In a system for cranking a crankshaft of an internal combustion engine, a starter is provided with a motor working to, when energized, rotatably drive an output shaft with a pinion and an actuator working to, when energized, shift the pinion toward the ring gear to be engaged with the ring gear. This invention incorporates methods for inactivating infectious virus particles while retaining protein integrity and antigenicity. Besides, a simple design of driving circuit is applied to achieve an effect of dynamically adjusting the current of the LED. The cascode stage communicatively couples to the transconductance stage and is operable to receive the output current signal and to produce an output voltage signal based thereupon. R1\u2550OCOCH2CH2COOH, R2\u2550H, R3\u2550COOH, R4 & R5\u2550O5.