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Gold (or electrum) in hydrothermal fluid precipitates directly from gold sulfide complex and/or partly via suspended nanoparticles. The hydrothermal fluid contains "invisible gold" that is atomically dispersed in sulfide minerals or as nanoparticles with a size of less than 10 nm. However, the contribution of these gold nanoparticles to the formation of native gold and its alloy with silver (electrum) remains unclear. The Higashi–Aogashima Knoll Caldera hydrothermal field, south of Tokyo, Japan, is an area of significant seafloor hydrothermal activity that is known for high-grade gold-containing minerals in sulfide-rich rocks. In this study, dry-polished thin sections were created to minimize sample damage and scanning and transmission electron microscopy were used to investigated the cross-sectional and three-dimensional morphologies of native gold grains in a sulfide-rich mound rock from the Central Cone site of the caldera. The surfaces of the gold grains comprised nanoparticles with sizes of 5–50 nm that were also attached to their periphery, which suggests that gold nanoparticles in deep-sea hydrothermal fluid were involved in the mineralization of the gold. In addition, the distribution of silver was uneven within the gold grains, which suggests that the gold precipitation comprised multiple stages at different temperatures that resulted in the post-deposition or secondary remobilization of silver. [ABSTRACT FROM AUTHOR]

The recurrent occurrence of public health crises has significantly accelerated the development of nano-metal-based antimicrobial textiles. However, several challenges remain, including poor solution stability, low affinity and binding fastness to textiles, and the difficulty of recovering nanometal-containing wastewater in the antimicrobial treatment of fabrics. This can damage the natural microbial ecological balance and reduce the performance of the fabrics. Herein, we synthesized an amino-terminated hyperbranched poly(amidoamine) -capped core–shell structured silver /gold nanoparticles (HBPAA-capped Ag@AuNPs), which exhibited high hot water resistance, high solution stability, and strong affinity to natural textiles. These properties were dependent on the reducible cationic HBPAA. The as-prepared Ag@AuNPs exhibited a positive surface charge of + 48.06 mV and demonstrated the capacity to withstand 100 °C heating in water due to their inherent self-reducing ability. Accordingly, we devised a novel bottom-up coating strategy for cotton fabric, whereby Ag@AuNPs were adsorbed onto the cotton surface with HBPAA serving as a "molecular motor" driven by intermolecular interactions between cationic HBPAA and anionic cotton. The results demonstrated that up to 60 mg/L of Ag@AuNPs were nearly completely adsorbed by cotton, indicating that up to ~ 3 g/kg of Ag@AuNP-coated fabric could be prepared by the cleaning adsorption method. The antimicrobial cotton fabric exhibited active adsorption ability toward bacteria and demonstrated strong organic–inorganic coupling antibacterial properties (cationic HBPAA contributed approximately 30– 60% of the antibacterial activity). Even after 50 standard washes, cotton fabric with Ag@Au content as low as 0.9 g/kg was still capable of killing ~ 100% of E. coli and S. aureus. [ABSTRACT FROM AUTHOR]

The main motivation for this study was to improve implant materials. The influence of silver and gold on the structure and mechanical properties of Mg–Nd–Zr alloy was studied. In the work, quantitative and qualitative evaluation of the structural components of magnesium alloy with noble metal additives was performed. The research methods used were investigation of the mechanical properties and observation of micro– and macrostructures. The results showed that modification of magnesium alloy with Ag and Au contributes to the formation of spherical intermetallics of smaller size groups, which become additional centers of crystallization and grind the cast structure. The best composition from additional alloying with silver and gold was determined. Their positive effect on the strength and ductility properties of the metal was established. Preclinical and clinical testing was performed and the prospects for noble metal modification of bioabsorbable magnesium alloy for implant production usage were shown. [ABSTRACT FROM AUTHOR]

We report the first mass photometric characterization of nanoaggregates of atomically precise nanoclusters (NCs) in solution. The differently-sized nanoaggregates of silver–gold alloy NCs, [Ag11−xAux(DPPB)5Cl5O2]2+ [x = 1–5 and DPPB = 1,4-bis(diphenylphosphino)butane], formed in solution, were examined by mass photometry (MP) with a protein calibration. In addition, we conducted MP studies of varying solvent composition to understand the structural evolution of nanoaggregates. The masses of nanoaggregates were correlated to structures of 15 to 50 nm diameter observed in cryo-electron microscopy. [ABSTRACT FROM AUTHOR]

