Au System Research Articles

Thiocoumarin-based Au(I) Complexes and Au(0) Systems over TiO2 as Hybrid Photocatalysts for Hydrogen Generation under UV-Vis Light.

This work focuses on the photocatalytic production of hydrogen from the photodehydrogenation of ethanol using several gold(I) complexes and gold(0) systems over titanium dioxide (P90 TiO2) as hybrid photocatalysts. The photocatalytic systems are composed of at least one coumarin-based ligand, which can enhance the photocatalytic activity by its photon-absorbing capacity due to its chromophore properties. The photocatalytic behavior for hydrogen generation of the studied samples is compared under UV-vis light setting the total gold-based co-catalyst loading at 1 wt% onto the TiO2 photocatalysts and when the gold content is maintained at 0.25 wt%. The incorporation of gold co-catalysts results in an enhancement of hydrogen production up to 2.7 times compared to a conventional Au/TiO2 reference sample. The results show an increase in the total hydrogen production under UV-vis light due to the combined presence of coumarin chromophore, gold-based co-catalysts, and gold plasmonic nanoparticles. A deep characterization of the samples from each group is performed by UV-vis spectroscopy, XPS, HRTEM, and HAADF-STEM, observing the presence of plasmonic gold nanoparticles for sample "AuL1NPs" and the reduction of the gold present in sample "AuL1a," which explains the highest observed hydrogen production rates of this study.

A-084 Performance evaluation of Sentinel Diagnostics’ Ammonia Ultra assay on Beckman Coulter AU/DxC AU Systems

Abstract Background The analytical performances of the Ammonia Ultra assay for in vitro quantitative enzymatic determination of Ammonia in human plasma have been evaluated on Beckman AU/DxC AU Systems. Ammonia, derived from the amino acids catabolism and from the action of intestinal bacteria on dietary proteins, is converted to non-toxic urea by the liver. An excess of ammonia can have toxic effects on the Central Nervous System with possible neurological disturbances. Elevated ammonia levels can also be observed in severe liver failure as may occur in Reye’s syndrome, viral hepatitis or cirrhosis. Methods Ammonia, in the presence of glutamate dehydrogenase (GLDH), combines with alpha-ketoglutarate and NADH to yield glutamate and NAD+. The decrease in 340 nm absorbance (NADH → NAD+) is proportional to the ammonia level in the examined plasma. The reagent contains excess of lactate dehydrogenase (LDH) to rapidly reduce endogenous pyruvate and avoid its interference with the assay system. Performances evaluation have been done following current CLSI guidelines protocols. Results 3 calibrator lots and 2 reagent lots have been used for testing. For each test and among different combinations of reagents and calibrators, worst case has been reported in the table. Conclusions Analytical performances of Ammonia Ultra assay on Beckman AU/DxC AU Systems meet the requirements for its use as quantitative determination of Ammonia in human plasma and make this assay very suitable for the routine measurement of this analyte.

B-008 An Evaluation of the Analytical Performance of the New Beckman Coulter DxC 500i Clinical Analyzer

