The Chemical Composition of 9P/Tempel 1 from Radio Observations

2009 ◽  
pp. 243-248 ◽  
Author(s):  
J. Crovisier ◽  
N. Biver ◽  
D. Bockelée-Morvan ◽  
J. Boissier ◽  
P. Colom ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Radio Observations

scholarly journals On the determination of the solar chemical composition from a study of the ultraviolet resonance lines

1965 ◽  
Vol 23 ◽  
pp. 105-107 ◽  
Author(s):  
S. R. Pottasch
Keyword(s):  
Chemical Composition ◽  
Solar Radio ◽  
Radiative Transition ◽  
Collisional Excitation ◽  
Radio Observations ◽  
Solar Abundance

On the assumption that the ultraviolet resonance lines are formed by collisional excitation followed by direct radiative transition of a quantum which eventually escapes from the atmosphere, it is shown how the chemical composition may be found. These assumptions are discussed, as is the accuracy of the determinations. The effects of non-radial inhomogeneities are also discussed. Finally the question of the determination of the hydrogen abundance is raised, for which purpose the solar radio observations are used.The results of this analysis are compared with other solar abundance determinations.

The Origin of the Moon

1962 ◽  
Vol 14 ◽  
pp. 149-155 ◽  
Author(s):  
E. L. Ruskol
Keyword(s):  
Chemical Composition ◽  
Solar System ◽  
The Moon ◽  
The Earth ◽  
The Difference ◽  
Origin Of The Moon

The difference between average densities of the Moon and Earth was interpreted in the preceding report by Professor H. Urey as indicating a difference in their chemical composition. Therefore, Urey assumes the Moon's formation to have taken place far away from the Earth, under conditions differing substantially from the conditions of Earth's formation. In such a case, the Earth should have captured the Moon. As is admitted by Professor Urey himself, such a capture is a very improbable event. In addition, an assumption that the “lunar” dimensions were representative of protoplanetary bodies in the entire solar system encounters great difficulties.

On the Inhomogeneity of Chemical Composition over the Surface of 21 Per

1976 ◽  
Vol 32 ◽  
pp. 343-349
Author(s):  
Yu.V. Glagolevsky ◽  
K.I. Kozlova ◽  
V.S. Lebedev ◽  
N.S. Polosukhina
Keyword(s):  
Chemical Composition ◽  
Spectral Line ◽  
Variable Star ◽  
Radial Velocities ◽  
Crimean Astrophysical Observatory ◽  
Line Intensities ◽  
Magnetic Variable

SummaryThe magnetic variable star 21 Per has been studied from 4 and 8 Å/mm spectra obtained with the 2.6 - meter reflector of the Crimean Astrophysical Observatory. Spectral line intensities (Wλ) and radial velocities (Vr) have been measured.

Structural Studies on Mitotic Spindle Fibres

1978 ◽  
Vol 36 (3) ◽  
pp. 615-626
Author(s):  
J.R. Mcintosh
Keyword(s):  
Chemical Composition ◽  
Mitotic Spindle ◽  
Structural Studies ◽  
Mitotic Apparatus ◽  
Chemical Studies ◽  
Medical Interest ◽  
Spindle Fibres

The mitotic apparatus is a structure of obvious biological and medical interest, but it has proved to be a difficult cellular machine to understand. The chemical composition of the spindle is only slightly elucidated, largely because of the difficulties in preparing useful isolates of the structure. Chemical studies of the mitotic spindle have been reviewed elsewhere (Mcintosh, 1977), and will not be discussed further here. One would think that structural studies on the mitotic apparatus (MA) in situ would be straightforward, but even with this approach there is some disagreement in the results obtained with various methods and by different investigators. In this paper I will review briefly the approaches which have been used in structural studies of the MA, pointing out the strengths and problems of each approach. I will summarize the principal findings of the different methods, and identify what seem to be fruitful avenues for further work.

Effects of 5-5'-Diphenyl-2-thiohydantoin (DPTH) and Thyroxine on the Ultrastructure and Chemical Composition of Rat Liver

1971 ◽  
Vol 29 ◽  
pp. 570-571
Author(s):  
E. A. Elfont ◽  
R. B. Tobin ◽  
D. G. Colton ◽  
M. A. Mehlman
Keyword(s):  
Chemical Composition ◽  
Rat Liver ◽  
Future Study ◽  
Mode Of Action ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Effective Inhibitor ◽  
Biochemical Effects ◽  
Glycerophosphate Dehydrogenase ◽  
Stimulation Of

Summary5,-5'-diphenyl-2-thiohydantoin (DPTH) is an effective inhibitor of thyroxine (T4) stimulation of α-glycerophosphate dehydrogenase in rat liver mitochondria. Because this finding indicated a possible tool for future study of the mode of action of thyroxine, the ultrastructural and biochemical effects of DPTH and/or thyroxine on rat liver mere investigated.Rats were fed either standard or DPTH (0.06%) diet for 30 days before T4 (250 ug/kg/day) was injected. Injection of T4 occurred daily for 10 days prior to sacrifice. After removal of the liver and kidneys, part of the tissue was frozen at -50°C for later biocheailcal analyses, while the rest was prefixed in buffered 3.5X glutaraldehyde (390 mOs) and post-fixed in buffered 1Z OsO4 (376 mOs). Tissues were embedded in Araldlte 502 and the sections examined in a Zeiss EM 9S.Hepatocytes from hyperthyroid rats (Fig. 2) demonstrated enlarged and more numerous mitochondria than those of controls (Fig. 1). Glycogen was almost totally absent from the cytoplasm of the T4-treated rats.

