Design and Control of a Trapezoidal Piezoelectric Bimorph Actuator for Optical Fiber Alignment.

To align a pair of optical fibers, it is required that the micro actuators used be small and have the characteristics of high accuracy and fast response time. A trapezoidal piezoelectric bimorph actuator was proposed for pushing and pulling an optical fiber. Based on a mathematical model and finite element model established in this paper, we analyzed the output displacement and output force of the proposed trapezoidal piezoelectric actuator under the influence of structural parameters. Since the piezoelectric bimorph actuator had a hysteresis effect, we applied particle swarm optimization to establish a Prandtl-Ishlinskii (PI) model for actuator and parameter identification. Then, two control methods, namely feedforward control considering hysteresis effects and fuzzy proportional-integral-derivative (PID) control employing feedback, were proposed. Finally, a composite control model combining the two control methods with fewer tracking errors was designed. The results show that the output displacement of this actuator is larger than that of a rectangular one. Additionally, the fuzzy PID control has a lower response time (15 ms) and an overshoot (5%).

Inhibitory effects of estrogenic endocrine disrupting chemicals on fin regeneration in zebrafish are dependent on estrogen receptors.

For fish and other aquatic organisms, disrupting their capacity for repair and regeneration will reduce their quality of life and survivorship in the wild. Studies have shown that 17α-ethinylestradiol (EE2), a synthetic estrogenic endocrine disrupting chemical (EEDC), can inhibit caudal fin regeneration in larval zebrafish following fin amputation. However, whether the inhibitory effects of EE2 are dependent on estrogen receptor (ER) remains unknown. Therefore, in this study, amputated zebrafish larvae were exposed to the ER agonist EE2 alone and in combination with the ER antagonist ICI 182,780 (ICI), and the change in regenerative capacity was determined. The inhibition of fin regeneration caused by EE2 alone (100 ng/L) was ameliorated after combination with ICI (30-300 µg/L), and these changes in regeneration-related signaling and the immune system corresponded with morphological observations, implying that the effects of EE2 on regeneration were possibly initiated by the activation of ER. Furthermore, the role of ER was confirmed with a natural ligand of ER, namely, 17ß-estradiol (E2), and as expected, the effects of E2 (10, 100 and 1000 ng/L) paralleled those of EE2. In conclusion, EEDCs can disrupt the regenerative capacity in zebrafish, possibly due to the binding and activation of ERs and the consequent alteration of signaling pathways that regulate fin regeneration and immune competence. Given that EEDCs appear to be ubiquitous in the aquatic environment, the risk of these chemicals might be readdressed regarding their potential effects on tissue repair and regeneration.

Development and validation of an activated immune model with zebrafish eleutheroembryo based on caudal fin acupuncture.

Environmental pollutants are ubiquitous in global aquatic ecosystems and may cause immunotoxicity in aquatic organisms. However, disadvantages remain in the existing in vivo immunotoxicological methods, which make it difficult to meet the increasing demands for screening and for discriminating the immunotoxicity of environmental pollutants. In this study, the immune response in zebrafish eleutheroembryo was activated by acupuncture of the caudal fin at 72 hours post fertilization (hpf), and this immune model was further validated with a well-defined immunosuppressor, beclomethasone dipropionate (BDP). It was shown that acupuncture resulted in no increase in mortality in zebrafish eleutheroembryos. The transcription and protein levels of most immune genes were significantly increased after acupuncture, which indicated that acupuncture can effectively activate the immune response in zebrafish eleutheroembryos. Following exposure to BDP (0.01-1 µmol/L), the suppressive effects on the immune system were more significant in zebrafish that received acupuncture than in zebrafish that did not receive acupuncture. Considering these advantages, including its sensitivity, safety, and simple operation, over existing methods, the established immune model of zebrafish is promising for assessing the immunotoxicity of environmental pollutants.