Elemental Mapping Techniques Research Articles

Design and synthesis of a versatile cooperative catalytic aerobic oxidation system with co-immobilization of palladium nanoparticles and laccase into the cavities of MCF

We have designed a versatile reusable cooperative catalyst oxidation system, consisting of palladium nanoparticles and laccase with unprecedented reactivity. This biohybrid catalyst was synthesized by the stepwise immobilization of laccase as an enzyme and Pd as a nanometallic component into the same cavity of siliceous mesocellular foams (MCF). MCF and nanobiohybrid catalyst were characterized by BET, SAXS, SEM, EDX elemental mapping, ICP-OES, TEM, TGA, FT-IR, and XPS techniques and the stepwise immobilization of laccase enzyme and Pd onto MCF was evaluated through several compelling electrochemical studies. The present catalytic system exhibits high activity toward (i) aerobic oxidation of alcohols to the corresponding carbonyl compounds, (ii) aerobic oxidation of cyclohexanol and cyclohexanone to phenol and (iii) aerobic dehydrogenation of important N-heteocyclic compounds (tetrahydro quinazolines, quinazolonones, pyrazolines and 1,4-diydropyridines) in the presence of catalytic amount of hydroquinone (HQ) as mediator in phosphate buffer (0.1 M, pH 4.5, 4 mL)/THF (4%, 1 mL) as solvent under mild conditions. The immobilization of both oxygen-activating catalyst (laccase) and oxidizing catalyst (Pd) onto the same support makes the present catalyst system superior to other currently available heterogeneous palladium based catalytic aerobic oxidation systems.

Improved Catalytic Performance of Ethane Dehydrogenation in the Presence of CO2 over Zr-Promoted Cr/SiO2.

The Zr-, Ce-, Sr-, and Sn-promoted Cr/SiO2 catalysts were prepared by the incipient wetness impregnation method, then characterized by N2 adsorption/desorption, X-ray diffraction, X-ray photoelectron spectroscopy, H2-TPR, CO2-TPD, UV–vis, high-angle annular dark-field imaging–scanning transmission electron microscopy—energy dispersive X-ray spectroscopy elemental mapping, Raman, and thermogravimetric techniques to study the structural evolution under the preparation/reaction conditions, and applied to catalyze ethane oxidative dehydrogenation with CO2. The results suggested that the Cr6+ species were indispensable for activating the dehydrogenation reaction thanks to the oxidation–reduction cycle between Cr6+ and Cr3+. The type of the promotor also affected significantly the ability of replenishing the lattice oxygen through the disassociation of CO2, leading to the different catalytic performances. The Zr-promoted sample had the best performance in converting the reactants as well as the catalytic stability.

Addressing K/L-edge overlap in elemental analysis from micro-X-ray fluorescence: bioimaging of tungsten and zinc in bone tissue using synchrotron radiation and laser ablation inductively coupled plasma mass spectrometry.

Synchrotron radiation micro-X-ray fluorescence (SR-μXRF) is a powerful elemental mapping technique that has been used to map tungsten and zinc distribution in bone tissue. However, the heterogeneity of the bone samples along with overlap of the tungsten L-edge with the zinc K-edge signals complicates SR-μXRF data analysis, introduces minor artefacts into the resulting element maps, and decreases image sensitivity and resolution. To confirm and more carefully delineate these SR-μXRF results, we have employed laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to untangle the problem created by the K/L-edge overlap of the tungsten/zinc pair. While the overall elemental distribution results are consistent between the two techniques, LA-ICP-MS provides significantly higher sensitivity and image resolution compared with SR-μXRF measurements in bone. These improvements reveal tissue-specific distribution patterns of tungsten and zinc in bone, not observed using SR-μXRF. We conclude that probing elemental distribution in bone is best achieved using LA-ICP-MS, though SR-μXRF retains the advantage of being a non-destructive method with the capability of being paired with X-ray techniques, which determine speciation in situ. Since tungsten is an emerging contaminant recently found to accumulate in bone, accurately determining its distribution and speciation in situ is essential for directing toxicological studies and informing treatment regimes. Graphical abstract Tungsten and zinc localization and uptake in mouse femurs were imaged by synchrotron radiation, left, and by laser ablation ICP-MS, right. The increased resolution of the LA-ICP-MS technique resolves the problem of the overlap in tungsten's L-edge and zinc's K-edge.