Abstract Background The DxC 500i Clinical Analyzer* is Beckman Coulter’s latest integrated Clinical Chemistry and Immunoassay analyzer. It provides reliability, scalability, and workflow efficiency via a flexible independent maintenance mode, increased uptime, and a dynamic sample handler to optimize sample management. Standard Beckman Coulter Chemistry and Immunoassay consumables and reagents ensure network standardization and commutability. The purpose of this study was to evaluate the analytical performance of the new DxC 500i analyzer and to compare the performance against the Beckman Coulter stand-alone Clinical Chemistry and Immunoassay analyzers on the market. Methods To assess performance over a range of assay methodologies, several DxC 500i Beckman Coulter Immunoassays and Chemistry assays were evaluated. Precision was assessed using human samples following CLSI EP05-A3 guidelines. Linear range was assessed following CLSI EP06-A guidelines. Method Comparison and Bias Estimation studies compared the DxC 500i Clinical Analyzer against the Access 2 Immunoassay System, the AU480 and the DxC 700 AU Clinical Chemistry analyzers, following CLSI EP09c-ED3 guidelines. To investigate carryover potential as samples are processed across the integrated system, a carryover study was designed. This focused on evaluating potential sample-to-sample carryover caused by the AU sample probe and its effects on immunoassay samples during reflex scenarios. Results DxC 500i Chemistry results: Glucose Serum (OSR6x21) Assessments of repeatability and within laboratory precision at multiple critical analyte concentrations showed total imprecision of <3% and within-run imprecision of <3%. The Glucose serum assay demonstrated acceptable linearity throughout the 10-800 mg/dL analytical measuring range. Method comparison studies compared the DxC 500i analyzer against the AU480 and DxC 700 AU systems. A Weighted Deming regression of serum patient samples (n>100 measured across the analytical range) yielded a 0.986 slope, 0.227 mg/dL intercept, and R=0.9999 correlation coefficient against the DxC 700 AU and a 0.995 slope, 0.356 mg/dL intercept, and R=0.9999 correlation coefficient against the AU480. DxC 500i Immunoassay results: Cortisol (33600) Beckman Coutler’s Cortisol assay exhibited total imprecision of <12%CV at <5 μg/dL or <10CV% at ≥5 μg/dL for serum. The Cortisol assay demonstrated acceptable linearity throughout the 0.4-60 μg/dL analytical measuring range. A method comparison study compared the DxC 500i against the Access 2 system. A Weighted Deming regression of serum patient samples (n>100 measured across the analytical range) yielded a 0.9785 slope, 0.2764 μg/dL intercept, and R=0.9932 correlation coefficient. DxC 500i Carryover Assessment The Total βhCG (5th IS) assay was used to evaluate the potential of chemistry analyzer to immunoassay analyzer sample carryover. The study used High hCG serum samples (>1,000,000 mIU/mL) and Low hCG serum samples (4-6 mIU/mL). The DxC 500i exhibited a cumulative carryover of ≤2 parts per million (PPM) for serum. Conclusions These studies demonstrate excellent analytical performance for the new Beckman Coulter DxC 500i Clinical Analyzer* and confirm comparable performance to current Beckman Coulter standalone Clinical Chemistry and Immunoassay analyzers on the market. *Pending clearance by the United States Food and Drug Administration; not yet available for in vitro diagnostic use in the U.S. Product availability and regulatory status depends on country registration per applicable regulations.

A-116 Pleural Fluid pH - Are We Collecting and Measuring It Correctly?

Abstract Background Pleural fluid pH has diagnostic, therapeutic, and prognostic implications in the management of pleural space infections and malignancy. Pleural fluid sample collection, transportation and processing are known for source of pre-analytical error which contribute to inaccuracy of measured pH with clinical implication to patient care. Some clinical practices observed locally include pleural fluid collection in sterile container for ease of other biochemistry analytes measurement in addition to pH. This study aimed to compare the differences in pleural fluid pH and other commonly ordered biochemistry analytes collected using sterile container against heparinized blood gas syringe. Methods Total 20 Pleural fluid samples were collected from patient using a procedure called thoracentesis from, with approximately 2 to 3ml of fluid directly transferred into heparinized blood gas syringe as well as in a sterile container. Both samples were then transported to Clinical Biochemistry Laboratory within an hour. Both samples were analyzed on 3 analytical systems; 1) pH on Roche COBAS b221 blood gas analyzer, 2) Glucose, Total Protein, LDH on Beckman AU System and 3) Specific Gravity on Reflectometer. Statistical analysis was performed using Analyze-It software. Results pH fluid collected in sterile container demonstrates significant high bias (absolute of 0.4 units or 5%) as compared to sample collected in heparinizes blood gas syringe. Other commonly ordered tests in fluid profile (Glucose, Total Protein, LDH and SG) demonstrate good correlation (Altman-Bland Difference Plot <5%) for pleural fluid collected in sterile container as compared to heparinized syringe. Conclusions This positive bias observed is likely attributed to air exposure in pleural fluid collection in sterile container as compared to heparinized syringe. The accuracy of measured pleural pH is critically dependent on the method of sample collection. This study highlights the need for a standardized protocol for pleural pH collection for accurate measurement.

