(A, B, C, D) 5:1, (E, F, G, H) 2:1, (I, J, K, L) 1:1, (M, N, O, P) 1:2, and (Q, R, S, T) 1:5, v/v. The solutions were electrospun under the lowest applied voltage. RH 60%, collecting distance 15 cm, feeding rate 1.5 ml/h, and applied voltage 5 kV. Table 1 Summary of the typical morphologies of the droplets and fibers

THF/DMF ratio Droplet Coarse fiber Finer fiber Fibers 5:1 Porous Grooved Grooved Single grooved 2:1 Smooth Single grooved Single grooved Single grooved 1:1 Smooth Wrinkled Grooved Grooved 1:2 Smooth Smooth Smooth Smooth 1:5 Porous Smooth Smooth Smooth When THF/DMF ratio was 1:1, no voids were found on the droplet surface and the coarse fiber MK0683 at the connection appeared as a wrinkled

surface, which resulted in a grooved texture at the end of the coarse fiber. In this case, we should attribute the formation of grooved texture to the wrinkled surface formed on the initial jet. When THF/DMF ratio was 1:2, both droplets and fibers had a smooth surface. Further reducing the ratio to 1:5, fibers having a smooth surface were observed, even though the droplet showed a porous surface. To further investigate the formation mechanism of grooved texture, 10% (w/v) PS solutions (THF/DMF ratio, 1:1 v/v) were electrospun under the applied voltage of 5 kV. It is intriguing that both porous droplets and HSP phosphorylation Beaded fibers were produced. However, there were no voids but wrinkles on the surface of beads, while the nanofibers between beads Elongation factor 2 kinase also exhibited a grooved texture (Figure  9). Figure 9 SEM pictures of fibers and their surfaces from buy BKM120 10% ( w / v ) PS solutions (THF/DMF ratio 1:1  v / v ). The solutions were electrospun under the lowest applied voltage. (A) Beaded nanofibers. (B, C) Bead. (D) Nanofiber. RH 60%, collecting distance

15 cm, feeding rate 1.5 ml/h, and applied voltage 5 kV. Based on the electrospinning results, we proposed that the formation mechanism of grooved texture should be attributed to two possible hypotheses. When THF/DMF ratio was higher than 2:1, as schematically illustrated in Figure  7D, the formation mechanism should be attributed to the formation of voids on the jet surface at the early stage of electrospinning and subsequent elongation and solidification of the voids into a line surface structure (mechanism I) [15]. This hypothesis can be supported by Figure  1C,D,E,F,G,H, Figure  6C,D,E,F,G,H, Figure  7A,B,C, and Figure  8A,B,C,D,E,F,G,H. Concerning fibers from 10% (w/v) PS solutions (THF/DMF ratios, 5:1, 4:1, 3:1 v/v), though there were wrinkles on the surface of void beads, the fibers between beads were single grooved, indicating that the formation of grooved texture should be attributed to voids but not wrinkles when THF/DMF ratio was higher than 2:1 (Figure  6C,D,E,F,G,H, Figure  7A,B,C).