Ultrasonic assisted functionalization of MWCNT and synergistic electrocatalytic effect of nano-hydroxyapatite incorporated MWCNT-chitosan scaffolds for sensing of nitrofurantoin.

In the present work, we report the fabrication of stable composite of chitosan hydrogels (CHI) on multiwalled carbon nanotubes (MWCNT) using a simple ultrasonic-assisted method. Also, rod-like hydroxyapatite nanoparticles (HA NPs) were synthesised using a hydrothermal route and were incorporated into the highly conductive MWCNT-CHI scaffolds using an ultrasonication method. The functionalization of MWCNT and preparation of HA NPs on MWCNT-CHI nanocomposite were done using the sonication over the frequency of 37 kHz with the ultrasonic power capable of 150 W (Elmasonic Easy 60H bath sonicator). The resulting hybrid HA NPs/MWCNT-CHI nanocomposites have an excellent surface area and high surface to volume ratio, which leads to the sensitive detection of nitrofurantoin than pristine MWCNT and HA NPs. The complete elemental and morphological analyses of the HA NPs/MWCNT-CHI nanocomposites were characterised by XRD, FTIR, RAMAN, FESEM, TEM, EDX, and elemental mapping techniques. Electrochemical analysis of the HA NPs/MWCNT-CHI nanocomposites was carried out by cyclic voltammetry, electrochemical impedance spectroscopy and amperometry methods. The modified glassy carbon electrode (GCE) of HA NPs/MWCNT-CHI nanocomposites exhibit the nitrofurantoin detection activity at the linear range of 0.005-982.1 µM with the detection limit of 1.3 nM. The synergistic electrocatalytic activity of HA NPs/MWCNT-CHI nanocomposites modified GCE is correlated to the sensitivity of 0.16 µAµM-1 cm-2 with excellent precision and accuracy towards the sensing of nitrofurantoin.

Investigations of hot corrosion resistance of HVOF coated Fe based superalloy A-286 in simulated gas turbine environment

The main aim of the present work is to investigate the high-temperature corrosion behavior of bare, high-velocity oxy-fuel coated on iron-based superalloy A-286. Ni-20%Cr and Cr3C2-25%NiCr powders are deposited on the Fe based superalloy A-286 material by high-velocity oxy-fuel (HVOF) process. Surface roughness and coating thickness of the coated specimen is evaluated using surface roughness tester and optical microscope (OM). The hot corrosion study was performed on bare, and HVOF coated Fe-based superalloy A-286 in Na2SO4-50%V2O5-10%NaCl environment at 700 °C under cyclic conditions. Kinetics of corrosion has been determined by thermo-gravimetric analysis using mass change measurement; Cr3C2-25%NiCr coating shows the better corrosion resistance due to the formation of stable Cr2O3 layer. The uncoated superalloy is severely suffered by spallation and sputtering of oxide scales during hot corrosion study. The surface microstructure, chemical composition and phase identification of coatings before and after hot corrosion are analyzed using scanning electron microscope/ energy dispersive spectroscopy (SEM/EDS) and X-ray diffraction (XRD) analysis. Depth of corrosion attack and oxide scales are characterized using EDS compositional analysis and elemental mapping technique. The result of the cross-sectional image shows that uncoated material was severely suffered by hot corrosion to a depth of 200 µm.

Au sensitized La–CeO2 catalyst coated ceramics monoliths for toluene catalysis application

Coating procedure for ceramic monoliths was optimized by wash coating with ϒ-alumina for the deposition of Au sensitized La–CeO2 catalyst. Effect of four different catalyst coating methods on ceramics monolith surface for toluene catalytic activity was investigated. Au sensitized La–CeO2 catalyst was prepared via wetness impregnation and co-precipitation chemical methods. The catalyst was characterized using XRD, FESEM, EDS, TEM, XPS, Raman, BET and Elemental mapping techniques. Nanoparticles composed flakes morphology of catalyst was confirmed by electron microscopy. Average nanocrystalline size of 6.7 nm and surface area 33 m2/g of catalyst was estimated using Scherrer's formula and BET analysis respectively. Adherence tests were carried out by applying ultrasonic vibrations and hot air blower to optimize ϒ-alumina coating on ceramics monolith. Toluene catalytic activity studied at different operating temperatures and concentrations. Stability and reuse of catalyst coated ceramics monoliths for toluene activity were confirmed. A mechanism of toluene degradation was briefed.

