Metal Core Research Articles

Activity model for 36 elements in Fe-Ni-Si-S-C liquids with application to terrestrial planet accretion and mantle geochemistry: New data for Ru, Re, Pt, Os, Ti, Nb, and Ta

Understanding siderophile element partitioning between metal and silicate melts under diverse conditions can be used to place important constraints on the materials and conditions of planetary accretion and core formation, as well as post core formation processes. However, the effects of Si on the partitioning and activity coefficients for these elements are not well known, despite Si likely being one of the dominant light elements in Earth’s core. To address this gap in understanding, we have undertaken a systematic study of the highly siderophile elements Re, Pt, Os, and Ru, and the refractory lithophile elements Nb, Ta and Ti at 1600 °C and 1 GPa, to derive epsilon interaction parameters for these elements in FeSi metallic liquids. Positive epsilon interaction parameters were measured for Nb, Ta, Ti, Ru, Re, Pt, and Os, indicating that dissolved Si in Fe liquids causes a decrease in their metal/silicate partition coefficients (or ‘silicophobic’ behavior). Furthermore, εRe,Os,orRuSi > εRe,Os,orRuS which means Si causes a larger decrease in D(metal/silicate) than S, and the chalcophile behavior expected from some elements will be completely masked by the presence of Si in a metallic liquid. The new parameters are used to update an activity model that now includes 36 siderophile elements in Fe-Ni-Si-S-C liquids (27 trace elements considered here). Systematic assessment of these 27 elements shows which have the strongest affinity for Si, C, and S, and also how activity coefficients for these elements would vary during accretion and core formation in Earth, Mars, and Mercury of widely differing fO2 and core compositional conditions. The activity model is combined with new partitioning expressions for Mo, W, Cr, Re Ru, Pt, and Os and applied to aspects of post core formation mantle geochemistry of Earth, Mars, and Mercury. Our updated expressions show that the BSE Mo/W ratio can easily be achieved with metal/silicate partitioning during growth of the Earth, whereas Re, Os and Ru become lower than and highly fractionated compared with BSE values during core formation and accretion, and thus nearly 99% of their BSE abundances are likely contributed by late accretion. Ru isotopes should be a very good indicator of the source material for the late accretion. The high Pt/Os and Re/Os developed in a deepening magma ocean during the growth of the Earth, indicates 186Os and 187Os isotopes could be coupled if this ancient material remained isolated and subsequently became entrained in mantle plumes and measured in surficial lavas. The extent to which this occurred will be limited by the low Os content of this ancient material, thus requiring mixing as a major component in plume sources. Martian mantle Hf/W ratio stays low during accretion and core formation modelling, suggesting that W isotope anomalies are more likely due to solid/liquid silicate fractionation than to core formation. Finally, Ti contents measured by MESSENGER at Mercury’s surface can be explained by segregation of either a metallic core (IW-6 to -8) or metallic core + sulfide (IW-4 to -7.5) followed by mantle melting.

Slow evolution of Europa's interior: metamorphic ocean origin, delayed metallic core formation, and limited seafloor volcanism.

Europa's ocean lies atop an interior made of metal and silicates. On the basis of gravity data from the Galileo mission, many argued that Europa's interior, like Earth, is differentiated into a metallic core and a mantle composed of anhydrous silicates. Some studies further assumed that Europa differentiated while (or soon after) it accreted, also like Earth. However, Europa probably formed at much colder temperatures, meaning that Europa plausibly ended accretion as a mixture containing water-ice and/or hydrated silicates. Here, we use numerical models to describe the thermal evolution of Europa's interior assuming low initial temperatures (~200 to 300 kelvin). We find that silicate dehydration can produce Europa's current ocean and icy shell. Rocks below the seafloor may remain cool and hydrated today. Europa's metallic core, if it exists, may have formed billions of years after accretion. Ultimately, we expect the chemistry of Europa's ocean to reflect protracted heating of the interior.

Carbon isotope composition of basalts from Loihi Seamount: Primordial or recycled carbon in the Hawaiian mantle plume?

