RESUMO
The application of a versatile, low-temperature thin-film transistor (TFT) technology is presently described as the implementation on a flexible substrate of an analog front-end (AFE) system for the acquisition of bio-potential signals. The technology is based on semiconducting amorphous indium-gallium-zinc oxide (IGZO). The AFE system consists of three monolithically integrated constituent components: a bias-filter circuit with a bio-compatible low cut-off frequency of ≈1 Hz, a 4-stage differential amplifier offering a large gain-bandwidth product of ≈955 kHz, and an additional notch filter exhibiting over 30 dB suppression of the power-line noise. Respectively built using conductive IGZO electrodes with thermally induced donor agents and enhancement-mode fluorinated IGZO TFTs with exceptionally low leakage current, both capacitors and resistors with significantly reduced footprints are realized. Defined as the ratio of the gain-bandwidth product of an AFE system to its area, a record-setting figure-of-merit of ≈86 kHz mm-2 is achieved. This is about an order of magnitude larger than the < 10 kHz mm-2 of the nearest benchmark. Requiring no supplementary off-substrate signal-conditioning components and occupying an area of ≈11 mm2 , the stand-alone AFE system is successfully applied to both electromyography and electrocardiography (ECG).
RESUMO
n-Hexane is an organic solvent widely used in industry. 2,5-Hexanedione (2,5-HD), the major neurotoxic metabolite of n-hexane, decreases the levels of neurofilaments (NFs) in neurons. Neurogenesis occurs throughout life, and the hippocampal dentate gyrus is one of two major brain areas showing neurogenesis in adulthood. In the current study, rats were intraperitoneally injected with normal saline solution or 2,5-HD five times per week for five continuous weeks. 2,5-HD was administered to the low-dose and high-dose groups at 200 and 400 mg/kg/day, respectively. Then, immunoreactive cells were counted in the hippocampal granule cell layer (GCL) and subgranular zone (SGZ). Ki67+ cells significantly decreased in the high-dose group, while the percentage of proliferative Sox2+ cells significantly increased, consistent with high hippocampal Sox2 expression. Additionally, western blotting showed that exposure to high doses of 2,5-HD led to decreased NF-L in both the cortex and hippocampus, whereas low doses led to a significant reduction in the cortex only. In conclusion, 2,5-HD increases the percentage of proliferating neural stem and progenitor (Sox2+) cells in the SGZ/GCL.
