Search

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]

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]

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]

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]

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]

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]

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.

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]

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]

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]

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]

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]

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]

Laser-induced breakdown spectroscopy (LIBS) was applied for qualitative and quantitative analysis of gold alloys. A frequency double-pulsed Nd:YAG laser was used to generate plasma on the surface of gold alloys. The plasma temperatures of gold and copper were calculated using Boltzmann plots whereas electron number densities were determined via Saha–Boltzmann equations. The effect of self-absorption in the laser-induced emission spectra was evaluated for correction in the intensity of spectral lines. By combining electron number density conservation approach (ENDC) with LIBS, an algorithm for gold alloys composition determination was derived by matching the theoretically derived ratios of the number densities and the experimentally obtained ratios of the number densities extracted from LIBS spectra. The results of ENDC–-LIBS approach were compared with those estimated by a conventional calibration-free LIBS approach and other established analytical technique energy dispersive X-ray. The results clearly demonstrated that ENDC–LIBS methodology appeared to be very promising for analysis of LIBS spectra of gold alloys. [ABSTRACT FROM AUTHOR]

This paper presents the possibilities of applying atomic force microscopy (AFM) techniques to the study of the wear of prosthetic biomaterials. In the conducted research, a zirconium oxide sphere was used as a test piece for mashing, which was moved over the surface of selected biomaterials: polyether ether ketone (PEEK) and dental gold alloy (Degulor M). The process was carried out with constant load force in an artificial saliva environment (Mucinox). An atomic force microscope with an active piezoresistive lever was used to measure wear at the nanoscale. The advantage of the proposed technology is the high resolution of observation (less than 0.5 nm) in the three-dimensional (3D) measurements in a working area of 50 × 50 × 10 µm. The results of nano wear measurements in two measurement setups are presented: zirconia sphere (Degulor M and zirconia sphere) and PEEK were examined. The wear analysis was carried out using appropriate software. Achieved results present a tendency coincident with the macroscopic parameters of materials. [ABSTRACT FROM AUTHOR]

The Desana treasure is a remarkable assemblage of items made of gold, silver, gemstones and glasses found in north-western Italy. Most scholars agree on the fact that the core of the treasure might have belonged to a single deposit resulted from a long period of selection, accumulation and use. The treasure testifies to the evolution of goldsmiths' art in Ostrogothic Italy and represents an extraordinary material trace of the Italian elites of the 5th–6th centuries. The Desana treasure was investigated with non-invasive instrumental analytical techniques, namely optical microscopy, UV-visible diffuse reflectance spectrophotometry with optical fibres and X-ray fluorescence spectrometry in order to record the chemical features of gemstones, coloured glasses and precious metals employed to produce the items. As for the gemstones, besides identifying typologies, data suggested India as the source for a sapphire pendant and for most of the garnets, whereas the emeralds may belong to different sources, among which Pakistan, India and Egypt. The investigation revealed the colouring agents and compositional features of the glasses, and the composition of the gold alloys. The results of the investigation highlight that the raw materials used by Late Antique Italian goldsmiths did not differ significantly from other neighbouring European and Mediterranean regions, although the garnets show some differences if compared with coeval jewels recorded north of the Alps. The dataset produced in this work complements the stylistic approach for the study of these amazing traces of the past and deepens our knowledge on the role of the Italian "Ostrogothic" jewellery in the frame of the coeval Mediterranean, Central European and Northern Pontic metalwork traditions. [ABSTRACT FROM AUTHOR]

Despite the advent of metal-free solutions, porcelain-fused-to-metal restorations (PFM) are still widely used. Particularly for the latest ceramic systems, scarce information is present in the scientific literature about the ideal opaque layer thickness and the alloy color impact to achieve the desired final color of PFM restorations. This study aimed to evaluate the influence of opaque thickness variation layered on different metal alloys on the final color of PFM restorations. Opaque porcelain of one metal–ceramic system (VITA VM13) was layered in four different thicknesses (0.10 mm, 0.15 mm, 0.20 mm, and 0.25 mm) on three differently colored dental alloys: a gold–platinum alloy (yellowish), a gold–palladium alloy (light grayish), and a nickel–chromium alloy (dark grayish). The veneering porcelain layered over the opaque was kept constant (Base Dentine 0.45 mm, Transpa Dentine 0.50 mm, and Enamel 0.20 mm). Sixty specimens were fabricated, five samples for each combination of alloy/opaque thickness. The color difference (ΔE) between specimen and reference was measured using a clinical spectrophotometer. The two-way ANOVA revealed that the thickness of both the opaque (p < 0.001) and the metal alloy (p < 0.001) significantly influenced the ΔE values. Gray-colored alloys covered by a 0.10 mm thick opaque layer enabled the closest color match, whereas this occurred for yellow-color alloys covered by a 0.15 mm thick opaque layer. In contrast, the samples covered by a 0.25 mm thick opaque layer obtained the worst ΔE. [ABSTRACT FROM AUTHOR]