Impact of calcium and magnesium substituted strontium nano-hexaferrite on mineral uptake, magnetic character, and physiology of barley (Hordeum vulgare L.)

In this study, calcium and magnesium substituted strontium nano-hexaferrites (Sr0.96Mg0.02Ca0.02Fe12O19, SrMgCa nano-HF) were synthesized by the sol-gel auto-combustion method and their impact on the nutrient uptake, magnetic character and physiology of barley (Hordeum vulgare L.), a crop plant, was investigated. Structural, microstructural, and magnetic properties of nano-HF were evaluated by using vibrating sample magnetometry (VSM), X-ray diffraction (XRD), scanning electron microscopy (SEM) along with energy-dispersive X-ray (EDX) and elemental mapping techniques. Plants were hydroponically exposed to nano-HF (ranging from 125 to 1000 mg/L) for three weeks. Results showed that the SrMgCa nano-HF application enhanced germination rate (about 20%), tissue growth (about 38%), biomass (about 20%), soluble protein content (about 41%), and chlorophyll pigments (about 33–42%) when compared to the untreated control. In general, the plants showed the highest growth achievement at 125 or 250 mg/L of nano-HF treatment. However, higher doses diminished the growth parameters. Element concentrations and magnetic behavior analyses of plant parts proved that SrMgCa nano-HF with a size of 42.4 nm are up-taken by the plant roots and lead to increase in iron, calcium, magnesium, and strontium contents of leaves, which were about 20, 18, 3, and 60 times higher in 500 mg/L nano–HF–treated leaves than those of control, respectively. Overall, this study shows for the first time that the four elements have been internalized into the plant body through the application of substituted nano-HF. These findings suggest that mineral-substituted nanoparticles can be incorporated into plant breeding programs for the i) enhancement of seed germination and ii) treatment of plants by fighting with mineral deficiencies.

Pd, Pd–Ni and Pd–Ni–Fe nanoparticles anchored on MnO2/Vulcan as efficient ethanol electro-oxidation anode catalysts

Pd–Ni–Fe nanoparticles supported on MnO2/Vulcan XC-72 R (carbon black powder) as the electrocatalyst for the anodic oxidation of ethanol in a direct ethanol alkaline fuel cell (DEAFC) has been conducted. Electrocatalyst structures and morphologies are investigated by XRD, FE-SEM, EDX and elemental mapping techniques and subsequently electrochemical performance of electrocatalysts for ethanol oxidation reaction (EOR) are studied by cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS). Pd/MnO2/Vulcan, Pd–Ni/MnO2/Vulcan and Pd–Ni–Fe/MnO2/Vulcan efficiently advanced ethanol electro-oxidation reaction under alkaline conditions. Pd/MnO2/Vulcan revealed best potential window and low charge transfer resistance (Rct) for EOR. Pd–Ni/MnO2/Vulcan and Pd–Ni–Fe/MnO2/Vulcan electrocatalysts have a good anti CO-poisoning capability. Pd–Ni–Fe/MnO2/Vulcan has significantly high current density, excellent catalyst durability and cyclic stability for ethanol oxidation which encourage researchers for application of such exceptional materials as anode electrocatalysts in DEFC.

Modification of rheological and filtration characteristics of water-based mud for drilling oil and gas wells using green SiO2@ZnO@Xanthan nanocomposite.

