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Gold nanoclusters have attracted significant attention due to their unique physical-chemical properties, which can be tuned by alloying with elements such as Cu, Pd, Ag, and Pt to design materials for various applications. Although Au-nanoalloys have promising applications, our atomistic understanding of the descriptors that drive their stability is far from satisfactory. To address this problem, we considered 55-atom model nanoalloys that have been synthesized by experimental techniques. Here, we combined data mining techniques for creating a large sample of representative configurations, density functional theory for performing total energy optimizations, and Spearman correlation analyses to identify the most important descriptors. Among our results, we have identified trends in core–shell formation in the AuCu and AuPd systems and an onion-like design in the AuAg system, characterized by the aggregation of gold atoms on nanocluster surfaces. These features are explained by Au's surface energy, packing efficiency, and charge transfer mechanisms, which are enhanced by the alloys' preference for adopting the structure of the alloying metal rather than the low-symmetry one presented by Au55. These generalizations provide insights into the interplay between electronic and structural properties in gold nanoalloys, contributing to the understanding of their stabilization mechanisms and potential applications in various fields. [ABSTRACT FROM AUTHOR]

Element doping/alloying is a common strategy to tune the electrical and thermal transports of thermoelectric (TE) materials, but the doping/alloying limit of foreign elements in many TE materials is usually very low, bringing a great challenge to improve the TE performance. In this work, beyond the classic principle of “like dissolves like,” it is found that choosing the compound with a severely distorted lattice and diversified chemical bonding as the matrix also facilitates achieving a high doping/alloying limit. Taking ductile semiconductors as an example, this work shows that gold (Au) element is nearly immiscible in Ag2S and Ag2Te, but has a relatively high alloying limit in complex Ag2S0.5Te0.5 meta‐phase. Au in Ag2S0.5Te0.5 significantly decreases the carrier concentration and improves the TE performance, but scarcely changes the mechanical properties. Consequently, Ag1.99Au0.01S0.5Te0.5 demonstrates both a high figure‐or‐merit of 0.95 at 550 K and extraordinary room‐temperature ductility. This work offers an effective and general strategy to develop stabilized doped/alloyed TE materials. [ABSTRACT FROM AUTHOR]

This study reports ambient electrosynthesis of dimethyl carbonate with a palladium–gold catalyst. Material screening identifies a region of intermediate‐catalyst binding energy that facilitates interfacial electron and proton transfers for selective carbonylation, achieving a distinct maximum of 92% faradaic efficiency to dimethyl carbonate. Structural and electrochemical analyses suggest that the alloying of palladium and gold effectively modulates the CO* binding energy to the catalytic surface, in accord with subsequent computational studies. With an extended heterogeneous–homogeneous catalytic environment with a halide redox mediator, a remarkable partial current density of 52 mA cm−2 is observed for dimethyl carbonate for 100 h of continuous operation. [ABSTRACT FROM AUTHOR]

In this study, we assess the suitability of Pd alloys in direct mechanocatalytic coupling reactions. Copper (Cu) and nickel (Ni) were alloyed with palladium (Pd), alongside testing a high entropy alloy and palladium gold alloy. Compared to pure Pd balls the alloys are promising in terms of mechanical properties and costs. Combining Pd with Cu and Ni improved mechanical resilience by up to 330 % while retaining catalytic activity, for the tested Suzuki‐Miyaura and Sonogashira‐Hagihara couplings. Both of which led to good to excellent yields within one hour. Notably, alloys containing 20 % Pd showed increased yields of over 80 % in the Sonogashira coupling, comparable to pure Pd. XPS and in‐situ PXRD analysis showcased the influence of alloyed metals on catalytic processes, emphasizing the significance of the surface composition of milling balls. [ABSTRACT FROM AUTHOR]

Traditional metallic biomaterials including titanium and its alloys, stainless steel, cobalt‐chromium alloys, magnesium alloys are gold standards for load bearing hard tissue applications, because of adequate mechanical properties such as elastic modulus, ductility and strength for long term support and stability. However, metallic implants suffer from poor osteointegration and early degradation in host body, owing to an array of factors which include stress shieling effect, corrosion, metal toxicity, microbial contamination and low bioactivity. Therefore, to improve integration of implants with host tissue and overall mechanical and biological functions, metallic implants are coated with bioactive glasses (BG). BG are one of the most promising implant coating materials used for bone repair and reconstruction, mainly because of excellent angiogenic, osteoconductive, osteoinductive, corrosion resistance, resorbability, biocompatibility, bioactivity and anti‐microbial properties. Various BG compositions are employed for diverse biomedical applications ranging from wound healing, bone formation, corrosion resistance, drug delivery to scaffolds in tissue engineering and different methods are used for coating BG on implants to enhance stability and bond strength between implant and coating. This narrative review gives a detailed overview on metallic implants, issues of metal alloys when used in implants and how metallic implants are improved by various BG compositions and coating methods. This review provides an updated information on advantages of different BG compositions in implants fabrication in order to address challenges and tailor mechanical and biological properties of implants for future applications. [ABSTRACT FROM AUTHOR]

Tuning the color of Au has been a longstanding problem in the luxury industry. Conventional approaches, involving Au alloying, compromise purity and demand distinct alloy compositions for each hue. This study demonstrates a lithography‐free method for generating structural colors on a gold surface by adjusting the thickness of titanium dioxide, a high‐index dielectric. While color tuneability is limited if TiO2 is coated directly on the Au surface, a range of vivid colors can be generated if a 50−100 nm thick AuAl2 underlayer is used. AuAl2, an accepted alloy for purple gold, broadens the color gamut, providing a protective coating without diminishing gold purity. The reflectance dip of the bilayer structure exhibits a significant red shift with increasing thickness of the TiO2 layer, allowing diverse colors by TiO2 insulator tuning. Simulation studies corroborate experimental results, affirming that coating a TiO2 layer on the AuAl2 underlayer yields a wide range of colors. This method, based on thin‐film interference, shows promise for widespread use, offering a broad spectrum of structural colors in an industry striving for diverse Au color representation. [ABSTRACT FROM AUTHOR]

