycrystalline aggregate three different spatial distributions of grains have been considered. The calculations have been performed within a wide range of strain rates varying from $1.66 \cdot 10^4 ~ \text{s}^{-1}$ to $3.33 \cdot 10^5 ~ \text{s}^{-1}$, and the rings have been modeled with four different initial textures: isotropic texture, $\left\langle 001\right\rangle\parallelΘ$ Goss texture, $\left\langle 001\right\rangle\parallel$ R Goss texture and $\left\langle 111\right\rangle\parallel$ Z fiber texture. The finite element results show that: (i) the spatial distribution of grains affects the location of the necks, (ii) the decrease of the grain size delays the formation of the necking pattern and increases the number of necks, (iii) the initial texture affects the number of necks, the location of the necks, and the necking time, (iv) the development of the necks is accompanied by a local increase of the slip activity. This work provides new insights into the effect of crystallographic microstructure on dynamic plastic localization and guidelines to tailor the initial texture in order to delay dynamic necking formation and, thus, to improve the energy absorption capacity of ductile metallic materials at high strain rates.

Z. Khurshid, Muhammad Sohail Zafar, S. Qasim et al.

Rationalizing has become a new trend in the world of science and technology. Nanotechnology has ascended to become one of the most favorable technologies, and one which will change the application of materials in different fields. The quality of dental biomaterials has been improved by the emergence of nanotechnology. This technology manufactures materials with much better properties or by improving the properties of existing materials. The science of nanotechnology has become the most popular area of research, currently covering a broad range of applications in dentistry. This review describes the basic concept of nanomaterials, recent innovations in nanomaterials and their applications in restorative dentistry. Advances in nanotechnologies are paving the future of dentistry, and there are a plenty of hopes placed on nanomaterials in terms of improving the health care of dental patients.

ZHAO Lei, LIANG Qichao, LIU Chuanlong, WANG Tianguo

At present,there are few studies focusing on the effect of negative bias voltage on the corrosion resistance of TiAlN films deposited by arc ion plating.In this paper,TiAlN films were deposited on M2 high speed steel by arc ion plating,and scanning electron microscope (SEM),X-ray diffraction (XRD),electrochemical test and other methods were used to study the influences of negative bias voltage on substrate on the microstructure,surface morphology and corrosion resistance of the as-prepared films.Results showed that the negative bias voltage was an important process parameter affecting the surface morphology of TiAlN films deposited by arc ion plating.A proper negative bias voltage could effectively improve the morphology and compactness of the surface film and reduce the size and number of large molten droplets on the surface.The main phase of TiAlN films was AlTi3N(111),and the films mainly grew along the (111) direction.When the negative bias voltage was increased,a new reaction would occur and a Ti2AlN (100) diffraction peak would appear.With the increase of the negative bias voltage on substrate,the microhardness of the films increased first and then decreased.When the negative bias voltage was 150 V,the microhardness reached the maximum value of 2 725 HV,the relative corrosion rate was the lowest,and the corrosion resistance was the best.

Len van Deurzen, Ryan Page, Vladimir Protasenko et al.

Multimode lasing at sub-300 nm wavelengths is demonstrated by optical pumping in AlGaN heterostructures grown on single-crystal AlN substrates by plasma-assisted molecular beam epitaxy. Edge-emitting ridge-based Fabry–Pérot cavities are fabricated with the epitaxial AlN/AlGaN double heterostructure by a combined inductively coupled plasma reactive ion etch and tetramethylammonium hydroxide etch. The emitters exhibit peak gain at 284 nm and modal linewidths on the order of 0.1 nm at room temperature. The applied growth technique and its chemical and heterostructural design characteristics offer certain unique capabilities toward further development of electrically injected AlGaN laser diodes.

Jie Ye, Chao Wang, Chao Gao et al.

While the combination of synthetic and biological systems offers an appealing strategy for solar-to-fuel conversion, such hybrid systems typically suffer from low selectivity. Here, authors integrate a bimetallic alloy with a CdS-containing methanogen for selective CO2 reduction to methane.