We analyzed the carbon isotope composition of vesicle CO2, plus He isotopes and He and CO2 concentrations in the vesicle (vapor) and glass (melt) phases of 37 submarine basalts from the summit, north and south rifts, and east flank of Loihi Seamount. Tholeiites and transitional basalts lie in a narrow range of vesicle δ13C = −4.6 to −0.9‰, while alkali basalts range from −7.2 to −2.1‰. Calculated total (vesicle+glass) δ13C for the majority of the basalts ranges from −6 to −2‰ assuming the vapor-melt fractionation factor Δ (= δvapor - δmelt) is +2 to +4‰ as measured in basaltic systems. This relatively narrow range of δ13C resembles mantle source values deduced from gas-rich mid-ocean ridge basalts and basalts from Iceland, and for Kilauea volcano deduced from its fumarole gas. However, this similarity presents a conundrum because Loihi basalts have degassed >97% of their initial CO2 as deduced from CO2 - Ba systematics and crystal fractionation modeling.Loihi parental magma (MgO=18 wt.%) had initial CO2 concentrations of 0.6 to 1.9 wt.%. Most tholeiitic and transitional basalts appear to have followed a quasi closed-system degassing history. Correcting for this degassing indicates the median δ13C for Loihi undegassed parental magmas is −1.5‰ and the δ13C range is −4 to +1‰. Estimates of this δ13C range are only weakly dependent on the choice of Δ and initial [CO2] in closed-system degassing scenarios. The Loihi mantle plume source is therefore characterized by δ13C values that are higher than the range of −6 to −4‰ prevalent in mantle-derived basalts and many diamonds. This could be due to primordial carbon isotope heterogeneity in Earth's mantle, exchange of carbon at the core-mantle boundary between ultra-low velocity zone silicates and the metallic liquid outer core, or to the presence of a small fraction (<1% by mass) of surficial carbonate that was tectonically recycled to the Hawaiian plume source region. Currently, an origin from recycled carbonate has the most supporting evidence.

Temporal Ni K-Edge X-ray Absorption Spectroscopy Study Reveals the Kinetics of the Ni Redox Behavior of the Iron-Nickel Oxide Bimetallic OER Catalyst

Operando X-ray absorption spectroscopy (XAS) can be utilized to probe the phase and structural changes of FeNiOx and similar transition metal oxide electrocatalysts during electrocatalytic reactions. However, capturing the temporal changes occurring in the operando chemistry of electrocatalysts has been little studied. In this work, we successfully capture the time-resolved changes at the Ni K-edge for both the X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) regions of an aqueous phase synthesized FeNiOx bimetallic nanoparticle electrocatalyst. During a stepped voltage experiment, the temporal change in the Ni K-edge was observed as the applied voltage was stepped from 0.7 to 0.8 V versus the silver/silver chloride reference electrode, and the change observed is associated with the Ni redox transition from the 2+ to 3+/4+ oxidation state. Individual XAS spectra were obtained in 90 s, and a total of 9 scans post voltage step showed a unique transition from a hydroxide to an oxyhydroxide phase. The shift in absorption edge energy position and the changes in spectral shape for individual scans explain the typically observed broadening of the Ni K-edge XANES spectrum during time-averaged operando XAS, and a kinetic analysis revealed a first-order observed rate constant, |kobs|, of 0.00426 s–1 and a half-life (t1/2) of 163 s. Multivariate curve resolution-alternating least squares analysis followed by linear combination fitting analysis for time-averaged versus time-resolved Ni K-edge changes upon voltage step show distinct differences in estimated contributions from Ni2+ oxide/hydroxide phases. Detailed EXAFS modeling shows the phase transition from hydroxide to oxyhydroxide on top of the unchanged metallic core.

Mantle fragmentation and incomplete core merging of colliding planetesimals as evidenced by pallasites

Main group pallasites were likely formed by the collision of their parent body with a smaller impactor that caused a mixing of mantle and core material from the target and impactor, respectively. In order to better constrain the collision, we present particle size distribution (PSD) analyses of olivines in seven main group pallasites and of the Eagle station pallasite. The PSDs of two fragmental pallasites (Admire and Huckitta) contain linear segments in bi-logarithmic particle number versus size diagrams that are similar to terrestrial cataclasites or impact-related rocks. On the other hand, the PSDs of four angular pallasites only display linear segments above their respective average grain sizes. We argue that fragmental pallasites record brittle rock deformation close to the impact site of the collision, while angular pallasites represent deeper-lying mantle rocks of the target body that were disintegrated by the downward percolation of core metal from the impactor. High strain-rate deformation experiments with the system olivine – FeS melt ± Au melt produced microstructures and PSDs that are broadly similar to these two textural groups. The experiments also suggest that de-localized metal melt percolation and concomitant mantle disintegration as evidenced in angular pallasites is facilitated by weak grain boundaries caused by a small fraction of previously present metal melt in the mantle as opposed to localized diking that is dominant in a melt-free mantle. The former mechanism is expected to prevent efficient core-merging and instead causes mantle-impregnation with metal melt, which could be active when planetesimal mantles were still warm due to short-lived radiogenic heating. In addition to the parent body of the PMG, asteroid 16 Psyche may be an example of this inefficient core-merging mechanism.