In this study, a green, simple and economical approach was used to synthesise the SiO2@ZnO@Xanthan nanocomposite (NC) to modify the rheological and filtration characteristics of the water-based drilling mud. The green synthesised NCs were identified using scanning electron microscopy, energy dispersive X-ray spectroscopy, elemental mapping, X-ray diffraction and UV-Vis analytical techniques. Additionally, the effect of SiO2@ZnO@Xanthan NCs on the filtration and rheological properties of mud including apparent viscosity, plastic viscosity, yield point, gel strength, mud cake and fluid loss was investigated. The obtained results confirmed that the synthesised NCs effectively improved the rheological properties of drilling mud, and considerably decreased its fluid loss and filter cake by about 54 and 92.5%, respectively. The results highly recommend the SiO2@ZnO@Xanthan NC as an excellent additive to improve the rheological properties, and reduce the fluid loss and the filter cake of the drilling mud.

Revealing the Elemental Distribution within Latent Fingermarks Using Synchrotron Sourced X-ray Fluorescence Microscopy.

Fingermarks are an important form of crime-scene trace evidence; however, their usefulness may be hampered by a variation in response or a lack of robustness in detection methods. Understanding the chemical composition and distribution within fingermarks may help explain variation in latent fingermark detection with existing methods and identify new strategies to increase detection capabilities. The majority of research in the literature describes investigation of organic components of fingermark residue, leaving the elemental distribution less well understood. The relative scarcity of information regarding the elemental distribution within fingermarks is in part due to previous unavailability of direct, micron resolution elemental mapping techniques. This capability is now provided at third generation synchrotron light sources, where X-ray fluorescence microscopy (XFM) provides micron or submicron spatial resolution and direct detection with sub-μM detection limits. XFM has been applied in this study to reveal the distribution of inorganic components within fingermark residue, including endogenous trace metals (Fe, Cu, Zn), diffusible ions (Cl-, K+, Ca2+), and exogeneous metals (Ni, Ti, Bi). This study incorporated a multimodal approach using XFM and infrared microspectroscopy analyses to demonstrate colocalization of endogenous metals within the hydrophilic organic components of fingermark residue. Additional experiments were then undertaken to investigate how sources of exogenous metals (e.g., coins and cosmetics) may be transferred to, and distributed within, latent fingermarks. Lastly, this study reports a preliminary assessment of how environmental factors such as exposure to aqueous environments may affect elemental distribution within fingermarks. Taken together, the results of this study advance our current understanding of fingermark composition and its spatial distribution of chemical components and may help explain detection variation observed during detection of fingermarks using standard forensic protocols.

Synthesis, characterization and anti-bacterial screening of complex nanocomposite structures of SiO[formula omitted]@ZnO@Fe[formula omitted]O[formula omitted] and SnO[formula omitted]@ZnO@Fe[formula omitted]O[formula omitted

In this research paper, the synthesis was aimed at the development of complex nanocomposites of SiO2@ZnO@Fe3O4 and SnO2@ZnO@Fe3O4. These materials were achieved through the chemical double co-precipitation technique. The nanocomposites were characterized by Powder X-ray Diffraction (PXRD), Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), Selected Area Electron Diffraction (SAED), EDAX and Elemental mapping techniques. The developed nanocomposites were further evaluated by magnetic studies at room temperature. Also, the nanocomposites were subjected to antimicrobial studies. The minimum inhibitory concentrations indicated that the silica coated nanocomposite found better antibacterial activity due to is porous surface.

In situ biogenic synthesis of Pd nanoparticles over reduced graphene oxide by using a plant extract (Thymbra spicata) and its catalytic evaluation towards cyanation of aryl halides.