Developing Online ICP-MS Methodology for Examining Catalyst Degradation Dynamics during Electrochemical CO2 Reduction

The electrochemical CO2 reduction reaction (CO2RR) provides a path towards sustainable production of carbon-based fuels and chemicals, using renewable electricity to drive the conversion of CO2 into products such as ethylene, ethanol, and methane. A challenge limiting the implementation of CO2RR is catalyst stability during operation, and greater fundamental understanding is needed to uncover the governing physical, chemical, and electrochemical factors, as well as degradation mechanisms, operative under reducing conditions. One tool that can be used for conducting such fundamental studies is online inductively coupled plasma mass spectrometry (ICP-MS). In this study, an experimental framework was developed for using online ICP-MS for time-resolved degradation studies during CO2RR conditions. Using a customized flow cell setup, we coupled an ICP-MS to a potentiostat to simultaneously apply a potential or current while evaluating dynamics and degradation for both Au and Cu catalysts. Both ionic dissolution and degradation in the form of nanoparticle detachment can be detected and analyzed. The presence of nanoparticles is indicated by spikes in ICP-MS data. The intensity of the spikes is directly related to particle size. We used ICP-MS to determine particle mass, size distribution, and cumulative mass loss over time. We found the use of ICP-MS to obtain particle size distribution gave comparable results to transmission electron microscopy (TEM) determination of particle size distribution.Au foil as the CO2 reduction catalyst was used as a model system for detecting and quantifying degradation in situ using ICP-MS. We found Au degradation to occur in the form of nanoparticle detachment, with increasingly negative applied potential (0 V vs RHE to -1 V vs. RHE) in the presence of CO2 leading to increased number of nanoparticles in the electrolyte; however, no ionic dissolution was observed. In comparison, when the electrolyte was saturated with N2, nanoparticles detached from the electrode at a lower rate than in CO2-saturated conditions. We also examined Cu degradation under the same conditions as the Au system. Cu degradation occurs as both ionic dissolution and nanoparticle detachment, but under all conditions, Cu has less nanoparticle detachment and cumulative mass loss due to nanoparticles than Au. The developed experimental framework in this study would be translatable to a variety of electrocatalytic reactions and environments. Examination of catalyst degradation behavior in situ, including non-traditional degradation mechanisms such as nanoparticle detachment from bulk materials, can be used to obtain greater fundamental understanding of degradation mechanisms and rational design of materials with improved stability.

WITHDRAWN: Comprehensive phase analysis of GaAs:(Cu, Au) systems in molten core fibers

The recently developed “flux assisted molten core method,” used previously to fabricate GaAs core fiber with Sn as a solvent phase, is further extended here to Cu and Au fluxes. Unlike the GaAs:Sn system whose observed phases were same in the precursor, as-drawn, and laser annealed fiber, the GaAs:Cu and GaAs:Au systems exhibited differing phases at each stage of the process. These systems undergo reactions during the molten core fiber fabrication and CO2 laser post-processing. X-ray diffraction is employed to determine the phases resulting from As volatility during the pre-melt, fiber draw, and CO2 laser post-processing. The phases, while unanticipated, are determined to be thermodynamically stable. In some of the systems, remnant Ga is suggested as being located in the flux compounds. This is a break with the conventional molten core method, where the fiber consists of the same phases as the starting material, and cases where reactions are driven in the molten core. The volatility of GaAs brings about unexpected reactions.

Hydrothermal alteration and its geochemistry of the Xiadian gold deposit, Jiaodong Peninsula, China: Implications for fluid-rock interaction processes and mineral 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 (ΔCi/CiO = −21.2 %) and Fe2O3 (−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 Fe2O3 (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 Fe2O3 (108.2 %), accompanied by aMg2+/(aH+)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 fO2 and reduced fH2S (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.

