Nickel‒cobalt bimetallic catalysts prepared from hydrotalcite-like compounds for dry reforming of methane

Ni–Co/Mg(Al)O alloy catalysts with different Co/Ni molar ratios have been prepared from Ni- and Co-substituted Mg–Al hydrotalcite-like compounds (HTlcs) as precursors and tested for dry reforming of methane. The XRD characterization shows that Ni–Co–Mg–Al HTlcs are decomposed by calcination into Mg(Ni,Co,Al)O solid solution, and by reduction finely dispersed alloy particles are formed. H₂-TPR indicates a strong interaction between nickel/cobalt oxides and magnesia, and the presence of cobalt in Mg(Ni,Co,Al)O enhances the metal-support interaction. STEM-EDX analysis reveals that nickel and cobalt cations are homogeneously distributed in the HTlcs precursor and in the derived solid solution, and by reduction the resulting Ni–Co alloy particles are composition-uniform. The Ni–Co/Mg(Al)O alloy catalysts exhibit relatively high activity and stability at severe conditions, i.e., a medium temperature of 600 °C and a high space velocity of 120000 mL g^?1 h^?1. In comparison to monometallic Ni catalyst, Ni–Co alloying effectively inhibits methane decomposition and coke deposition, leading to a marked enhancement of catalytic stability. From CO₂-TPD and TPSR, it is suggested that alloying Ni with Co favors the CO₂ adsorption/activation and promotes the elimination of carbon species, thus improving the coke resistance. Furthermore, a high and stable activity with low coking is demonstrated at 750 °C. The hydrotalcite-derived Ni–Co/Mg(Al)O catalysts show better catalytic performance than many of the reported Ni–Co catalysts, which can be attributed to the formation of Ni–Co alloy with uniform composition, proper size, and strong metal-support interaction as well as the presence of basic Mg(Al)O as support.     

Ocular conditions and dry eye due to traditional and new forms of smoking: A review

Addiction to cigarette smoking has high prevalence rates recorded worldwide. Smoking has been linked to several life-threatening systemic conditions such as cancer, heart attack and stroke, in addition to a range of ocular pathologies. In recent years, electronic cigarettes (EC) have emerged as alternatives to smoking. ECs are nicotine delivery devices which produce an aerosol by heating, rather than combusting, a liquid which contains nicotine, flavours and preservatives. This review focuses on the association of traditional and new forms of smoking with dry eye disease, contact lens wear and four other common ocular diseases: cataract, age-related macular degeneration, glaucoma and Graves’ ophthalmopathy. It is concluded that smoking and vaping appear as a risk factor for the aforementioned ocular conditions. An evidence-based, clear link between cigarette smoking, or EC vaping and ocular problems is yet to be discovered.     

Solvent fractionation of hard palm stearin to increase the concentration of tripalmitoylglycerol and dipalmitoyl-stearoyl-glycerol as substrates for synthesis of human milk fat substitute

This research aimed to produce triacylglycerols fraction rich in palmitic acid (PA) at the sn-2 position from hard palm stearin (HPS) through acetone fractionation. Fractionations were done at HPS-to-acetone ratios of 1:3, 1:5 and 1:7 (w/v) and at temperatures of 25, 30 and 35 °C for 3 h. Triacylglycerols with PA at the sn-2 position, such as tripalmitoylglycerol (PPP) and dipalmitoyl-stearoyl-glycerol (PPS), were concentrated in the solid fraction, obtained after separation by filtration. The optimal fractionation conditions were at a HPS-to-acetone ratio of 1:5 (w/v) and 30 °C. The total PPP and PPS content was more than 91%, with a corresponding yield of more than 59%. Triacylglycerols obtained were composed of more than 91% PA in which 88% were at the sn-2 position. Conclusively, the solvent fractionation is a suited alternative method for the preparation of triacylglycerols used for the enzymatic synthesis of 1,3-dioleoyl-2-palmitoylglycerol which is the main triacylglycerol for human milk fat substitute.     

Quantitative UPLC‐MS/MS analysis of chlorogenic acid derivatives in antioxidant fractionates from dandelion (Taraxacum officinale) root

While qualitative studies have identified chlorogenic acids in antioxidant extracts, particularly ethyl acetate‐derived extracts, of Taraxacum officinale, quantitative analysis of these phenolic compounds remains largely unreported for this species. In this study, bioactivity‐guided fractionation of an antioxidant crude ethyl acetate extract (DPPH = 295.481 ± 0.955 mg TE g^?1 extract) from T. officinale root resulted in a number of reverse‐phase fractions that demonstrated high antioxidant activity (DPPH = 1058.733–1312.136 mg TE g^?1 extract), stronger than that of the synthetic antioxidant Trolox^®. UPLC‐MS/MS screening of these fractions for the presence of selected mono‐ and di‐caffeoylquinic acids revealed large quantities of 1,5‐dicaffeoylquinic acid present in several fractions (853.052–907.324 μg mg^?1), respectively. Due to the antioxidant potency and high levels of 1,5‐dicaffeoylquinic acid observed in these fractions, it was concluded that specifically this chlorogenic acid derivative is a major contributor to the antioxidant efficacy of dandelion root.     

A design of experiments investigation into dry separation using a Knelson Concentrator

Enhanced gravity, or centrifugal, separators have revolutionised gold processing over the past decades, significantly increasing the recovery of fine (−100 μm) free gold. One of the main drawbacks of centrifugal gravity concentrators is the large volume of water required (even if it is all recycled). With water becoming an ever increasingly important “commodity”, reducing this is of importance both from an environmental and a monetary point of view. This work investigated operating a laboratory scale Knelson Concentrator with a dry feed and using air as the fluidising medium. The feed used was a synthetic mixture of tungsten and quartz, used to mimic a gold ore. The response surface method and central composite design techniques were used to design the experiments and to model the results, with the experimental variables being the bowl speed (G-Level), air fluidising pressure and the feed rate. The models corresponded well to the experimental results, indicating that for this experimental setup, the optimal conditions were a bowl G-Level of 40 G, a feed rate of 220 g/min and an air fluidising pressure of 8 psi.     

Intramolecular crosslinking of poly(vinyl alcohol)

Poly(vinyl alcohol) is crosslinked in dilute solution (c=0.1 wt%) with glutaraldehyde. The reaction product is characterized by viscometry and gel permeation chromatography (g.p.c.). The intrinsic viscosity decreases with increasing degree of crosslinking and does not depend on temperature. G.p.c. reveals that the reaction product is not homogeneous, but consists of a mixture of particles with different sizes, possibly both intra- and intermolecularly crosslinked molecules. The intramolecularly crosslinked molecules are smaller in size than the initial polymer molecules and their size depends on the degree of crosslinking. They possess a narrow particle size distribution even if the initial polymer sample had a broad molecular weight distribution.