Proceedings of the Japan Academy, Series B

Reviews

New circuit theory of multiconductor transmission lines resulting from a new practice of noise reduction

Hiroshi TOKI, Kenji SATO

2014 Volume 90 Issue 2 Pages 29-46
Published: February 10, 2014
Released on J-STAGE: February 10, 2014

DOIhttps://doi.org/10.2183/pjab.90.29

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In modern life, we are surrounded by and filled with electromagnetic noise caused by the dominant use of energy in the form of electricity. This situation is brought about by the fact that the noise is not understood theoretically. A new practice of noise reduction was introduced for the construction of Heavy Ion Medical Accelerator in Chiba (HIMAC). The key concept is a symmetric three-line circuit that arranges power supplies, noise filters and magnets around a third central ground line. A continuous theoretical effort forced us to find a new circuit theory involving a multiconductor transmission-line system starting from Maxwell’s equations without any approximation. We discuss the essence of all of these experimental and theoretical developments with the hope to remove unnecessary electromagnetic noise not only from power supplies, but also from all electric devices. The newly derived circuit theory of multiconductor transmission lines is universal, and establishes the validity of the practice of noise reduction.

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Studies on stress distribution in pavements subjected to surface shear forces

Tsutomu KIMURA

2014 Volume 90 Issue 2 Pages 47-55
Published: February 10, 2014
Released on J-STAGE: February 10, 2014

DOIhttps://doi.org/10.2183/pjab.90.47

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It has been pointed out by some researchers¹⁾^,²⁾ that road pavements are subjected to vertical stress due to vehicles on them as well as shear stress at the time of braking or acceleration of vehicles. In this paper, the results of elastic analysis to obtain the rigorous solution for an elastic two-layer system subjected to surface shear stress are described and it is shown that the effect of shear stresses applied at the surface gives rise to fairly large stresses in the system. On the basis of these findings, the author attempts to explain why pavement failure takes place frequently at places such as crossings and curved parts where pavements are subjected to high magnitude of surface shear stresses.

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Chemical construction and structural permutation of neurotoxic natural product, antillatoxin: importance of the three-dimensional structure of the bulky side chain

Masayuki INOUE

2014 Volume 90 Issue 2 Pages 56-66
Published: February 10, 2014
Released on J-STAGE: February 10, 2014

DOIhttps://doi.org/10.2183/pjab.90.56

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Antillatoxin 1 is a unique natural product that displays potent neurotoxic and neuritogenic activities through activation of voltage-gated sodium channels. The peptidic macrocycle of 1 was attached to a side chain with an exceptionally high degree of methylation. In this review, we discuss the total synthesis and biological evaluation of 1 and its analogues. First we describe an efficient synthetic route to 1. This strategy enabled the unified preparation of nine side chain analogues. Structure-activity relationship studies of these analogues revealed that subtle side chain modification leads to dramatic changes in activity, and detailed structural analyses indicated the importance of the overall size and three dimensional shape of the side chain. Based on these data, we designed and synthesized a photoresponsive analogue, proving that the activity of 1 was modulated via a photochemical reaction. The knowledge accumulated through these studies will be useful for the rational design of new tailor-made molecules to control the function and behavior of ion channels.

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Intracellular lectins are involved in quality control of glycoproteins

Kazuo YAMAMOTO

2014 Volume 90 Issue 2 Pages 67-82
Published: February 10, 2014
Released on J-STAGE: February 10, 2014

DOIhttps://doi.org/10.2183/pjab.90.67

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Glycoprotein quality control is categorized into three kinds of reactions; the folding of nascent glycoproteins, ER-associated degradation of misfolded or unassembled glycoproteins, and transport and sorting of correctly folded glycoproteins. In all three processes, N-glycans on the glycoproteins are used as tags that are recognized by intracellular lectins. We analyzed the functions of these intracellular lectins and their sugar-binding specificities. The results clearly showed that the A, B, and C-arms of high mannose-type glycans participate in the folding, transport and sorting, and degradation, respectively, of newly synthesized peptides. After correctly folded glycoproteins are transported to the Golgi apparatus, N-glycans are trimmed into Man₃GlcNAc₂ and then rebuilt into various complex-type glycans in the Golgi, resulting in the addition of diverse sugar structures that allow glycoproteins to play various roles outside of the cells.

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