Genesis of the sediment-hosted Qukuleke Au deposit in the East Kunlun Orogenic Belt, NW China: Constraints from geology, apatite U–Pb age, and C–O–S–Pb isotopes

Genetic classification of sediment-hosted Au deposits is often disputed in many orogenic belts around the world. The marine sediment-hosted Qukuleke Au deposit (>5 t Au) is an example of this, which has been attributed to orogenic or intrusion-related type. This paper addresses its metallogeny through detailed geologic and petrographic studies, together with apatite U–Pb dating and C–O–S–Pb isotopes.The hydrothermal paragenesis at Qukuleke is divided into three stages (I to III): Stage I (pre-ore) sheeted quartz veins; Stage II (main ore) pervasive sericite ± carbonate ± apatite ± pyrite ± arsenopyrite alteration associated with quartz–calcite ± stibnite veins; Stage III (post-ore) barren calcite veins. LA-ICP–MS hydrothermal apatite U–Pb dating on Stage II disseminated Au ore yielded 208.1 ± 6.5 Ma, coeval with the Late Triassic post-collisional intrusions from the periphery of Qukuleke deposit. Carbon–oxygen isotopes of Au–Sb ore-related hydrothermal calcite show that the hydrothermal fluids were derived from the marine carbonate ore host with considerable magmatic input. Lead–sulfur isotopes of the Au–Sb ore-related are consistent with those of coeval intrusions around the deposit, but different from those of the local sedimentary strata. Our age and geochemical data suggest the presence of a magma source that supplied the hydrothermal fluids, sulfur and metals for the mineralization. Combining the low sulfide content and the Au–As–W–Sb–Mo assemblage characteristics, the Qukuleke is best classified as a sediment-hosted intrusion-related Au deposit. Considering also the discovery of the large coeval Qukukekedong Au deposit nearby, we propose that Late Triassic intrusion-related Au system is a high-potential exploration target in the western EKOB.

Investigation of phonons and magnons in [Ni80Fe20/Au/Co/Au] N multilayers

The interaction between phonons and magnons is a rapidly developing area of research, particularly in the field of acoustic spintronics. To discuss this interaction, it is necessary to observe two different waves (acoustic and spin waves) with the same frequency and wavelength. In the Ni80Fe20/Au/Co/Au system deposited on a silicon substrate, we observe the interaction between spin waves and surface acoustic waves using Brillouin light scattering spectroscopy. As a result, we can selectively control (activate or deactivate) the magnetoelastic interaction between the fundamental spin wave mode and surface acoustic waves. This is achieved by adjusting the magnetostrictive layer thickness in the multilayer. We demonstrate that by adjusting the number of layers in a multilayer structure, it is possible to precisely control the dispersion of surface acoustic waves while having minimal impact on the fundamental spin wave mode.

Critical differences between typical arc magmas and giant porphyry Cu ± Au systems: Implications for exploration

Abstract Porphyry Cu, and porphyry Cu-Au deposits, are associated with arc magmatism and their ore-forming systems generally follow the magmatic evolution of typical arcs. However, most arc magmas are barren and giant economic porphyry Cu ± Au deposits are rare. In this study, we model variations in rare earth element concentrations in the evolving arc magmas and giant porphyry Cu ± Au systems to quantify the percentage of the fractionating minerals required to produce the observed changes. We find that, during the andesitic stage of fractionation, ore-forming systems in thick crusts fractionate ~35% more amphibole than an average of thick arc magma systems (the thick-crust reference suite) and that ore-forming systems in thin crusts fractionate twice as much amphibole as their equivalent thin-arc magma reference suite. Thick-crust ore-forming suites also fractionate ~50% less plagioclase, and thin-crust ore systems ~40% less plagioclase, than their associated reference suites during the same andesitic stage of fractionation. Taken together, these observations imply that ore-producing magmas are appreciably wetter than their associated barren reference suites. Our modelling also shows that 80% more amphibole is required to reproduce the andesite stage of fractionation in the thick-crust reference suite than in its thin-crust equivalent, suggesting that magmas produced under thick crusts are wetter than those produced under thin crusts. On the other hand, the chalcophile element contents of the thick- and thin-crust ore-forming systems are similar to and higher than those of the thick- and thin-crust reference suites, respectively. Therefore, we suggest that the high water content plays a critical role in the formation of giant porphyry Cu ore in thick crusts, whereas both high chalcophile contents and high water contents are required to form giant porphyry Cu-Au deposits in thin crusts. The high fraction of amphibole fractionation in giant economic porphyry suites, compared with their relevant reference suites, results in lower Y in the ore-associated suites and this difference increases with fractionation. As a consequence, plots of Y against MgO can be used to identify porphyries that have economic potential and are preferred to Sr/Y plots because they are less affected by the intense alteration associated with giant porphyry Cu ± Au deposits.