The information leaflets provided by manufacturers contain only basic information on the elemental composition of the sealers used in endodontic treatment. They usually lack detailed data on the levels of individual elements, especially fluoride (F-), which plays a key role in tooth regeneration as part of fluoroapatite. As calcium silicate-based sealers are becoming increasingly popular among clinicians, we decided to determine the mineral composition of two representative bioactive calcium silicate based endodontic sealers, Well-Root ST™ and AH Plus® Bioceramic Sealer, and compare them with the current gold standard in endodontics, the synthetic resin based endodontic sealer AH Plus™. The concentrations of (F-) were measured using an ionselective electrode and that of various elements were determined by inductively coupled plasma optical emission spectrometry (ICP-OES) in order to demonstrate the potential influence of F- on the properties of the sealers. Our tests indicate that, apart from the elements indicated by the manufacturer such as Ca, Si, Zr, and Fe, the tested sealers contained all the elements we determined in our study. Some were present in high concentrations, e.g., Sr: Well-Root ST™ -- 76.64 mg/kg; Li: AH Plus® Bioceramic Sealer -- 430.51 mg/kg and Ti: Well-Root ST™ -- 1604.12 mg/kg). A high F- content was found in all tested preparations. The highest concentration was found in the preparation AH Plus™ (23.28 mg/kg), followed by AH Plus® Bioceramic Sealer (14.37 mg/kg). Detailed mineral composition should be indicated before the sealers receives an official recommendation for clinical use. This is particularly important both for the most effective treatment and for determining the expected course and prognosis of treatment. [ABSTRACT FROM AUTHOR]

Nanoporous gold as obtained by corrosion of alloys of gold and a less noble metal is a system with manifold applications. The process of dealloying, however, can result in partially porous samples, when dealloying conditions are not optimized with respect to composition and pre-treatment of the master alloy. In the present work, we investigate the dealloying interface between porous material and non-porous alloy in two samples, in which dealloying either stopped automatically or was interrupted manually. Reasons for unintended termination of dealloying in the former case are suggested. [ABSTRACT FROM AUTHOR]

This work deals with a physical and chemical surface characterization of quaternary 18K, 14K, and 9K gold alloys and pure polycrystalline gold substrates. Surface microstructure and composition are evaluated by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray fluorescence spectroscopy. Corrosion resistance of 18K gold alloys is explored by potentiodynamic polarization showing the influence of the manufacturing process on materials fabricated as plates and wires. The research is also in the framework of one of the most common strategies on the modification of metallic surface properties, i.e., the building of self-assembled monolayers (SAM) from organic thiols. The metal affinity of the head group to produce the coating of the substrate by covalent binding is approached by using thiol compounds with different molecular structures and functional group chemistries exposed to an electrolyte solution. Therefore, a comparative study on the surface protection of a quaternary 18K gold alloy and pure gold substrates by SAMs of 6-mercaptopurine (6MP), 1-decanethiol (DT), and 11-mercaptoundecanoic acid (MUA) has been carried out. Surface modification and SAM organization are followed by cyclic voltammetry (CV), and the behavior of the double layer of the electrode–electrolyte interface is evaluated by electrochemical impedance spectroscopy (EIS). The study of these materials allows us to extract fundamental knowledge for its potential application in improving the bioactive properties of different jewelry pieces based on 18K gold alloys. [ABSTRACT FROM AUTHOR]

This study investigated the two-body wear resistance of a first generation 3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP), a second generation 3Y-TZP, a third generation 4 mol% yttria partially stabilized zirconia (4Y-PSZ), a 5 mol% yttria partially stabilized zirconia (5Y-PSZ), and a type III gold alloy (Aurocast 8), performed using opposing antagonistic cusps made out of the same material. Eight cylindrical specimens were prepared for each material (n = 8) for a total of forty specimens (N = 40). Conical cusps were fabricated for each material. Each cylinder–cusp pair was arranged inside a two-axis chewing simulator over up to 360,000 loading cycles. The wear resistance was analyzed by measuring the vertical substance loss (mm) and the volume loss (mm3). The antagonist wear (mm) was recorded before and after the wear test to evaluate the linear difference. Statistical analysis was performed using one-way analysis of variance (ANOVA); multiple comparisons were performed according to Tukey's method. No statistically significant differences (p > 0.05) among the first generation 3Y-TZP, second generation 3Y-TZP, and 4Y-PSZ wear were found. 5Y-PSZ showed statistically significant higher wear compared to other the zirconias. Aurocast 8 displayed the highest values in terms of vertical wear, antagonist cusp wear, and volumetric loss. Although still not statistically comparable, the wear behavior of the latest 5Y-PSZ was the closest to the widely recognized gold standard represented by the type III gold alloy. [ABSTRACT FROM AUTHOR]