An eco-friendly biosynthesized Pd NP anchored Thymbra spicata extract-modified graphene oxide (Pd NPs/rGO-T. spicata) nanohybrid material has been introduced. Initially, the herb, Thymbra spicata extract was immobilized on the surface of GO via their natural adhering capability. The polyphenolic function grafted in situ prepared RGO acted as the natural reductant of Pd precursor. The as-prepared nanocomposite (Pd NPs/rGO-T. spicata) was characterized using Fourier transform infrared (FTIR), UV-vis, X-ray diffraction (XRD), inductively coupled plasma (ICP), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), high resolution transmission electron microscopy (HRTEM), Fast Fourier Transform (FFT), Raman spectroscopy and EDX elemental mapping techniques. It has been observed that the Pd NPs with perfect crystal structure, uniform shape and size were dispersed homogeneously on the rGO surface. The material showed excellent water dispersibility due to the hydrophilicity of biomolecules attached over them, which is very essential in heterogeneous catalysis. The T. spicata contained biomolecules served as effective capping, reducing and stabilizing agents for the uniform immobilization of Pd precursors on graphene sheet surface without aggregation. The catalytic activity of this nano hybrid was assessed comprehensively in the cyanation of aryl halides with a wide range of substrates using K4[Fe(CN)6] as a cheap source of cyanide. The model reaction resulted outstanding catalytic performance with a great reusability of the catalysis.

A facile hydrothermal synthesis of visible-light responsive BiFeWO6/MoS2 composite as superior photocatalyst for degradation of organic pollutants

Abstract In the present study, we have fabricated a new Z-scheme BiFeWO6/MoS2 composite for photocatalytic elimination of organic contaminants from the waste-water. A series of BiFeWO6/MoS2 composites were obtained by changing the amounts of BiFeWO6 from 1 to 10 mg through a facile hydrothermal method. The phase structures and morphologies of these BiFeWO6/MoS2 composites were analyzed by SEM, HR-TEM, XRD, UV–vis DRS, element mapping and XPS techniques. Afterward, the dye-degradation experiments were conducted for the removal of Rhodamine B (RhB) using as-obtained BiFeWO6/MoS2 composite samples under visible-light illumination to evaluate their photocatalytic activity. It is found that the BiFeWO6/MoS2 composites exhibited great photocatalytic behavior than the pure BiFeWO6 and MoS2 samples. In particular, the BiFeWO6/MoS2 composite with 5 mg of BiFeWO6 showed a quickly complete photocatalyst degradation ability of RhB in 75 min with high photo-stability and reusability behavior. This superior catalytic response of BiFeWO6/MoS2 composite may be contributed by its high light harvesting capacity as well as fast separation and movement of photo-generated electron-hole pairs. This proposed BiFeWO6/MoS2 composite is a very promising photocatalyst for environmental remediation work.

Improved selectivity and low concentration hydrogen gas sensor application of Pd sensitized heterojunction n-ZnO/p-NiO nanostructures

Heterojunction based gas sensor was fabricated by forming two semiconductor nanostructures interface i.e. n-type ZnO nanorods and p-type NiO nanoplates. These nanostructures were synthesized via chemical routes. Palladium (Pd) nanoparticles (NPs) were synthesized and sensitized on the surface of heterojunction sensor material to enhance the gas response. Sensor materials were characterized using XRD, TEM, FESEM, EDS, Elemental mapping, and XPS techniques for their physicochemical properties. The n-ZnO/p-NiO heterojunction sensors with and without Pd NPs sensitization were investigated for low hydrogen gas concentration 2–100 ppm. Pd NPs sensitized n-ZnO/p-NiO heterojunction sensor showed higher response of 72% towards 100 ppm hydrogen (H2) gas concentration at the operating temperature 225 °C, whereas 53% response was noted by p-NiO/n-ZnO heterojunction sensor for 100 ppm concentration at 237 °C operating temperature. Both the sensors were investigated for selectivity studies using methane (CH4), carbon monoxide (CO), nitrogen dioxide (NO2), carbon dioxide (CO2) and H2 gases. Higher selectivity was observed towards H2 gas for both the sensors. The gas responses of both sensors were investigated at various operating temperatures and concentrations. Transient response, repeatability, and stability were also confirmed for both sensors. The gas sensing mechanism for heterojunction sensors was elucidated.