Frequency shifts of surface plasmon resonances in calculating the absorption coefficient of a composite based on bimetallic 1D-systems

In this paper analyzes the electromagnetic radiation absorption by a composite based on bimetallic nanowires. Using the Drude-Lorentz theory it was obtained the relationship for the polarizability frequency dependences, as well as real and imaginary parts of the dielectric function of layered 1D-systems was obtained. It is shown that the structure in the form of a metal core covered with a layer of another metal leads to splitting and the appearance of two maxima in the frequency dependence of the absorption coefficient. The magnitude and position of the maxima are determined by the composition of bimetallic nanowires and the volume content of metals. The influence of the dimensionality of the systems has been established by comparing the frequency dependences of the composite absorption coefficient based on bimetallic nanowires and nanoparticles. Calculations were performed for Ag@Au and Au@Ag nanowires immersed in Teflon.

Ligand-induced surface reconstruction in Ag2S colloidal quantum dots for highly luminescent infrared fluorescence

Silver sulfide (Ag2S) colloidal quantum dots (CQDs) have attracted attention as potential bio-imaging materials owing to their narrow bandgap and biocompatibility; however, their low photoluminescence quantum yield (PLQY) has limited their applications. Here we introduce ligand-induced surface reconstruction strategy to dramatically improve the PLQY of Ag2S CQDs. We found that the low PLQY of Ag2S CQDs is due to the undesirable formation of a metallic Ag core during the CQD synthesis. By introducing alkyl thiols as oxidizing agents, the metallic Ag core is reoxidized that Ag vacancies in CQDs are refilled. This induces a reduced metallic Ag core and Ag-rich stoichiometry in the CQDs. The CQDs after the surface reconstruction show a 150× enhancement of photoluminescence at 1230 nm, with an absolute PLQY of 9%. This research suggests that simple ligand treatments can help improve the surface and optical properties of silver chalcogenide CQDs, including Ag2S CQDs, which may allow development of advanced optoelectronic devices.

Synthesis of phosphine derivatives of [Fe2(CO)6(μ-sdt)] (sdt = SCH2SCH2S) and investigation of their proton reduction capabilities

The reactions of [Fe2(CO)6(μ-sdt)] (1) (sdt = SCH2SCH2S) with phosphine ligands have been investigated. Treatment of 1 with dppm (bis(diphenylphosphino)methane) or dcpm (bis(dicyclohexylphosphino)methane) affords the diphosphine-bridged products [Fe2(CO)4(μ-sdt)(μ-dppm)] (2) and [Fe2(CO)4(μ-sdt)(μ-dcpm)] (3), respectively. The complex [Fe2(CO)4(μ-sdt)(κ2-dppv)] (4) with a chelating diphosphine was obtained by reacting 1 with dppv (cis-1,2-bis(diphenylphosphino)ethene). Reaction of 1 with dppe (1,2-bis(diphenylphosphino)ethane) produces [{Fe2(CO)4(μ-sdt)}2(μ-κ1-dppe)] (5) in which the diphosphine forms an intermolecular bridge between two diiron cluster fragments. Three products were obtained when dppf (1,1′-bis(diphenylphosphino)ferrocene) was introduced to complex 1; they were [Fe2(CO)5(μ-sdt)(κ1-dppfO)] (6), the previously known [{Fe2(CO)5(μ-sdt)}2(μ-κ1-κ1-dppf)] (7), and [Fe2(CO)4(μ-sdt)(μ-dppf)] (8), with complex 8 being produced in highest yield. Single crystal X-ray diffraction analysis was performed on compounds 2, 3 and 8. All structures reveal the adoption of an anti-arrangement of the dithiolate bridges, while the diphosphines occupy dibasal positions. Infra-red spectroscopy indicates that the mono-substituted complexes 5, 6, and 7 are inert to protonation by HBF4.Et2O, but complexes 2, 3, 4 and [Fe2(CO)5(μ-sdt)(κ1-PPh3)] (9) show shifts of their ν(C-O) resonances that indicate that protons bind to the metal cores of the clusters. Addition of the one-electron oxidant [Cp2Fe]PF6 does not lead to any discernable shift in the IR resonances. The redox chemistry of the complexes was investigated by cyclic voltammetry, and the abilities of complexes to catalyze electrochemical proton reduction were examined.