Comprehensive phase analysis of GaAs:(Cu, Au) systems in molten core fibers

The recently developed “flux assisted molten core method,” used previously to fabricate GaAs core fiber with Sn as a solvent phase, is further extended here to Cu and Au fluxes. Unlike the GaAs:Sn system whose observed phases were the same in the precursor, as-drawn, and laser annealed fiber, the GaAs:Cu and GaAs:Au systems exhibited differing phases at each stage of the process. These systems undergo reactions during the molten core fiber fabrication and CO2 laser post-processing. X-ray diffraction is employed to determine the phases resulting from As volatility during the pre-melt, fiber draw, and CO2 laser post-processing. The phases, while unanticipated, are determined to be thermodynamically stable. In some of the systems, remnant Ga is suggested as being located in the flux compounds. This is a break with the conventional molten core method, where the fiber consists of the same phases as the starting material, and cases where reactions are driven in the molten core. The volatility of GaAs brings about unexpected reactions.

ВЛИЯНИЕ ПРИМЕСЕЙ НА ДЕГРАДАЦИЮ СОЕДИНЕНИЙ В СИСТЕМЕ Al – Au

Typical reasons for degradation of micro–welded bimetallic compounds of the aluminum-gold binary system are considered. These types of compounds are often used in the manufacture of semiconductor products (SCPs) and integrated circuits (ICs). Degradation of compounds, revealed during screen tests or during products operating, leads to failures, which dramatically reduces the reliability of electronic equipment (EE). The majority of degradation processes are based on diffusion phenomena, which are mainly determined by temperature, chemical composition and microstructure of metals and alloys. Impurity elements included in the gold coating have a significant effect on the degradation of the wire connections such as crystal contact pads – traverses of package terminals of SCPs. In this regard, it is worth analyzing the effect of various impurities on the diffusion processes and changes in the microstructure of the coating in order to find out the most dangerous chemical elements and determine their role in the degradation of compounds. The paper presents a review of references on the research subject. In the conclusion, the results of analysis in the field of the influence of impurity elements on the degradation of compounds in Al – Au system are summarized, conclusions are drawn about the key role of grain-boundary diffusion on the degradation of micro-welded bimetallic compounds.

Calculation of momentum correlation functions between π, K , and p for several heavy-ion collision systems at sNN=39 GeV

Momentum correlation functions between π, K, and p are calculated for several heavy-ion collision systems, namely B510+B510, O816+O816, Ca2040+Ca2040, and Au79197+Au79197 in central collisions as well as Au79197+Au79197 collision in different centralities at center-of-mass energy sNN=39 GeV within the framework of a multiphase transport model complemented by the Lednický and Lyuboshitz analytical method. The results present the centrality and system-size dependence of the momentum correlation functions among pairs of π, K, and p, from which the emission source-size can be deduced. It is found that the deduced source sizes increase with the decreasing of centrality for Au + Au system or with the increasing of system size in central collisions with different nuclear size. In addition, through the momentum correlation functions of nonidentical particle pairs gated on velocity, the average emission sequence of nonidentical particles can be indicated. The results illustrate that in the small relative momentum region, protons are emitted in average earlier than π+ and K+, and K+ are emitted averagely earlier than π+. Furthermore, it seems that larger interval of the average emission order among them is exhibited for smaller collision systems. The present study sheds light on the dynamics of light particle emission at RHIC energy. Published by the American Physical Society 2024

Positive Δ199Hg anomalies in Mesozoic porphyry Mo deposits of Northeastern China and their implications to the metallogeny of arc-related hydrothermal systems at convergent margins

