20 research outputs found

    Catalytic <i>In Situ</i> Hydrogenation of Fatty Acids into Fatty Alcohols over Cu-Based Catalysts with Methanol in Hydrothermal Media

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    The catalytic hydrogenation of fatty acids has witnessed rapid development in recent years. However, the conventional hydrogenation process often requires high-pressure hydrogen. This paper describes a novel protocol to produce fatty alcohols via an <i>in situ</i> hydrogenation of fatty acids in water and methanol using Cu-based catalysts. Cu/ZrO<sub>2</sub>, Cu/MgO, and Cu/Al<sub>2</sub>O<sub>3</sub> were prepared by the co-precipitation method. All Cu-based catalysts exhibited excellent activity for <i>in situ</i> hydrogenation of fatty acids, and the stability of Cu/ZrO<sub>2</sub> was the best. The structures and properties of Cu-based catalysts are demonstrated by transmission electron microscopy, X-ray diffraction, H<sub>2</sub> temperature-programmed reduction, N<sub>2</sub> adsorption–desorption, CO temperature-programmed desorption, and CO<sub>2</sub> temperature-programmed desorption. The stability of Cu/ZrO<sub>2</sub> is caused by the good hydrothermal stability and tetragonal phase formation of ZrO<sub>2</sub>, which strongly binds to active Cu. The better activity over Cu/Al<sub>2</sub>O<sub>3</sub> is caused by the larger surface area, higher Cu dispersion, smaller Cu particle size, and stronger basicity of Cu/Al<sub>2</sub>O<sub>3</sub>. Furthermore, the effects of the reaction time, catalyst loading, methanol loading, carbon number, and types of hydrogen donor on <i>in situ</i> hydrogenation of the fatty acids were investigated to demonstrate the reaction behaviors

    Data_Sheet_1_One-pot biosynthesis of N-acetylneuraminic acid from chitin via combination of chitin-degrading enzymes, N-acetylglucosamine-2-epimerase, and N-neuraminic acid aldolase.docx

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    N-acetylneuraminic acid (Neu5Ac) possesses the ability to promote mental health and enhance immunity and is widely used in both medicine and food fields as a supplement. Enzymatic production of Neu5Ac using N-acetyl-D-glucosamine (GlcNAc) as substrate was significant. However, the high-cost GlcNAc limited its development. In this study, an in vitro multi-enzyme catalysis was built to produce Neu5Ac using affordable chitin as substrate. Firstly, exochitinase SmChiA from Serratia proteamaculans and N-acetylglucosaminosidase CmNAGase from Chitinolyticbacter meiyuanensis SYBC-H1 were screened and combined to produce GlcNAc, effectively. Then, the chitinase was cascaded with N-acetylglucosamine-2-epimerase (AGE) and N-neuraminic acid aldolase (NanA) to produce Neu5Ac; the optimal conditions of the multi-enzyme catalysis system were 37°C and pH 8.5, the ratio of AGE to NanA (1:4) and addition of pyruvate (70 mM), respectively. Finally, 9.2 g/L Neu5Ac could be obtained from 20 g/L chitin within 24 h along with two supplementations with pyruvate. This work will lay a good foundation for the production of Neu5Ac from cheap chitin resources.</p

    Catalytic Decarboxylation and Aromatization of Oleic Acid over Ni/AC without an Added Hydrogen Donor

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    Ni/AC (nickel on active carbon) catalysts with different Ni loadings were synthesized and studied for the decarboxylation and aromatization of oleic acid in the absence of H<sub>2</sub> or hydrogen donors. Without the use of hydrogen source, the whole deoxygenation process became more economical. Moreover, oleic acid can be saturated using the H<sub>2</sub> derived from the production of aromatics, which were also considered as the critical component in aviation biofuels. The structure and properties of the catalysts were investigated using X-ray diffraction, transmission electron microscopy, and temperature-programmed desorption of CH<sub>3</sub>COOH and CO. The experimental and characterization results revealed that 30% Ni/AC had a higher adsorption capacity of CH<sub>3</sub>COOH among the other Ni/AC catalysts and highly dispersed and small Ni particles, providing a heptadecane yield of 40.7%. It also contained 13.8% aromatics, which fulfills the requirement of aviation fuels. This Ni/AC catalyst showed good stability even after being reused thrice

    Targeted delivery of microRNA 146b mimic to hepatocytes by lactosylated PDMAEMA nanoparticles for the treatment of NAFLD

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    <p>Non-alcoholic fatty liver disease (NAFLD) is one of the most common chronic liver diseases worldwide, and precision therapeutic will be a benefit for the NAFLD regression. In this study, we observed low microRNA 146 b (miR-146 b) expression in NAFLD mice model induced by methionine–choline-deficient diet (MCD) compared with control group. Furthermore, miR-146b<sup>−/−</sup> mice induced MCD exhibited severe liver steatosis and hepatitis. A bio-distribution study showed that novel Lactosylated PDMAEMA nanoparticles effectively targeted hepatocytes Lac-PDMAEMA. We coupled miR-146b mimic with Lac-PDMAEMA and then were administrated to NAFLD mice model, which could obviously alleviate the hepatic steatosis. Lac-PDMAEMA effectively delivered miR-146b mimic to hepatocytes with a ∼8-fold upregulation of miR-146b mimic targeting MyD88 and IRAK1, and in turn suppressed the expression of PPARγ. Meanwhile, TNF-α and IL-6 mRNA levels were decreased after administration of Lac-PDMAEMA/miR-146b mimic. So, we made a conclusion that targeted delivering miR-146b mimic to the hepatocytes by, coupling Lac-PDMAEMA nanoparticles could effectively alleviate the hepatic steatosis in NAFLD mice, which maybe bring a new and effective way to intervene and therapy the NAFLD.</p

    Role of Solvent in Catalytic Conversion of Oleic Acid to Aviation Biofuels

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    The role of solvents in the conversion of oleic acid over Pt/C was studied. Three solvent systems (solvent-free, water, and dodecane systems) were employed for the conversion of oleic acid over Pt/C at 350 °C. Decarboxylation, hydrogen transfer, and aromatization were observed in these three reaction systems. In comparison to the non-solvent reaction system, much slower decarboxylation and aromatization rates and fewer heptadecane and aromatic products were observed in the hydrothermal and dodecane reaction systems. The decarboxylation and aromatization rates and yields of heptadecane and aromatics decreased with increased dodecane loading in the dodecane reaction system, and the decarboxylation and aromatization rates and yields of heptadecane and aromatics significantly decreased with the increase of water in the hydrothermal reaction system. The effects of solvent loading, catalyst loading, and reaction time on the reactions (decarboxylation, hydrogen transfer, and aromatization) were investigated. The reaction behaviors of 1-heptadecene with different solvents were studied, and N<sub>2</sub> adsorption–desorption and thermogravimetric analysis of fresh and spent Pt/C in the three reaction systems were also performed. The results indicate that the competition of dodecane for the Pt/C active sites is mainly responsible for the slow decarboxylation and aromatization rates. In addition to the similar influencing factor to that in the dodecane system, H<sup>+</sup> released from water and hydrogen bonding, which inhibited the ionization of carboxyl groups, was the key influencing factor for the slower decarboxylation and aromatization rates obtained under hydrothermal conditions
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