Closed-Loop Control of Electroadhesion Using Current Regulation.

Electroadhesion displays provide controllable friction between the fingertip and screen. However, the change of contact condition causes variability in the produced friction. In this paper, we demonstrate a novel method for closed-loop control using current regulation to improve the precision of the electroadhesion force regardless of contact conditions. The current sensor obtains static current (when the finger is stationary) and dynamic current (when the finger is sliding). The static current is used to estimate the apparent contact area. The estimated contact area modulates the driving voltage along with the dynamic current. To verify the proposed method, we measured electroadhesion forces under open-loop control and closed-loop control. The benefit of using this closed-loop control is shown by comparing the relative static error of open-loop control and closed-loop control. The relative error reductions achieved over 34 % (max 112 %) for four changing contact conditions.

Proteomic analysis of NGF-induced transdifferentiation of adrenal medullary cells.

Nerve growth factor (NGF) is a polypeptide growth factor with specific trophic function in nerve cells and was initially investigated for its role as a key player in the regulation of peripheral innervations. The aim of this study was to examine the NGF-induced transdifferentiation of adrenal medullary cells, and to screen the major candidate differentially expressed proteins involved in the transdifferentiation. NGF was used to treat primary cultures of neonatal calf adrenal medullary cells and the effects of transdifferentiation were determined in association with cellular morphology, ultrastructure and changes in endocrine function. Differentially expressed proteins were screened and identified through two-dimensional gel electrophoresis and mass spectrometry. The protein spots showing differential expression were verified by western blot analysis. We observed neurite outgrowth in the adrenal medullary cells treated with NGF under a phase contrast microscope. Ultrastructure analysis revealed that there were rich drumstick-like and villiform processes on the cell membranes and vesicles were formed near the cell membranes. The cytoplasm was rich in mitochondria and the secretion of epinephrine was decreased. Two-dimensional gel electrophoresis revealed that among the differentially expressed proteins, 48 protein spots showed an upregulated expression and 37 protein spots showed a downregulated expression, and no 'all-or-none' spots with significant differences in expression were found. Fourteen protein spots with an upregulated expression and 6 with a downregulated expression were randomly selected for identification by mass spectrometry. Western blot analysis revealed that ras homologus oncogene (Rho) GDP dissociation inhibitor α (RhoGDIα) protein expression was significantly downregulated and peripherin protein expression was significantly upregulated. In brief, our data demonstrate that NGF can induce the differentiation of adrenal medullary cells into neurons, and that RhoGDIα and peripherin may play important roles in this process.