Complex gold-iridium-osmium placer deposits associated with the Guli massif of ultramafic, alkaline rocks and carbonatites are located within the Maimecha-Kotui province in the northern part of the Siberian Platform. Unlike natural Os-Ir alloys, which are genetically related to ultramafic rocks, the bedrock source of gold remains controversial. We report, for the first time, morphological and compositional features of gold mineralization from calcite-dolomite carbonatite of the Guli massif. Gold minerals are represented by natural Au-Ag alloys containing gold (69.64–88.57 wt %) and silver (11.73–30.83 wt %) with low concentrations of copper (up to 0.18 wt %), which predominate over minerals of the system Au–Cu–Ag (e.g., natural alloys Au0.74Cu0.14Ag0.12 and Ag0.51Au0.47Cu0.02, tetra-auricupride (AuCu) and auricupride (Cu3Au)). Gold minerals are characterized by an early pentlandite-troilite-chalcopyrite association that form polyphase euhedral inclusions. Later galena (PbS) occurring in the form of subhedral monophase inclusions is replaced by cerussite (PbCO3). The revealed similarity of gold minerals and mineral assemblages in gold from calcite-dolomite carbonatite with those of gold minerals from placer deposits of the Guli massif indicates that derivatives of ijolite-carbonatite magmatism played a significant role in gold ore formation. [ABSTRACT FROM AUTHOR]

Ternary gold alloys (TGAs) are highly regarded for their excellent electrical properties. Electrical resistivity is a crucial indicator for evaluating the electrical performance of TGAs. To explore new promising TGAs with lower resistivity, we developed a reverse design approach integrating machine learning techniques and proactive searching progress (PSP) method. Compared with other models, the support vector regression (SVR) was determined to be the most optimal model for resistivity prediction. The training and test sets yielded R2 values of 0.73 and 0.77, respectively. The model interpretation indicated that lower electrical resistivity was associated with the following conditions: a van der Waals Radius (Vrt) of 0, a Vr (another van der Waals Radius) of less than 217, and a mass attenuation coefficient of MoKα (Macm) greater than 77.5 cm2g−1. Applying the PSP method, we successfully identified eight candidates whose resistivity was lower than that of the sample with the lowest resistivity in the dataset by more than 53–60%, e.g., Au1.000Cu4.406Pt1.833 and Au1.000Pt2.232In1.502. Finally, the candidates were validated to possess low resistivity through the pattern recognition method. [ABSTRACT FROM AUTHOR]

Recent experimentally validated alloy design theories have demonstrated nanocrystalline binary alloys that are stable against thermally induced grain growth. An open question is whether such thermal stability also translates to stability under irradiation. In this study, we investigate the response to heavy ion irradiation of a nanocrystalline platinum gold alloy that is known to be thermally stable from previous studies. Heavy ion irradiation was conducted at both room temperature and elevated temperatures on films of nanocrystalline platinum and platinum gold. Using scanning/transmission electron microscopy equipped with energy-dispersive spectroscopy and automated crystallographic orientation mapping, we observe substantial grain growth in the irradiated area compared to the controlled area beyond the range of heavy ions, as well as compositional redistribution under these conditions, and discuss mechanisms underpinning this instability. These findings highlight that grain boundary stability against one external stimulus, such as heat, does not always translate into grain boundary stability under other stimuli, such as displacement damage. [ABSTRACT FROM AUTHOR]

Flexible low‐voltage organic thin‐film transistors (TFTs) with Ag source/drain contacts are fabricated, and the contact resistance is measured using the transfer length method. The TFTs are fabricated in the inverted coplanar (bottom‐gate, bottom‐contact) device architecture, using the vacuum‐deposited small‐molecule semiconductor dinaphtho[2,3′b:2′,3′‐f]thieno[3,2‐b]thiophene (DNTT). Prior to the semiconductor deposition, the contact surface is functionalized with a chemisorbed monolayer of pentafluorobenzenethiol (PFBT). For comparison, TFTs with PFBT‐functionalized Au source/drain contacts are fabricated on the same substrate. Overall, the performance of the TFTs with the Ag contacts is very similar to that of the TFTs with the Au contacts, and the contact resistance of the TFTs with the Ag contacts (377 Ωcm) is the smallest reported to date for p‐channel organic TFTs with a contact material other than Au or Pt. [ABSTRACT FROM AUTHOR]

Ceramic conversion treatment (CCT) is an effective way to modify the surface of titanium alloys. However, this process normally needs more than a 100-h treatment at 600–700 °C to form a hard and wear-resistant titanium oxide layer. In this paper, we pre-deposited a thin gold layer on the surface of Ti-6Al-2Sn-4Zr-2Mo (Ti6242) samples before CCT to investigate if Au can speed up the treatment. Treatments at 640/670/700 °C were carried out for 10 or 120 h. After CCT, the surface roughness, surface morphology, microstructure, elemental composition, and phase constituents were characterized. Surface hardness and the nano-hardness depth distribution were measured. Finally, reciprocating sliding tribological tests were carried out to study the friction and wear of the surface layers. Thin gold layers accelerated the CCT significantly with a much thicker oxide layer. The friction of the untreated Ti6242 alloy against the WC ball was unsteady and high, but it was much lower and stable for the CCTed samples pre-deposited with Au because of the formation of titanium oxides and lubrication effect of the gold particles. The wear resistance of the CCTed Ti6242 alloy samples with gold was reinforced significantly. By pre-depositing a thin gold layer on the surface of Ti6242, the treatment time can be cut significantly, and CCT becomes more efficient. [ABSTRACT FROM AUTHOR]