Mercury (Hg) isotopes display unique mass-independent isotope fractionation (MIF, reported as Δ199Hg), which is primarily generated via Hg photochemical processes in the land-ocean-atmosphere system. Magmatic and hydrothermal processes do not trigger MIF of Hg isotopes, therefore, Hg-MIF signals detected in deep reservoirs (mantle and crust) are theoretically sourced from recycled surface materials. Here, we observed positive Δ199Hg signals (0.10 ± 0.07‰, SD) in Mesozoic porphyry Mo deposits of NE China. These values correspond to the recently reported Δ199Hg signature of Mesozoic epithermal AuAg systems in NE China (Δ199Hg: 0.11 ± 0.07‰, SD), suggesting that both mineral systems receive large amounts of Hg from subducted marine materials, given that marine Hg has positive Δ199Hg composition. Our study thus provides novel geochemical evidence on the linkage between oceanic plate subduction and metallogeny of various hydrothermal systems at convergent margins. Subduction contributes large amounts of volatiles to arc magmas, which then release metal-rich magmatic-hydrothermal fluids of the porphyry to epithermal ore deposit spectrum.

Unveiling an early Paleozoic porphyry-epithermal gold system in Songshunangou district, North Qilian, northwest China: Geological and geochronological constraints

The Songshunangou district is located in the central part of the North Qilian orogenic belt and hosts both the Eastern and Western deposits. The Western deposit is a porphyry-Au deposit, characterized by concentrated high-grade Au mineralization within a quartz-dioritic porphyry and occurs along the contact to basaltic andesite. Alteration is concentric with potassic alteration associated with high-grade Au mineralization in the core zone, while surrounding propylitic alteration is associated with an only lower-grade Au mineralization. Barren sericite-chlorite alteration is restricted to shallow zones above or partially overprinted the potassic alteration. Mineralization, including chalcopyrite, bornite, pyrite, magnetite, native gold with minor galena, sphalerite, hematite, and covellite, is observed as quartz-sulfide stockworks and fine-grained disseminations in different alteration zones. LA-ICP-MS zircon U–Pb dating of samples from the ore-bearing quartz-dioritic porphyry, the post-mineralization dioritic porphyry and the granodioritic porphyry in the Western deposit yield mean 206Pb/238U ages of 456.3 ± 2.0 Ma to 454.9 ± 2.4 Ma, and 449.5 ± 4.5 Ma to 448.3 ± 1.4 Ma, respectively. Pyrite from quartz – chalcopyrite – bornite veinlets in the Western deposit yields a Re-Os isochron age of 454.6 ± 3.7 Ma. In the Eastern deposit, which is an intermediate-sulfidation epithermal deposit hosted in basaltic andesite, sericite-chlorite alteration is associated with the mineralization. The mineralization is predominantly found within veins and disseminated, primarily composed of galena, sphalerite, native gold, tetrahedrite, and minor chalcopyrite, pyrite, and covellite. The alteration mineral assemblage comprises sericite, chlorite, Mn-calcite, quartz, calcite, and minor epidote. A Mn-calcite – quartz – polymetallic vein from the Eastern deposit yields a calcite Sm-Nd isochron age of 453.2 ± 5.8 Ma, suggesting that intermediate-sulfidation mineralization was coeval with the emplacement of the ore-bearing quartz-dioritic porphyry and the porphyry mineralization in the Western deposit. Based on these geologic features and geochronological data, we conclude that an early Paleozoic porphyry-epithermal Au system developed in the Songshunangou district, which formed in an arc setting associated with the northward subduction of the North Qilian Ocean beneath the North Qilian orogenic belt. The occurrence of an early Paleozoic porphyry-epithermal Au system in the North Qilian orogenic belt provides new insights for regional mineral exploration.