Applications of Photoelectron Microscopy

1976 ◽  
Vol 34 ◽  
pp. 506-507
Author(s):  
William J. Baxter
Keyword(s):  
Electron Microscopy ◽  
Thermal Decomposition ◽  
Chemical Composition ◽  
Ultraviolet Radiation ◽  
Thin Layer ◽  
Edge Effects ◽  
Electron Optics ◽  
Surface Layers ◽  
Crystalline Orientation ◽  
Fluorescent Screen

In this form of electron microscopy, photoelectrons emitted from a metal by ultraviolet radiation are accelerated and imaged onto a fluorescent screen by conventional electron optics. image contrast is determined by spatial variations in the intensity of the photoemission. The dominant source of contrast is due to changes in the photoelectric work function, between surfaces of different crystalline orientation, or different chemical composition. Topographical variations produce a relatively weak contrast due to shadowing and edge effects.Since the photoelectrons originate from the surface layers (e.g. ∼5-10 nm for metals), photoelectron microscopy is surface sensitive. Thus to see the microstructure of a metal the thin layer (∼3 nm) of surface oxide must be removed, either by ion bombardment or by thermal decomposition in the vacuum of the microscope.

Thermomechanical Treatment of a 4340 Ni-Cr-Mo Alloy Steel

1981 ◽  
Vol 39 ◽  
pp. 314-315 ◽  
Author(s):  
M.T. Jahn ◽  
J.C. Yang ◽  
C.M. Wan
Keyword(s):  
Mechanical Property ◽  
Chemical Composition ◽  
Alloy Steel ◽  
Thermomechanical Treatment ◽  
Room Temperature ◽  
Good Combination ◽  
Thermal Treatments ◽  
Low Carbon ◽  
4340 Steel ◽  
Good Improvement

4340 Ni-Cr-Mo alloy steel is widely used due to its good combination of strength and toughness. The mechanical property of 4340 steel can be improved by various thermal treatments. The influence of thermomechanical treatment (TMT) has been studied in a low carbon Ni-Cr-Mo steel having chemical composition closed to 4340 steel. TMT of 4340 steel is rarely examined up to now. In this study we obtain good improvement on the mechanical property of 4340 steel by TMT. The mechanism is explained in terms of TEM microstructures4340 (0.39C-1.81Ni-0.93Cr-0.26Mo) steel was austenitized at 950°C for 30 minutes. The TMTed specimen (T) was obtained by forging the specimen continuously as the temperature of the specimen was decreasing from 950°C to 600°C followed by oil quenching to room temperature. The thickness reduction ratio by forging is 40%. The conventional specimen (C) was obtained by quenching the specimen directly into room temperature oil after austenitized at 950°C for 30 minutes. All quenched specimens (T and C) were then tempered at 450, 500, 550, 600 or 650°C for four hours respectively.

Application Of Electron Probe Analyses Of Minerals In Discussing The Relationship Between Ductile Deformation And Metamorphism

1990 ◽  
Vol 48 (2) ◽  
pp. 250-251
Author(s):  
Fan Guochuan ◽  
Sun Zhongshi
Keyword(s):  
Chemical Composition ◽  
Shear Deformation ◽  
Electron Probe ◽  
General Rule ◽  
Granulite Facies ◽  
Ductile Deformation ◽  
Higher Temperature ◽  
Ductile Shear ◽  
The Relationship ◽  
Ductile Shear Deformation

Under influence of ductile shear deformation, granulite facies mineral paragenesis underwent metamorphism and changes in chemical composition. The present paper discusses some changes in chemical composition of garnet in hypers thene_absent felsic gnesiss and of hypersthene in rock in early and late granulite facies undergone increasing ductile shear deformation .In garnet fetsic geniss, band structures were formed because of partial melting and resulted in zoning from massive⟶transitional⟶melanocrate zones in increasing deformed sequence. The electron-probe analyses for garnet in these zones are listed in table 1 . The Table shows that Mno, Cao contents in garnet decrease swiftly from slightly to intensely deformed zones.In slightly and moderately deformed zones, Mgo contents keep unchanged and Feo is slightly lower. In intensely deformed zone, Mgo contents increase, indicating a higher temperature. This is in accord with the general rule that Mgo contents in garnet increase with rising temperature.

Chemical composition of aerosol during particle formation events in boreal forest

Tellus B ◽  
2001 ◽  
Vol 53 (4) ◽  
pp. 380-393 ◽  
Author(s):  
J. M. MÄKELÄ ◽  
S. YLI‐KOIVISTO ◽  
V. HILTUNEN ◽  
W. SEIDL ◽  
E. SWIETLICKI ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Boreal Forest ◽  
Particle Formation

The Chemical Composition of Tool Steel

1907 ◽  
Vol 63 (1632supp) ◽  
pp. 26150-26152
Keyword(s):  
Chemical Composition ◽  
Tool Steel
Sign in / Sign up

Export Citation Format

Share Document