Atomic Structure of Pd-, Pt-, and PdPt-Based Catalysts of Total Oxidation of Methane: In Situ EXAFS Study

In this study, 3%Pd/Al2O3, 3%Pt/Al2O3 and bimetallic (1%Pd + 2%Pt)/Al2O3 catalysts were examined in the total oxidation of methane in a temperature range of 150–400 °C. The evolution of the active component under the reaction conditions was studied by transmission electron microscopy and in situ extended X-ray absorption fine structure (EXAFS) spectroscopy. It was found that the platinum and bimetallic palladium-platinum catalysts are more stable against sintering than the palladium catalysts. For all the catalysts, the active component forms a “core-shell” structure in which the metallic core is covered by an oxide shell. The “core-shell” structure for the platinum and bimetallic palladium-platinum catalysts is stable in the temperature range of 150–400 °C. However, in the case of the palladium catalysts the metallic core undergoes the reversible oxidation at temperatures above 300 °C and reduced to the metallic state with the decrease in the reaction temperature. The scheme of the active component evolution during the oxidation of methane is proposed and discussed.

DESIGNING OF NANOCOMPOSITE MODEL STRUCTURE USING GLYCITEIN AND GENISTEIN WITH TWELVE DIFFERENT METAL ATOMS USING IN SILICO METHOD

Nanocomposite formulation is still in its evolving state. However due to its significant therapeutic applications it has grabbed the attention of many researchers. Isoflavonewhich is widely found in soy products have tremendous medicinal propertieswhen it interacts with nanoparticles can become a boon. Hence in this study, we are reporting the interaction properties/patterns of two ubiquitous flavones namelyGlycitein and Genistein forming a nanocomposite model with 12 different metals such as Gold, Silver, Palladium, Platinum, Ruthenium, Rhodium, Cadmium, Iron, Nickel, Zinc, Copper and Antimony based ontheir potency to form nanoparticles. To mimic the Nanocomposite, model the formulation was conducted in Avogadro Software for windows. Glycitein and Genistein create a possibility of selecting the most suitable -OH position that would serve as the binding site. On selection of the appropriate binding site the interaction amid two molecules of glycitein and genistein placed sidewise held together by above-mentioned metals also surrounded by the same metal on another vacant -OH position forming a close saturated structure subjected for interaction. Based on predominantly energy levels the least energy obtained model was Cadmium and the peak procured by Antimony making it least stable and unfavorable for the perceived result.

CATALYST PROCESSING AND RECYCLING

Discussed auto catalysts contain interesting quantities of platinum noble metals, palladium and rhodium according to the type of auto catalyst, thereby becoming a possible source of these metal aims to acquaint themselves with catalysts in general, their history and last but not least the possibilities of processing and obtaining noble metals for further use. The article deals with knowledge at the theoretical level of use of methods in processing depleted catalysts. It is pyrometallurgical and hydrometallurgical methods. The platinum group metals (PGMs) palladium, platinum, and rhodium represent the key materials for automotive exhaust gas treatment. Since there are currently no adequate alternatives, the importance of these metals for the automotive industry is steadily rising. The high value of PGMs in spent catalysts justifies their recycling. The state-of the-art technology is to melt the ceramic carrier and collect the precious fraction in a liquid metal bath. As the feed material has quite high melting points, huge amounts of energy are required for this process. Hydrometallurgical treatments of the spent catalysts offer the possibility to recycle the PGMs with less energy and time demands. Moreover, automotive catalysts contain further valuable materials to improve the exhaust gas treatment. These compounds, like cerium oxide, cannot be recovered in pyrometallurgical processes.

Metal–Curcumin Complexes in Therapeutics: An Approach to Enhance Pharmacological Effects of Curcumin

Curcumin, an active component of the rhizome turmeric, has gained much attention as a plant-based compound with pleiotropic pharmacological properties. It possesses anti-inflammatory, antioxidant, hypoglycemic, antimicrobial, neuroprotective, and immunomodulatory activities. However, the health-promoting utility of curcumin is constrained due to its hydrophobic nature, water insolubility, poor bioavailability, rapid metabolism, and systemic elimination. Therefore, an innovative stride was taken, and complexes of metals with curcumin have been synthesized. Curcumin usually reacts with metals through the β-diketone moiety to generate metal–curcumin complexes. It is well established that curcumin strongly chelates several metal ions, including boron, cobalt, copper, gallium, gadolinium, gold, lanthanum, manganese, nickel, iron, palladium, platinum, ruthenium, silver, vanadium, and zinc. In this review, the pharmacological, chemopreventive, and therapeutic activities of metal–curcumin complexes are discussed. Metal–curcumin complexes increase the solubility, cellular uptake, and bioavailability and improve the antioxidant, anti-inflammatory, antimicrobial, and antiviral effects of curcumin. Metal–curcumin complexes have also demonstrated efficacy against various chronic diseases, including cancer, arthritis, osteoporosis, and neurological disorders such as Alzheimer’s disease. These biological activities of metal–curcumin complexes were associated with the modulation of inflammatory mediators, transcription factors, protein kinases, antiapoptotic proteins, lipid peroxidation, and antioxidant enzymes. In addition, metal–curcumin complexes have shown usefulness in biological imaging and radioimaging. The future use of metal–curcumin complexes may represent a new approach in the prevention and treatment of chronic diseases.