Rational design and facile synthesis of binary metal sulfides VS2-SnS2 hybrid with functionalized multiwalled carbon nanotube for the selective detection of neurotransmitter dopamine

In this work, we report a sensitive and selective electrochemical sensor for the detection of dopamine (DA) neurotransmitter based on VS2-SnS2/f-MWCNT hybrids. Herein, the binary metal sulfide (VS2-SnS2) was synthesized via single step hydrothermal route and hybrids with f-MWCNT via the ultrasonication process. The as-prepared VS2-SnS2/f-MWCNT hybrids were characterized through the FESEM, EDX and elemental mapping, TEM, XPS, Raman and XRD techniques. The electrochemical performance and catalytic activity of the modified electrodes were probed using electrochemical impedance spectra (EIS), cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Interestingly, DPV results exhibits an appreciable linear range from 0.025 to 1017 μM and LOD of 0.008 μM. The selectivity study was performed to prove the high selectivity of the VS2-SnS2/f-MWCNT hybrids modified electrode. Furthermore, the practical applicability of the DA sensor was scrutinized in human serum sample and rat brain sample.

Facile sonochemical synthesis of perovskite-type SrTiO3 nanocubes with reduced graphene oxide nanocatalyst for an enhanced electrochemical detection of α-amino acid (tryptophan)

In this paper, perovskite-type SrTiO3 nanocubes decorated reduced graphene oxide is synthesized by sonochemical method. The as-synthesized SrTiO3@RGO nanocomposite was confirmed by XRD, TEM, SEM, elemental mapping and electrochemical technique. Furthermore, surface morphological and X-ray diffraction studies revealed the formation and high loading of SrTiO3 nanocubes on reduced graphene oxide matrix. The SrTiO3@RGO nanocomposite modified electrode shows an excellent electrochemical detection towards of amino acid (tryptophan). The developed sensor was showed a wide linear range from 30 nM to 917.3 µM and detection limit is 7.15 nM. Furthermore, the sensitivity was calculated to be 9.11 µA µM−1 cm2. In addition, the proposed modified sensor is exhibited good selectivity, stability, reproducibility and repeatability. The SrTiO3@RGO catalyst modified electrode was successfully applied to tryptophan analysis in biological samples.

Evaluation of cyclic oxidation behavior and mechanical properties of nanocrystalline composite HVOF coatings on SA 210 grade C material

Abstract The cyclic oxidation behavior of high velocity oxygen fuel (HVOF) sprayed nanocrystalline and conventional (27% Cr3C2–23% Ni-50% Cr) powder coatings on SA 210 Grade C boiler material was investigated in air at 900 °C for 50 cycles. The kinetics of oxidation has been developed with the help of weight change measurements for both the nanocrystalline and conventional coated specimens, and the results were compared with the bare boiler material. The coatings were characterized relative to coating thickness, porosity, microhardness, and microstructure. The oxidation products of the nanocrystalline, conventional coated, as well as bare boiler material, were analyzed using X-ray diffraction (XRD), elemental mapping techniques and scanning electron microscopy/ energy dispersive spectroscopic analysis (SEM/EDS). The characterization of the feedstock powder was performed using high resolution transmission electron microscope (HRTEM). The bare boiler material suffered during oxidation in the form of intense spalling and peeling of oxide scale from the surface, which may be due to the formation of unprotective oxide scale, Fe2O3. From the results, it was identified that both conventional and nanocrystalline coatings have better oxidation resistance compared to the bare material. However, the nanocrystalline coating was found to be more protective against oxidation. The grain boundary diffusion was improved in the nanocrystalline coating which promotes the creation of a denser scale of Cr2O3 with a higher rate, and also it helps to mitigate the Cr depletion at the metal/scale interface. The nanocrystalline coating was found to be superior to the conventional coating and reduced the weight gain of SA 210 Gr C steel by 98.76%. The protective Cr2O3 phase formed on the oxide scale was found to impart a better oxidation resistance. The low percentage of porosity in the nanocrystalline coating was observed to be favorable for anti-corrosion properties.