Silver‐gold nanocrystalline films were sputtered on HDPE substrates by a physical vapour deposition process using alloys with a nominal composition of 65% silver/35% gold or 35% silver/65% gold by weight, with comparison to a 100% silver target. Novel process conditions were introduced to include both water and oxygen as reactive gases. X‐ray diffraction and chemical digests were used to assess the structure and chemical composition of the films. Log reductions and corrected zone of inhibition tests were used to measure the biological properties. Despite a range of physical and chemical properties, biological tests showed that the bactericidal properties of all silver‐gold films were comparable with silver‐only films in the short term and 65% silver films made with Novel sputtering conditions had comparable bacteriostatic abilities to silver‐only over a 7‐day period. The benefit of including gold may be seen in future studies of anti‐inflammatory activity. [ABSTRACT FROM AUTHOR]

The potential of Sn-Bi alloys as low-temperature solders for electronics manufacturing has spurred significant research on their mechanical properties, both in the as-soldered condition and after aging. Previous studies have demonstrated that, because of the extreme temperature sensitivity of the solubility of Bi in Sn, the mechanical properties of Sn-Bi solder alloys are very sensitive to their thermal history. While the properties of the bulk solder alloy are a factor in its performance as a solder joint, the reliability in service is also affected by the joint geometry and the interaction of the solder alloy with the joint substrate. In the work reported in this paper the effect of thermal history on solder joints formed with representative Sn-Bi alloy solder balls was assessed by measuring the performance in a standard ball shear test of a solder ball reflowed to solder mask defined (SMD) copper pads with organic solderability preservative (OSP) or electroless nickel/immersion gold (ENIG) finishes. The solder ball/substrate combinations were tested within 10 min of reflow and after room-temperature storage for up to 10 days to determine the effect of aging on their response to the ball shear test. Our results show that the peak force and fracture mode of Sn-Bi solder joints is influenced by the Sn-Bi alloy composition, the substrate type, and the aging time. These observations provide new information on the capability of these alloys to deliver reliable service over a range of operating conditions. [ABSTRACT FROM AUTHOR]

Gold and silver are, for all their chemical similarities, optically very different. Small Ag clusters show a localized surface-plasmon resonance (LSPR), whereas in Au clusters smaller than about 300 atoms, the resonance is absent due to the coupling with the interband transitions from the d electrons. This opens the possibility of tuning the cluster properties depending on their composition and chemical configuration. Earlier work on AgAu alloy clusters has shown that the outermost shell of atoms is crucial to their overall optical properties. In the present contribution, we consider the optical spectroscopic properties associated with the structural rearrangement in 55-atom AgAu alloy clusters in which the core transforms from pure silver to pure gold. Calculations using time-dependent density-functional theory are complemented by an in-depth study of the subtle effects that the chemical configuration has on the details of the materials' d bands. Although the cluster surface remains alloyed, the geometrical changes translate into strong variations in the optical properties. [ABSTRACT FROM AUTHOR]

Carbon dots@noble metal nanoparticle composites are formed by combining carbon dots and metal nanoparticles using various strategies. Carbon dots exhibit a reducing ability and function as stabilisers; consequently, metal-ion solutions can be directly reduced by them to synthesise gold, silver, and gold–silver alloy particles. Carbon dots@gold/silver/gold–silver particle composites have demonstrated the potential for several practical applications owing to their superior properties and simple preparation process. Until now, several review articles have been published to summarise fluorescent carbon dots or noble metal nanomaterials. Compared with metal-free carbon dots, carbon dots@noble metal nanoparticles have a unique morphology and structure, resulting in new physicochemical properties, which allow for sensing, bioimaging, and bacteriostasis applications. Therefore, to promote the effective development of carbon dots@noble metal nanoparticle composites, this paper primarily reviews carbon dots@gold/silver/gold–silver alloy nanoparticle composites for the first time in terms of the following aspects. (1) The synthesis strategies of carbon dots@noble metal nanoparticle composites are outlined. The principle and function of carbon dots in the synthesis strategies are examined. The advantages and disadvantages of these methods and composites are analysed. (2) The characteristics and properties of such composites are described. (3) The applications of these composite materials are summarised. Finally, the potentials and limitations of carbon dots@noble metal nanoparticle composites are discussed, thus laying the foundation for their further development. [ABSTRACT FROM AUTHOR]

Electropolishing or electrochemical polishing (EP) is an ultrafinishing process that improves esthetic, technical and functional properties of metallic surfaces by reducing their roughness. This process is based on anodic dissolution of the workpiece through an oxidation reaction. For many years, cyanide-based electrolytes were used to electropolish precious metals like gold and its alloys. The need for safer working conditions encouraged the replacement of cyanide by other complexing agents, mainly thiourea. However, the latter is also harmful. Therefore, the aim of this work is to electropolish pure gold and 18k jewelry gold alloys (yellow, rose, red and gray) in a cyanide-free electrolyte, to evaluate the electrochemical behavior and the influence of different parameters. For this purpose, a previously reported solution based on hydrochloric acid and glycerol was used. In the first part of the study, the influence of chloride concentration on pure gold EP was determined by electrochemical techniques and surface properties analysis. The effects of adding ethanol to electrolyte composition and of variating rotation speed were also evaluated. The best results were obtained for a HCl 50% vol. - Glycerol 25 % vol. - Ethanol 25 % vol. electrolyte at a rotation speed of 1000 rpm. In the second part of the study, this solution was used to electropolish 18 K gold alloys. Silver-containing alloys were not uniformly polished due to the formation of an AgCl film on the surface that partially masks the substrates.

