Abstract: In some embodiments, a polymer film includes a base composition of poly(ethylene-vinyl acetate) and a surface composition comprising hydroxy groups. In some embodiments, a polymer film includes a base layer of a first composition of poly(ethylene-vinyl acetate), a surface layer at a surface of the base layer, and a coating layer of a second composition of a copolymer of glycerol and sebacic acid. The surface layer includes surface hydroxy groups converted from acetate groups of the poly(ethylene-vinyl acetate). The second composition is attached to the surface layer by ester bonds between carboxyl groups of the copolymer and the hydroxy groups. A single-use bioreactor bag includes a polymer film including a base composition of poly(ethylene-vinyl acetate) and a surface composition comprising hydroxy groups. A method of modifying a poly(ethylene-vinyl acetate) film includes converting acetate groups at a first surface of the poly(ethylene-vinyl acetate) film to hydroxy groups.

Abstract: A hydrostatic propulsion system includes a hydrostatic circuit fluidly connecting left front and right front motors in parallel with an outlet of a pump, left rear and right rear motors in parallel with an inlet of the pump, left front motor and right rear motor in series, and the right front motor and left rear motor in series. A valve system has a first relief valve line providing flow from a right rear motor inlet side to a left rear motor inlet side, and a second relief valve line providing flow from a left rear motor inlet side to a right rear motor inlet side. A first check valve line provides flow from a right rear motor outlet side to the right rear motor inlet side, and a second check valve line provides flow from a left rear motor outlet side to the left rear motor inlet side.

Abstract: A hydrostatic propulsion system includes a hydrostatic circuit fluidly connecting left front and right front motors in parallel with an outlet of a pump, left rear and right rear motors in parallel with an inlet of the pump, left front motor and right rear motor in series, and the right front motor and left rear motor in series. A valve system has a first relief valve line providing flow from a right rear motor inlet side to a left rear motor inlet side, and a second relief valve line providing flow from a left rear motor inlet side to a right rear motor inlet side. A first check valve line provides flow from a right rear motor outlet side to the right rear motor inlet side, and a second check valve line provides flow from a left rear motor outlet side to the left rear motor inlet side.

Abstract: A hydrostatic propulsion system includes a hydrostatic circuit fluidly connecting left front and right front motors in parallel with an outlet of a pump, left rear and right rear motors in parallel with an inlet of the pump, left front motor and right rear motor in series, and the right front motor and left rear motor in series. A valve system has a first relief valve line providing flow from a right rear motor inlet side to a left rear motor inlet side, and a second relief valve line providing flow from a left rear motor inlet side to a right rear motor inlet side. A first check valve line provides flow from a right rear motor outlet side to the right rear motor inlet side, and a second check valve line provides flow from a left rear motor outlet side to the left rear motor inlet side.