Silver-gold alloy nanoparticles were grown using heat treatment of soda-lime glass slides with depercolated gold film subjected to silver-to-sodium ion exchange. Varying the regime of the heat treatment allows one to control the proportion of silver in the nanoparticles and adjust the spectral position of their local surface plasmon resonance (LSPR) in the spectral range between the resonances of gold and silver nanoparticles. The position of LSPR in gold nanoparticles can be shifted by 15% via their dilution by silver in 50 wt % concentration. This shift is accompanied by only a 3% decrease in HeLa cell viability on the slides with alloy nanoparticles on the surface and by a slight decrease in the cell functionality/adhesion (FA) that show the biocompatibility of these nanoparticles. On the contrary, a notable decrease in the viability and ∼100% drop of FA were registered for the slides with purely silver nanoparticles. [ABSTRACT FROM AUTHOR]

The article discusses a signature specimen called the Gold Horn, which is a wire of gold from the Ground Hog mine in Colorado. The Gold Horn is known for its unique wire habit, with tight curls at the ends. It is considered the world's rarest form of gold. The article also mentions the history of the specimen, its exhibition at various museums and shows, and recent scientific research conducted on its internal structure and chemistry. The Gold Horn has both natural and social histories, making it a valuable and fascinating museum object. [Extracted from the article]

The rising number of antibiotic‐resistant bacteria requires alternative antibacterial substances as therapeutics. However, besides a strong effect against bacteria, they should not exhibit cytotoxicity towards human cells. Typically, both properties are tested in separate in vitro experiments that do not take into account naturally occurring interactions. To analyze whether the bacteria‐cell interaction influences the results of antibacterial and cytotoxic testing, surfactant‐free antibacterial silver‐gold alloy nanoparticles produced by laser ablation in liquid were examined both separately and in a straightforward coculture setup. Whereas different commensal bacteria and human skin cells exhibited reduced metabolic activity at comparable concentrations when treated separately, their response completely differed when analyzed in a combined coculture. For the combination of oral keratinocytes and Staphylococcus aureus, reduced cytotoxicity with increasing cell numbers, but a similar antibacterial effect quantified by standard plate counting could be observed. In contrast, coculture of keratinocytes and Porphyromonas gingivalis resulted in a complete absence of cytotoxicity and antibacterial effect, probably due to bacterial invasion of cells. These results clearly showed that the bacteria‐cell interaction greatly influences the results of antibacterial and cytotoxic testing and highlight the importance of more complex in vitro experiments to reliably characterize novel antibacterial substances for efficient clinical translation. [ABSTRACT FROM AUTHOR]

Evaluation of the electron-nuclear dynamics and relaxation mechanisms of gold and silver nanoclusters and their alloys is important for future photocatalytic, light harvesting, and photoluminescence applications of these systems. In this work, the effect of silver doping on the nonradiative excited state relaxation dynamics of the atomically precise thiolate-protected gold nanocluster [Au25-nAgn(SH)18]−1 (n = 1, 12, 25) is studied theoretically. Time-dependent density functional theory is used to study excited states lying in the energy range 0.0–2.5 eV. The fewest switches surface hopping method with decoherence correction was used to investigate the dynamics of these states. The HOMO–LUMO gap increases significantly upon doping of 12 silver atoms but decreases for the pure silver nanocluster. Doped clusters show a different response for ground state population increase lifetimes and excited state population decay times in comparison to the undoped system. The ground state recovery times of the S1–S6 states in the first excited peak were found to be longer for [Au13Ag12(SH)18]−1 than the corresponding recovery times of other studied nanoclusters, suggesting that this partially doped nanocluster is best for preserving electrons in an excited state. The decay time constants were in the range of 2.0–20 ps for the six lowest energy excited states. Among the higher excited states, S7 has the slowest decay time constant although it occurs more quickly than S1 decay. Overall, these clusters follow common decay time constant trends and relaxation mechanisms due to the similarities in their electronic structures. [ABSTRACT FROM AUTHOR]

The authors studied forty-three beautiful nose ornaments from the Moche tomb of the Lady of Cao, located in the north of Peru, which has been dated to be around 300–400 d.C. Of these items, thirty-nine are composed of a sheet of gold alloy joined together in various manners to a silver alloy sheet, which provides a strong contrast at their interface. Two nose ornaments are on gold alloy and two on silver alloy. These nose ornaments were studied using the following methods: (i) Energy-dispersive X-ray fluorescence (EDXRF); (ii) Transmission of monoenergetic X-rays (XRT) and (iii) X-ray Radiography (RAD). The conclusion, deduced from all applied methods, was that two sheets of gold and silver alloys were joined together with various methods, including gluing, mechanically joining, soldering, smelting with the aid of heating or using mercury to create an amalgam. It cannot be excluded that a few areas, visibly appearing as silver, were obtained by depletion silvering from the base Au-Cu-Ag alloy. By analyzing a fragment from the silver area of a nose ornament and by studying a few other nose ornaments from the tomb of the Lady of Cao in situ, G. Ingo and co-workers concluded that a unique sheet of three-component alloy (Ag-Cu-Au), whichemployed and transformed the surface of the objects to appear to be gold and silver by depletion gilding and silvering. [ABSTRACT FROM AUTHOR]