3Y-TZP ceramics are widely used in dental restoration materials due to their excellent biocompatibility, mechanical properties, and aesthetics. However, the low temperature aging characteristics seriously affect the service life of 3Y-TZP. This study aimed to investigate the mechanical properties, low temperature degradation properties and biocompatibility of a certain amount of alumina doped dental 3Y-TZP ceramics. The 3Y-TZP powder was produced by co-precipitation and then combined in a predetermined ratio with alumina powder. The fitting results of the Johnson-Mehl-Avramorow-Kolmogorow (JMAK) equation shows that the doping of alumina is beneficial to improve the low temperature degradation resistance of 3Y-TZP. The doped 3Y-TZP exhibited favorable biocompatibility, indicating its potential suitability as a dental restorative material. [ABSTRACT FROM AUTHOR]

Using gas-phase deposition (Physical Vapor Deposition (PVD) and Metal Organic Chemical Vapor Deposition (MOCVD)) methods, modern implant samples (Ti alloy and CFR-PEEK polymer, 30% carbon fiber) were functionalized with film heterostructures consisting of an iridium or gold sublayer, on the surface of which an antibacterial component (silver) was deposited: Ag/Ir(Au)/Ti(CFR-PEEK). The biocidal effect of the heterostructures was investigated, the effect of the surface relief of the carrier and the metal sublayer on antibacterial activity was established, and the dynamics of silver dissolution was evaluated. It has been shown that the activity of Ag/Ir heterostructures was due to high Ag+ release rates, which led to rapid (2–4 h) inhibition of P. aeruginosa growth. In the case of Ag/Au type heterostructures, the inhibition of the growth of P. aeruginosa and S. aureus occurred more slowly (from 6 h), and the antibacterial activity appeared to be due to the contribution of two agents (Ag+ and Au+ ions). It was found, according to the in vitro cytotoxicity study, that heterostructures did not exhibit toxic effects (cell viability > 95–98%). An in vivo biocompatibility assessment based on the results of a morphohistological study showed that after implantation for a period of 30 days, the samples were characterized by the presence of a thin fibrous capsule without volume thickening and signs of inflammation. [ABSTRACT FROM AUTHOR]

Platinum thin films comprising nominally 1 to 20 atomic overlayers were formed on a gold-coated substrate using the self-terminating electrodeposition (STED) method. The platinum overlayer loading and morphology were characterized using X-ray Photoelectron Spectroscopy (XPS), Inductively Coupled Plasma – Optical Emission Spectroscopy (ICP-OES), Field Emission Scanning Electron Microscopy (FESEM), Cyclic Voltammetry (CV) and Chronoamperometry (CA). The durability of these platinum overlayer samples was estimated by subjecting the samples to ex-situ electrochemical potential cycling. The extent of platinum overlayer growth is lower than expected till four STED cycles and then increases non-linearly, leading to increased roughness. The shifts of platinum redox peaks in CVs and Pt4f signals in XPS spectra indicate surface-alloying of gold and platinum. After the durability test, the morphological evolution of platinum overlayers conforms with the extent of platinum dissolution estimated from CVs. Our results reveal that more than four STED cycles are needed to form platinum overlayers that meet the US Department of Energy (DOE) criteria for durability. [Display omitted] • Systematic study of the durability of platinum overlayers formed using 1 to 20 Self-Terminating Electrodeposition cycles. • Non-linear growth in thickness of platinum overlayers with increasing number of Self Terminating Electrodeposition cycles. • Electrochemically durable platinum overlayers correspond to complete surface coverage with platinum. • More than four Self-Terminating Electrodeposition cycles are needed to meet the US Department of Energy durability target. [ABSTRACT FROM AUTHOR]

Dental grillz, which come in many forms, have gained global popularity. This article explores their origins, online purchasing process and potential risks. A case study highlights limitations in remote provision and ill-fitting grillz. Risks include periodontal disease, caries and occlusal derangement. Dentists can play a role in minimizing these risks. The article emphasizes the need for increased awareness among dental professionals and parents regarding the potential drawbacks of grillz, particularly among teenagers. [ABSTRACT FROM AUTHOR]

Objective This study investigated biomechanical behavior of custom post core made of six different materials on the tooth with and without the ferrule under different occlusal load. Materials and Methods Three-dimensional models of mandibular first premolar, with and without ferrule, reconstructed from micro-computed tomography image are restored with different custom post core and zirconia crowns. By using the finite element analysis, von Mises stress shown in MPa was measured under simulated axial and oblique load of 200 [N]. To compare the stress distribution, six different custom post core materials were chosen: zirconia, Ni-Cr alloy, gold alloy, glass fiber-polyether ether ketone, polyether ether ketone, and carbon fiber-polyether ether ketone. Results Custom post cores with a higher modulus of elasticity showed higher measured stress in the posts, but less stress in dentin. Measured stress in custom post core under oblique loading was approximately three times higher compared with axial loading. Stress in custom post core and in dentin under both types of loads was slightly higher in teeth without ferrule effect. Conclusion The use of custom cast post cores made of different alloys is recommended in restoration of endodontically treated teeth, with extensive loss of tooth structure especially in teeth without ferrule effect. [ABSTRACT FROM AUTHOR]

Nanomedicine relies on the exploitation of nanoscale constructs for therapeutic and diagnostic functions. Gold and gold–iron alloy nanoparticles (NPs) are two examples of nanomaterials with favorable features for use in nanomedicine. While gold NPs have been studied extensively in the last decades, they are not biodegradable. Nonetheless, biodegradation was recently observed in gold alloys with iron obtained using laser ablation in liquid (LAL). Hence, there is a significant interest in the study of the biological effects of gold and gold–iron alloy nanoparticles, starting from their tolerability and cytotoxicity. In this study, these two classes of NPs, obtained via LAL and coated with biocompatible polymers such as polyethylene glycol, were investigated in terms of their cytotoxicity in fibroblasts, prostate cancer cells (PC3) and embryonic kidney cells (HEK). We also explored the effects of different synthetic procedures, stabilizing additives, and the possible mechanisms behind cell mortality such as the formation of reactive oxygen species (ROS) or ferroptosis. NPs larger than 200 nm were associated with lower cell tolerability. The most tolerable formulations were pure PEG-Au NPs, followed by PEG-Au–Fe NPs with a hydrodynamic size < 50 nm, which displayed a toxicity of only 20% in fibroblasts after 72 h of incubation. In addition, tumor cells and highly proliferating HEK cells are more sensitive to the NPs than fibroblasts. However, a protective effect of catalase was found for cells incubated with PEG-Au–Fe NPs, indicating an important role of hydrogen peroxide in alloy NP interactions with cells. These results are crucial for directing future synthetic efforts for the realization of biocompatible Au NPs and biodegradable and cytocompatible Au–Fe alloy NPs. Moreover, the correlation of the cytocompatibility of NPs with ROS and ferroptosis in cells is of general interest and applicability to other types of nanomaterials. [ABSTRACT FROM AUTHOR]