Probing radiation resistance in simulated metallic core–shell nanoparticles

We present molecular dynamics (MD) simulations of radiation damage in Fe nanoparticles (NP) and bimetallic FeCu core–shell nanoparticles (CSNP). The CSNP includes a perfect body-centered cubic (bcc) Fe core coated with a face-centered cubic (fcc) Cu shell. Irradiation with Fe Primary Knock-on Atoms (PKA) with energies between 1 and 7 keV leads to point defects, without clustering beyond divacancies and very few slightly larger vacancy clusters, and without interstitial clusters, unlike what happens in bulk at the same PKA energies. The Fe-Cu interface and shell can act as a defect sink, absorbing radiation-induced damage and, therefore, the final number of defects in the Fe core is significantly lower than in the Fe NP. In addition, the Cu shell substantially diminishes the number of sputtered Fe atoms, acting as a barrier for recoil ejection. Structurally, the Cu shell responds to the stress generated by the collision cascade by creating and destroying stacking faults across the shell width, which could also accommodate further irradiation defects. We compare our MD results to Monte Carlo Binary Collision Approximation (BCA) simulations using the SRIM code, for the irradiation of an amorphous 3-layer thin film with a thickness equal to the CSNP diameter. BCA does not include defect recombination, so the number of Frenkel pairs is significantly higher than in MD, as expected. Sputtering yield (Y) is underestimated by BCA, which is also expected since the simulation is for a thin film at normal incidence. We also compare MD defect production to bulk predictions of the analytic Athermal Recombination Corrected Displacements Per Atom (arc-dpa) model. The number of vacancies in the Fe core is only slightly lower than arc-dpa predictions, but the number of interstitials is reduced by about one order of magnitude compared to vacancies, at 5 keV. According to the radiation resistance found for FeCu CSNP in our simulations, this class of nanomaterial could be suitable for developing new radiation-resistant coatings, nanostructured components, and shields for use in extreme environments, for instance, in nuclear energy and astrophysical applications.

The use of pile columns during the building construction by the top-down method

The article examines the analysis of publications regarding the use of various types of piles-columns during top-down construction. Today, the following types of piles can be used during construction using the "up-down" technology: bored piles, bored piles with a barrel extension (bell pile), barrettes (barrette), combined piles with a steel core (king post). The article analyzes the buildings that were built by the "up-down" method, as well as the structural characteristics of the piles-columns that were used during their construction. It was established that pile-columns are expected to absorb loads in a wide range from 1.5 to 44.5 MN, on average the calculated load is from 10 to 14 MN. The length of the piles varies from 16 to 67 m, on average - 30...35 m, and they were placed with steps from 1.8 to 4.3 m, on average - 3 m. A growing trend of using combined piles with a metal core (king post) was revealed. Their main advantage is the ability to immediately perceive significant loads from the above-ground part of the building during the simultaneous construction of its underground part and guaranteed indicators of strength and stability of the column. Installation of combined piles with a metal core (king post) involves two stages. At the first stage, a pit is arranged and a reinforcing frame is installed to it, then a concrete mixture is laid to the lower monolithic part of the pile, into which the steel core of the upper part is mounted and it is covered with gravel in the pit. At the second stage, during the construction of the underground floors, the metal core is concreted. At the same time, it was established that the installation and concreting of a metal body is a technologically complex and expensive process that requires a more detailed study of the possibility of improving structural and technological solutions and reducing the cost of work.