Facile synthesis of metal nanoparticles with controlled physicochemical properties using environment-friendly reagents can open new avenues in biomedical applications. Nanomaterials with controlled physicochemical properties have opened new prospects for a variety of applications. In the present study, we report a single-step photochemical synthesis of ~5 nm-sized silver (Ag) and gold (Au) nanoparticles (NPs), and Ag–Au alloy nanoparticles using L-tyrosine. The physicochemical and surface properties of both monometallic and bimetallic NPs were investigated by analytical, spectroscopic, and microscopic techniques. Our results also displayed an interaction between L-tyrosine and surface atoms that leads to the formation of AgAu NPs by preventing the growth and aggregation of the NPs. This method efficiently produced monodispersed NPs, with a narrow-sized distribution and good stability in an aqueous solution. The cytotoxicity assessment performed on breast cancer cell lines (MCF-7) revealed that the biofriendly L-tyrosine-capped AgNPs, AuNPs, and bimetallic AgAu NPs were biocompatible. Interestingly, AgAu NPs have also unveiled controlled cytotoxicity, cell viability, and in vitro peroxidase nanozyme activity reliant on metal composition and surface coating. [ABSTRACT FROM AUTHOR]

Materials belonging to the polychromy and gilding of the sculpture 'Our Lady of Sorrows, which belongs to the collection of a church in Garopaba, Santa Catarina, southern Brazil, were analyzed by multiple techniques. The analysis by μ-Raman and FTIR indicated the use of the ultramarine blue pigment, confirmed by EDS, with calcium carbonate observed in the base of preparation. The results show the use of gold leaf based on a gold and silver alloy, and the use of Armenian bole with clay and traces of manganese, as the base for fixing the gold leaf was characterized. GC-MS analysis suggested the use of plant oil in the painting process. Finally, the EPR analysis showed the presence of Fe3+, Mn2+ and organic radicals from the degradation of the binder, suggesting the formation of complexes with the degradation products, this being one of the first reports in this type of painting. [ABSTRACT FROM AUTHOR]

Samsonow selects the symbolic power of the ancient girl Electra whose cries, Woolf suggests, can be heard as the scream of cosmic crisis. Samsonow: Electra is the daughter of a Great Mother and thus inhabits a world where mother provides the primary identification. Though Freud rejected Jung's proposed Electra complex, her mythological association with his account of the castration complex that failed to recognize the differences of sexual development nonetheless implicates Electra. The theoretical ground is now prepared for Electra to be placed more squarely within her pre-Hellenic universe to establish an analogy between, on one side, the animal totemism of Minoan and Cretan cultures as a mode of becoming-human, and on the other, the pre-oedipal mother-child relation. [Extracted from the article]

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The east wall leads to the tomb corridor and tomb entrance, and the north and south walls are connected to the side chambers by passages (Figure 11). The walls between the main chamber, side chambers, and adjacent side chambers are adobe and gravel. The outer wall surface of the adobe walls is treated to be neat and clean, while the inner wall surface remains the original adobe shape and is uneven. The south side of the tomb pit extends out of the adobe wall in a slightly northeast-southwest direction, with a four-degree angle to the adobe wall. [Extracted from the article]