This article deals with the analysis of metal threads in weaving from historical Croatian textiles, liturgical vestments, and folk costumes from the seventeenth to the twentieth century. The independent narrow stripes, wires, and the srma that was formed by a combination of metal thread wrapped around a non-metal textile yarn were collected and analysed. Using physicochemical method scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), the metal composition and content in the threads were analysed. By cross-sectional analysis of metal threads by the SEM-EDX method, it was determined whether the metal threads were homogeneous, gilded, or silver-plated. The composition and structure of non-metal textile yarns were determined by light microscopy. Metal threads were primarily made of gold, silver, or copper and their alloys, but recently less valuable metals having a similar shine have generally been used. Non-metal textile threads in srma are most often made of silk, cotton, and linen. The aim of this study was to determine which type and composition of metal threads were used in different regions of Croatia, which can serve as a database for the restoration and conservation of valuable historical textiles. Also, according to the composition of metal threads, the technology of production threads can be determined and the temporal and spatial dating of textile objects can be determined approximately. [ABSTRACT FROM AUTHOR]

This study presents the results and information revealed by in-depth physicochemical investigations carried out on an 18th-century polychrome wooden pedestal of the holy relics of Saint Demetrius Basarabov preserved at the Romanian Patriarchy of Bucharest. The preliminary stylistic observations and examinations on its present state of conservation were followed by optical microscopy, X-ray fluorescence (XRF) spectrometry, and attenuated total reflectance Fourier-transform infrared spectroscopy (FTIR-ATR) analysis performed in order to adopt an appropriate restoration treatment for bringing the artifact, as close as possible, to its original appearance as well as for dating/attributing the artifact and assessing its state of conservation. It was revealed that several interventions were subsequently undertaken on the original gilded surface consisting of a gypsum support layer with an iron oxide layer of bolus on which a silver foil or a gold foil and a natural resin on top of it as a protective layer were applied. The regilding and later restoration interventions consisted in applying, over the original, layers of a copper–zinc alloy foil (Dutch metal as an imitation of gold) with a resin layer of vernis over it. The final decision on the restoration intervention was taken based on the scientific analysis outcome. This work attempts also to highlight the importance of the interdisciplinary collaboration between researchers, conservation scientists, restorers/conservators, and curators for the preservation and valorization of the historical religious Romanian heritage artifacts, largely unknown worldwide. [ABSTRACT FROM AUTHOR]

This study focuses on the magnificent decoration of a painted and gilded wooden panel with signs of fungal biodeterioration caused by Aspergillus species in the Mausoleum of Sultan al-Ashraf Qaytbay, Cairo, Egypt. Numerous spectroscopic analyses and investigation techniques, including Scanning Electron Microscope Equipped with Energy Dispersive X-ray analysis (SEM–EDX), Fourier Transform Infrared analysis (FTIR), and X-Ray Diffraction (XRD) have been used to study the materials that comprise this painted and gilded wooden panel composition. Aspergillus niger, A. flavus, and A. terreus were recognized as isolated fungi, and their accession numbers are OQ820164, OQ820163, and OQ820160, respectively. The findings showed that the wooden support is of pinewood (Pinus halepensis), the white priming layer on top of the wooden support was identified as gypsum, the blue paint layer has been proposed to be Azurite, Au (gold) was the primary composition of the gilding layer, while Pb (lead) was detected in some spots, suggesting the use an alloy of gold with lead, and finally, animal glue was the bonding medium. Based on these findings, mimic samples with identical substrates and structural components have been designed, and the biodeterioration signs by the growing of the three Aspergillus species—A. niger, A. flavus and A. terreus were evaluated via SEM and color change. However, A. niger was discovered with density growth on surfaces of pinewood, gypsum, and Azurite and with less growth on the gilding layer after 6-month incubation. This contrasts with A. terreus and A. flavus, which had greater density growth on Azurite and stucco than on pinewood and less growth on the gilding layer. The used analytical methods with detailed analyses revealed the novelty and significant future aspects of the conservation of the painted and gilded wooden panel. Particularly given that this location is used for prayer and is crowded with people five times a day, which increases the accumulation of fungi and negatively affects both the historic Mosque and the worshippers' health. [ABSTRACT FROM AUTHOR]

The Moche civilization in Peru developed marvelous metallurgy, primarily using alloys of gold, copper and silver, with the most famous of them called Tumbaga, which resembles pure gold after a depletion process on its surface. However, they also created objects with more standard single-layer alloys or gilding. To distinguish between these techniques in a non-destructive manner is essential. Here, we analyzed a thigh protector, composed of two parts, one seemingly in silver and the other seemingly in gold. The sample was analyzed using X-ray fluorescence measurements integrated with Monte Carlo simulation. The results show that the silver part is formed of a silver-based alloy covered in a corrosion layer, while the gold part is made of Tumbaga. Moreover, for the first time, the gold profiles of different Tumbaga gold objects, from the same burial, were compared, allowing us to obtain information about the standardization of their manufacture. [ABSTRACT FROM AUTHOR]

