Search

Sargassum fusiforme polysaccharide (SFP) was extracted from Sargassum fusiforme by hot water boiling, concentration and ethanol precipitation. The composition was determined as 58.10 ± 2.12% carbohydrate, 1.01 ± 0.15% protein, 9.85 ± 0.96% sulfate group and 17.66 ± 0.54% glucuronic acid. The average molecular weight of SFP was 224 kDa. The monosaccharide composition of SFP was 43.2% L-fucose, 3.5% rhamnose, 18.4% galactose, 1.5% glucose, 18.5% fructose, 5.9% xylose and 9.0% mannose respectively. SFP showed significant protective effect against ultraviolet B (UVB) radiation in hairless Kun Ming (KM) mice by manipulating the skin water content and thymus and spleen indexes. SFP could also alleviate UVB-induced oxidative stress by enhancing the activities of superoxide dismutase (SOD) and catalase (CAT) and reducing the levels of reactive oxygen species (ROS) and malondialdehyde (MDA) equivalents. The levels of matrix metalloproteinase (MMP)-1 and 9 were also suppressed in SFP treatments. These findings suggest that SFP could be used as a potential functional food supplement for skin protection. [ABSTRACT FROM AUTHOR]

In this study, Sargassum fusiforme polysaccharide was purified using a DEAE-Sepharose fast-flow column to obtain Sargassum fusiforme polysaccharides fraction (SFP-P1). As expected, the SFP-P1 contains mainly carbohydrates (87%) with less than 1% protein. Within the carbohydrate, it contains about 10% sulfate and 18% uronic acids. SFP-P1 consisted of l -fucose (13.17%), galactose (4.28%), glucose (1.95%), xylose (5.50%), and mannose (75.10%) with an average molecular weight of 113 kDa. Mannose and l -fucose were two predominant monosaccharides. In addition, (1 → )-linked or (1 → 6)-linked, (1 → 2)-linked or (1 → 4)-linked and (1 → 3)-linked glycosyl linkages accounted for 1.62%, 60.69% and 37.69% of all linkages in the molecule, respectively. The glycosidic linkage types of SFP-P1 were proven to be → 3,6)-α- d -Man p (1 →, → 4)-α- d -GalA p (1 →, → 4)-β- d -Xyl p (1 → and → 3,4)-α- d -GlcA p (1 →. The results indicated the SFP-P1 had cytoprotective activity against UVB-induced oxidative stress in HaCaT cells through stimulation of SOD, GSH-P X enzymes activities and ROS. Also SFP-P1 suppressed the UVB-induced expression of MMP-1 & MMP-9. [ABSTRACT FROM AUTHOR]

Abstract: Roller chain drive is widely used in timing mechanism of gasoline engine. However, its polygonal action and meshing impact effect resulted from the non-conjugated meshing feature may damage the synchronization and uniformity of transmission. In this paper, new sprocket tooth profile is developed to reduce polygonal action and meshing impact under high speed. A new conjugated profile is derived by modifying involute profile to guarantee that the moving distance of chain is equal to the arc length of pitch circle that a sprocket rotates at the same time and the center line of chain at tight side is always tangent to the pitch circle. An asymmetrical modification method for sprocket tooth profile is also proposed. A multi-body dynamic model of the timing mechanism of a gasoline engine with the intake and exhaust sprockets is developed. The fluctuation and meshing impact of the chain are analyzed under different rotational speeds. The results show that newly developed sprocket profile can efficiently reduce meshing impact and friction of chain. The stability of chain transmission under high speed can be improved. [Copyright &y& Elsevier]

[Display omitted] • The synthesis of Acifluorfen by continuous flow nitration was performed within droplet-based microreactor. • The effects of operating parameters were characterized by hydrodynamics and thermodynamics. • The apparent and intrinsic kinetic model was established. Aromatic nitration still faces unmet technical challenges in relation to being heterogeneous and highly exothermic. In this work, a continuous flow aromatic nitration was developed with mixed acid within droplet-based microreactors. The effects of key operating parameters were characterized on the nitration of 3-[2-chloro-4-(trifluoromethyl)phenoxy] benzoic acid. The optimized reaction temperature, M-ratio and N/S were found to be 308 K, 1.6 and 0.57, respectively. Under these conditions, a conversion of 83.03% and selectivity of 79.52% were achieved. The addition of acetic anhydride improved both the solubility of etherate in the organic phase and the absorbability of water produced from the reaction, leading to increase in conversion, however increased by-products accordingly with reduced selectivity. Pseudo-homogeneous kinetics models were developed of apparent and intrinsic reaction rate constant, supporting the second-order reaction assumption. The calculated results based on the kinetics model were found to be in good agreement with the experimental results. [ABSTRACT FROM AUTHOR]