The total mass of the atmosphere varies mainly from changes in water vapor loading; the former is proportional to global mean surface pressure and the water vapor component is computed directly from specific humidity and precipitable water using the 40-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analyses (ERA-40). Their difference, the mass of the dry atmosphere, is estimat...

The optical transmittance of the commonly used Cerenkov counter gases, Freon 12, Freon 13; C02, SF8, and N2, was measured in the range from 1875 A to 8000 A, and normalized for a 100 cm X 1 atm path. Calculations of efficiency for Cerenkov counters, particularly threshold type, require a knowledge of the optical transmittance of the counter filling for the Cerenkov light. For many of the gases ...

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...

Introduction: The carbon dioxide (CO2) Martian atmosphere undergoes large-amplitude seasonal variations due to CO2 condensation and sublimation in the polar regions. This atmospheric mass cycle, present in surface pressure measurements (such as those obtained by the Viking landers), is clearly a first order effect which must be well represented by Global Climate Models (GCMs) which aim to reali...

1. Photoxidation in leaves is measured by exposing them to light in an atmosphere free from carbon dioxide but containing varied percentages of oxygen. 2. Photoxidation is observed in living leaves as well as in dead ones and in plant juices. Its rate is only slightly enhanced by feeding the leaves with sugar, but the respiration (autoxidation) becomes considerably enlarged during the exposure ...

In this research, the production of Fe-TiN and Fe-Ti(N,C) composite powders by mechanical alloying was investigated and evaluated. Ferrotitanium (containing 70%Ti), titanium and graphite were used as the raw materials. Initial mixtures were milled in different time durations under the pure nitrogen atmosphere with the pressure of 5atm. The results showed that when N2 pressure is 5 at...

Commercially available gases contain residual impurities leading to a background oxygen partial pressure of typically several 10 bar, independent of temperature. This oxygen partial pressure is inappropriate for the growth of some single crystals where the desired oxidation state possesses a narrow stability field. Equilibrium thermodynamic calculations allow the determination of dynamic atmosp...