PubMed · 3801230
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W H Ko. Solid-state transducers for biomedical applications.. https://pubmed.ncbi.nlm.nih.gov/3801230/
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We measured the long term spontaneous electrical activity of neuronal networks with different sizes, grown on lithographically prepared substrates and recorded with multi-electrode-array technology. The time sequences of synchronized bursting events were used to characterize network dynamics. All networks exhibit scale-invariant Lévy distributions and long-range correlations. These observations suggest that different-size networks self-organize to adjust their activities over many time scales. As predictions of current models differ from our observations, this calls for revised models.
Geometric scaling of microelectrical field flow fractionation (micro-EFFF) systems is investigated experimentally and compared to theory and to macroscale EFFF systems. Experimental results are presented to demonstrate that the miniaturized system operates according to the scaling theory associated with the system. Demonstrated improvements in the channels include increased retention and resolution and decreased peak broadening, electrical time constants, relaxation time, power consumption, and sample size. Additionally, scaling effects related to the compression of separation zones in the miniaturized EFFF systems are discussed.
PROBLEM: Transurethral vaporization of the prostate (TUVP) and vaporization-resection of the prostate (TUVRP) ("vapor cut, band electrode") seem to be alternatives to conventional resection of the prostate (TURP). For TUVP and TUVRP, little in vitro data has yet been published. The aim of this study was to determine settings for optimal performance with TUVP and TUVRP and to investigate electrosurgical parameters relevant to safety. METHODS: Standardized experiments were performed on porcine muscle. Mass loss and coagulation zones were measured optically. Additionally, electrical parameters were recorded. RESULTS: The maximum tissue ablation rates were 3.8 cm3 per min and 6.1 cm3 per min for TUVP and TUVRP, respectively, compared to 6.5 cm3 per min for TURP. The maximum coagulation depths reached 2.1 mm (TUVP), 1.4 mm (TUVRP), and 0.9 mm (TURP). Optimal in vitro settings for TUVP/TUVRP/TURP were as follows: generator power of 250/120/90 W, drag speed of 5/15/20 mm/s, and pressure of 0.40/0.15/0.05 N. Different power generators and electrodes showed considerably varying performance. The energy to remove 1 g of tissue averaged 7.500 J (TUVP), 620 J (TUVRP). and 400 J (TURP). CONCLUSIONS: These results allow quantification of the influence of different variables on TUVP, TUVRP, and TURP in vitro. The TUVP proves to be an effective ablation alternative. Nevertheless, a 15 to 20 times higher energy demand has to be considered. TUVRP combines excellent ablation features with greater coagulation volumes, indicating better hemostasis.