Gold Bulletin最新文献

{"title":"Microstructural evolution of 42CrMo steel during isothermal transformation","authors":"Yanning Liu,&nbsp;Chunfang Wang,&nbsp;Jikang Li,&nbsp;Zhaobo Wu","doi":"10.1007/s13404-026-00378-0","DOIUrl":"10.1007/s13404-026-00378-0","url":null,"abstract":"<div><p>The isothermal phase-transformation behaviour of commercial rolled 42CrMo medium-carbon Cr-Mo alloy steel was systematically investigated over a broad temperature range of 350–725 °C using Gleeble-3800 thermomechanical simulation, combined with optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron back-scatter diffraction (EBSD), and X-ray diffraction (XRD). The ferrite-pearlite microstructure forms at 625–675 °C, exhibiting polygonal ferrite and lamellar pearlite. Within the bainite transformation regime (350–475 °C), typical morphological transition from lower bainite to upper bainite was observed: specimens isothermally held at 400 °C show fine acicular bainite with carbide-like features inside ferrite laths, whereas samples transformed at 450 °C develop sheaf-type upper bainite with carbide-like precipitates distributed along lath boundaries. EBSD characterization reveals non-monotonic evolution of ferritic orientation-domain size and grain-boundary misorientation distribution across the bainite transformation temperature window. The area-weighted equivalent circular diameter (ECD) of BCC orientation domains reaches maximum near 450 °C, while the fraction of 2–15° low-angle grain boundaries achieves its maximum value at 425 °C. TEM-EDS characterisation confirms ubiquitous existence of TiN inclusions; MnS particles are frequently observed adjacent to TiN in lower-bainite specimens, and these particles are inherited from steel-making solidification process rather than precipitated during isothermal bainite transformation. XRD phase screening demonstrates that bcc/bct ferritic matrix dominates the microstructure for samples treated between 400 and 450 °C, and retained austenite is only present as a minor constituent below the reliable quantitative detection limit of the current experimental setup. This work quantitatively clarifies the temperature-dependent microstructural evolution law of isothermally transformed 42CrMo steel, provides experimental reference for heat-treatment process optimisation of this widely used engineering steel.</p></div>","PeriodicalId":581,"journal":{"name":"Gold Bulletin","volume":"59 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s13404-026-00378-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149339265","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Logic-gate assisted colorimetric platform based on α-sulfophenylacetic acid functionalized gold nanoparticles for ultrasensitive detection and removal of Cr(III) and Cr(VI)","authors":"Anshu Kumar,&nbsp;Krishna Kanta Ghara,&nbsp;Naveen Gupta","doi":"10.1007/s13404-026-00376-2","DOIUrl":"10.1007/s13404-026-00376-2","url":null,"abstract":"<div><p>Chromium contamination in aquatic systems represents a major environmental and public health concern due to the high toxicity and mobility of its hexavalent species. In this work, α-Sulfophenylacetic acid functionalized gold nanoparticles (α-SPAA-AuNPs) were developed as a dual-functional colorimetric platform for the selective detection and removal of chromium ions in aqueous media. The functionalized nanoparticles enable ultrasensitive sensing of Cr(III) and Cr(VI) through analyte-induced aggregation, producing a distinct color transition resulting from localized surface plasmon resonance changes. By integrating Cr(VI), Cr(III), ethylenediaminetetraacetic acid (EDTA), and ascorbic acid (AA) as chemical inputs, molecular logic gate operations including AND, OR, and INHIBITOR were successfully constructed. The proposed sensing system exhibited excellent selectivity toward chromium species over other competing metal ions. The limits of detection were determined to be 15.6 ppb for Cr(III) and 20.8 ppb for Cr(VI) after reduction with AA. The sensing mechanism is attributed to coordination interactions between chromium ions and the carboxyl functional groups of α-Sulfophenylacetic acid on the nanoparticle surface, leading to nanoparticle aggregation. Furthermore, the platform demonstrated practical applicability through successful analysis of environmental water samples including drinking water, tap water, and lake water, highlighting its potential for environmental monitoring and remediation of chromium contamination.