Broadband high silica optical waveguide coupler

Yanagawa, H.; Nakamura, S.; Ohyama, I.; Ueki, K.

doi:10.1364/ofc.1990.we4

Cited by 2 publications

(2 citation statements)

References 3 publications

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“…An extension of this analysis to the %-type proteins revealed [26] that the peptide encoded by the primitive exons has the secondary structure of the apa'-type (a' is usually an a helix, but can be of no secondary structure) and that the lengths of the exons are uniform, around 20. On the other hand, Yanagawa [27] found recently that the molecular weight of the longest peptides synthesized under the conditions of the primitive earth might be about 2000. When we take into account the discussion of Eigen and Schuster [24] that the limit of the length of the primitive tRNA without the informational catastrophe might be about 60, then the coincidence of the length of the primitive gene (E the pAmitive tRNA) with the length of the primitive informational peptides is quite interesting from both the genetic and synthetic points of view.…”

Section: C4n In the Ancient Biosystemmentioning

confidence: 97%

Molecular electric mechanism for discrimination of amino acid by cognate tRNA

Shimizu

2009

Int. J. Quantum Chem.

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In previous article [l-31, we pointed out by using the CPK molecular model that the complex of the three anticodon bases and the discriminator base (C4N) on tRNA can discriminate the cognate amino acid by the lock and key relationship. Analysis of the amino acid sequences of the aminoacyl-tRNA-synthetases reveals an electric machine mechanism for the conformational change of tRNA from an L letter shape to a U letter shape, resulting in the formation of C4N in the active =% structure of the synthetase. From this point of view, a possible ancient protein synthesis system has been speculated. The C4N SchemeThe stereochemical hypothesis of the genetic code usually assumes that either codon or anticodon bases have specific interaction with the cognate amino acid. If the assumption is strictly correct, protein could be formed directly on DNA or RNA by aligning an amino acid on every three bases with some help from the skillfully invented enzymes to connect the amino acids. Since the genetic code dictates only the -correspondence (not the direction of information transfer) of codon or anticodon to amino acid, the above synthetic system might have resulted in the nucleic acid synthesis on protein. However, the acquired heredity advocated by Lamarck has hardly been accepted.Consequently, it appears that another factor is necessary to specify the cognate amino acid by nucleotides. We have previously pointed out by model building [l-31 that a complex of four nucleotides (C4N), namely, that of three anticodon bases with the discriminator base at the fourth position of the 3' end of a tRNA, has a pocket to discriminate the cognate amino acid by the lock and key relationship. This scheme can explain [4] (1) how 20 kinds of protein amino acids were selected from more than 300 amino acids, (2) the unique chirality of protein amino acids on the earth, and (3) the central dogma of molecular biology.The central dogma is guaranteed by the whole system of protein synthesis, in particular, the presence of the adaptor, tRNA. In the C4N scheme, the C4N should first be formed in the aminoacylation process to charge the cognate amino acid, but later be

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Section: C4n In the Ancient Biosystemmentioning

confidence: 97%

Molecular electric mechanism for discrimination of amino acid by cognate tRNA

Shimizu

2009

Int. J. Quantum Chem.

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“…This is because the operational wavelength window is narrowed by the accumulation of the wavelength dependence of constituent 2 X 2 directional couplers. In this paper, we propose the use of an asymmetric directional coupler [4] instead of a conventional symmetric one as a constituent element , and the general wavelength characteristics of the couplers are discussed. Then, design examples are given to show how the operational wavelength window can be widened in the new star coupler proposed here.…”

Section: Introductionmentioning

confidence: 99%

Broad-band high-silica optical waveguide star coupler with asymmetric directional couplers

Yanagawa

Nakamura

Ohyama

et al. 1990

J. Lightwave Technol.

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A broad-band optical waveguide star coupler with asymmetric directional couplers is proposed. A coupling or splitting ratio of the coupler is flattened with respect to wavelength by choosing appropriate values for AD and complete power transfer length. Uniform and alternating Ap directional couplers are investigated theoretically and experimentally. A fabricated 8 x 8 star coupler exhibited 2-dB loss variation in the wavelength range of 1.3-1.55 pm, and this value was almost one fourth of that of a star coupler composed of symmetric directional couplers.

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Broadband high silica optical waveguide coupler

Cited by 2 publications

References 3 publications

Molecular electric mechanism for discrimination of amino acid by cognate tRNA

Molecular electric mechanism for discrimination of amino acid by cognate tRNA

Broad-band high-silica optical waveguide star coupler with asymmetric directional couplers

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