Recent advances in polyoxometalate-based lanthanide–oxo clusters

Polyoxometalate (POM)-based lanthanide-oxo clusters (LnOCs) are a class of polynuclear lanthanide–oxygen complexes formed by polyoxometalate stabilization through oxygen bridges in which POMs can be viewed as multidentate inorganic ligands. POM-based LnOCs have received interest owing to their interesting structures and potential applications. In this paper, we summarize the classification, synthesis strategies, and properties of POM-based LnOCs. POM-based LnOCs are classified into three main categories according to their metal core element type and quantity: pure 4f clusters, 5d–4f clusters, and 3d–4f clusters. Their synthetic strategies are divided into four categories based on the source of the POM involved in the structural assembly: the lacunary POMs ligand-directed method, the in-situ transformation of lacunary POMs ligand-directed method, the in-situ generation of lacunary POMs ligand-directed method, and mixed synthesis strategies. In addition, the single-molecule magnets of POM-based LnOCs and their proton conduction properties are summarized.

Mechanisms in the Catalytic Reduction of N2O by CO over the M13@Cu42 Clusters of Aromatic-like Inorganic and Metal Compounds.

Metal aromatic substances play a unique and important role in both experimental and theoretical aspects, and they have made tremendous progress in the past few decades. The new aromaticity system has posed a significant challenge and expansion to the concept of aromaticity. From this perspective, based on spin-polarized density functional theory (DFT) calculations, we systematically investigated the doping effects on the reduction reactions of N2O catalyzed by CO for M13@Cu42 (M = Cu, Co, Ni, Zn, Ru, Rh, Pd, Pt) core-shell clusters from aromatic-like inorganic and metal compounds. It was found that compared with the pure Cu55 cluster, the strong M-Cu bonds provide more structural stability for M13@Cu42 clusters. Electrons that transferred from the M13@Cu42 to N2O promoted the activation and dissociation of the N-O bond. Two possible reaction modes of co-adsorption (L-H) and stepwise adsorption (E-R) mechanisms over M13@Cu42 clusters were thoroughly discovered. The results showed that the exothermic phenomenon was accompanied with the decomposition process of N2O via L-H mechanisms for all of the considered M13@Cu42 clusters and via E-R mechanisms for most of the M13@Cu42 clusters. Furthermore, the rate-limiting step of the whole reactions for the M13@Cu42 clusters were examined as the CO oxidation process. Our numerical calculations suggested that the Ni13@Cu42 cluster and Co13@Cu42 clusters exhibited superior potential in the reduction reactions of N2O by CO; especially, Ni13@Cu42 clusters are highly active, with very low free energy barriers of 9.68 kcal/mol under the L-H mechanism. This work demonstrates that the transition metal core encapsulated M13@Cu42 clusters can present superior catalytic activities towards N2O reduction by CO.

Effects of TiC on the microstructure refinement and mechanical property enhancement of additive manufactured Inconel 625/TiC metal matrix composites fabricated with novel core-shell composite powder

The flexible product shape of additive manufacturing (AM) is attractive, but the process suffers from a lack of material property diversity due to a limited number of printable alloys and post-processing options. To overcome this problem, the AM of metal matrix composites (MMCs) is a highly suitable solution because the properties of MMC can be tailored using various reinforcements. Therefore, extensive research has been conducted on the AM of MMCs; however, the major huddle for this process has been the difficulties in preparing feedstock powder and operating the AM process. This study introduces an easily synthesizable core-shell composite powder, which was fabricated by a recently developed process called the SMART process. The core-shell powder has a novel morphology, consisting of a metal core and composite shell, distinguishing it from the powders used in conventional AM approaches. Inconel 625/TiCp composites were fabricated using the core-shell composite powder, with various fractions of TiCp up to 10 vol.%. Compared to additive-manufactured Inconel 625, the additive-manufactured MMCs showed enhanced strength with significantly fewer defects. The results of this study may accelerate the application of MMC fabricated by AM, which offers superior properties and reliability compared to casting and powder metallurgy due to the higher degree of dislocation density and reinforcement dispersion.

A Three-Dimensional Vibration Theory for Ultralight Cellular Sandwich Plates Subjected to Linearly Varying In-Plane Distributed Loads.