Morphology and symmetry driven by lattice accommodation in polycrystalline bcc–fcc core–shell metallic nanoparticles

Body-centered-cubic–face-centered-cubic (bcc–fcc) multi-metallic nanoparticles (NPs) associating a single-crystal core (Fe, FeCo alloys, etc.) with a polycrystalline noble metal shell (Au, AuAg alloys, etc.) are perfectly symmetrical or more irregular, even dramatically dissymmetrical, yet presenting a good crystalline organization. Here, a combination of experimental analysis and theoretical symmetry analysis is proposed, in order to provide a unified description of the observed morphologies (Fe–Au and Fe–AuAg systems), whatever their symmetry, and predict some morphology variability in a population of NPs. First, the central role of the crystal lattice accommodation is comprehensively analyzed from the experimental Fe–AuAg system. The two possible bcc–fcc epitaxial relationships generate a core–shell interface in the shape of a truncated rhombic dodecahedron. This results in two different types of grains in the shell, which are elastically accommodated between them by an equal distribution of twins and low-angle grain boundaries, however, at the cost of internal stresses. At the same time, symmetry breaking results from two possible growth variants originating from the Nishiyama–Wasserman epitaxial relationships. The shell grains fit together in a nanopuzzle-like organization, resulting in a large number of possible arrangements distributed in 13 different point groups of symmetry, all of lower order than the core symmetry (highest order of cubic symmetry). If the variants are randomly distributed, the probability for the NP to be asymmetric (group 1) is 80%. The dissymmetrical development of the NPs is then discussed. Extending this approach to other core shapes succeeds in predicting dissymmetrical or dramatically off-centered morphologies experimentally observed in Fe–Au NPs.

Atomic Layer Deposition of Antibacterial Nanocoatings: A Review.

In recent years, antibacterial coatings have become an important approach in the global fight against bacterial pathogens. Developments in materials science, chemistry, and biochemistry have led to a plethora of materials and chemical compounds that have the potential to create antibacterial coatings. However, insufficient attention has been paid to the analysis of the techniques and technologies used to apply these coatings. Among the various inorganic coating techniques, atomic layer deposition (ALD) is worthy of note. It enables the successful synthesis of high-purity inorganic nanocoatings on surfaces of complex shape and topography, while also providing precise control over their thickness and composition. ALD has various industrial applications, but its practical application in medicine is still limited. In recent years, a considerable number of papers have been published on the proposed use of thin films and coatings produced via ALD in medicine, notably those with antibacterial properties. The aim of this paper is to carefully evaluate and analyze the relevant literature on this topic. Simple oxide coatings, including TiO2, ZnO, Fe2O3, MgO, and ZrO2, were examined, as well as coatings containing metal nanoparticles such as Ag, Cu, Pt, and Au, and mixed systems such as TiO2-ZnO, TiO2-ZrO2, ZnO-Al2O3, TiO2-Ag, and ZnO-Ag. Through comparative analysis, we have been able to draw conclusions on the effectiveness of various antibacterial coatings of different compositions, including key characteristics such as thickness, morphology, and crystal structure. The use of ALD in the development of antibacterial coatings for various applications was analyzed. Furthermore, assumptions were made about the most promising areas of development. The final section provides a comparison of different coatings, as well as the advantages, disadvantages, and prospects of using ALD for the industrial production of antibacterial coatings.

Nature of magma and ore-forming conditions at the Randu Kuning porphyry Cu-Au deposit, Indonesia: a comparative study with other Cu-Au deposits in the region

ABSTRACT The subduction-related Sunda-Banda arc hosts several giant and major Cu–Au–Mo porphyry and epithermal Au systems, making it one of the most important magmatic-related metallogenic belts in Indonesia. They are accompanied by a number of smaller systems, one of which is the recently discovered Randu-Kuning porphyry Cu-Au deposit on Java Island. The present study investigates the geochemical characteristics of this deposit through whole-rock and mineral geochemistry and mineral geothermobarometry, focusing on three sequential dioritic intrusions that make up the host igneous complex, two barren and the third mineralized. Moreover, a comparative analysis is performed between other porphyry deposits in the Sunda-Banda arc and with Grasberg in Papua. This study shows that the older porphyry deposits have mostly similar geochemical characteristics to the younger deposits, suggesting the same magma source, which is mantle-derived oxidized I-type magma. Amphibole geothermobarometry shows that the formation of syn-ore intrusion in the older porphyry was higher in temperature and pressure than those at the younger porphyry. The halogen and oxygen fugacities inferred from biotite and amphibole chemistry indicate an oxidized, water- and halogen-rich melt. Our study shows that combining amphibole and biotite chemistry and whole-rock geochemical data is useful to fingerprint the magmatic-hydrothermal processes, especially where multiple magmatic phases occur. This research also provides valuable insights into the magmatic-hydrothermal physiochemical conditions during the formation of the mineralized system.