With this study, we present the development of a transportable x‐ray emission spectrometer (XES) that was realized in a net time of 20 h, in order to verify the presence of Platinum (Pt) in gold Celtic coins belonging to 3rd–1st century BCE. Prior to the XES study, measurements using Scanning Electron Microscopy coupled with Energy Dispersive Spectroscopy (SEM‐EDS) revealed that the coins were made of highly concentrated gold (Au) alloy with trace amounts of bismuth (Bi) and, in one case, osmium (Os) and iridium (Ir). Os and Ir together with Pt and other components belong to the Platinum Group Elements (PGE). They form inclusions in ancient gold alloys and their presence is significant in provenance studies since they indicate the use of alluvial gold. Detection of platinum trace elements in a golden matrix is not possible using energy dispersive x‐ray emission techniques (SEM‐EDS, ED‐XRF, or PIXE) because of the limited energy resolution of the Si detectors. A way to overcome this problem is by using a high‐resolution wavelength dispersive x‐ray emission technique. For this purpose, we built a crystal spectrometer in Von‐Hamos geometry. In the framework of this study three samples/coins have been measured, and the presence of Pt was verified in one of them. The limitations of our spectrometer are critically evaluated and ways to optimize the performance of the spectrometer are discussed. [ABSTRACT FROM AUTHOR]

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Gold-tantalum alloy films are of interest for biomedical and magnetically-assisted inertial confinement fusion applications. Here, we systematically study the effects of substrate tilt (0 ° – 80 °) and negative substrate bias (0–100 V) on properties of ≲ 3- μ m-thick films deposited by high-power impulse magnetron sputtering (HiPIMS) from a Au–Ta alloy target (with 80 at. % of Ta). Results reveal that, for all the substrate bias values studied, an increase in substrate tilt leads to a monotonic decrease in film thickness, density, residual compressive stress, and electrical conductivity. Larger substrate bias favors the formation of a body-centered cubic phase, with films exhibiting lower column tilt and higher density, electrical conductivity, and residual compressive stress. These changes are attributed to metal atom ionization effects, based on the lack of correlation with distributions of landing energies and incident angles of depositing species as calculated by Monte Carlo simulations of ballistic collisions and gas phase atomic transport. By varying substrate tilt and bias in HiPIMS deposition, properties of Au–Ta alloy films can be controlled in a very wide range, including residual stress from − 2 to + 0.5 GPa, density from 12 to 17 g/ cm 3 , and the electrical resistivity from 50 to 4500 μ Ω cm, enabling optimum deposition conditions to be selected for specific applications. [ABSTRACT FROM AUTHOR]

No doubt, the use of biomedical implants in the world has been of tremendous benefit to humans (animals as well), still gaining much relevance today, and commands greater prospects in the future. Developments in this field have been from the progression of the use of materials like wood, iron and gold as external limb support and indental applications, to more sophisticated materials today like biodegradable metal alloys, polymers, ceramics and composites materials capable of replacing damaged or worn‐out organs (eye, heart, lungs, liver, kidney, etc.), mimicking the bone, or for boosting other physiological features as in cosmetology. Appropriate applications of these implants in the human body still remain a challenge today due to several post‐surgical issues like cytotoxicity, thrombogenicity, allergenicity, carcinogenicity and inflammations all of which could be attributed to factors like biocompatibility, osseointegration, mechanical properties and corrosion resistance of these biomedical implants during service. The aspect of implants' corrosion is of much concern in the biomedical industry of which there have been several methods used to tackle it viz ‐use of corrosion resistant materials and inhibitors, metal plating, environmental and design considerations and protective coating techniques. This paper reviews five different surface coating techniques for preventing corrosion in biomedical implants, their descriptions and working principles. [ABSTRACT FROM AUTHOR]

The present study aims to evaluate the effects of fluoride varnish (FV), bioactive glass varnish (BV), sodium-trimetaphosphate treated eggshell, and eggshell membrane containing varnish (EV) against dental erosion. In this study, 27 teeth were cut using a low-speed diamond separator. Two 2×3 mm windows were created on buccal surfaces, and the remaining area was covered with acid-resistant nail polish. Fluoride varnish, Bioactive glass varnish, Sodium-trimetaphosphate treated eggshell, and eggshell membrane containing varnish were applied to one of the windows, and the other window was used as a control. Using separate containers, samples were immersed in cola drink for two minutes and shaken gently. Then, the samples were kept in 0.4 ml artificial saliva for two minutes. This pH cycle was repeated four times. The surface properties of the samples were examined in a scanning electron microscope, the Ca, P, F, O, C, Mg and Na ratios were determined, and the Ca/P ratio was calculated. The Ca/P ratio in the area where FV is applied is 1.56, lower than 1.61, the stoichiometric ratio in human enamel. This ratio was 1.50 in the FV control group. The Ca/P ratio was 1.63 in the BV group and 1.51 in the BV control group, 1.63 in the EV group, and 1.52 in the EV control group. No statistical difference was found among the groups. On the enamel surface treated with BV and EV, a protective layer was observed. Against dental erosion, BV and EV can be used as an alternative to fluoride varnishes. [ABSTRACT FROM AUTHOR]

