This paper describes natural garlic oil (NGO) as a high-performance, environmentally friendly, extreme pressure additive for lubricating oils. The chemical composition of NGO was analyzed by gas chromatography–mass spectrometry (GC-MS). The load-carrying capacities of NGO and sulfurized isobutylene (SIB) in different base fluids were comparatively evaluated by a four-ball tester and an optimol SRV-IV oscillating reciprocating friction and wear tester (SRV tester). The four-ball test results revealed that incorporation of 1 wt % NGO into the base fluids could significantly improve the weld point of the base fluids from approximately 126 to 800 kgf or higher. Moreover, the four-ball test and SRV test results demonstrated that NGO could provide superior load-carrying ability in the selected base fluids than the conventional extreme pressure additive SIB. In addition, X-ray photoelectron spectroscopy (XPS) results showed that NGO and SIB experienced a similar tribochemical process with the generation of tribofilms composed with iron oxides, iron sulfates, iron sulfide, etc. NGO showed great promise for use as an effective, eco-friendly, extreme pressure additive for application in environmentally sensitive areas.

No abstract

No abstract

This paper describes 3-(3,5-di-tert-butyl-4-hydroxy-phenyl)-propionic acid 2-(4-meth yl-thiazol-5-yl)-ethyl ester (BHMT) as a high-performance multifunctional additive in lithium complex grease (LCG). The tribological properties and antioxidant behaviors of BHMT were evaluated by tribological test and thermal analysis respectively, and compared with those of zinc dialkyldithiophosphate (ZDDP). The tribochemical film BHMT generated on the worn surface was analyzed by X-ray photoelectron spectroscopy (XPS). Tribological results indicated that BHMT exhibited better friction-reduction and antiwear properties than ZDDP. The thermal analysis demonstrated that the anti-oxidation ability of BHMT was superior to that of ZDDP.Moreover, XPS results showed that lubrication film composed of iron oxide, iron sulfate and nitrogen oxide was formed on the worn surface, which was an explicit explanation of the tribochemical mechanism of BHMT.

A catalyst-free and transition-metal-free method for the synthesis of 1,2-diketones from aerobic alkyne oxidation was reported. The oxidation of various internal alkynes, especially more challenging aryl-alkyl acetylenes, proceeded smoothly with inexpensive, easily handled, and commercially available potassium persulfate and an ambient air balloon, achieving the corresponding 1,2-diketones with up to 85% yields. Meanwhile, mechanistic studies indicated a radical process, and the two oxygen atoms in the 1,2-diketons were most likely from persulfate salts and molecular oxygen, respectively, rather than water.

Osteoarthritis (OA) is associated with lubrication failure of articular cartilage and severe inflammatory response of joint capsule. Synergistic therapy combining joint lubrication and anti-inflammation emerges as a novel treatment of OA. In this study, bioinspired by ultralow friction of natural articular synovial fluid and mussel adhesion chemistry, a biomimetic nanosystem with dual functions of enhanced lubrication and stimuli-responsive drug release is developed. A dopamine mediated strategy realizes one step biomimetic grafting of hyaluronic acid (HA) on fluorinated graphene. The polymer modified sheets exhibit highly efficient near-infrared absorption, and show steady lubrication with a long time under various working conditions, in which the coefficient of friction is reduced by 75% compared to H 2 O. Diclofenac sodium (DS) with a high loading capacity of 29.2% is controllably loaded, and responsive and sustained drug release is adjusted by near-infrared light. Cell experiments reveal that the lubricating nanosystem is taken up by endocytosis, and anti-inflammation results confirm that the nanosystem inhibits osteoarthritis deterioration by upregulating cartilage anabolic gene and downregulating catabolic proteases and pain-related gene. This work proposes a promising biomimetic approach to integrate polymer modified fluorinated graphene as a dual-functional nanosystem for effective synergistic therapy of OA.

No abstract

A novel oil‐soluble arylamine antioxidant N1,N2‐diphenylethane‐1,2‐diamine (ND) was successfully synthesized, and the potential antioxidant behavior of which had never been reported before. The structure of ND was characterized via nuclear magnetic resonance (1H NMR, 13C NMR) and electron ionization mass spectrometry. The antioxidant performance of ND and its synergistic effect with 2,6‐di‐tert‐butyl‐4‐methylphenol (BHT) in di‐2‐ethylhexyl sebacate were evaluated by pressurized differential scanning calorimetry, thermogravimetry analysis, and hot oil oxidation test. All the results indicated that the synthesized antioxidant ND exhibited outstanding antioxidant performance and showed prominent synergistic effect with BHT in ester base oil. Furthermore, the probable synergistic anti‐oxidative effect between ND and BHT was discussed, which was mainly induced by the formation of a fresh BHT radical and the regeneration of ND antioxidant.