• Au-Ag NPs with different morphologies were synthesised and deposited on carbon nanofibers. • HRTEM-EDX and CV confirm the formation of a random alloy and two core-shell structures. • Au-Ag, Au and Ag-based catalysts were tested in the electrocatalytic reduction of organic halides. • Bimetallic NPs showed an increased reactivity compared to monometallic catalysts. • Au-Ag NPs with different morphology exhibit diverse reactivity in the reactions considered. Bimetallic gold-silver nanoparticles (NPs) have unique chemical and physical properties due to the synergistic effect of the two metals. From a catalytic point of view, supported AuAg NPs possess different properties depending on their structure, e.g. random alloy or core-shell. Herein, we synthesised bimetallic Au-Ag nanoparticles using a sol-immobilisation method to obtain different bimetallic structures. These colloids were then deposited on high heat-treated (HHT) carbon nanofibers characterised through high-resolution transmission microscopy coupled with energy-dispersive X-ray spectroscopy (HRTEM-EDX), and cyclic voltammetry (CV). Combining these complementary techniques revealed the formation of a random alloy, AuAg, and two core-shell structures, Ag@Au and Au@Ag. In the first case, the structure presents a silver shell and a gold core, while the second possesses a silver core covered in gold. Finally, the catalysts were tested in the electrocatalytic reduction of organic halides, i.e. acetobromo-α-D-glucose and benzyl bromide, two model well-studied molecules, and compared with the catalytic performance of the respective monometallic counterparts. For both the substrates the bimetallic NPs showed an increased reactivity compared to the monometallic counterparts, underlining the synergistic effect of the two metals. More importantly, the different structures assumed by the NPs had an impact on the catalytic activity. Indeed, the Ag@Au/HHT catalyst showed the lowest reduction potential for the reduction of acetobromo-α-D-glucose, while for benzyl bromide reduction the random alloy results to be the best employed catalyst. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Gold silver alloy nanocoral clusters were synthesized to develop a novel sensor. • Innovative sensor for simultaneously detecting antibiotic residues in food samples. • Picomolar sensitivity with exceptional stability, reproducibility and repeatability. • Exhibited remarkably low detection limits of 0.11 pM for VAN and 0.017 pM for CFT. • Effective analytical tool for addressing the ongoing antibiotic residues crisis. The widespread use of antibiotics in humans and animals has resulted in the accumulation of their residues in food and the environment, posing significant threats to human health, the environment, and the global economy. Herein, we have developed a highly sensitive and selective electrochemical sensor by integrating gold-silver alloy nanocoral clusters (Au-Ag-ANCCs) with reduced graphene oxide (r -GO) and poly(L-histidine) composites at the surface of glassy carbon electrode (GCE). The developed sensor (Au-Ag-ANCCs/r-GO/poly(L-histidine)/GCE) was designed for the simultaneous determination of vancomycin (VAN) and ceftriaxone (CFT) residues in food samples. Its morphological and electrochemical properties were exhaustively examined using UV–Vis spectroscopy, FT-IR, XRD, SEM, EDX, EIS, and CV. The sensor showed exceptional performance in a linear range of 1.0 pM to 120 μM for VAN and 1.0 pM to 290 μM for CFT. The limits of detection were 0.11 pM for VAN and 0.017 pM for CFT, while the limits of quantification were 0.36 pM for VAN and 0.057 pM for CFT. The sensor exhibited remarkable reproducibility, repeatability, stability, and selectivity. It was successfully applied to detect VAN and CFT residues in chicken meat, fish, and milk, achieving recoveries of 96.2–102.1 % with relative standard deviation (RSD) below 5 %. Therefore, the sensor is an ideal tool for addressing the global antibiotic residue crisis in food samples. [ABSTRACT FROM AUTHOR]

[Display omitted] In the current work, we investigate the transformation mechanics of gold-silver nanoparticles with cuboctahedral and icosahedral geometries by varying relevant attributes including size, composition, morphology, and chemical order. Our findings reveal that the transformation occurs via a martensitic, symmetric mechanism, irrespective of the specific attributes for all nanoparticles under consideration. The associated transformation barriers are observed to be strongly dependent on both size and composition as the activation energies increase with higher silver content. The chemical order is also a significant factor for determining how readily the transformation occurs since core–shell nanoparticles with gold exteriors display higher barriers in comparison to their silver counterparts. Likewise, for a given composition, core–shell morphologies indicate reduced ease of transformation relative to alloy nanoparticles. [ABSTRACT FROM AUTHOR]

The aim of this Special Issue was to serve as a platform to present contributions toward the various trends and challenges related to advanced electrical measurements technologies. Topics of interest for the call included, but were not limited to: advanced electrical measurements technologies in power systems and smart grids advanced electrical measurements technologies in renewable energy systems advanced electrical measurements technologies in avionics, automotive, and transportation systems advanced electrical measurements technologies in smart homes and buildings advanced electrical measurements technologies in healthcare advanced electrical measurements technologies in education and teaching advanced electrical measurements technologies in a green economy advanced electrical measurements technologies in critical infrastructure protection and security advanced electrical measurements technologies in physics The response to the call is summarized to the following Table 1. Many combinations of numbers had mystical implications in ancient times, prompting many mathematicians and historians to believe that the ancients often embraced intricacy for its own sake. The state estimation technique may run in either a grid-connected or islanded mode, while single or multiple breaker status errors at major substations and feeders are successfully identified. [Extracted from the article]

