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In the 1960s, sperm cryopreservation was developed as a method to preserve fertility. Currently, techniques for the cryopreservation of human spermatozoa have been widely used in assisted reproduction. However, although sperm cryobiology has made notable achievements, the optimal method for the recovery of viable spermatozoa after cryopreservation remains elusive. Postthawing sperm quality can be affected by cryoprotectants, ice formation, storage conditions, and osmotic stress during the freezing process. This review discusses recent advances in different cryopreservation techniques, cryoprotectants, and freezing and thawing methods during cryopreservation and new indications for the use of cryopreserved spermatozoa. [ABSTRACT FROM AUTHOR]

For the problems existed in DSP experimental teaching, an idea of improving the experimental effect is raised based on associating learning and contrast learning. According to the idea, a TMS320VC5416 DSP experiment teaching platform is designed by the teaching principles of step-by-step. The platform is made of the system module, power module, ADDA module, analog signal conditioning modules and communication modules. The system design and main circuit of platform are given. And a comprehensive experiment of the platform is shown as an example. Actual application shows that the DSP technology experiment teaching platform meets teaching laws and habits of students. The platform can reduce the difficulty of learning about DSP technology and improve the effect of experimental teaching. Therefore the platform has a certain value of practical and promotional. [ABSTRACT FROM AUTHOR]