Thin structural elements such as large-scale covering plates of aerospace protection structures and vertical stabilizers of aircraft are strongly influenced by gravity (and/or acceleration); thus, exploring how the mechanical behaviors of such structures are affected by gravitational field is necessary. Built upon a zigzag displacement model, this study establishes a three-dimensional vibration theory for ultralight cellular-cored sandwich plates subjected to linearly varying in-plane distributed loads (due to, e.g., hyper gravity or acceleration), with the cross-section rotation angle induced by face sheet shearing accounted for. For selected boundary conditions, the theory enables quantifying the influence of core type (e.g., close-celled metal foams, triangular corrugated metal plates, and metal hexagonal honeycombs) on fundamental frequencies of the sandwich plates. For validation, three-dimensional finite element simulations are carried out, with good agreement achieved between theoretical predictions and simulation results. The validated theory is subsequently employed to evaluate how the geometric parameters of metal sandwich core and the mixture of metal cores and composite face sheets influence the fundamental frequencies. Triangular corrugated sandwich plate possesses the highest fundamental frequency, irrespective of boundary conditions. For each type of sandwich plate considered, the presence of in-plane distributed loads significantly affects its fundamental frequencies and modal shapes.

Impact of the metal core on the electrochemiluminescence of a pair of atomically precise Au20 nanocluster isomers

Although the electrochemiluminescence (ECL) of metal nanoclusters has been reported, revealing the correlation between structure and ECL at an atomic level is highly challenging. Here, we reported the impact of the metal core of Au20(SAdm)12(CHT)4 (Au20-AC for short; SAdm = 1-adamantanethiolate; CHT= cyclohexanethiol) and its isomer Au20(TBBT)16 (TBBT = 4-tert-butylthiophenol) on their solution-state and solid-state electrochemiluminescence. In self-annihilation ECL experiments, Au20-AC showed a strong cathodic ECL but a weak anodic ECL, while the ECL signal of Au20(TBBT)16 was weak and barely detectable. Density functional theory (DFT) calculations showed that the Au7 kernel of [Au20-AC]- is metastable, weakening its anodic ECL. Au20-AC in solution-state displayed an intense co-reactant ECL in the near-infrared region, which is 7 times higher than that of standard Ru(bpy)32+. The strongest solid-state ECL emissions of Au20-AC and Au20(TBBT)16 were at 860 and 770 nm, respectively — 15 nm red-shifted for Au20-AC and 20 nm blue-shifted for Au20(TBBT)16, compared to their corresponding solid-state photoluminescence (PL) emissions. This work shows that ECL is significantly affected by the subtle differences of the metal core, and offers a potential basis for sensing and immunoassay platforms based on atomically precise emissive metal nanoclusters.

Integration of Metal Catalysis and Organocatalysis in a Metal Nanocluster with Anchored Proline.

Chiral metal nanoclusters have recently been attracting great attention. It is challenging to realize asymmetric catalysis via atomically precise metal nanoclusters. Herein, we report the synthesis and total structure determination of chiral clusters [Au7Ag8(dppf)3(l-/d-proline)6](BF4)2 (l-/d-Au7Ag8). Superatomic clusters l-/d-Au7Ag8 display intense and mirror-image Cotton effects in their CD spectra. Density functional theory (DFT) calculations were carried out to understand the correlation between electronic structures and the optical activity of the enantiomeric pair. Surprisingly, the incorporation of proline in a metal nanocluster can significantly promote the catalytic efficiency in asymmetric Aldol reactions. The increase of catalytic activity of Au7Ag8 in comparison with organocatalysis by proline is attributed to the cooperative effect of the metal core and prolines, showing the advantages of the integration of metal catalysis and organocatalysis in a metal nanocluster.

Ceramic Open Cell Foams Featuring Plasmonic Hybrid Metal Nanoparticles for In Situ SERS Monitoring of Catalytic Reactions

AbstractThis work presents porous zirconia‐toughened alumina ceramics functionalized with Au@Pd/Au@Pt core–shell nanoparticle (NP) for in situ monitoring of catalytic reactions via surface‐enhanced Raman scattering (SERS) which is augmented by the open cell foam structure of the ceramic support. In this respect, the porous ceramic enables efficient light trapping and propagation onto the coated surface, which provides good accessibility of the catalyst, while the core–shell particles are equipped with a catalytically active shell and a plasmonic core which enables SERS sensing. The metallic hybrid core–shell NPs are synthesized by the Au‐seed mediated method and colloidally deposited onto the open porous ceramic matrix prepared via the polymer replica method. The Au@Pt NP functionalized porous ceramic show a Raman enhancement factor up to 106, which is significantly higher than that of non‐porous samples. In situ reaction monitoring via SERS is demonstrated by the Pt‐catalyzed reduction of 4‐nitrothiophenol to 4‐aminothiophenol, showing high specificity for analysis of reactants and products. This multifunctional material concept featuring ceramics‐augmented SERS and catalytic activity could be extended beyond real‐time, sensitive reaction monitoring toward high temperature reactions, photothermal catalysis, bioprocessing and ‐sensing, green energy conversion, and related applications.