</p></div>","PeriodicalId":581,"journal":{"name":"Gold Bulletin","volume":"59 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s13404-026-00376-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149234897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimized Catha edulis leaf extract mediated synthesis of silver nanoparticles and their antibacterial activity against selected pathogenic bacteria","authors":"Hana Samuel Mamo,&nbsp;Muluken Aklilu Solomon","doi":"10.1007/s13404-026-00377-1","DOIUrl":"10.1007/s13404-026-00377-1","url":null,"abstract":"<div><p>Green synthesis of metal nanoparticles using plant-derived extracts has emerged as a sustainable alternative to conventional chemical and physical methods. In this work, silver nanoparticles (AgNPs) were synthesized using aqueous leaf extract of <i>Catha edulis</i> as a reducing and stabilizing agent. The formation of AgNPs was confirmed by the characteristic color change of the reaction mixture and the appearance of a distinct surface plasmon resonance (SPR) band at 416 nm in the UV–Vis spectrum. Structural characterization by X-ray diffraction revealed diffraction peaks at 2θ values of 38.23°, 44.34°, 64.52°, and 77.39°, corresponding to the (111), (200), (220), and (311) planes of face-centered cubic silver, confirming crystallinity. Fourier transform infrared analysis indicated the involvement of phytochemicals, including flavonoids, phenolics, alkaloids, and tannins, in nanoparticle formation and stabilization. The biosynthesized AgNPs exhibited measurable antibacterial activity against <i>K. pneumoniae</i> and <i>S. pyogenes</i>, producing a zone of inhibition (ZOI) of 21.20 ± 0.78 mm and 18.63 ± 0.53 mm respectively. These findings highlight the potential of <i>Catha edulis</i> extract for the eco-friendly synthesis of functional AgNPs with promising biomedical applications.</p></div>","PeriodicalId":581,"journal":{"name":"Gold Bulletin","volume":"59 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s13404-026-00377-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149133095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Green synthesized silver nanoparticles act as algal growth inhibitors","authors":"Angela Candreva,&nbsp;Tayyaba Shoukat,&nbsp;Chiara Lauritano,&nbsp;Silvestro Antonio Ruffolo,&nbsp;Mauro Francesco La Russa,&nbsp;Alex Santillán-Sarmiento,&nbsp;Massimo La Deda","doi":"10.1007/s13404-026-00375-3","DOIUrl":"10.1007/s13404-026-00375-3","url":null,"abstract":"<div><p>Nanoparticles are increasingly being employed in a variety of industrial and environmental applications. In this study, we aimed to develop a sustainable method for synthesizing silver nanoparticles and to evaluate their potential as algal growth inhibitors. A seedless protocol was established using ascorbic acid and polyvinylpyrrolidone (PVP) to obtain spherical silver nanoparticles, thereby avoiding the use of strong reducing agents. The nanoparticles were characterized by UV-Vis spectroscopy, transmission electron microscopy (TEM), and IR spectroscopy. Since microalgae and other marine organisms often grow on the surfaces of boats, ships, and other human-made devices in aquatic environments, antifouling products are necessary to prevent unwanted fouling. The algal growth inhibition capacity of the synthesized silver nanoparticles was assessed using two marine diatoms <i>Cylindrotheca Closterium</i> and <i>Skeletonema marinoi</i>. The results revealed a marked inhibitory effect on algal proliferation in treated samples compared to controls. Overall, this study demonstrates the effectiveness of the proposed synthetic method and paves the way for the use of these silver nanoparticles as a tool for controlling microalgal growth.</p></div>","PeriodicalId":581,"journal":{"name":"Gold Bulletin","volume":"59 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s13404-026-00375-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148926860","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Field performance evaluation of comminution and gravity processing circuits for artisanal saprolite gold ores","authors":"Anthony Druiventak,&nbsp;Kimberly Chen Poun Joe","doi":"10.1007/s13404-026-00374-4","DOIUrl":"10.1007/s13404-026-00374-4","url":null,"abstract":"<div><p>Artisanal and Small-scale Gold Mining (ASGM) operations increasingly adopt mechanized comminution, assuming it universally improves gold recovery. This case study challenges that generalized approach through a comparative field performance evaluation of two gravity recovery circuits processing saprolite ore in Suriname: a traditional direct sluicing system (IST) and a mechanized hammer mill-centrifuge system (HS). Operational parameters and fractional gold deportment were evaluated using a reconstituted head grade methodology to mitigate the fundamental sampling error inherent to high-nugget deposits. Feed characterization revealed that approximately 80% of the gold is in the coarse fractions (&gt; 100 μm), indicating natural amenability to simple gravity recovery. Results demonstrate both circuits severely underperformed due to operational misapplication. The IST