Abstract: A method for producing a polyester polyol is provided, which includes: feeding a first antioxidant and a raw material reactant that includes a polyacid and a polyol into a reactor; subjecting the polyacid and the polyol to an esterification reaction to form an oligomer; and performing a prepolymerization reaction on the oligomer to obtain a prepolymerization reactant. During the prepolymerization reaction, the method includes sampling and monitoring an acid value of the prepolymerization reactant. When the acid value of the prepolymerization reactant reaches a first acid value, an esterification reaction catalyst is added to the prepolymerization reactant for carrying out a polycondensation reaction and generating a polycondensation reactant that contains the polyester polyol. During the polycondensation reaction, the method includes sampling and monitoring an acid value of the polycondensation reactant.

Abstract: A semiconductor device includes a plurality of channel layers vertically separated from one another. The semiconductor device also includes an active gate structure comprising a lower portion and an upper portion. The lower portion wraps around each of the plurality of channel layers. The semiconductor device further includes a gate spacer extending along a sidewall of the upper portion of the active gate structure. The gate spacer has a bottom surface. Moreover, a dummy gate dielectric layer is disposed between the gate spacer and a topmost channel layer of plurality of channel layers. The dummy gate dielectric layer is in contact with a top surface of the topmost channel layer, the bottom surface of the gate spacer, and the sidewall of the gate structure.

Abstract: A foldable bicycle contains: a front frame, a rear frame, and a folding device. The front frame includes a front fork connected on a front wheel, and the rear frame includes a rear fork connected on a rear wheel and includes a seatpost coupled with a connection post and a saddle. The folding device is rotatably connected between the front frame and the second frame. The front fork has a sole column, the front wheel is inserted through a hub by using a hollow hub shaft to connect with the sole column, and the hollow hub shaft has a first connection element defined in a central portion thereof The rear wheel has a second connection element extending outward from a central portion thereof so as to fit with the first connection element after folding the front wheel and the second wheel.

Abstract: A chainless transmission mechanism includes a reinforcing shell capped on a front casing and locked by a lock nut to reinforce the structural strength of the front casing, a locating rod inserted into an inside locating groove of a fourth bevel gear and a second locating groove of a rear-wheel axle to prohibit rotation of the fourth bevel gear relative to the rear-wheel axle, and screw rods respectively threaded into respective screw holes on the fourth bevel gear and engaged into a first locating groove of the rear-wheel axle to prohibit axial displacement of the fourth bevel gear relative to the rear-wheel axle.

Abstract: A chainless transmission mechanism for a bicycle, including a casing mounted in a bottom bracket to hold a bottom bracket bearing axle, permitting the bottom bracket bearing axle to be driven by pedals to turn a rear-wheel hub through a transmission shaft and two transmission gear sets, wherein the bottom bracket has a first end, a second end, and a notch at the second end thereof; the casing is a cylindrical shell inserted through the bottom bracket, having a first end secured to the bottom bracket outside the first end of the bottom bracket by a clamp, a second end disposed outside the second end of the bottom bracket, and a hollow projecting block raised from its second end and forced into engagement with the notch at the second end of the bottom bracket.

Abstract: A wheel hub and transmission gear arrangement of a chainless transmission mechanism for a bicycle, including a wheel hub having an axle block with an outside annular groove and intersected locating grooves, a transmission gear having an annular base mounted on the axle block, the annular base having a plurality of inward projecting blocks respectively forced into engagement with the locating grooves of the axle block and an inside annular groove, and a split binding ring mounted within the outside annular groove of the axle block and the inside annular groove of the transmission gear to firmly secure the axle block and the transmission gear together.