Effects of Fiber Type on the Mechanical Properties of the Open-Graded Friction Course Mixture.

The open-graded friction courses (OGFCs) have a large number of interconnected voids, which may cause serious water damage to the pavement. Hence, the road performance needs to be investigated. In this study, the mechanical properties of OGFCs containing two different fibers (lignin and mineral fiber) were investigated. Based on the procedure proposed by the Chinese specification JTG F40-2004, OGFCs were designed with the asphalt content between 4.1 and 4.7 wt % to find the optimal asphalt content (OAC). The mesh-basket draindown test was used to check the fiber's stabilization and absorption of bitumen. OGFCs containing the lignin/mineral fiber with OAC would be preferred in terms of the bulk specific gravity. These results indicate that the fiber can bring higher air voids to the OGFCs, and the different specific gravities of fibers may primarily account for the result. Both the lignin and mineral fibers can bring much more asphalts padded in the pores of mineral aggregates and subsequently larger OAC in OGFCs due to their higher asphalt absorption. Performance experiments were carried out to check the dynamic stability and moisture susceptibility of OGFCs containing the lignin/mineral fiber. The study suggests that the lignin and mineral fiber can be used to adjust the internal environment of OGFCs, enhancing the moisture damage resistance and improving the rutting resistance of OGFCs at high temperatures.

Photomediated Spirocyclization of N-Benzyl Propiolamide with N-Iodosuccinimide for Access to Azaspiro[4.5]deca-6,9-diene-3,8-dione.

A metal- and oxidant-free route for affording azaspiro[4.5]deca-6,9-diene-3,8-dione via photomediated iodinated spirocyclization of N-(4-methoxybenzyl) propiolamide has been developed. The reaction underwent a radical addition/ipso-cyclization/dearomatization process at room temperature and successfully constructed C-C and C-I bonds. This green and convenient approach could be generally expanded to produce a range of iodinated spirocyclization products in moderate to good yields.

Continuous-flow electrosynthesis of selenium-substituted iminoisobenzofuran via oxidative cyclization of olefinic amides and diselenides.

A green and efficient approach for the synthesis of selenium-substituted iminoisobenzofuran using 2-vinylbenzamides and diselenides in a continuous electrochemical microreactor has been developed. This strategy enabled the preparation of a series of iminoisobenzofuran derivatives in moderate to good yields under metal-free and oxidant-free conditions. The application of the electrochemical flow system successfully overcomes the difficulty of process control in traditional electrochemistry and achieves efficient transformation of electricity. Moreover, the continuous-flow system combined with electrosynthesis overcomes the difficulty in realizing a scale-up reaction in conventional batch-type electrolysis.

Electrochemical Synthesis of Spiro[4.5]trienones through Radical-Initiated Dearomative Spirocyclization.

A novel and green route has been developed for the electrochemical synthesis of spiro[4.5]trienones through radical-initiated dearomative spirocyclization of alkynes with diselenides. This metal-free and oxidant-free electrosynthesis reaction was performed in an undivided cell under mild conditions. A variety of selenation spiro[4.5]trienones products were prepared in moderate-to-good yields, showing a broad scope and functional group tolerance. Moreover, the developed continuous-flow system combined with electrosynthesis possesses the potential to achieve scaled-up reactions, overcoming the low efficiency of conventional electrochemical scaled-up reactions.