Copyright of Diyala Journal for Pure Science is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Hexagonal boron nitride (hBN) is a graphite-like crystal that possesses high potential in two-dimensional (2D) heterojunction devices, nano-electronic devices and deep ultraviolet photoelectronic devices. Unfortunately, a highly efficient atmospheric-pressure method for fabricating bulk hBN crystals with low defect density is not yet developed. The addition of carbon into the growing alloy in the metal-flux-based fusion synthesis of hBN was found dramatically improved the hBN single crystal sizes but gave rise to a large number of random-shaped cracks. In this work, these cracks were confirmed to contain highly separated graphene formed from the aggregation of carbon impurities. However, the crack density was remarkably reduced by adding gold into the Ni–Cr alloy for the additional gold improves the dispersion of carbon in the alloy. Carbon control and removal of cracks suppressed the fast non-radiative recombination process, thus enhancing the photoluminescence efficiency. This work provided the guidance to improve the quality of bulk hBN crystals and control their defect-related emission properties by using an atmospheric-pressure technique, which is essential for device fabrication in the future. [ABSTRACT FROM AUTHOR]

In this paper, we present the idea and development of a new gold-copper-zinc-germanium (AuCuZnGe) alloy, which is related to the method of production and research of its key properties, so that the new Au alloy could be used for jewelry production and in dental technology. The research design was associated with the determination of appropriate chemical composition, manufacturing technology, and performing the characterization. Melting and casting technologies were used to cast the AuCuZnGe alloy while rolling was used to prepare the cylinders and cutting to make square plates with a = 10 mm and thickness of 1 mm. Such plates were provided for corrosion testing. Observation of the plate′s microstructure was performed with Scanning Electron Microscopy (SEM) equipped by Energy-Dispersive X-ray spectrometry (EDS) and X-ray diffraction (XRD). Corrosion testing involved performing the following measurements: Polarization, the open circuit potentials, and linear polarization resistance. Based on the SEM, EDS, XRD, and results of corrosion testing it can be concluded that the new AuCuZnGe alloy possesses high corrosion stability and can be classified as a high noble alloy. [ABSTRACT FROM AUTHOR]

Controlling the morphology, orientation, and crystal phase of semiconductor nanowires is crucial for their future applications in nanodevices. In this work, zinc sulfide (ZnS) nanowires have been grown by metalorganic chemical vapor deposition (MOCVD), using gold or gold–gallium alloys as catalyst. At first, basic studies on MOCVD growth regimes (mass-transport, zinc- or sulfur- rich conditions) have been carried out for ZnS thin films. Subsequently, the growth of ZnS nanowires was investigated, as a function of key parameters such as substrate temperature, S/Zn ratio, physical state and composition of the catalyst droplet, and supersaturation. A detailed analysis of the structural properties by transmission electron microscopy (TEM) is given. Depending on the growth conditions, a variety of polytypes is observed: zinc-blende (3C), wurtzite (2H) as well as an uncommon 15R crystal phase. It is demonstrated that twinning superlattices, i.e., 3C structures with periodic twin defects, can be achieved by increasing the Ga concentration of the catalyst. These experimental results are discussed in the light of growth mechanisms reported for semiconductor nanowires. Hence, in this work, the control of ZnS nanowire structural properties appears as a case study for the better understanding of polytypism in semiconductor 1D nanostructures. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mineral substitution and mass balance across four alteration stages are elucidated. • Bleaching of mafic rock supplies essential Fe for sulfidation during later alteration. • Lower rock CaO contents facilitate further K-metasomatism and Au mineralization. • Fluid composition and physicochemical conditions are constrained by mineral assemblages and whole-rock geochemistry. • Gold-Ag-Cu-As-Bi-W elements as reliable indicators for gold exploration. The interaction between hydrothermal fluids and host rocks, along with associated alteration geochemistry within the Mesozoic Jiaodong gold system, presents significant gaps in our understanding. This study systematically examines the petrographic, mineralogical, and geochemical characteristics of alteration at the Xiadian gold deposit, including comprehensive whole-rock geochemistry analyses, mass balance calculations, and phase equilibria modeling. The alteration history of Xiadian could be divided into four stages. Amid Stage 1, the predominant process involves the replacement of plagioclase by K-feldspar-albite, accompanied by the simultaneous bleaching of amphibolite and associated significant depletion of MgO ( Δ C i / C i O = −21.2 %) and Fe 2 O 3 (−27.2 %) owing to the decomposition of mafic minerals. Stage 2a involves sericitization of albite and continued mafic mineral decomposition, resulting in the lowest recorded MgO (avg. 0.23 wt%) and Fe 2 O 3 (avg. 0.92 wt%) contents in all alteration lithologies. Stage 2b is characterized by abundant chlorite vein formation, corresponding to the proximal enrichment of MgO (158.1 %) and Fe 2 O 3 (108.2 %), accompanied by a Mg 2 + / (a H + ) 2 decreased in the fluid. Stage 3, the main stage of gold mineralization, involves chlorite substitution with sericite during quartz-sericite-pyrite (QSP) alteration, suggesting mild acidification of the ore-forming fluid. Insights from phase equilibrium modeling suggest that sulfidation has contributed to gold precipitation, leading to increased f O 2 and reduced f H 2 S (extending into quartz-carbonate alteration of stage 4). Mass balance calculations indicate gold is enriched compared to protolith at all stages, with the most intense enrichment in stage 3. This suggests that hydrothermal fluids at Xiadian were auriferous throughout their evolution. The process may induce fluid modifications, particularly through the dissolution of mafic minerals, more so in mafic mineral-rich rocks (e.g., amphibolite) than in granite, promoting the incorporation of hydrothermal chlorite into the Au system to contribute to sulfidation. Our results provide insights into lithology controls on gold mineralization at Xiadian, indicating that felsic rocks (Linglong granite and quartz porphyry) with lower initial CaO contents often develop K-metasomatism and Au-bearing QSP alteration, while mafic rocks (amphibolite and lamprophyre) with higher CaO contents develop carbonization. This is likely due to the influence of lower CaO contents on alteration minerals, which promote rock porosity, affecting rock deformation, pore-fluid flow, and reacting with wall rocks. Principal component analysis (PCA) results indicate that elements including Au, Ag, As, Bi, W, and Cu are proxies for Au mineralization, suggesting their mobilization and deposition together during the gold mineralization process. This highlights their significance as a proxy for gold exploration. [ABSTRACT FROM AUTHOR]

