THE use of contrast media in the orbit dates from 1927, when Staunig and Herrenschwand injected air into the episcleral space, and since that time various media have been used. The ideal medium should provide good contrast in small quantities, be non-irritant, and have suitable qualities of permeation and absorption. The following media will be considered: (1) Air or other gas, (2) Oily media, ...

A number of mechanisms have been proposed to explain the phenomenon of frequency aging in the rubidium atomic clock. Helium permeation is one such mechanism. Briefly, the four millitorr of helium in the Earth’s atmosphere can permeate into the resonance cell, changing the clock frequency via the pressure shift of the 0-0 hyperfine transition. On orbit, any He in the resonance cell would permeat...

A fire experiment conducted in a British 1950s-style house is described. Measurements of temperature, smoke, CO, CO2 , and O2 were taken in the Lounge, stairwell, and front and back bedrooms. The front bedroom door was wedged open, while the door to the back bedroom was wedged closed. Contrary to expectations and despite the relatively small fire load, analysis and hazard calculations show perm...

A supported Pd-Au (Au 7wt%) membrane was produced by electroless plating deposition. Permeation tests were performed with pure gas (H₂, H₂, N₂, CO₂, CH₄) for long time operation. After around 400 h under testing, the composite Pd-Au membrane achieved steady state condition, with an H₂/N₂ ideal selectivity of around 500 at 420 °C and 50 kPa as transmembrane pressure, remaining stable up to 1100 ...

Graphene oxide (GO) nanosheets were engineered to be assembled into laminar structures having fast and selective transport channels for gas separation. With molecular-sieving interlayer spaces and straight diffusion pathways, the GO laminates endowed as-prepared membranes with excellent preferential CO2 permeation performance (CO2 permeability: 100 Barrer, CO2/N2 selectivity: 91) and extraordin...