Laser Ablation-Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS) elemental mapping and its applications in ore geology

With the development of two-dimensional trace element mapping by laser-ablation inductively-coupled-plasma mass spectrometry (LA-ICP-MS), it is now possible to reveal in much greater detail any compositional interior textures of the pyrites, thus permitting the investigation of the history of pyrite crystals and providing new insight into the genesis and evolution of mineralisation. Exploiting the advantages of high spatial resolution, low detection limits, and capability of full quantification, LA-ICP-MS elemental mapping is being widely applied to imaging sulphides from various types of deposits. In this study, we applied the LA-ICP-MS elemental mapping technique on pyrites from different types of deposits from China and Canada, for the purpose of monitoring the changes of physio-chemical condition, defining ore genesis, and revealing the distribution patterns of precious metals. The interior compositional textures of pyrites show that the mineralization system of the Bayinwula roll-front U deposit in Inner Mongolia was open and continuously affected by the re-charge of oxidized groundwater, along with a periodic change of pH and Eh that affected the activities of sulphate bacteria and the associated U mineralization. The trace element maps of pyrites from the Zhenzigou Pb-Zn deposit in Liaoning Province indicate that several episodes of fluids were involved and responsible for the mineralisation, namely, an early stage of syn-sedimentary origin and a late hydrothermal mineralisation related to the Yanshanian magmatic activity. The trace element distribution patterns of pyrites from the Palaeoproterozoic placer Au deposit in Canada showed that the subeuhedral-euhedral pyrite, which is a dominant type of pyrite in the conglomerates, is detrital origin and later modified by hydrothermal (or metamorphic) fluids, and Au is mostly associated with the detrital pyrite grains/cores, and disseminated in the porosity on the surface.

The influence of skeletal micro-structures on potential proxy records in a bamboo coral

Assessing the physicochemical variability of the deeper ocean is currently hampered by limited instrumental time series and proxy records. Bamboo corals (Isididae) form a cosmopolitan family of calcitic deep sea corals that could fill this information gap via geochemical information recorded in their skeletons. Here we evaluate the suitability of high-resolution chemical imaging of bamboo coral skeletons for temperature and nutrient reconstruction. The applied elemental mapping techniques allow to verify the suitability of the chosen transect on the sample section for paleo-reconstructions and enhance the statistical precision of the reconstruction. We measured Mg/Ca via electron microprobe at 1 µm resolution and Ba/Ca via laser ablation ICP-MS at 35 µm resolution in a historic specimen of Keratoisis grayi from the Blake Plateau off Eastern Florida. Long-term growth temperatures of 7.1 ± 3.4 °C (± 2 SD) that are in agreement with recent ambient temperature range can be reconstructed from Mg/Ca ratios provided that anomalously Mg-enriched structural features around the central axis and isolated features related to tissue attachment are avoided for reconstruction. Skeletal Ba/Ca measurements reflect mean seawater barium [Ba]SW concentrations ([Ba]SW = 51 ± 24 nmol kg-1 (± 2 SD)), in agreement with instrumental data (47 nmol kg-1). We show for the first time that Ba/Ca forms concentric structures in a bamboo coral skeleton section. Our investigations suggest that, while bamboo coral skeletons do record environmental parameters in their mean chemical composition, the magnitude of environmental variability reconstructed from high-resolution chemical maps exceeds that expected from instrumental time series. This necessitates additional investigation of the factors driving bamboo coral skeletal composition.

Furfural oxidation to maleic acid with H2O2 by using vanadyl pyrophosphate and zirconium pyrophosphate supported on well-ordered mesoporous KIT-6

The improvement of catalytic technology in oxidation of organic compounds especially renewable resources to value-added compounds is currently extended. In this work, the well-ordered mesoporous structure of KIT-6 was synthesized. Then, a mixture of vanadyl pyrophosphate and zirconium pyrophosphate was successfully stabilized on KIT-6 scaffold and characterized using XRD, N2 adsorption/desorption, SEM/ EDX/ elemental mapping, TEM, ICP-AES, FT-IR and Raman spectroscopic techniques. The activity of catalysts was examined on the oxidation reaction of furfural to maleic acid using H2O2. In order to improve the reaction conditions and maleic acid yield over vanadium and zirconium supported on KIT-6, furfural oxidation was performed in the presence of 0.25 Zr/V ratio-loading at 70 °C with 3:1 (H2O2: furfural mole ratio), in acetonitrile as the solvent. Under these reaction conditions, 81.2% furfural conversion and 29.2% maleic acid yield were observed after one hour reaction time. Finally, the stability and reusability of the catalysts were evaluated in several consecutive times under optimum reaction conditions.