The phytochemical tetrahydrocurcumin (THC), a major metabolite of curcumin, demonstrates higher anticancer activity, systemic bioavailability, and stability than curcumin itself. However, the poor aqueous solubility of THC causes it to be susceptible to oxygen and is poorly absorbed in the gastrointestinal tract. Therefore, a delivery system is needed to address the delivery issues of THC. Gold-copper nanocomposites (Au-CuNPs) are good candidates for drug delivery and have been shown to have anticancer and antibacterial effects with the advantages of decreasing the cost of gold and enhancing the stability of copper. In this study, a nanocomposite composed of gold and copper alloy was used to design a THC delivery system. The Turkevich method was used to create a bioengineered Au-CuNP system for delivering the herbal phytochemical THC. UV spectroscopy, FTIR analysis, drug entrapment efficiency, and zeta potential were used to characterise the prepared bioengineered nanocomposite system. To confirm the biological properties, xCELLigence real-time monitoring of the Caco-2 cell cytotoxic activity of THC-loaded gold-copper nanocomposites (THC Au- CuNPs) was performed. Au-CuNPs in a 1:1 ratio was selected to prepare the THC delivery system. The amount of THC loaded was optimised by selecting 2 mg THC due to the highest possible amount of drug loading with optimum nanoparticle size characteristics. FTIR analysis showed that THC was successfully loaded in the delivery system. The mean particle diameter of THC Au-CuNPs was 248.8 nm, indicating the successful formation of nanocomposites. The cell culture studies showed that the THC Au-CuNPs have significant cytotoxic activity on Caco-2 cell lines. Finally, the anticancer activity of the THC Au-CuNPs was confirmed in this study. [ABSTRACT FROM AUTHOR]

We demonstrate a simple, low-energy method whereby tomato mosaic virus (ToMV) particles can be used to template the production of nanowires and particles consisting of alloys of gold (Au), platinum (Pt) and palladium (Pd) in various combinations. Selective nanowire growth within the inner channel of the particles was achieved using the polymeric capping agent polyvinylpyrrolidone (PVPK30) and the reducing agent ascorbic acid. The reaction conditions also resulted in the deposition of alloy nanoparticles on the external surface of the rods in addition to the nanowire structures within the internal cavity. The resulting materials were characterized using a variety of electron microscopic and spectroscopic techniques, which revealed both the structural and chemical composition of the alloys within the nanomaterials. [ABSTRACT FROM AUTHOR]

Titanium and its alloys represent the gold standard for osteointegrated implants, but their characteristic bioinertness still hinders their optimal integration within the host tissues. This limitation can be overcome by introducing osteoinductive functionalities on their surface. Plasma electrolytic oxidation (PEO) has emerged as a cost‐effective and rapid electrochemical method for generating bioactive titanium dioxide (TiO2) coatings, but the incorporation of pro‐osteogenic cations with this technique is typically passive and, in turn, characterized by a low efficiency. Here, alternate current (AC) PEO is investigated as a flexible solution to incorporate zinc into TiO2 coatings by exploiting the active transport of cations during the cathodic phase of the process. The resulting microporous surfaces show a greater zinc incorporation and an increased presence of rutile domains compared to conventional direct current (DC) PEO coatings, without, however, yielding significant morphological differences. In vitro assays with human mesenchymal stem cells (hMSCs) reveal an increased metabolic activity of cells adhering onto AC PEO surfaces. In addition, the increased expression of osteogenic differentiation markers (RUNX2 and osteocalcin) indicates significant surface‐driven osteoinductive effects, particularly for coatings grown by applying a short cathodic spike. Taken together, these aspects make Zn‐doped AC PEO surfaces a promising solution for osteoinductive orthopedic and dental applications. [ABSTRACT FROM AUTHOR]

Ranging from silver‐entrapped dyes and gold‐entrapped enzymes through palladium‐entrapped graphene oxide, molecularly doped metals (or metal organic alloys, MORALs) are active, stable and uniquely versatile catalysts in a number of reactions of relevance to the chemical industry. Reactions successfully catalyzed by MORALs concern both industry's main sectors, producing bulk and fine chemicals. Though first reported in 2005, and clearly holding a great applicative potential, their use in catalysis is still surprisingly limited. This study investigates a number of practical aspects concerning molecularly doped metals as heterogeneous catalysts. [ABSTRACT FROM AUTHOR]

Two variants of magnesium alloy surface modification were considered to increase the intensity of spectral lines. Use of gold nanoparticles for the alloy components increased the signal-to-noise ratio by 1.5–2 times. Use of a dye decreased this ratio. The absorption efficiency of laser radiation on the surface did not substantially influence the ablation of metals affected by nanosecond pulses. Accumulation of signal from three pulses with surface cleaning was enough to overcome the effect from the use of nanoparticles. [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]

Glasses, based on the CaO-MgO-SiO2 ternary system with Na2O/K2O, P2O5, CaF2, and Al2O3 additives, were successfully prepared by melting. The effect of alumina addition, low (1.70 wt.% or 1 mol.%), and high (12.50 wt.% or 7-8 mol.%), on glass structure, thermal properties, and their potential use in biomedical applications (bioactivity, machinability), was investigated. The Raman spectra suggest that the Al ions insert into the glass network forming Si-O-Al chains. Hence, the Q3 silicate units decrease, but there is no increase in the Q2 units. Liquid–liquid phase separation occurs in the glasses. Alumina doping favors the increase in Tg and Ts, except for the K-containing glasses. The glasses with low alumina content are bioactive in SBF tests, while the glasses with a high amount of alumina are bioinert. Both glasses have a positive value of the machinability parameter, suggesting that both glasses can be shaped by digital milling technology. [ABSTRACT FROM AUTHOR]

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A study of both in situ and detrital gold from different deposit types in British Columbia was undertaken to establish deposit-specific compositional characteristics in terms of alloy composition and suites of mineral inclusions. The study is based on 11,840 particles from 160 localities in which nine gold deposit types are represented, although there is a strong bias towards gold of orogenic, low-sulphidation epithermal, and alkalic porphyry origin. In general, Ag values in gold alloys are not a powerful discriminator for deposit type, but minor metals may prove useful where detectable, e.g., Cu in gold from ultramafic associations and Pd and Hg in gold from alkalic porphyry systems. The characterization of inclusion suites is far more illuminating, as they correlate strongly with the mineralogy of auriferous ores from different deposit types. This outcome has confirmed the validity of designing an indicator methodology based on inclusion suites and has permitted the prediction of inclusion suites for gold from other deposit types where data are more scarce. The compositional templates generated in the study were applied to identify the source deposit type(s) of gold from 41 localities (a total of 2916 detrital gold particles) where gold genesis was previously unknown. [ABSTRACT FROM AUTHOR]