The results of studies of the process of obtaining wire for the manufacture of jewelry chains from new nickel-free 585 gold fineness alloys are presented. New 585 gold fineness alloys, alloyed with palladium, silver and other elements, and as modifiers – with rhodium and ruthenium in the stated quantities have been proposed. By modeling the process of section rolling of rods in octagonal calibers using the variation method of minimum total power, the broadening of the metal and the energy-power parameters of rolling rods from the investigated alloys have been determined. The regularities of their change have been found. Software has been developed for designing processes for the production of longish deformed semi-finished products and technological modes of rolling and drawing of new gold alloys. With the help of experimental studies, the adequacy of the results of calculations and modeling was checked, and new data were obtained on the mechanical properties of the metal and its structure. It has been found that the proposed alloys and the modes of their processing using the processes of section rolling and drawing make it possible in industrial conditions to obtain jewelry wire with a diameter of up to 0.25 mm with the level of mechanical and operational properties required for chain tying. [ABSTRACT FROM AUTHOR]

Featured Application: Authors are encouraged to provide a concise description of the specific application or a potential application of the work. This section is not mandatory. Due to the aggravating situations regarding climate change, resource supply, and land consumption by the landfilling of residual materials, it is necessary to develop recycling processes that allow the recovery of valuable metals from industrial residues with significantly reduced CO2 emissions. In this context, it is conceivable that processes using chlorination reactions will be of importance in the future. The simultaneous selective chlorination and evaporation of nine valuable metals was evaluated theoretically and experimentally in small-scale STA trials; then, it was tested practically on six different iron precipitation residues from the zinc and nickel industries. The metal chlorides FeCl3∙6H2O and MgCl2∙6H2O were identified as the most effective reactants, resulting in high extraction rates for the metals In, Ag, Zn, Pb, Au, and Bi, while lower yields are achievable for Sn, Cu, and Ni. Iron, which is predominant in volume in the residual materials, shows lower chlorination tendencies which allows the effective separation of the valuable elements of interest from the iron containing matrix. [ABSTRACT FROM AUTHOR]

This work presents electroless deposition of palladium films onto gallium nitride from aqueous palladium dichloride using sodium L-ascorbate as the reducing agent in an acidic bath. Profilometry, four-point probe measurements, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy were used to measure film thickness, sheet resistance, resistivity, morphology, and composition. The resistivity of Pd was 1–3 × 10–5 Ω cm. Schottky diodes were produced from plated films, and the barrier heights and ideality factors were determined from current–voltage measurements. Average barrier heights were 1.13–1.26 eV, with ideality factors from 1.02 to 1.05, depending on the gallium nitride epilayer and substrate. A method for depositing palladium-gallium alloy films is also presented onto gold surfaces from palladium dichloride and gallium (III) sulfate using sodium hypophosphite as the reducing agent; however, palladium-gallium alloys were not readily deposited on gallium nitride. [ABSTRACT FROM AUTHOR]