Nanowires of different metals undergoing elongation were studied by means of canonical Monte Carlo simulations and the embedded atom method representing the interatomic potentials. The presence of a surfactant medium was emulated by the introduction of an additional stabilization energy, represented by a parameter Q. Several values of the parameter Q and temperatures were analyzed. In general, it was observed for all studied metals that, as Q increases, there is a greater elongation before the nanowire breaks. In the case of silver, linear monatomic chains several atoms long formed at intermediate values of Q and low temperatures. Similar observations were made for the case of silver-gold alloys when the medium interacted selectively with Ag. [ABSTRACT FROM AUTHOR]

Vibrational spectra of AunAg+m·Ark (n + m = 4, 5; k = 1-4) clusters are determined by far-infrared resonant multiple photon dissociation spectroscopy in the range v = 100-250 cm-1. The experimental spectra are assigned using density functional theory for geometries obtained by the Birmingham cluster genetic algorithm. Putative global minimum candidates of the Ar complexes are generated by adding Ar atoms to the AunAg+m low energy isomers and subsequent local optimization. Differential Ar binding energies indicate exceptionally strong Au-Ar bonds in Au-rich clusters, leading to fundamental changes to the IR spectra. The stronger Ar binding is attributed to a relativistically enhanced covalent character of the Au-Ar bond, while in Au-rich species charge-induced dipole interactions overcompensate the relativistic affinity to Au. Moreover, not only the absolute composition but also the topologies are essential in the description of Ar binding to a certain cluster. [ABSTRACT FROM AUTHOR]

We studied localized surface plasmon resonances (LSPR) at different compositions, substrate temperatures, and mass thicknesses of Ag-Au alloy nanoparticle films grown by sequential pulsed laser deposition. The LSPRs were pronounced at all compositions of the films grown at high substrate temperature of about 300 °C as compared to those grown at room temperature. The alloy formation and composition of the films were determined using X-ray photoelectron and energy dispersive spectroscopy. Films' mass thickness and compositional uniformity along the thickness were determined using X-ray reflectometry and secondary ion mass spectroscopy. Atomic force microscopic analysis revealed the formation of densely packed nanoparticles of increasing size with the number of laser ablation pulses. The LSPR wavelength red shifted with increasing either Au percentage or film mass thickness and corresponding LSPR tuning was obtained in the range of 450 to 690 nm. The alloy dielectric functions obtained from three different models were compared and the optical responses of the nanoparticle films were calculated from modified Yamaguchi effective medium theory. The tuning of LSPR was found to be due to combined effect of change in intrinsic and extrinsic parameters mainly the composition, morphology, particle-particle, and particle-substrate interactions. [ABSTRACT FROM AUTHOR]

Bimetallic or alloy nanoparticles (NPs) have improved properties compared to their monometallic forms. Microalgae being rich in biocompatible reductants and being ecofriendly are potential sources to synthesize fuctionalized NPs. In this study, biosynthesis of silver, gold, and bimetallic NPs was carried out via bioreduction using aqueous extract of algal isolate Chlorella acidophile, inhabitant of non-arable land. C. acidophile is known to contain highly bioactive functional moieties, which can serve as nanobiofactories for metallic NPs. Various characterization techniques viz, UV–visible spectrophotometer, X-ray diffraction analysis, X-ray photo-electron spectroscopy, and Raman spectroscopy were employed to determine their composition, structure, and crystal phase. The monometallic and bimetallic particles were found to be crystalline state and generally in a spherical shape. Their size ranged from 5 to 45 nm and the corresponding FTIR spectra indicated that the specific organic functional groups from algal extract were involved in the bio-reduction. Furthermore, the core–shell in the case of Au–Ag NPs was formed due to the simultaneous reduction of gold and silver ions. An enhanced and more pronounced Raman spectra of Au–Ag NP compared to individual Au NP indicated the improved properties of bimetallic NPs, the latter having been of immense potential to be used as sensors in industries. [ABSTRACT FROM AUTHOR]

A nitrogen-doped carbon shell loaded with a gold and silver alloy (Au/Ag@NCS) was constructed for highly sensitive electrochemical detection of NO. The Au/Ag@NCS material was prepared by use of SiO 2 particles as a template to polymerize imidazolium-based ionic liquids loaded with gold and silver salts, and subsequent carbonization treatment and template removal. The hollow structure of the carbon material acted as a carrier for electrochemical sensing, offering high specific surface area, large pore capacity, robust electron conductivity, and excellent mechanical stability. The inclusion of gold in the composite enhanced its catalytic and sensing capabilities, while silver oxidation was employed as a reference signal for accurate detection. By utilization of the Au/Ag@NCS-modified electrode, a wide detection range from 0.5 nM to 1.05 μM with a low detection limit of 0.32 nM was achieved for NO detection. The electrochemical sensor also exhibited high selectivity and excellent stability. The fabricated sensor was further utilized to explore the release of NO from breast cancer cells, revealing that the electrochemical platform could be regarded as an important method to study the daily tests of NO in clinical application. A nitrogen-doped carbon shell loaded with a gold and silver alloy (Au/Ag@NCS) was constructed for highly sensitive electrochemical detection of NO. [Display omitted] • Au/Ag@NCS was prepared by in-situ polymerization of ILs and subsequent treatment. • NCS structure and dispersed Au/Ag alloy provided high electrocatalytic activity. • High sensitivity and selectivity for NO detection were obtained. • Ag oxidation as an internal reference endowed accurate detection of NO from cells. [ABSTRACT FROM AUTHOR]

