SCUBA diving equipment is the most commonly used compressed gas system in civilian diving and illustrates the important features and function relevant to diving physiology. Basic SCUBA equipment consists of a cylinder of air at high pressure, a demand valve regulator, and a device for holding this equipment on the diver's back. In the modern context the latter is usually an inflatable jacket ca...

background: the most reliable indicator of vitamin d status is circulating concentration of 25‑hydroxycalciferol (25(oh) d) routinely determined by enzyme‑immunoassays (eia) methods. this study was performed to compare commonly used competitive protein‑binding assays (cpba)‑based eia with the gold standard, high‑pressure liquid chromatography (hplc). methods: concentrations of 25(oh) d in sera ...

We report a stable field emission ~FE! current from sharp tungsten ~W! tips in relatively poor vacuum ~up to 10 mbar) conditions. We use small tip–anode spacing to keep the extraction voltage low. A simple current regulator circuit, with a bandwidth of ;1.6 kHz, was designed, which controls the voltage applied according to the emission current measured. Without a current regulator circuit, an u...

A high-precision variable-thrust control method based on real-time measurement of pintle displacement and closed-loop feedback is proposed to solve the technical problems deep throttling regulation liquid rocket engines (LRE). By optimizing system structure parameters, with high precision a fast response under wide range variable thrust can be realized, thus large-range, fast-response, chamber ...