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Your search keyword '"Yen T"' showing total 129 results
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129 results on '"Yen T"'

8. A search for porphyrin biomarkers in Nonesuch Shale and extraterrestrial samples.

Author

Rho, J. H, Bauman, A. J, Boettger, H. G, and Yen, T. F

Subjects
Biosciences
Abstract

An organic solvent extract of billion year old Nonesuch Shale was examined for porphyrins by means of fluorometry and high resolution mass spectrometry. It appears to contain at least three or more classes of porphyrins, one similar to tetraphenyl porphin and the others more complex. Many are apparently chelated with copper, nickel, zinc, iron and vanadyl and are highly aromatic. We have also examined the extracts of Apollo 11, 12 and 14 surface fines for porphyrins by spectrophotofluorometry, but we found none.

Published
1973

9. Analyses of the returned lunar surface fines for porphyrins.

Author

Rho, J. H, Bauman, A. J, Cohen, E. A, Yen, T. F, and Bonner, J

Subjects
Space Sciences
Abstract

Apollo 11, 12, and 14 lunar surface fines were examined for the presence of porphyrins by a sensitive fluorescent technique. The returned lunar samples studied were of bulk fines collected from the Sea of Tranquillity by Apollo 11, from the Ocean of Storms by Apollo 12, and from the nonmare Fra Mauro formation by Apollo 14. It was found that no porphyrins are present in lunar surface fines which have been extensively irradiated and sorted.

Published
1972

18. Luminescence in photoconducting zinc telluride

Author

Yen T. Tan, J.R. Fischer, and R.P. Khosla

Subjects
Range (particle radiation), Materials science, Zinc telluride, Photoluminescence, business.industry, Analytical chemistry, chemistry.chemical_element, General Chemistry, Condensed Matter Physics, Oxygen, chemistry.chemical_compound, chemistry, Impurity, Optoelectronics, General Materials Science, business, Luminescence, Conduction band
Abstract

The photoluminescent spectrum of ZnTe: Ga: Zn has been obtained over a range of temperatures from 323 to 4·2°K. Two prominent emissions are observed. One is due to an isoelectronic oxygen center and the other is due to two transitions, both involving a deep impurity level located about 0·6 eV from the conduction band. Such deep minority-carrier traps are consistent with those found in other highly photosensitive II–VI compounds.

Published
1973

19. A model for surface space charge in thin films of AgBr

Author

Yen T. Tan and H.A. Hoyen

Subjects
Surface (mathematics), Materials science, Condensed matter physics, business.industry, Ionic crystal, Surfaces and Interfaces, Condensed Matter Physics, Space charge, Surfaces, Coatings and Films, Condensed Matter::Soft Condensed Matter, Condensed Matter::Materials Science, symbols.namesake, Optics, Depletion region, Potential difference, Impurity, Condensed Matter::Superconductivity, Materials Chemistry, symbols, Thin film, business, Debye length
Abstract

A model for the surface space charge layer in ionic crystals has been developed for thin films where the film thickness is less than or comparable to the Debye length. A potential difference between the surface and the bulk is present which depends on the film thickness and the impurity concentration. The implications of this model have been examined with respect to thin films of AgBr at room temperature.

Published
1973

20. Degradation of Oil Shale by Sulfur-Oxidizing Bacteria

Author

Findley, J., Appleman, M. D., and Yen, T. F.

Abstract

Approximately 40% of oil shale can be solubilized by the action of sulfur-oxidizing bacteria. Thiobacillus thiooxidansand Thiobacillus concretivorousare equally effective in solubilization. Continuous leaching experiments show that this process can be completed within 14 days. The growth of Thiobacillusand the production of acid were measured under several conditions. Almost all of the CaMg(CO3)2was removed by this process, leaving a complex of silica and kerogen that could be burned as low-energy fuel. The silica-kerogen complex had not yet been biologically degraded.

Published
1974
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22. Vibration of Beam-Mass Systems With Time-Dependent Boundary Conditions

Author

Yen, T. C. and Kao, S.

Abstract

Vibration problems of beams with time-dependent boundary conditions are solved by the method of Laplace transforms. The problems treated include the simply supported, cantilevered, and fixed beams carrying a single arbitrarily placed mass; two equal masses symmetrically placed on a simply supported or fixed-end beam and a beam carrying a mass at the center and two equal masses at tips, striking a spring.

Published
1959
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