We present a comparison of the two types of metallic magnetic calorimeters (MMCs) developed for a large-scale neutrinoless double beta decay ($0\nu \beta \beta$) search experiment. As high resolution micro-calorimeters, MMCs employ micro-fabricated superconducting circuits to measure the changes in magnetization of a paramagnetic sensor material. We constructed two alpha spectrometers with two MMC sensors made of Au:Er and Ag:Er (i.e., gold and silver alloys with small concentrations of Er). A piece of gold foil with a heat capacity comparable to that of 350 g CaMoO $_4$ crystal near 10 mK was used as the absorber for each alpha spectrometer. These detector setups allowed us to investigate the temperature dependence of magnetization for the different sensor materials over a wide temperature range with various amounts of field current. The magnetization measurements for both the Au:Er and Ag:Er sensors were in good agreement with calculations for field currents of up to 100 mA. Moreover, the measured and estimated pulse heights of alpha events agreed with each other, and were compared between the different sensor materials. We discuss how the excess heat capacity from the nuclear spins in Au:Er influences the pulse size and shape in calorimetric detection. Moreover, we describe the benefit of using Ag:Er sensors in thermal calorimeters with large crystal absorbers in a $0\nu \beta \beta$ search experiment. [ABSTRACT FROM AUTHOR]

The energy landscape and kinetics of medium-sized Ag-Au and Ag-Ni nanoalloy particles are explored via a discrete path sampling approach, focusing on rearrangements connecting regions differing in chemical order. The highly miscible Ag27Au28 supports a large number of nearly degenerate icosahedral homotops. The transformation from reverse core-shell to core-shell involves large displacements away from the icosahedron through elementary steps corresponding to surface diffusion and vacancy formation. The immiscible Ag42Ni13 naturally forms an asymmetric core-shell structure, and about 10 eV is required to extrude the nickel core to the surface. The corresponding transformation occurs via a long and smooth sequence of surface displacements. For both systems the rearrangement kinetics exhibit Arrhenius behavior. These results are discussed in the light of experimental observations. [ABSTRACT FROM AUTHOR]

The specific heat of dilute alloys of holmium in gold and in silver plays a major role in the optimization of low temperature microcalorimeters with enclosed 163 Ho , such as the ones developed for the neutrino mass experiment ECHo. We investigate alloys with atomic concentrations of x Ho = 0.01 - 4 % at temperatures between 10 and 800 mK . Due to the large total angular momentum J = 8 and nuclear spin I = 7 / 2 of Ho 3 + ions, the specific heat of Au:Ho and Ag:Ho depends on the detailed interplay of various interactions, including contributions from the localized 4f electrons and nuclear contributions via hyperfine splitting. This makes it difficult to accurately determine the specific heat of these materials numerically. Instead, we measure their specific heat by using three experimental setups optimized for different concentration and temperature ranges. The results from measurements on six holmium alloys demonstrate that the specific heat of these materials is dominated by a large Schottky anomaly with its maximum at T ≈ 250 mK , which we attribute to hyperfine splitting and crystal field interactions. RKKY and dipole–dipole interactions between the holmium atoms cause additional, concentration-dependent effects. With regard to ECHo, we conclude that for typical operating temperatures of T ≤ 20 mK , silver holmium alloys with x Ho ≳ 1 % are suited best. [ABSTRACT FROM AUTHOR]

