Re:[IAWA Forum] Radial water transport

From: satoshi nagai <nagaides@pop14.odn.ne.jp>
Subject: Re:[IAWA Forum] Radial water transport
Date: Thu, 10 Oct 2002 17:56:12 +0900

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Dear IAWA members,

I study the air permeability in wood of Cryptomeria japonica D. Don.
The moisture content of the intermediate wood is low and it looks
white, so it can be distinguished easily and called ヤwhite zone woodユ
(Cf. : Y. Sano, R. Nakada (1998) IAWA J., 19, 285-299) .
To investigate the air permeability in green logs of Cryptomeria
japonica, each log section consisting of heartwood, white zone wood
and sapwood was set in a vacuum chamber which was connected to a
mercury manometer, and the changes in pressures were measured during
the different stages of vacuuming. As a result, the air permeability
in white zone wood was remarkably high, in comparison with those in
heartwood and sapwood.
More detailed summary is : http://www.jsms.jp/kaishi/50/paper50-4-15.htm
This reference is : S. Nagai and Y. Taniguchi (2001) Air Permeability
in Wood of Cryptomeria japonica D. Don : Air Permeability in
Heartwood, White Zone Wood and Sapwood in Green Logs (in Japanese with
English summary and figure captions). ヤZairyoユ(Journal of the Society
of Materials Science), 50 (4), 409-414.

Furthermore, to investigate the air permeability between white zone
wood, sapwood and ambient atmosphere in the radial direction in green
log, the log specimen, in which the transverse section was sealed and
the log surface was exposed, was prepared. Each log section,
consisting of heartwood, white zone wood and sapwood, was set in a
vacuum chamber which was connected to a mercury manometer, and the
changes in pressures were measured during the different stages of
vacuuming. Subsequently, the exposure and seal conditions of the
transverse section of white zone wood were changed, and the changes in
pressures were measured during the various stages of vacuuming and
leaking. As a result, 1) although the log surface only was exposed,
the first detected decrease in pressure was in the white zone wood. It
was demonstrated that there were some radial passages, through which
air flowed from the ambient atmosphere to the intermediate wood (I
guess they are intercellular spaces). 2) Pressure variation in sapwood
consistently depended on not that in the ambient atmosphere but that
in the white zone wood. 3) Air permeation to the sapwood in the radial
direction progressed from the white zone wood rather than the log
surface (now in a contribution).

Cordially,

Satoshi Nagai
Forestry technology institute
Hyogo prefectural technology center for agriculture, forestry and fisheries
Ikaba, Harima-yamasaki, 671-2515, Japan
mail : nagaides@pop14.odn.ne.jp

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