The establishment of an immunosensor for the detection of SPOP

In this paper, we first synthesis three-dimensional jasmine-like Cu@L-aspartic acid(L-ASP) inorganic–organic hybrid nanoflowers to load palladium-platinum nanoparticles (Pd–Pt NPs) as the signal enhancer in order to quantify intracellular speckle-type POZ domain protein. Scanning electron microscope, fourier transform infrared, energy dispersive spectrometer, X-ray photoelectron spectroscopy analysis was used to characterize the newly synthesized materials. The newly formed Cu@L-Asp/Pd-PtNPs can catalyze the decomposition of hydrogen peroxide and exhibit excellent catalytic performance. When different concentration of speckle-type POZ domain protein is captured by speckle-type POZ domain protein antibody linked to the surface of Cu@L-Asp/Pd–Pt NPs, the current signal decreases with the increase concentration of speckle-type POZ domain protein. After optimization, the speckle-type POZ domain protein immunosensor exhibited a good linear response over a concentration range from 0.1–1 ng mL−1 with a low detection limit of 19 fg mL−1. The proposed sensor demonstrates good stability within 28 days, acceptable reproducibility (RSD = 0.52%) and selectivity to the speckle-type POZ domain protein in the presence of possible interfering substances and has potential application for detecting other intracellular macromolecular substances.

Chlorodifluoromethane Hydrodechlorination on Carbon-Supported Pd-Pt Catalysts. Beneficial Effect of Catalyst Oxidation

Previously tested 2 wt % palladium-platinum catalysts supported on Norit activated carbon preheated to 1600 °C have been reinvestigated in CHFCl2 hydrodechlorination. An additionally adopted catalyst oxidation at 350–400 °C produced nearly an order of magnitude increase in the turnover frequency of Pd/C, from 4.1 × 10−4 to 2.63 × 10−3 s−1. This increase is not caused by changes in metal dispersion or possible decontamination of the Pd surface from superficial carbon, but rather by unlocking the active surface, originally inaccessible in metal particles tightly packed in the pores of carbon. Burning carbon from the pore walls attached to the metal changes the pore structure, providing easier access for the reactants to the entire palladium surface. Calcination of Pt/C and Pd-Pt/C catalysts results in much smaller evolution of catalytic activity than that observed for Pd/C. This shapes the relationship between turnover frequency (TOF) and alloy composition, which now does not confirm the Pd-Pt synergy invoked in the previous work. The absence of this synergy is confirmed by gradual regular changes in product selectivity, from 70 to 80% towards CH2F2 for Pd/C to almost 60% towards CH4 for Pt/C. The use of even higher-preheated carbon (1800 °C), completely free of micropores, results in a Pd/C catalyst that does not need to be oxidized to achieve high activity and excellent selectivity to CH2F2 (>90%).

An Immunosensor for the Detection of Speckle-type Poz Domain Protein Based on Pioneering Jasmine-like Cu@l-asp Hybrid Nanoflowers and Palladium-platinum Nanoparticles.

In this paper, we first synthesis three-dimensional(3D) jasmine-like Cu@L-Asp inorganic-organic hybrid nanoflowers to load palladium-platinum nanoparticles as the signal enhancer in order to quantify intracellular speckle-type POZ domain protein (SPOP). Scanning electron microscope (SEM), fourier transform infrared (FT-IR), energy dispersive spectrometer (EDS), X-ray photoelectron spectroscopy (XPS) analysis was used to characterize the newly synthesized materials. The newly formed Cu@L-Asp/Pd-PtNPs can catalyze the decomposition of hydrogen peroxide and exhibit excellent catalytic performance. When different concentration of SPOP is captured by SPOP antibody linked to the surface of Cu@L-Asp/Pd-Pt NPs, the current signal decreases with the increase concentration of SPOP. After optimization, the SPOP immunosensor exhibited a good linear response over a concentration range from 0.1 pg mL-1-1 ng mL-1. The proposed sensor demonstrates good stability, acceptable reproducibility and excellent selectivity to the SPOP in the presence of possible interfering substances and has great potential application for detecting other intracellular macromolecular substances.

Unallocated Metal Accounts in Russia: Determinants of Quoted Bid-Ask Spreads

Due to economic instability there has been an increase in demand for unallocated metal accounts offered by Russian commercial banks since April 2020. Although opening unallocated metal accounts gives banks an opportunity to expand the range of their products, diversify income, attract new clients and retain old ones, most Russian banks do not provide such services. For those, it is important to understand the determinants of bid-ask spreads (the difference between the quoted metal bid and ask prices), since the demand for unallocated metal accounts and the bank’s income from this service depend on the bid-ask spread. The purpose of this paper is to investigate the main determinants of quoted bid-ask spreads on unallocated metal accounts in commercial banks. Multiple regression models are applied for the period from October 2017 to May 2020. There are very few articles on the determinants of quoted bid-ask spreads on unallocated metal accounts; for this reason the paper is based on the results of studies of bid-ask spreads in other markets. Based on recent theoretical results, which indicate that bid-ask spreads depend on price volatility, we confirm this hypothesis on unallocated metal accounts. Moreover, we reveal that banks’ assets and the share of state participation influence bid-ask spreads on unallocated metal accounts in commercial banks. It is also proven that bid-ask spreads for unallocated metal accounts in gold are, on average, lower than those for palladium, platinum and silver.