Bimetallic silver‐gold alloy nanoparticles on zirconia with varying Ag/Au ratios were designed by a rational approach and tested as catalysts for the selective oxidation of the promising biomass platform molecule 5‐(hydroxymethyl)furfural (HMF). For this purpose, colloidal AgxAu10‐x particles with molar compositions x=1/3/5/7/9 were prepared by laser ablation in liquids, a surfactant‐free method for the preparation of highly pure nanoparticles, before adsorption on zirconia. In‐depth characterization of the supported catalysts evidenced alloyed nanoparticles with distinct trends of the surface and bulk composition depending on the overall Ag/Au molar ratio as determined by X‐ray photoelectron spectroscopy (XPS) and X‐ray absorption spectroscopy (XAS), respectively. To uncover the synergistic effect of the Ag/Au ratio, the catalysts were further studied in terms of the catalytic activity and selectivity in HMF oxidation. Either the aldehyde moiety or both functional groups of HMF were selectively oxidized depending on the Ag/Au composition resulting in 5‐hydroxymethyl‐2‐furan‐carboxylic acid (HFCA) or 2,5‐furandicarboxylic acid (FDCA), respectively. Optimization of the reaction conditions allowed the quantitative production of HFCA over most catalysts, also after re‐use. Only gold rich catalysts Ag1Au9/ZrO2 and particularly Ag3Au7/ZrO2 were highly active in FDCA synthesis. While Ag3Au7/ZrO2 deactivated upon re‐use due to sintering, no structural changes were observed for the other catalysts and all catalysts were stable against metal leaching. The present work thus provides fundamental insights into the synergistic effect of Ag and Au in alloyed nanoparticles as active and stable catalysts for the oxidation of HMF. [ABSTRACT FROM AUTHOR]

Precious alloys are subjected to a series of mechanical and thermal operations during manufacturing. For 18 carat gold alloys the processing operations can induce L1 0 ordered nanodomains, known to lead to the build-up of residual stresses, which are the prime cause for shape distortion. Here, in situ high-energy synchrotron X-ray diffraction experiments in combination with electron microscopy observations reveal the influence of the thermo-mechanical history and chemical composition on the ordering kinetics during isochronal heating. Initially, during heating, the elastic lattice strain in the ordered nanodomains increases. The ordering rate and accumulation of lattice strain depend on the cooling rate, predeformation and chemical composition. Above a given temperature, which depends on the deformation state and chemical composition, the lattice strain in the ordered domains relaxes which is ascribed to the formation of a tweed structure. Image, graphical abstract [ABSTRACT FROM AUTHOR]

• Si substrate was implanted sequentially with Au and Ag ions at different fluences. • Nanoparticles were found at maximum distribution depths of Au and Ag ions. • Ag nanoparticles aggregate in the silicon matrix along with the dissolved Au atoms. • The size of formed nanoparticles was controlled by varying Ag ion fluence. • HAADF contrast imaging was used to confirm the formation of Au-Ag alloy structure. Au-Ag alloy nanoparticles were formed into amorphous silicon by sequential ion implantation of Au and Ag. Monocrystalline Si was amorphized at the initial moment of implantation with 1 × 1016 ions/cm2 gold ions, and then different silver fluences were applied in the range of 1 × 1016–1 × 1017 ions/cm2. After implantations the samples were investigated by means of Rutherford backscattering spectrometry and transmission electron microscopy. The nanoparticles were found to be formed at surface and sub-surface regions of the Si substrate, at depths corresponding to the maximum distribution of Au and Ag ions. The particles are crystalline in nature with sizes from 2 nm to 30 nm in diameter, increasing with silver ion fluence. Although the lattice constants of gold and silver are too close to be distinguished by measuring the characteristic interplanar spacings, imaging in scanning transmission mode confirms the formation of Au-Ag bimetallic nanoparticles, presenting a solid-solution alloy of gold and silver. [ABSTRACT FROM AUTHOR]

Arsenic is toxic, so being able to detect and monitor arsenic in aqueous environments is important. Here, we report a biosensor for As3+ (Arsenic (III)) which uses a glassy carbon electrode modified with Ag-Au alloy NPs (i.e. Silver and gold alloy nanoparticles) and loaded with an aptamer. The electrode contains apta deep trapped Ag-Au alloy NPs, and the detection method employs cyclic voltammetry and differential pulse voltammetry. Captured As3+ ions undergo electrochemical reaction, producing a significant increase in the current which is observed in the voltammetry curves. This current increase is a result of the electrocatalytic properties of the NPs. The electrode is used for the determination of As3+ in real water samples. The activity curve is linear for As3+ concentrations of 0.01µg/L to 10 µg/L, and the detection limit is 0.003 × 10−3µg/L. The operation of the biosensor is reproducible, stable, and selective, and the biosensor performs well in determining As3+ in water from natural water courses, lakes, and wells. [ABSTRACT FROM AUTHOR]

