Poly [ (chloromethyl) styrene-co-divinylbenzene] Continuous Rod Column of Weak Cation Exchange Chromatography and its Applications in the Separation of Biopolymers

Macroporous poly [(chloromethyl) styrene-co-divinylbenzene] continuous rod was prepared by direct polymerization of the monomers in the presence of a porogenic diluent inside an empty chromatographic column. A new 'in-situ' technique was used to modify the synthesized polymer rod for a weak cation exchanger and it has been used successfully for the separation of biopolymers. It was found that the back pressure of the continuous rod column was much lower and its surface was proved to be modified well.

Simulation on the dynamic stability derivatives of battle-structure-damaged aircrafts

Accurately evaluating the aerodynamic performance of a battle-structure-damaged aircraft is essential to enable the pilot to optimize the flight control strategy. Based on CFD and rigid dynamic mesh techniques,a numerical method is developed to calculate the longitudinal and longitudinal-lateral coupling forces and moments with small amplitude sinusoidal pitch oscillation, and the corresponding dynamic derivatives of two fragment-structure-damaged and two continuous-rod-damaged models modified from the SACCON UAV. The results indicate that, at the reference point set in this paper, additional positive damping is generated in fragment-damaged configurations;thus, the absolute values of the negative pitch dynamic derivative increase. The missing wingtip induces negative pitch damping on the aircraft and decreases the value of the pitch dynamic derivative. The missing middle wing causes a noticeable increase in the absolute value of the pitch dynamic derivative;the missing parts on the right wing cause the aircraft to roll to the right side in the dynamic process, and the pitch-roll coupling cross dynamic derivatives are positive. Moreover, the values of these derivatives increase as the damaged area on the right wing increases, and an optimal case with the smallest cross dynamic derivative can be found to help improve the survivability of damaged aircraft.

The Tribological Properties of the Hot-extrusion Nylon Coating in the Oil Well Environment

The friction and wear properties of the nylon coating,prepared by hot-extrusion, used to protect the surface of the flexible continuous sucker rod were studied by using a pin-on-disc wear tester in the simulated oil well environment.The effects of sliding speed and load were considered.The wear mechanism was also studied by using a scanning electron microscope (SEM).The result shows that the friction coefficients of both kinds of materials,JKPA and ZZ7024B,used to protect the surface of the flexible continuous sucker rod decrease with sliding speed increase,but change little with load increase in the simulated oil well environment.The value of friction coefficient of ZZ7024B is smaller than that of JKPA.The minimum value of friction coefficient of ZZ7024B is about 0.05.The wear volume of ZZ7024B is smaller than that of JKPA under the same conditions of experimentation.