This editorial article discusses advanced materials (AMs) and their significance in biomedical applications. AMs are materials that have improved properties compared to common counterparts and can be homogeneous or heterogeneous structures at the molecular level. They are characterized by their size, which is measured on the nanometric and micrometric scales. The development of AMs dates back to ancient times, with examples such as bronze and gold alloys. In recent years, AMs have become a focus of research in various fields, particularly in biomedical applications. The goal of this special issue is to bring together advances in material development for areas such as wound healing, cancer treatment, biosensing, and drug delivery, with the aim of improving patients' quality of life and saving lives worldwide. [Extracted from the article]

The biomechanical effects of dental tissue according to various dental crown materials were investigated using finite element analysis. Bone, prepared tooth, root canal, and periodontal ligament were modeled based on computed tomography. Depending on the characteristics of the crown material, it was classified into zirconia, hybrid ceramic, gold alloy, and acrylic resin. A loading force of 200 N was applied in the vertical direction to the occlusal surface of the crown, and analysis was performed under the condition that all interfaces were tied. The results demonstrate that the highest von Mises stress was shown in the prepared tooth of the acrylic resin model, which is a temporary prosthesis, and the pulpal pressure was also the highest. Additionally, among the final prosthesis, the highest stress was shown in the hybrid ceramic model prepared teeth. The properties of restoration materials can be a factor influencing the tooth structure. Thus, in order to make a correct decision when selecting a material for restorative treatment, it is necessary to understand, analyze, and evaluate the properties of these restoration materials. [ABSTRACT FROM AUTHOR]

Introduction: Currently, Fluoride ions are added to commercially available tooth paste, mouth washes and cariostatic gels for their prophylactic action. However, the preventive effect may also be accompanied by the corrosive activity, through infiltration of fluoride-containing saliva in the contact between crowns and bridges or into the implant supported structure. Aim: To evaluate the corrosion action of Sodium Fluoride (NaF) on Pure Titanium (PT) and its alloy coupled with Nickel-Chromium (Ni-Cr) alloy (NC) and Gold (Au) Alloy (GA). Materials and Methods: This in-vitro study was conducted in the Department of Prosthodontics at Central Electrochemical Research Institute, Karaikudi, Tamil Nadu, India. The duration of the study was six months, from April 2010 to September 2010. A total of 48 specimens were categorised under four groups. The four groups included for the study were pure group I (PT+GA), group II (PT+NC alloy), group III {Titanium Alloy (TA)+GA) and group IV (TA+NC alloy}. The specimens under each group were divided into half and were immersed in 100 mL of either artificial saliva or artificial saliva with 1000 Parts Per Million (ppm) fluoride. The current was passed at a scanning rate of 1800 mV/hour for 60 minutes and changes in corrosion potential were observed. The elemental release analysis test was conducted by using inductively coupled plasma-mass spectrometry to quantitatively analyse the elements (metal ions) released in the test solution from the galvanic coupling alloys. In order to evaluate the corrosion behaviour, the surfaces of the specimens were examined with an optical microscope (Eclipse LV100D, Nikon, USA). Analysis of Variance (ANOVA) was done for intergroup comparison. Statistical significance was set at 5%. Results: The mean value of corrosion of PT+GA and PT+NC was 13 μg/cm² and 27 μg/cm² respectively. The mean value of corrosion of TA+GA and TA+NC was 12 μg/cm² and 24 μg/cm² respectively, in artificial saliva without sodium fluoride. In the presence of sodium fluoride, the mean value of corrosion of PT+GA and PT+NC was 17 μg/cm² and 60 μg/cm² respectively, and the mean value of corrosion of TA+GA and TA+NC was 15 μg/cm² and 41 μg/cm². The PT and TA specimens coupled with NC alloy specimens showed more corrosion in saliva either with or without sodium fluoride compared to GA. Conclusion: The NC alloy specimens coupled with PT and TA specimens showed severe pitting corrosion in artificial saliva containing sodium fluoride. [ABSTRACT FROM AUTHOR]

Additive Manufacturing (AM) allows to manufacture new designs and novel geometries interesting for jewelry and watchmaking items. However, pure gold and gold alloys are challenging materials to manufacture by Laser Powder Bed Fusion (LPBF). Due to the low absorptivity at 1 064 nm Infrared (IR) wavelength combined to high thermal conductivity, it is difficult to manufacture pure gold and gold-based alloys by this process. Recent evolutions in laser technology allowed to build a machine using a 515 nm "green" laser. By changing the wavelength (1 064 nm to 515 nm), absorptivity can be improved from 7 to 37%. This paper will focus on 18 karat gold single tracks analysis produced by both wavelengths on a steel substrate. Different melting states will be detailed and indexed in order to select, correctly, machine parameters for producing gold items. It will be shown that 515 nm laser is more adapted to the material than 1 064 nm laser for manufacturing gold alloys. [ABSTRACT FROM AUTHOR]

Cobalt–chromium alloys (Co-Cr) are widely used in dentistry due to their excellent mechanical properties and corrosion resistance. Since prosthetic materials must be permanently stable in the oral cavity, it is very important to determine the release of ions from alloys in the oral cavity. In dentistry today, metals and alloys are mainly joined by laser and tungsten inert gas (TIG) welding. Therefore, in this work, the release of metal ions from six different Co-Cr alloys joined by these two welding methods was quantified to determine the effects of the welding method on an ion release. Static immersion tests, atomic absorption spectrometry and statistical analysis were performed for this purpose. The results showed that laser-welded alloys release a lower amount of metal ions compared to TIG-welded alloys. [ABSTRACT FROM AUTHOR]