نتایج جستجو برای: chlorofluorocarbons

تعداد نتایج: 647  

2005
E.-S. Yang D. M. Cunnold M. J. Newchurch R. J. Salawitch

[1] Long-term ozone variations at 60–70 S in spring are investigated using ground-based and satellite measurements. Strong positive correlation is shown between year-to-year variations of ozone and temperature in the Antarctic collar region in Septembers and Octobers. Based on this relationship, the effect of year-to-year variations in vortex dynamics has been filtered out. This process results...

2004
Anna M. Michalak Lori Bruhwiler Pieter P. Tans

[1] Inverse modeling methods have been used to estimate surface fluxes of atmospheric trace gases such as CFCs, CH4, and CO2 on the basis of atmospheric mass fraction measurements. A majority of recent studies use a classical Bayesian setup, in which prior flux estimates at regional or grid scales are specified in order to further constrain the flux estimates. This paper, on the other hand, exp...

Journal: :Physical chemistry chemical physics : PCCP 2009
Arne Dinse Reinhard Schomäcker Alexis T Bell

The oxidative dehydrogenation (ODH) of ethane on alumina-supported vanadia was investigated with the aim of understanding the effects of lattice oxygen and vanadium oxidation state on the catalyst ODH activity and ethene selectivity. Transient-response experiments were carried out with both a fully oxidized sample of 10 wt% VO(x)/Al(2)O(3) (7 V nm(-2)) and a sample that had been partially reduc...

Journal: :The Journal of chemical physics 2015
G A Vdovichenko A I Krivchikov O A Korolyuk J Ll Tamarit L C Pardo M Rovira-Esteva F J Bermejo M Hassaine M A Ramos

The thermal conductivity, specific heat, and specific volume of the orientational glass former 1,1,2-trichloro-1,2,2-trifluoroethane (CCl2F-CClF2, F-113) have been measured under equilibrium pressure within the low-temperature range, showing thermodynamic anomalies at ca. 120, 72, and 20 K. The results are discussed together with those pertaining to the structurally related 1,1,2,2-tetrachloro-...

2003
Fred Hallett

In 1974, the famous ozone depletion theory by Rowland and Molina claimed that CFCs diffuse into the stratosphere where they are broken down by photolysis to release chlorine atoms that catalytically destroy ozone. Although the understanding of the science is still imperfect, there is little doubt that CFCs play a major role in the Antarctic ozone hole phenomenon and the decline in ozone observe...

2005
DARRYN W. WAUGH TIMOTHY M. HALL

The propagation of a range of tracer signals in a simple model of the deep western boundary current is examined. Analytical expressions are derived in certain limits for the transit-time distributions and the propagation times (tracer ages) of tracers with exponentially growing or periodic concentration histories at the boundary current’s origin. If mixing between the boundary current and the s...

Journal: :Physical review. E, Statistical, nonlinear, and soft matter physics 2008
Masafumi Fukuto Oleg Gang Kyle J Alvine Benjamin M Ocko Peter S Pershan

We report the results of a synchrotron x-ray reflectivity study of bulk liquid-crystal surfaces that are coated by thin wetting films of an immiscible liquid. The liquid-crystal subphase consisted of the nematic or isotropic phase of 4-octyl- 4;{'} -cyanobiphenyl (8CB), and the wetting film was formed by the fluorocarbon perfluoromethylcyclohexane (PFMC), a volatile liquid. The thickness of the...

Journal: :Therapeutic apheresis : official journal of the International Society for Apheresis and the Japanese Society for Apheresis 1979
J P Hester R M Kellogg A P Mulzet V R Kruger K B McCredie E J Freireich

A single-stage disposable channel and seal that provides for leukocyte and granulocyte collection by continuous-flow cell separation (CFCS) has been designed by the IBM Corporation. This paper describes (1) the separation characteristics of whole blood as it responds to varying gravitational (G) forces and flow rates through the channel; (2) the mechanism by which the buffy coat accumulates and...

2007
D. W. Waugh S. E. Strahan P. A. Newman

Correctly modeling stratospheric inorganic chlorine (Cly) is crucial for modeling the past and future evolution of stratospheric ozone. However, comparisons of the chemistry climate models used in the latest international assessment of stratospheric ozone depletion have shown large differences in the modeled Cly, with these differences explaining many of the differences in the simulated evoluti...

Journal: :The Plant cell 1992
A. E. Stapleton

Plants use sunlight for photosynthesis and, as a consequence, are exposed to the ultraviolet (UV) radiation that is present in sunlight. UV radiation is generally divided into three classes: UV-C, UV-6, and UV-A. The UV-C region of the UV spectrum includes wavelengths below 280 nm; these highly energetic wavelengths are effectively absorbed by ozone in the stratosphere and, thus, are not presen...

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