ON THE INTERACTION OF H[AuCl2] WITH 2-ETHYLIMIDAZOLE INTERACTION OF [AuCl2]- WITH 2-ETHYLIMIDAZOLE AT 278-318K

Using the potentiometric titration method, the process of complexation of gold (I) with 2-ethylimidazole was studied. Adding an organic ligand solution to the [AuCl2]-/Au system leads to a smooth decrease in the electrode potential (without any jumps). The nonlinearity of the dependence of E on –log[2EI] indicates the stepwise nature of complex formation between [AuCl2]- and 2-ethylimidazole. The general stability constants of successively formed complexes were determined in the temperature range 278-318K (at T=298K, logβ1=4.41±0.03; logβ2=10.81±0.02). An increase in temperature leads to the stability of the formed complexes. It has been shown that trivalent gold complexes are superior in stability to similar gold(I) complexes. The thermodynamic functions of the process of complex formation of gold (I) with 2-ethylimidazole were calculated using the temperature coefficient method. The value of enthalpy (∆Н0) was determined by the tangent of the slope of the direct dependence logβί0=f(1/T), the value of entropy (∆S0) by the segment cut off by this straight line on the ordinate axis, while the change in the isobaric-isothermal potential was calculated according to the equation ∆G0 =∆H0-T∆S0. It was revealed that the replacement of chloride ions with the ultraspherical molecule of 2-ethylimidazole is accompanied by a positive change in enthalpy. This experimental fact is associated with the difference in the binding energies of gold-chlorine (Au-Cl) and gold-2-ethylimidazole (Au-2-EI). A positive change in enthalpy makes a negative contribution to the spontaneous occurrence of complexation reactions. At the same time, the value of ∆S0 for the studied system has a positive value. In the [AuCl4]- –2-EI-H2O system, the number of particles participating in the complexation reaction remains unchanged. The positive change in entropy is most likely due to the release of the H2O molecule from the hydration shell of each of the reactants. A positive change in entropy promotes the spontaneous occurrence of complexation reactions in the studied system.

Three-Dimensional Mineral Prospectivity Modeling with the Integration of Ore-Forming Computational Simulation in the Xiadian Gold Deposit, Eastern China

Finding new, effective predictive variables for 3D mineral prospectivity modeling is both important and challenging. The 3D ore-forming numerical modeling quantitively characterizes the complex coupling-mineralization process of the structure, fluid, heat, and wall rock, which may be potential indicators for mineral exploration. We here conducted 3D mineral prospectivity modeling with the integration of ore-forming computational simulation information in the Xiadian orogenic gold deposit, China, to examine whether the simulation data input can improve the reliability of prospectivity modeling. First, we constructed the 3D models of the orebody and fault to extract the fault geometric features using spatial analysis, as they are always considered to be the crucial controls of gold distribution. Second, we performed 3D numerical modeling of the deformation–fluid–heat-coupling process of the structurally controlled hydrothermal Au system using the FLAC3D platform. Finally, the fault-geometry features (buffer, dip, dip variation, and undulation) and the ore-formation-simulation indices (volume strain, shear strain, temperature variation, and fluid flux) were integrated using Bayesian decomposition modeling, which has a promising nonlinear model ability and a flexible variable-integration ability. The prospectivity modeling results demonstrated that the model generated by combining geometry and simulation variables achieved significantly higher AUC, precision, accuracy, Kappa, and F1 scores compared to other models using a single-predictor-variable dataset. This suggests that the joint use of geometry and simulation variables construct a comprehensive association between gold and its ore-controlling factors, thereby resulting in a highly reliable prospectivity model. Thus, the approach of 3D mineral prospectivity modeling aided by ore-forming numerical simulation proves to be more useful in guiding mineral exploration, especially in the condition of fewer variables. Based on the prospectivity modeling outcomes, we identified four gold targets at depth in the Xiadian district that warrant focused exploration efforts.