Titanium biogenic nanoparticles to help the growth of Trichoderma harzianum to be used in biological control

BackgroundThe biogenic synthesis of metallic nanoparticles is a green alternative that reduces the toxicity of this nanomaterials and may enable a synergy between the metallic core and the biomolecules employed in the process enhancing biological activity. The aim of this study was to synthesize biogenic titanium nanoparticles using the filtrate of the fungus Trichoderma harzianum as a stabilizing agent, to obtain a potential biological activity against phytopathogens and mainly stimulate the growth of T. harzianum, enhancing its efficacy for biological control.ResultsThe synthesis was successful and reproductive structures remained in the suspension, showing faster and larger mycelial growth compared to commercial T. harzianum and filtrate. The nanoparticles with residual T. harzianum growth showed inhibitory potential against Sclerotinia sclerotiorum mycelial growth and the formation of new resistant structures. A great chitinolytic activity of the nanoparticles was observed in comparison with T. harzianum. In regard to toxicity evaluation, an absence of cytotoxicity and a protective effect of the nanoparticles was observed through MTT and Trypan blue assay. No genotoxicity was observed on V79-4 and 3T3 cell lines while HaCat showed higher sensitivity. Microorganisms of agricultural importance were not affected by the exposure to the nanoparticles, however a decrease in the number of nitrogen cycling bacteria was observed. In regard to phytotoxicity, the nanoparticles did not cause morphological and biochemical changes on soybean plants.ConclusionThe production of biogenic nanoparticles was an essential factor in stimulating or maintaining structures that are important for biological control, showing that this may be an essential strategy to stimulate the growth of biocontrol organisms to promote more sustainable agriculture.Graphical

Robust Superamphiphobic Coating Applied to Grease-Proof Mining Transformer Components.

The iron core and heat sink in a mining transformer are susceptible to damage from oil spills or the harsh mine environment; the deterioration of oil products in the underground environment and transformers produce massive amounts of harmful liquid substances, which may lead to unnecessary economic losses in drilling engineering. To overcome this issue, a convenient and economical way to protect transformer components was developed. Herein, we proposed an air spray technology at room temperature for the preparation of antigreasy superamphiphobic coatings, which are suitable for bulk metallic glass transformer cores and ST13 heat sinks. The addition of polypyrrole powder effectively improves the thermal conductivity and specific heat of the coating in the range of 50-70 °C. More importantly, the fabricated coating has excellent repellency to liquids, such as water, ethylene glycerol, hexadecane, and rapeseed oil. Meanwhile, the coating has excellent physical and chemical resistance and outstanding antifouling features, which provide a feasible solution for combating grease pollution and corrosion in the mine environment. Taking multifaceted stability into consideration, this work contributes to enhancing the application of superamphiphobic coatings in the fields of protecting transformer components in the harsh environment or during transformer operation faults.

Prediction of Cu4Zn4 aggregates based on superatom network model

Recently, the tetrahedral Cu4Zn4 cluster composed of superimposed Cu4 and Zn4 was reported, which can be used as a building block for assembling Cu5Zn8-type structures. Here, we confirm that tetrahedral structures of (Cu4Zn4)4+, (Cu4Zn4)(C5H5)4, (Cu4Zn4)Cl4 and (Cu4Zn4)(SH)4 clusters are highly stable on the potential energy surfaces, and their metallic cores conform to the superatom model despite different ligand effects. The molecular dynamics simulations also show that the constructed clusters still possess good thermal stability at 500 K. Based on the superatomic characteristics of these clusters, two Cu4Zn4 aggregates are predicted, and configurations and electronic properties of them are analyzed in detail. The molecular orbitals and density of states show the tetrahedral Cu4Zn4 building blocks maintain superatom properties in extended brass structures. Hence, we give an effective strategy for assembling new brasses.