Background: Cancer is one of the most important diseases of concern worldwide. The advanced in nanotechnology were focused in many scientific researches on the formation of nanoparticles and their application in cancer treatment. The aim of current study was to synthesize Au-Ag bimetallic nanoalloys with tunable localized surface plasmon resonance frequency for use in photothermal therapy for MCF7 breast cancer cell line. Method: In this work, nanoparticles were made of silver: gold alloy with different gold ratio for use in phototherapy with tuned plasmon resonance peak between 405 to 526nm using UV-visible absorbance. Results: From the comparison between FTIR spectrum of controlled breast cancer cell line (MCF7) before and after the addition of metal nanoparticles, was found essential difference due to the conjugated of cell protein with added metal nanoparticles. There was a selectivity of metal nanoparticles effects on the band where the N–H braches of the protein are directly involved in its interaction with the metal surface due to surface enhanced infrared absorption. Conclusion: Growth inhibition of cancer cell line treatment using phototherapy employed metal nanoparticles and UV radiation illustrates good results with best GI ratio when use silver nanoparticles with 67.06% ratio before irradiation and 82.02 % after irradiation. This percentage decreases with increasing the gold ratio. [ABSTRACT FROM AUTHOR]

This study investigated the mechanism of the interfacial reaction of Ag-alloy wires in the gold bond pad of an LED die after a wire bonding process and their reliability. The results showed that in the as-bonded condition, no intermetallic compounds (IMCs) formed between the Ag-alloy wire and the gold bond pad and that the interfacial reaction mechanism was diffusional solid solution reaction. After 168 h of thermal aging at 200 °C, it was found that adding Pd to the Ag-alloy wire could improve the mechanical properties of the wire, and the bonding strength between the Ag-alloy wires and gold bond pad showed an increasing trend. It was speculated that increasing the thermal aging period allowed sufficient time for the diffusion reaction between the silver alloy and gold bond pad. The gold ball residual area difference indicated that adding Pd to Ag-alloy wire was more helpful than adding Au for boosting bond shear test (BST) strength in the as-bonded condition, while adding Au to a ternary Ag-alloy wire helped the bonding strength in terms of thermal stability. BST and wire pull test (WPT) specifications are suggested for Ag-alloy wire joints in LED packaging products based on tests of the critical quality parameters of Cpk. [ABSTRACT FROM AUTHOR]

Using molecular dynamics simulations, an embedded-atom model potential, and the mechanistic route, we have computed the pressure tensor and the surface tension γ of Ag-Au liquid alloys. Although the model generally underestimates γ for pure metals, calculations for a bulk planar slab exhibit nonlinear variations of γ with increasing gold concentration, which agree with experiments and can be accounted for by a perfect solution model. Calculations for various nanoscale droplets containing between 100 and 3200 atoms show a systematic decrease of γ with increasing droplet radius R. The positive Tolman length of the alloy determined from these size variations is estimated to vary slightly with gold concentration. The effects of temperature in the range 1300-1700 K are discussed. [ABSTRACT FROM AUTHOR]

A theoretical model for a gas sensor based on chalcogenide prism and surface plasmon resonance is proposed. The metal layer consists of Ag–Au alloy nanoparticles. The chalcogenide prism is made of sulfide glass Ge20Ga5Sb10S65, commonly known as 2S2G. The angular interrogation method is used to analyze the sensor’s performance in terms of its intrinsic sensitivity that takes into account both the angular shift as well as the angular width of plasmon resonance curve. The effect of operating wavelength along with the size and composition ratio of alloy nanoparticle is studied on sensor's performance. The sensor’s performance improves with an increase in nanoparticle size and silver fraction. Large operating wavelength is found to be useful for accurate gas sensing. Therefore, proposed sensor can be very useful for gaseous sensing in infrared due to large operating window of chalcogenide materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • Unraveling the multistage formation mechanism for silver-gold alloy nanoparticles. • Successful mechanistic modeling of a highly complex nanoparticle formation process. • Unprecedented process insights via the calibrated multidimensional population balance equation model. • Determination of material and rate constants, hardly measurable experimentally. The large-scale synthesis of nanoparticles (NPs) with defined properties requires detailed understanding of the underlying formation mechanisms and kinetics. The formation mechanisms of bimetallic NPs are still not sufficiently understood due to the complex reaction chemistry, which makes the control of the supersaturation as the thermodynamic driving force challenging. Particle size, chemical composition, and the distribution of the elements within the particles change dynamically during particle formation. In this work, we propose a mechanism for the formation of bimetallic silver-gold alloy NPs via a green liquid-phase co-reduction synthesis and develop a two-dimensional population balance model to quantitatively describe the evolution of particle size distribution, composition, and optical properties. We shed light on the complex multi-stage formation mechanism of a highly relevant bimetallic NP system, lay the foundation for tailoring the process conditions to achieve targeted optical particle properties and unravel predictive property-process relationships. [ABSTRACT FROM AUTHOR]