circuit operated with extreme slurry viscosity (&gt; 30% solids), causing hydrodynamic carry-over. Conversely, the HS circuit suffered from mechanical overloading and extreme hydraulic dilution (11–17% solids). Furthermore, deportment data suggests the hammer mill failed to achieve effective liberation, discarding ~ 70% of unrecovered gold in mid-size fractions (+ 250–1000 μm) and potentially flattening malleable nuggets. These combined inefficiencies project an estimated annual unrealized value of US$6.9 million (IST) and US$3.8 million (HS) under 2019 pricing. The findings strongly indicate that for gold in the coarse fraction of a saprolitic ore, the routine application of hammer mills may represent a metallurgical mismatch. Implementing strict process control over pulp density and feed rate, alongside proactive on-site ore characterization, are more critical drivers of operational profitability than deploying complex comminution technology.</p></div>","PeriodicalId":581,"journal":{"name":"Gold Bulletin","volume":"59 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s13404-026-00374-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148751756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Review of gold nanoparticles: synthesis, properties and applications","authors":"Md Atiqur Rahman,&nbsp;Dugyala Vishala,&nbsp;S. M. Mozammil Hasnain,&nbsp;Prabhu Paramasivam,&nbsp;Abinet Gosaye Ayanie","doi":"10.1007/s13404-026-00370-8","DOIUrl":"10.1007/s13404-026-00370-8","url":null,"abstract":"<div><p>Gold nanoparticles (AuNPs) exhibit exceptional physicochemical properties, notably localized surface plasmon resonance (LSPR), enabling diverse applications in biomedicine, molecular imaging (CT/PAI/MRI), photothermal therapy (PTT), and targeted drug delivery. This review systematically examines synthesis strategies, emphasizing pulsed laser ablation in liquid (PLAL) as a surfactant-free, eco-friendly “top-down” method producing pristine 5–50 nm AuNPs via plasma plume confinement and cavitation-induced nucleation. Complementary “bottom-up” green biosynthesis leverages plant/fruit extracts (polyphenols/flavonoids), microorganisms, and fungi (nitrate reductase) to yield biofunctionalized AuNPs (10–80 nm) with inherent stability for theranostics. Comparative analyses highlight PLAL’s superiority in purity/yield compared to chemical methods, while biological methods excel in scalability and multifunctionality. Shape-dependent plasmonic heating: nanorods achieve ΔT = 45–55 °C vs. spheres (25 °C), underpinning PTT efficacy. The review elucidates targeting strategies (passive EPR vs. active ligand-receptor), hybrid imaging, and challenges, including EPR heterogeneity, synthesis reproducibility, and clinical translation. Future directions prioritize fs-PLAL optimization, biohybrid architectures, and multimodal AuNP platforms for precision oncology. </p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture><span>The alternative text for this image may have been generated using AI.</span></div></div></figure></div></div>","PeriodicalId":581,"journal":{"name":"Gold Bulletin","volume":"59 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s13404-026-00370-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148261771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on the surface fluctuation characteristics of liquid metal under gas jet excitation","authors":"Da Liu,&nbsp;Yuhao Shen,&nbsp;Xuanze Wang,&nbsp;Shanting Ding,&nbsp;Zhongsheng Zhai,&nbsp;Zhenkun Lei,&nbsp;Hao Jiang,&nbsp;Zhenfei Guo","doi":"10.1007/s13404-026-00372-6","DOIUrl":"10.1007/s13404-026-00372-6","url":null,"abstract":"<div><p>To address the challenge of in-situ monitoring of melt pool dynamics in laser additive manufacturing (LAM), this work proposes a gas-jet excitation method to probe surface wave behavior in liquid metals. Using an In51Bi32.5Sn16.5 alloy (melting point ≈ 60 °C), controlled airflow was applied across temperatures from 90 °C to 60 °C, and surface ripple evolution was captured via high-speed imaging. Image analysis revealed that both wave velocity and wavelength decrease markedly with cooling: stable concentric ripples form at 70 °C, while coherent waves vanish at 60 °C due to incipient solidification. Numerical simulations qualitatively reproduced the ring-like waves and keyhole-like depressions, showing trend-level consistency with the experimental observations. The findings suggest that gas-jet-excited surface-wave characteristics may provide potential observable signals for characterizing the near-solidification state of liquid metal and may offer a conceptual basis for future melt-pool monitoring methods.