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Harvesting energy from ambient vibration sources with ultrathin flexible piezoelectric energy harvesters(PEHs)for battery-free electronics has received attention in recent years.However,the excitation modes in the env...Harvesting energy from ambient vibration sources with ultrathin flexible piezoelectric energy harvesters(PEHs)for battery-free electronics has received attention in recent years.However,the excitation modes in the environment and human body motion are more complicated than the ideal harmonic modes employed in previous theoretical analyses,and their influence on the efficiency of PEHs has received little attention.In this study,these environmental excitation modes are classified into three types,i.e.,the triangular,sinusoidal,and square wave modes,with varied duty ratios.We derived theoretically the output power of flexible PEHs under these excitation modes and establish a simple scaling law,in which the normalized output power depends only on two combined normalized parameters,i.e.,the intrinsic system parameter and the excitation mode.Results reveal that the output power of PEHs changes dramatically for different excitation modes with varied duty ratios even when all the other parameters including excitation ampli tude,excitation frequency,elec trical parameter,and geometrical and material parameters of the PEHs are identical.This paper may provide a systematic understanding in the effect of exc计ation modes on the output power of flexible PEHs and promote the realization of energy harvesting from the complex environmental and human body motions.展开更多
A new method for establishing ES cell lines from 129/ter、C57BL/6J mice was set up which was characterized by the murine embryonic fibroblast cell(MEF) feeder, the medium of rat heart cell-conditioned medium(RH-CM)for...A new method for establishing ES cell lines from 129/ter、C57BL/6J mice was set up which was characterized by the murine embryonic fibroblast cell(MEF) feeder, the medium of rat heart cell-conditioned medium(RH-CM)for ES cells, and the consecutive digestion by the digestion liquid containing 1% serum. Every group of improved experiments was done with a control of routine method. The results showed that, compared with routine method, the improved way increased the ratio of ES cell lines of 129/ter mice from 11.8% to 33.3%, and of C57BL/6J from 3.7% to 13.3%. The difference is distinct. The passage culture of ES cells showed that, compared with medium added LIF, RH-CM not only inhibited the differentiation of murine ES cells, maintained its dipoild karyotype, but also promote its adherence growth. This kind of culture condition not only maintained the ES cells in an undifferentiated state and their normal dipoild karyotype, but also a series of other characteristics of totipotent embryonic stem cells during extended culture period.展开更多
文摘Your comments are welcome!Please feel free to contact us with your personal stories or vivid pictures!Address:24 Baiwanzhuang St., Xicheng Dist., Beijing,100037E-mail:chinatodaynews@aliyun.com.
文摘Harvesting energy from ambient vibration sources with ultrathin flexible piezoelectric energy harvesters(PEHs)for battery-free electronics has received attention in recent years.However,the excitation modes in the environment and human body motion are more complicated than the ideal harmonic modes employed in previous theoretical analyses,and their influence on the efficiency of PEHs has received little attention.In this study,these environmental excitation modes are classified into three types,i.e.,the triangular,sinusoidal,and square wave modes,with varied duty ratios.We derived theoretically the output power of flexible PEHs under these excitation modes and establish a simple scaling law,in which the normalized output power depends only on two combined normalized parameters,i.e.,the intrinsic system parameter and the excitation mode.Results reveal that the output power of PEHs changes dramatically for different excitation modes with varied duty ratios even when all the other parameters including excitation ampli tude,excitation frequency,elec trical parameter,and geometrical and material parameters of the PEHs are identical.This paper may provide a systematic understanding in the effect of exc计ation modes on the output power of flexible PEHs and promote the realization of energy harvesting from the complex environmental and human body motions.
文摘A new method for establishing ES cell lines from 129/ter、C57BL/6J mice was set up which was characterized by the murine embryonic fibroblast cell(MEF) feeder, the medium of rat heart cell-conditioned medium(RH-CM)for ES cells, and the consecutive digestion by the digestion liquid containing 1% serum. Every group of improved experiments was done with a control of routine method. The results showed that, compared with routine method, the improved way increased the ratio of ES cell lines of 129/ter mice from 11.8% to 33.3%, and of C57BL/6J from 3.7% to 13.3%. The difference is distinct. The passage culture of ES cells showed that, compared with medium added LIF, RH-CM not only inhibited the differentiation of murine ES cells, maintained its dipoild karyotype, but also promote its adherence growth. This kind of culture condition not only maintained the ES cells in an undifferentiated state and their normal dipoild karyotype, but also a series of other characteristics of totipotent embryonic stem cells during extended culture period.
