ABSTRACT
Herein, polysiloxane-based aggregation-induced emission (AIE) polymers and rubbers were prepared which display interesting multi-stimuli responsive fluorescence. TPE-modified polydimethylsiloxanes (PDMS-TPE) as polysiloxane-based AIE polymers were synthesized through Heck reaction of bromo-substituted tetraphenylethene (TPE-Br) and vinyl polysiloxanes. As expected, TPE moiety endows the modified polysiloxane with typical AIE behavior. However, limited by the long polymer chains, the aggregation process of PDMS-TPE shows obvious differences compared with the small molecule TPE-Br. The fluorescence of PDMS-TPE in THF/H2O starts to increase when the H2O fraction (fw) is 70% while TPE-Br is nearly non-luminous until the fw is up to 99%. The fluorescence intensity ratio (I/I0) of PDMS-TPE in the aggregated state and dispersed state is over 1300, greater than that of TPE-Br (I/I0 = 380). More importantly, the exceptional thermal motion of Si-O-Si chains and AIE characteristic of TPE moiety work together, enabling PDMS-TPE to show specific temperature-dependent fluorescence with a wider response range of room temperature to 190°C, which is distinguished from TPE-Br. And such fluorescence responsiveness possess good fatigue-resistance. Furthermore, fluorescent silicone rubbers, r-PDMS-TPE were prepared by using PDMS-TPE as additive of the base gum. They display interesting solvent-controllable fluorescence and higher tensile strength (4.42 MPa) than the control sample without TPE component (1.96 MPa). Notably, a unique stretching-enhanced emission (SEE) phenomenon is observed from these TPE-modified silicone rubbers. When being stretched, the rubbers' fluorescent emission intensity could increase by 143%.
ABSTRACT
This investigation was directed to the physiological load intensity in the curricula of track and field studies offered in 8 general colleges. We adopted the sampling survey method and monitored the heart rate of 80 first-year students who were from different grades in 8 colleges and were attending the track and field class. The data collected from these male student show: (1) The pre-exercise heart rate is 80 per minute; the first inflection point appears at 28 minutes after exercise; the heart rate is 132 per minute and the slope is -0.031. (2) The data of exercise load at mobilization stage and at fatigue stage are 90.09 and 104.126 kUw respectively; the data of lasting time are both 28 minutes, and the average heart rates are 133 per minute and 140 per minute respectively. The exercise load is 84.231 kUw at stable stage. (3) When the heart rates are 120-140 per minute and 140-150 per minute respectively, the ratios of load are 32.786% and 31.316% respectively. When the heart rate is 120-150 per minute, the ratio of load is 64.102%. But we are surprised to find that when the heart rate is 150-160 per minute, the ratio of load is only 17.639%. In the analysis of data from this investigation we have noticed that the physiological load intensity is in accord with the changing rule of body function. In order to further adjust the training plan and arrange the load of exercise rationally and promptly, we, the teachers, should pay adequate attention to the heart rate monitoring data on students.