</p></div>","PeriodicalId":581,"journal":{"name":"Gold Bulletin","volume":"59 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s13404-026-00372-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148261769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Inaugural editorial for discover metals","authors":"Jax Jiang,&nbsp;Qing-Qiang Ren","doi":"10.1007/s13404-026-00373-5","DOIUrl":"10.1007/s13404-026-00373-5","url":null,"abstract":"","PeriodicalId":581,"journal":{"name":"Gold Bulletin","volume":"59 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s13404-026-00373-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148261772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mechanism guided microalloying controls microstructure evolution and strengthening in gold based materials","authors":"Zhaodi Li,&nbsp;Manmen Liu,&nbsp;Yongtai Chen,&nbsp;Kunhua Zhang,&nbsp;Xiaolong Zhou","doi":"10.1007/s13404-026-00371-7","DOIUrl":"10.1007/s13404-026-00371-7","url":null,"abstract":"<div><p>Gold-based materials are widely used in electronics, catalysis, and biomedicine due to their excellent conductivity, chemical stability, and biocompatibility; however, their low strength and poor wear resistance limit structural applications. Microalloying, defined as the addition of trace elements (&lt; 0.5 wt%), offers an effective strategy to overcome these limitations through microstructural control. This review presents a mechanism-oriented analysis of microalloying in gold-based systems, focusing on solid solution strengthening, grain boundary engineering, and precipitation hardening, with emphasis on their coupled, multiscale effects. Representative elements (e.g., Ti, Ce, Ag) are evaluated in terms of strengthening efficiency, ductility balance, and functional contributions, revealing roles governed by precipitation behavior, grain boundary regulation, and electronic structure modulation. The detrimental effects of impurity elements (Pb, Bi, Ge) are also examined from a grain boundary cohesion perspective, highlighting the importance of compositional control. By linking microstructure to properties, this review shows that optimal performance arises from synergy among phase stability, defects, and processing. Emerging strategies, including high-throughput computation, machine learning, and additive manufacturing, enable accelerated alloy design. Future advances will integrate data-driven design with precise microstructural engineering to develop high-performance, multifunctional gold-based materials.</p></div>","PeriodicalId":581,"journal":{"name":"Gold Bulletin","volume":"59 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2026-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s13404-026-00371-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148261847","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exploration of thermoelectric and optoelectronic features Rb₂AuMF₆ (M = Co, Rh) double perovskites for advanced technological applications: a computational evaluation","authors":"Wang Yurong,&nbsp;Aparna Dixit,&nbsp;Jisha Annie Abraham,&nbsp;Preeti Kumari,&nbsp;Meznah M. Alanazi,&nbsp;Taoufik Saidani,&nbsp;Ramesh Sharma","doi":"10.1007/s13404-025-00369-7","DOIUrl":"10.1007/s13404-025-00369-7","url":null,"abstract":"<div><p>The electronic, optical, and thermoelectric properties of flouro double perovskites (FDPs) Rb₂AuMF₆ (M = Co and Rh) have been investigated using density functional theory and semiclassical Boltzmann transport theory. Enthalpy of formation energy (E_f), cohesive energy, and Goldschmidt tolerance factor (t_f) are calculated to assure the stability of the structure. These materials exhibit band gaps between 1.454 eV and 1.828 eV, placing them within the visible light range and indicating their potential suitability for solar energy harvesting. Dielectric tensor, energy loss absorption, optical conductivity, refraction, and reflection are examples of optical properties that have been researched to look at how incident light interacts with the FDPs under investigation. The calculated bulk moduli are 66.72 GPa (Rb₂AuCoF₆) and 65.38 GPa (Rb₂AuRhF₆), reflecting their mechanical robustness. Optical analyses reveal low reflectivity (0.05–0.08), strong absorption, and high optical conductivity in the visible–UV spectrum, suggesting potential for optoelectronic applications. Additionally, these compounds’ thermoelectric behaviour has been examined to determine viability for thermoelectric applications. Thermoelectric performance is promising, with Seebeck coefficients of ~ 181 µV/K and ZT values of 0.177 (Rb₂AuCoF₆) and 0.138 (Rb₂AuRhF₆), while electrical conductivity (σ/τ) and power factors are also favorable. The assessed values of ZT predict that Rb₂AuCoF₆ is comparatively a promising material for TE applications.</p></div>","PeriodicalId":581,"journal":{"name":"Gold Bulletin","volume":"58 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145613094","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}