In-plane nanoelectromechanical resonators based on silicon nanowire piezoresistive detection.

We report an actuation/detection scheme with a top-down nanoelectromechanical system (NEMS) for frequency shift based sensing applications with outstanding performance. It relies on electrostatic actuation and piezoresistive nanowire gauges for in-plane motion transduction. The process fabrication is fully CMOS (complementary metal-oxide-semiconductor) compatible. The results show a very large dynamic range of more than 100 dB and an unprecedented signal to background ratio of 69 dB providing an improvement of two orders of magnitude in the detection efficiency presented in the state of the art in NEMS fields. Such a dynamic range results from both negligible 1/f noise and very low Johnson noise compared to the thermomechanical noise. This simple low power detection scheme paves the way for new class of robust mass resonant sensors.

Effect of D ala2 metenkephalinamide on feline jejunal and ileal water and electrolyte transport.

The aim of this investigation was to compare the effect of an opioid, D ala2 metenkephalinamide (DAMA), on net jejunal and ileal water and electrolyte fluxes using the gut perfusion technique in the anesthetized cat. Intestinal transport was measured during intravenous infusion of serial doses of 2, 6, and 18 micrograms.kg-1.h-1 of DAMA in 6 cats. Each cat was its own control during an intravenous infusion of 150 mmol/l NaCl preceding the first dose of peptide and following the last dose of DAMA. Both jejunal and ileal segments were isolated by inflated balloons and were studied at the same time. Fifteen ml of an iso-osmolar test solution with hypo-osmolar ion contents and complementary mannitol were administered in the upstream tube and collected 1 h later in the downstream tube. In the jejunum, water secretion was dose-dependently reversed to an absorption from a control value of +0.5 +/- 0.4 to -0.83 +/- 0.5 ml.h-1.10 cm-1; in the ileum, water absorption was increased from -0.5 +/- 0.3 to -1.5 +/- 0.2 ml.h-1.10 cm-1. The net absorption of all electrolytes, ie sodium, chloride, bicarbonate, potassium and calcium also increased during peptide administration. However, a qualitative difference in the ion transport was observed between the jejunum and the ileum.